1998 — 2002 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
U.S.-Germany Cooperative Research: Light Scattering From Colloids |
0.915 |
1999 — 2002 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Relationship of Structural Dynamics and Elasticity in Soft Materials
9971432 Weitz
This project will develop experimental probes leading to an understanding of the elastic properties of "soft" materials on a local scale, where the structure of the material directly influences its elasticity. The types of materials that will be studied include colloidal suspensions, gels, concentrated emulsions, and a variety of biologically important materials including actin networks, vesicles, model cells, and cells themselves. Many of these materials are structurally inhomogeneous, and thus their elastic properties can vary significantly in different regions of the material. Traditional bulk elastic measurements probe only the average properties; the methods to be developed here will probe local properties to differentiate the function and purpose of the different components of the material. The probes to be developed rely on the study of the motion of probe particles embedded within the medium; this motion will either be thermally induced, or driven with an external field. The motion of the probe will provide important information about the elasticity of the material on the length scale of these probes. The study will involve a post doc and several graduate students. %%% Many important materials can be highly inhomogeneous, and their properties can vary significantly within different regions of the material. The relationship of this inhomogeneous structure to the properties of the material can be crucial for its functioning. For example, an object as fundamental as a cell, is comprised of a wide variety of components, each with its own structure and each with its own function and each with its own properties. However, knowledge of the mechanical or elastic properties of such materials is typically obtained by measuring the response of a large collection of them; this provides some average information, but obscures important variations across the individual objects. The goal of this work is to develop new methods for making very local measurements of the elastic or mechanical properties of such inhomogeneous materials. The results will provide important insight into the function and role of the components of the material, and will assist in the rationale design of new materials that share or even improve upon the function of the material under study. This work will provide support and important education for both graduate students and post docs.
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0.915 |
2000 — 2001 |
Spaepen, Frans (co-PI) [⬀] Prentiss, Mara (co-PI) [⬀] Weitz, David Stone, Howard [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Acquisition of a Rheometer Enhanced With Scattering and Imaging For Complex Fluids Research and Education
This award from the Instrumentation for Materials Research program allows Harvard University to acquire a rheometer enhanced with scattering and imaging for complex fluids research and education. One of the key features of all complex fluids is their response to stresses or strains; as with all "soft" materials, the larger scale structures that typify complex fluids make them more easily deformed and thus help define their most fundamental properties. Unfortunately, the relationship of microscopic properties to macroscopic response is still poorly understood for many important complex materials. Of particular interest here are the mechanical responses of foams and emulsions, colloidal suspensions, thin polymer films, and electrorheological suspensions. For example, concerning foams and emulsions, we will explore the influence on the bulk properties of the interfacial rheology of the surfactants used, the related interfacial elasticity, and the drainage of fluid from the interstitial space. In addition, researchers at Harvard University will investigate "jammed" states that dramatically influence the properties of weakly attractive colloidal suspensions. In order to examine these systems, they will develop instrumentation around a stress-controlled rheometer, which will be outfitted with two different optical probes: dynamic light scattering and a high-speed digital camera. This collaborative interdisciplinary research involves scientists from engineering, physics, and materials science.
This award from the Instrumentation for Materials Research program allows Harvard University to acquire a rheometer enhanced with scattering and imaging for complex fluids research and education. We are all familiar with solids, liquids, and gases. However, many other common materials have properties that are intermediate to those of simple liquids or simple solids. For example, consider a foam such as used for shaving or washing dishes. These materials undergo a finite strain when exposed to a small stress (it is easy to do this experiment for yourself), which is characteristic of a solid, but the constituents of the foam (mostly water and air) are both fluids! Of course, this response is influenced greatly by the surfactants (basically large macromolecules) that reside at the interface between the gas and liquid. Materials whose macroscopic properties depend crucially on the different constituents are commonly referred to as complex fluids, which includes foams and emulsions, electrorheological suspensions (materials that respond to electric fields), polymer solutions, polymer films, etc. Because the macroscopic response is so dependent on the microscopic constituents, the proposed research will use modern optical and mechanical measurements to investigate further the world of complex fluids, and will elucidate more clearly the manner in which the microscopic and macroscopic properties are coupled.
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0.915 |
2000 — 2001 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Conference On Force Transduction in Biology; Arlington, Va.; July 24 - 26, 2000
This award provides support for an NSF-sponsored Workshop on Force Transduction in Biology, to be held in Arlington, VA, July 24-26. The transduction of mechanical force into biological response occurs at many length scales, ranging from the molecular to the macroscopic. This Workshop will examine mechanisms of force transduction that span these multiple length scales. Or particular interest are hierarchical aspects of force transduction, or common themes that may unify concepts at the cellular, sub-cellular, tissue, organ and organism levels. Also important are specific force-response events that may occur within the cell, between cells, among tissues, etc. The major themes of the conference will be (1) force transduction at the molecular, cellular tissue, and organism levels, (2) relations between molecular structure and mechanical properties, and (3) relations between mechanical forces and biological function. The Workshop is interdisciplinary and is intended to encourage and facilitate communication at the Physics/Biology interface. Participants come from a wide range of disciplines, including bioengineering, biology, mathematics, physics, and the neural sciences. Support will be provided for younger faculty and advanced graduate students. The results of the workshop will be presented in a Workshop Report, which will be discuss opportunities and challenges in the general area of force transduction in biology. %%% This award provides support for an NSF-sponsored Workshop on Force Transduction in Biology, to be held in Arlington, VA, July 24-26. The Workshop is interdisciplinary and is intended to encourage and facilitate communication at the Physics/Biology interface. Participants come from a wide range of disciplines, including bioengineering, biology, mathematics, physics, and the neural sciences. Support will be provided for younger faculty and advanced graduate students. The results of the workshop will be presented in a Workshop Report, which will be discuss opportunities and challenges in the general area of force transduction in biology
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0.915 |
2001 — 2003 |
Halperin, Bertrand [⬀] Mazur, Eric (co-PI) [⬀] Prentiss, Mara (co-PI) [⬀] Weitz, David Xie, Xiaoliang |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Acquisition and Development of a Non-Linear Optical Microscope Workbench Facility For Research and Education At the Harvard Center For Imaging and Mesoscale Structures
This award from the Major Instrumentation Program is for the acquisition of a confocal microscope at Harvard University. This confocal microscope will be the heart of a state-of-the-art optical microscopy facility which will be a core component of the Center for Imaging and Mesoscopic Structures (CIMS), recently established at Harvard University as part of a general initiative of renewed support for the sciences. The facility will provide the Harvard research community with a complete range of modern optical microscopy that will enable optical imaging with unprecedented resolution and sensitivity. This will facilitate a broad range of new research, and will help establish new interdisciplinary research programs at Harvard University, bridging the disciplines of chemistry, physics, engineering, materials science, biology and medicine. This will help meet the important educational aim of CIMS, and this facility, which is to ensure that students become skilled in state-of-the-art microscopy, and are well versed in interdisciplinary collaboration. The research to be conducted ranges from materials science to biology, from synthesis of novel structured materials to probing single macromolecules inside living cells.
This award from the Major Instrumentation Program will help Harvard University with the acquisition of a confocal microscope. This equipment will be the heart of a state-of-the-art optical microscopy facility which will be a core component of the Center for Imaging and Mesoscopic Structures (CIMS), recently established at Harvard University as part of a general initiative of renewed support for the sciences. The facility will provide the Harvard research community with a complete range of modern optical microscopy that will enable optical imaging with unprecedented resolution and sensitivity. This will facilitate a broad range of new research, and will help establish new interdisciplinary research programs at Harvard University, bridging the disciplines of chemistry, physics, engineering, materials science, biology and medicine. This will help meet the important educational aim of CIMS, and this facility, which is to ensure that students become skilled in state-of-the-art microscopy, and are well versed in interdisciplinary collaboration.
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0.915 |
2002 — 2026 |
Friend, Cynthia (co-PI) [⬀] Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Materials Research Science and Engineering Center
The Materials Research Science and Engineering Center (MRSEC) at Harvard University is a highly multidisciplinary research Center with participants from seven different schools and departments. The Center has a broad range of research activities from soft materials to biological materials. The research of the Harvard MRSEC is organized into three interdisciplinary research groups (IRGs): IRG 1: Micromechanics to explore the fascinating and technologically important mechanical behavior of systems where phenomena at very short length scales impact the materials properties and mechanics at macroscopic length scales. IRG 2: Droplet Templated Materials utilize microfluidic devices, or devices that control the flow of fluids at micron length scales, to produce new structures that are of use for delivery of drugs and other active ingredients that must be protected from their environment prior to delivery. IRG 3: Active Soft Materials addressing materials science required to create soft robotics, which are machines that can adapt to new geometries while still providing function. The MRSEC supports a vigorous program to educate and inspire the public about materials science. The MRSEC offers novel programs for high school teachers and research opportunities for undergraduates from all over the US. A collaborative Partnerships in Research and Education in Materials program with University of New Mexico attracts underrepresented minority undergraduates to a Summer Program at Harvard. The rigorous scholarship emblematic of the Harvard MRSEC ensures that the excellent students and postdoctoral fellows in the Center will become leaders of the next generation of scientists and engineers. The MRSEC has extensive collaboration with industry, both with large, established companies and with start-up firms that are inspired by the work of the Center. The MRSEC also collaborates with some equipment manufacturers to build an enhanced shared experimental facility for soft materials research.
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0.915 |
2003 — 2006 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
The Fluid to Solid Transitions in Soft Materials
Soft materials are often viscoelastic, displaying characteristics of both a fluid and a solid. Often one behavior dominates, and the material is dominantly either a fluid or a solid; however, this can depend sensitively on the measurement. For example, a glassy material can be solid at frequencies typically measured, but fluid at very low or very high frequencies. Thus, the transition between fluid-like and solid-like behavior can be quite subtle, yet it can provide great insight into the behavior can be quite subtle, yet it can provide great insight into the behavior of the material. This transition between fluid-like and solid-like behavior is the overarching theme of the work proposed here. Experiments proposed include investigation of colloidal crystals, glasses and gels with confocal microscopy to look at individual particles, scattering to measure average effects, and rheology to measure bulk effects. A shear cell will be built for a confocal microscope to probe the motion of particles when subjected to shear, and laser tweezers will be used to probe local perturbations of structure. These experiments will provide insight into important fluid to solid transitions in soft materials.
Many materials that are important in nature and in technology have a dual character they have both solid-like and fluid-like when squeezed from the tube or smeared on teeth, but maintains its shape and form like a solid when spread on a toothbrush. This research will investigate the nature of a wide class of materials that have this dual character, and will focus on the transformation from the fluid-like behavior to the solid-like behavior. The work will search for general features that can describe this behavior in wide classes of materials, and will investigate the structural properties of the materials that cause this behavior. The research will be highly leveraged through interactions with industry, ensuring that problems of practical and technological importance and addressed, in addition to problems of fundamental importance. In addition, the research will be coupled with educational efforts, through seminar and workshop series that enhance the researcher community for scientists in the local area, through projects that will engage undergraduate students and high school teachers for summer research, and through the design of a new course to explore creativity in scientific research.
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0.915 |
2006 — 2010 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Non-Equilibrium and Non-Linear Structure and Dynamics of Soft Materials
Technical Abstract:
Materials are typically characterized by their linear properties; for example, linear viscoelastic measurements are a powerful measure of structure-property relationships. However, many soft materials exhibit highly non-linear behavior which necessitates a fundamentally different way of investigating the behavior. The non-equilibrium and non-linear properties of soft materials is often of particular importance in technological applications. Similarly, biological materials are also often dominated by non-equilibrium behavior due to the large number of chemical reactions that burn energy to sustain life. This research will investigate non-linear and non-equilibrium behavior of important classes of materials, including biopolymer networks, gels of complex fluids and structured materials formed with microfluidic devices. New methods to probe and describe these properties will be developed. The work will be closely coupled to industrial collaborators, allowing students and post docs to gain valuable experience with technology and to directly contribute to the country's economic competitiveness. The participants will include undergraduate and graduate students and post docs, helping to train the next generation of the country's scientists. All participants will become part of a vibrant and interactive research community that has been established in the Boston area.
Non-technical abstract:
A traditional means of characterizing a material is to measure its properties under quiescent conditions, where its response to a very small perturbation is determined. This has proven to be a powerful principle of material science. However, many materials exist under much more extreme conditions. The goal of this research project is to develop qualitatively new methods to study materials under conditions that mimic their behavior in the real world, where they are subjected to very large perturbations. For example, the stability and aging of technologically important materials will be investigated. In addition, the mechanics of the protein networks that provide rigidity to living cells will be explored. The work will be closely coupled to industrial collaborators, allowing students and post docs to gain valuable experience with technology and to directly contribute to the country's economic competitiveness. The participants will include undergraduate and graduate students and post docs, helping to train the next generation of the country's scientists. All participants will become part of a vibrant and interactive research community that has been established in the Boston area.
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0.915 |
2007 — 2010 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Proposal: Instrumental Development of Microfluidics-Based Fluorescence Activated Cell Sorting Device For Research and Education
This award is for the development of a microfluidic-based fluorescent-activated cell sorting device (M-FACS). The M-FACS will combine the single droplet control of microfluidics with the cell screening and sorting of a FACS. If successful, the M-FACS will allow one to encapsulate individual cells, add additional compounds to each cell, incubate these and then sort the results, all at 1000-10,000 cells per second, allowing good statistics to be obtained on a distribution of a population of cells. M-FACS will enable the study of chemicals excreted by cells or presented on their surface. It will likewise enable using individual cells in an assay that screens a large library. This would significantly increase the utility of FACS. One way to encapsulate individual cells within drops is through the use of microfluidic techniques. Individual cells can be suspended in drops in an inert carrier fluid. Moreover, it is also feasible to completely control these drops: they can be combined with other drops, they can be divided into smaller drops, they can be interrogated with optical probes, and they can be sorted with electric fields. This new technology will be supported with essential theoretical work to fully understand the new possibilities that will be available. The M-FACS overcomes one significant limitation of FACS: with FACS, the cells must be sorted as soon as they are encapsulated. The M-FACS will qualitatively change the applicability of FACS. It will allow using cells as part of an assay, testing them against a library of compounds, and sorting the cells based on the results. It will allow cell growth to be a criterion of the sorting. This will allow myriad new problems to be investigated.
A desk-top Fluorescence-Activated Cell Sorting machine with greatly extended capabilities will be of great benefit to the broader scientific community. The machine will be developed by students and post docs, both experimental and theoretical. They will receive training in a field that merges engineering with biology to create novel devices that enable new science. The work will also be disseminated at a workshop that will describe the completed device.
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0.915 |
2010 — 2013 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Synthesis and Properties of Deformable Biomaterials and Soft Matter Systems
Technical Abstract: Soft materials are easily deformed, and their fundamental properties are often defined by their susceptibility to deformation. Deformation can occur on many length scales, defining the unique properties of a soft material. The proposed research is centered on investigation of soft materials where the basic components of the material are themselves deformable. For example, dispersions of microgel particles which can be deformed by compression, squeezing the fluid out of the particles will be probed to explore new dynamic behavior and to investigate possible crystallization. The unusual properties of biomolecular networks, which exhibit history-dependent mechanics resulting from stretching of the filaments due to deformation; will be investigated with a combination of imaging and rheology. New soft materials will be made using the exquisite precision of microfluidics, and methods to scale up the production to yield useful quantities of material will be developed. The research will be carried out in a highly collaborative, interdisciplinary environment that provides high quality training for the next generation of scientists and engineers that will provide the manpower for our nation's economic competitiveness. Much of the work will be done in collaboration with industry, and jobs will continue to be created by the success of the start-up companies that are created with the help of the support from the NSF.
Non-Technical Abstract: Soft materials are those that are very easily deformed by small forces. They are typically solids, but they can change in shape or even flow when small forces are applied. For example, a foam such as shaving cream, is made from water and air; however, mixing a liquid and a gas together produces a material that is a solid. But, it is a weak solid, that can also easily flow as happens, for example, when it is used for its intended purpose of helping to lubricate a razor blade. Thus, like all soft materials, both it solid-like and its fluid-like properties are important. This research will develop new methods to explore such materials, and will investigate the properties of these new materials. The results of the research will lead to new, fundamental understanding of the materials. This understanding will be applied to help learn about important biological materials, such as that which forms the cartilage so essential in the functioning of our knees. In addition, new materials will be created that have technological uses for applications including drug delivery or protection of active ingredients in foods and person care products. The research will be carried out in collaboration with industry, and will help train the next generation of scientists and engineers that will power the economic competitiveness of our nation. In addition, the technology developed will continue to form the basis of start-up companies, that are already providing new high-quality jobs.
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0.915 |
2011 — 2014 |
Mooney, David J [⬀] Scadden, David T (co-PI) [⬀] Weitz, David A Westervelt, Robert M (co-PI) [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Building the Hematopoietic Stem Cell Niche
DESCRIPTION (provided by applicant): A hierarchal and tightly controlled organization of various cell types is the hallmark of normal tissues and organs, and the hypothesis underlying this proposal is that pre-defining the specific location and resultant cell- cell interactions of individual cells within a 3D tissue construct will allow one to create highly functional tissues in which the role of cell-cell interactions on cell phenotype can be precisely delineated. This concept will be explored by developing a 3D model of human hematopoiesis, in which osteoprogenitors and vascular cells will be probed for their roles in defining the hematopoietic stem cell (HSC) niche. The specific aims include (1) the development of microfluidic techniques to allow large-scale encapsulation of single cells in highly defined extracellular matrix mimics in order to determine how matrix cues regulate mesenchymal stem cell differentiation at the single cell level, (2) the creation of hybrid integrated circuit/microfluidic circuit systems to enable one to assemble picoliter drops containing individual cells and synthetic ECM into 3D assemblies with pre-defined structure and organization, and (3) determining whether appropriate in vitro assembly of HSCs and cells representative of the bone marrow HSC niche can yield functional hematopoietic tissues capable of recreating hematopoiesis in vitro. Success in this project will lead to the creation of a new set of tools that will enable formation of 3D tissues with precisely defined cell placement, and homotypic and heterotypic cell-cell interactions. These tools are likely to be broadly useful to the creation of new in vitro models of tissue development and drug screening, and in vivo tissue replacements from a variety of cell types. As stem cells are particularly sensitive to environmental cues, inappropriate cell-cell and cell-matrix interactions likely lead to the irreversible and undesirable alterations in stem cell differentiation fate found in culture. The systems developed in this project will allow us to investigate the specific role of vascular cells and osteoprogenitors/osteoblasts in maintaining the human HSC niche, which is a difficult question to address in vivo. It is crucial to better define and create models of the niche to understand normal hematopoiesis and pathologies involving blood cells, and to enable hematopoiesis on demand in various therapeutic venues. The key studies to date on this topic have relied on rodent models, and the relevance of many findings to human biology is currently unclear. (End of Reviewers'Comment)
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1 |
2011 |
Weitz, David A |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Physical Approaches For Probing the Mechanical Properties of Intermediate Filamen @ Northwestern University At Chicago
The mechanical properties of cells fundamentally underlie all cellular behavior;the cell must support forces, must exert forces and must respond to forces (1-5). Moreover, while the genetic response within the cell ultimately provides the control mechanism, it is the mechanical response of the cell that dictates its primary function within a larger organism;without being able to withstand the forces of its environment, the cell would not be able to function at all. The mechanical properties of a cell are determined to a large extent by the three filamentous networks within the cytoskeleton, actin, microtubules and intermediate filaments (IF) (1). While actin networks and microtubules have been rather well studied, this is not the case for IF networks, whose study has significantly lagged that of the others (6, 7-9). Indeed, it has been proposed that networks of IF are essential in determining the mechanical properties of and mechanotransduction in virtually all vertebrate cells. However, there is little direct evidence supporting this proposed IF function. The IF networks within a cell are thought to be able to withstand very large strain;this can often be well in excess of 100% (6, 7, 10) In addition, the IF networks exhibit pronounced strain stiffening, effectively becoming much stiffer as they are stretched (6). However, the intracellular environment is highly heterogeneous and complex, making determination of the underlying mechanical properties of these networks extremely difficult. The IFs are remarkably dynamic, and are constantly being remodeled and reassembled, presumably driven in some fashion by the motors that run along either microtubules or actin filaments in the cell and these must guide the assembly of the VIF. There are also, presumably, associated proteins which regulate and control the VIF properties, and which provide crosslinking of the network to the surrounding networks within the cell, and within the VIF network itself (11-16). However, the complexity and richness of the behavior of the VIF within the cell, while controlling much of the function, also makes elucidating the fundamental properties much more difficult;moreover, it precludes measurement of the mechanical properties in a fashion that would allow determination of the underlying design principles of the network. The overarching goal of this section of the Program Project is therefore to measure the properties of VIF in a more controlled environment, thereby enabling us to elucidate their roles in establishing and regulating the mechanical properties of cells (17). The work proposed here will begin with a detailed study of the properties of networks of vimentin intermediate filament (VIF), which can be expressed in bacteria to enable us to produce sufficient quantifies to reconstitute the protein into networks and to make detailed measurements of the mechanical properties of these networks. These measurements will be performed using traditional bulk rheology (18). In addition, we will develop several new assays based on multi-particle tracking, measurements of the motion of small tracer particles embedded within the network and subject either to thermal agitation or to externally applied forces controlled by a magnetic field. The motion of these tracer particles will be interpreted using the formalism of microrheology to measure the elastic and viscous properties of the network. We will investigate the role of physiological concentrations of multivalent cations in regulating the network (6). In addition, we will work with the Goldman lab to investigate the role of phosphorylation in regulating VIF network elasticity (19, 20). We will also obtain constructs for vimentin mutants from our collaborator Harald Herrmann, and will use these to express the mutants in bacteria (21-23). This will enable us to elucidate fundamental design principles for the elasticity of these VIF networks. To complement these investigations of reconstituted networks, we will also form 'ghosts', where most of the cell proteins are washed away with detergent, leaving nearly the full IF network intact (24). By seeding these networks with probe particles, we will measure their elastic properties and compare to those of the reconstituted networks. This will provide a direct probe of the contribution of these VIF networks to cell elasticity. Importantly, these will also enable us to directly measure the response of the networks to shear;cells will be sheared prior to preparing the ghosts, allowing us to probe modifications in the structure and mechanics of the VIF networks due to the shear. We will, in addition, extend these particle tracking measurements to living cells: We will inject the cells with tracer particles and measure the motion of these particles due to both the internal molecular motors within the cell and to external forces, applied either with a magnetic field or with optical tweezers (8, 25 ). These studies will link with the others of this project program grant to elucidate the fundamental design principles of the elasticity of VIF networks.
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0.957 |
2012 — 2019 |
Spaepen, Frans [⬀] Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Colloids as Models For Crystals and Glasses
****TECHNICAL ABSTRACT**** Suspensions of colloidal particles, with well-controlled size and interactions, will be used to study complex structures, defects and transformations in crystals and glasses. The motion of these particles can be tracked in space and time with high precision using confocal microscopy. The analogy between these particles and individual atoms will make it possible to obtain unique visual access at the particle/atomic scale to complex processes, such as the formation of crystal nuclei in a supercooled liquid, the nucleation of a melt in a superheated crystal, the interaction of dislocations with other defects, the structure and motion of grain boundaries, and the nature and kinematics of the shear transformation zones that govern plastic flow of simple glasses. This work aims to contribute to the fundamental science of materials and will give new impetus to long-standing "hard problems" in the field, such as nucleation and glass science. The work is uniquely interdisciplinary, in that it combines two areas with their own unique perspective: expertise in materials science complemented by that in colloid science. The work will provide a very rich learning environment, not only for broadly-trained graduate students in materials science, but also for research projects at the undergraduate or even high-school level.
****NON-TECHNICAL ABSTRACT**** Physical modeling of atomic-scale processes has a long and venerable history in materials science. In the 1940s, for example, the deformation of two-dimensional hexagonal raft of soap bubbles provided convincing evidence for the role of dislocations in plastic deformation of metals. We can now do this in three dimensions. The arrival of confocal microscopy has made it possible to track hundreds of thousands of colloidal particles in a suspension in time and space. By arranging this particles into crystalline or glassy structures, similar to those formed by atoms, we can now make "movies" of the formation or straining of these structures , and thereby obtain a unique view of these complex processes on the atomic/particle scale. An example is the growth of small crystal from a liquid during solidification, which appears to be much more complex than the simple growth of sphere that most theories have been assuming so far. Another example is the deformation of glasses, which have a non-periodic structure, and appear to deform by the rearrangement of pockets of about a hundred atoms; the colloid technique will allow a detailed look at the number, size and motion of these pockets. Both these phenomena -- nucleation and glass science -- represent long-standing "grand challenges" in materials science, to which this unique, interdisciplinary approach should provide new insights and impetus. This work will provide a very rich learning environment for the training of broadly educated graduate students. At the same time, the direct, visual nature of the work makes it highly accessible to younger students, even at the high-school level.
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0.915 |
2013 — 2017 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Soft Materials: Synthesis and Properties
****Technical Abstract**** The proposed research focuses on the three main themes in soft matter physics: Properties of colloidal gels formed with depletion attraction will be investigated. The information will help explain the origin of delayed collapse, a major impediment to the use of such gels to stabilize commercial products. In a biophysics effort, the control of cell stiffness by cell volume will be explored. If preliminary results prove to be true, this would be a transformational change in our understanding of cell properties. Finally, new microfluidic devices will be developed to use spray drying to produce nanoparticles that are much smaller in size than can be produced by any other means. This will enable the study of the unique properties of such small particles; in particular, the kinetic delay in crystallization due to their very small size. The work will be highly leveraged through interactions with industry, which provides intellectual challenges, employment for students and post docs and leverages NSF support. In addition, important technological advances will be used to establish start-up companies, which create new, high-quality technical jobs. The major educational component of this research will be training of graduate students and post docs. In addition, a highly successful outreach program, based on a Science and Cooking course, will be put online, reaching literally hundreds of thousands of participants, teaching them soft matter science through cooking.
****Non-Technical Abstract**** This research focuses on a general class of materials that are "soft," or easily deformable. Examples include many foods and personal care products, made of gels, surfactants or suspensions of small particles in a fluid, and even the cells that make up all living organisms. The research will explore important properties of these materials. For example, a major limitation of many food and personal care products is the long-term instability of the materials; the fundament origin of this will be explored and industrial production of the materials will be enhanced. A new control parameter for cells will be developed that will offer new insight into their behavior, particularly when they malfunction, such as occurs in many diseases. New devices will be created to produce particles that are much smaller than can be produced by any other means, and that will enhance the bioavailability of many newly developed drugs. The work will be highly leveraged through interactions with industry, providing an important outlet for technical advances, while offering employment opportunities to the students and post docs whose training is supported by this research. In addition, this research will lead to the formation of start-up companies which create new, high-quality jobs. For example, previous NSF funding has led to formation of 4 start-up companies which have created more than 120 new jobs, enhancing our nation's economy. As outreach to bring science to the general public, a science course, based on cooking, will be offered online by the PI through Harvard, with several hundred thousand participants expected.
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0.915 |
2013 — 2014 |
Weitz, David A |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Merging Microfludics and Metagenomics For Novel High - Throughout Virus Discovery
DESCRIPTION (provided by applicant): Viral infections have a major impact on public health both domestically and worldwide. Consequently intense effort has been placed on the study of known human viral pathogens. However, it is likely that many diseases of unknown etiology are caused by viruses. Furthermore, new viral pathogens are constantly emerging. The ability to detect and identify novel human viruses is a major roadblock to understanding and curing diseases associated with these agents. We have developed a collaborative approach that combines the power of viral metagenomics with advances in microfluidics to allow the detection and isolation of individual viruses from complex biological samples. Here, metagenomics is the study of large populations of unknown viruses, while microfluidics is the application of micron size drops to isolate and assay single viruses at very high throughput. This application seeks support to broaden the types of viruses detected by this system and to apply it to the isolation and preliminary characterization of two novel viruses that potentially infect humans. The development of this platform will greatly enhance the ability to detect, isolate and thus rapidly characterize novel pathogens. The development of the microfluidics platform will provide emerging technology to the identification and study of heretofore unidentified viruses. This study will be the first effort to apply this technology to the identification of important new classes of viruses. This work represents a novel combination of two methods to advance the discovery process of new viruses that have a major impact on human health.
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1 |
2014 — 2018 |
Weitz, David A |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Cell Volume, Deformability & Dimensionability @ Harvard School of Public Health
PROJECT ABSTRACT In this revised application we propose to bridge cutting-edge topics in biology and physics in order to create a new physical picture of collective cellular migration in lung health and disease. The projects and cores of this program focus upon a common central hypothesis: In collective behaviors of epithelial cells in the lung, di- verse physical factors and their multiple biological effects are brought together by the concept of the glass transition as described on a unifying jamming phase diagram. Each project director is a leader in his or her respective discipline. Project 1 (Weitz) will investigate basic physics at the level of the single cell in isolation (0-D), in single-file migration (1-D), and in transition to 2-D behavior. This project will emphasize the unifying role of cell volume regulation in mechanical determinants of cell jamming. Project 2 (Fredberg) will investigate basic physics of jamming in monolayers (2-D) and cell clusters (3-D). Project 3 (Drazen) will investigate the role of jamming in the bronchial epithelium as a basic mechanisms of asthma pathogenesis. Core A (Butler, Zaman, Krishnan) will support and develop novel technologies for imaging of physical forces. Core B (Weiss) will seek common molecular network motifs that span projects and characterize regions of the jamming phase diagram. Core C (Fredberg) is administrative. Together, the interdisciplinary projects and cores of this pro- gram project combine physics and biology at a level that is realized only rarely. The projects are unified by a central hypothesis that is radical, mechanistic and testable, and that has the potential to impact basic under- standing of lung injury and repair.
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0.934 |
2016 — 2017 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Workshop On a Systematic Approach to Robustness, Reliability, and Reproducibility in Scientific Research February 24-26, 2017 in Atlanta, Ga
The goal of this workshop is to gain insight from the scientific community on aspects related to the robustness, reliability and reproducibility of the scientific practice. The workshop will explore fundamental concepts that underpin the collective understanding of how to assess the quality of science, a challenge for all scientific disciplines. The format of the workshop is designed to elicit a broad range of input from leaders in their respective fields.
This workshop concerns the development of effective practices with a manifestly cross-disciplinary character, designed to improve the transparency of the scientific process, to speed discovery and innovation, and to inform policy makers and the public. The output of the workshop will include a report that summarizes the conclusions reached by the attendees, together with a roadmap for future workshops that will address specific community needs identified at this workshop.
This project is supported by the Physics Division in the Directorate of Mathematical and Physical Sciences, the Division of Molecular and Cellular Biosciences in the Directorate for Biological Sciences, and the Division of Advanced Cyberinfrastructure in the Directorate for Computer & Information Science & Engineering.
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0.915 |
2017 — 2019 |
Mooney, David J [⬀] Scadden, David T (co-PI) [⬀] Weitz, David A |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Msc Encapsulation With Thin Gel Coating
Mesenchymal stem cell (MSC) therapies are currently in widespread clinical testing for a number of diseases, but a common theme of trials to date is the massive loss of the MSCs following transplantation. This outcome likely relates to the approach utilized for delivery ? clinical trials typically utilize intravenous (iv) infusion of suspended cells. In contrast, encapsulation of cells in various materials has been widely explored in preclinical studies to enhance transplanted cell survival, but the resulting particles and devices have been too large to allow iv infusion, providing a significant practical obstacle to their clinical implementation. Further, as the bioactivity of MSCs is now widely ascribed to paracrine secretions, control over the secretome of the cells following transplantation may be crucial to their clinical success. We recently developed a highly efficient microfluidic process to encapsulate single cells in a very thin layer of hydrogel (~ 5 microns); this thin coating still allows cells to be infused intravenously, but dramatically increases both their survival and the duration of their secreted products in the bloodstream. We hypothesize this technology will provide a timely new tool for MSC therapies and dramatically expand their clinical utility. Here, we propose to further develop this new technology, and to study its utility in context of hematopoietic stem cell therapy (HSCT). We have put together a unique team to address the hypothesis underlying this project, with leaders in microfluidics technology (Weitz), biomaterials (Mooney), and hematopoietic stem cell (HSC) biology and HSCT (Scadden). We will pursue our objectives by: (1) Tune the chemical and physical properties of microgels, and scale-up the microfluidics technology to enable clinically relevant numbers of MSCs to be encapsulated with high efficiency, (2) Determine how MSC persistence and paracrine secretions following transplantation can be tuned, both qualitatively and quantitatively, by the chemical and physical properties of the encapsulating alginate hydrogel, and (3) Study the impact of gel-encapsulated MSCs, following intravenous infusion, on the treatment of graft versus host disease (GVHD) following HSCT in a rodent model. At the completion of these studies we will have validated the effectiveness and practicality of this approach to MSC therapy. Importantly, the results of these studies will help to define how the MSC secretome impacts the effectiveness of MSCs in GVHD, and the importance of immunoprotection of the MSCs following transplantation. Further, this approach is also likely to be broadly useful to the wide array of other clinical applications of MSCs and to the use of many other types of stem cells.
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1 |
2017 — 2018 |
Weitz, David A |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Developing a Microfluidic Platform For Single Virus Genomics and Virus Discovery
PROJECT SUMMARY Viruses are the most abundant biological entities on Earth and have been one of the greatest threats to human health. Despite their ubiquity and impact, less than 0.01% of viruses are identified and well-characterized. Recent study showed that there are about 108 different viral species while only a few hundred of them have been studied. One major roadblock to isolating and studying viruses is the inability to grow them in culture. In fact, most of the known viruses cannot be grown in the laboratory. Another limiting factor in the study of viruses is the relatively low abundance of virus particles present in complex specimens such as human tissue or bodily fluids. This application seeks support to build new platforms enabling genome sequencing of single virions and isolation of extremely rare virions. Single virion sequencing will eliminate the need for establishing cultivable virus-host system and enable genome sequencing of uncultivable viruses directly from environmental samples. The new platform will integrate metagenomics, drop-based microfluidics, and up-to-date molecular biology techniques. Drop-based microfluidics is a technique that utilizes micron size channels to precisely control and manipulate small volumes of fluids separated by immiscible phase at a very high throughput. Within an hour, a microflulidic drop maker generates millions of picoliter-size test tubes that function as reaction vessels. In addition, individual droplets can be merged to add reagents, split to subtract droplet contents, or passed through a fluorescence detection system to detect droplets that are positive to the assays at the rate of ~ 1000/s. Droplet microfluidic techniques will be used to encapsulate single virions into micron-sized drops, perform single virus assays, and select target virions at an extremely high throughput. Metagenomics is the study of genetic materials recovered directly from environmental samples and enables researchers to sample all DNA fragments in a given sample. Metagenomic analysis will be used to identify the partial sequence of a target virus, and these sequences will be used to detect and isolate the target virus from a complex biological mixture. The first platform we propose will enable isolation and genome sequencing of a single selected virion. Using the platform, we will identify the genome sequence of novel viruses that are potentially human pathogens, African swine fever-like virus (ASFLV) and human rhino-like virus (HRLV). The second platform we propose will enable parallelized sequence analysis of single intact virions. We will use this platform to perform high throughput sequencing of single virions that are randomly sampled from untreated wastewater. Recent studies indicate that the vast majority of virions in wastewater are novel viruses; therefore, high-throughput genome sequencing of single virions in wastewater will reveal the genome sequence of diverse novel viruses. The successful merging of microfluidics and metagenomics towards the characterization of viral genomes will not only help identifying novel viruses that can be possible threats to humans but also open new avenues for the investigation of virus diversity, evolution, and adaptation.
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1 |
2017 — 2020 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Designer Soft Microparticles For a Changing Environment
Non-technical Abstract Polymeric particles and capsules with diameters of tens to hundreds of micrometers, similar to the size of a human hair, are extensively used for the encapsulation and protection of chemically or environmentally sensitive active molecules or nanoparticles, with uses, for example, for food and detergent additives, for cosmetics, as well as for drug delivery. During storage and delivery, the encapsulant protects the cargo, and releases it at the desired location, often through some external stimulus that breaks or degrades the encapsulant. Microcapsules, particles with thin shells and large hollow cores, are particularly valuable because only small amounts of encapsulant is needed to protect large amounts of the desired payload. In this project, novel microcapsules are developed with shells that release the capsule content reversibly in response to different external stimuli without shell destruction, leaving the capsule intact for reuse or repeated on-off switching of the release. These capsules are ideal for applications such as waste removal in water, where they can be opened to collect the waste, closed to remove it, and reopened to release the waste in appropriate storage containment. These capsules are obtained from complex emulsions, such as water-cored oil drops, that are fabricated using microfluidic devices with channel architectures of comparable size to the drops. This technology enables precise manufacturing of capsules with control over size, shell thickness, and composition with very low dispersity. The students involved in this project, both undergraduates and graduates, are trained in functional polymer synthesis, microfluidic technology, and materials characterization, giving them a broad set of tools that is indispensable for modern multidisciplinary research in materials science.
Technical Abstract Encapsulation of chemically or environmentally sensitive active molecules or nanoparticles is crucial in numerous applications, from food additives, to detergents and drug delivery; traditionally sacrificial encapsulants are used in a one-time, one-way encapsulate-and-release design. A primary aim of this project is to develop and fabricate a new class of dynamic encapsulant systems based on functional polymer microcapsules that exhibit active and reversible interactions with their environment. Microfluidic devices are used to create well-defined multiple emulsion drops of immiscible fluids that form templates for soft encapsulation materials. The physics of the assembly of functional materials in complex emulsions, and the dynamic functionalities of the materials themselves, are investigated, as is the influence of liquid confinement on these processes and properties. An additional aim of the project is to investigate the interactions of these functional polymeric microcapsules with solutes, the environment, and external stimuli for responsive and selective permeability in and out of the capsule. Encapsulation systems with such responsive permeability enable the reversible, on-demand release of actives, and allow the replenishment of actives inside the capsules through triggered uptake and trapping of cargo. This research extends the application of such encapsulants from one-way delivery systems to utilization in purification and separation. An additional objective of this project is the development of designer porous media with controlled mechanical properties to study fundamental mechanisms of the behavior of porous media and multiphase flow within it. These model systems provide insight into processes that are widely practiced but not well understood, including the fracturing of porous media due to pressure shocks, and the effects of polymer solutions on multiphase fluid flow in porous media.
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0.915 |
2017 — 2020 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Mechanics of Fusion of Dissimilar Lipid Bilayers and Multi-Lamellar Vesicles
Vesicles are small sacs surrounded by a lipid bilayer membrane and enclosing biomolecules essential for inter- and intra-cellular communication, transportation, and other physiological functions. Vesicles can fuse with cells and other vesicles to deliver designated drugs, segments of DNA for gene therapy, and neurotransmitters in a wide spectrum of medical treatments. Understanding the mechanism of membrane fusion is critical to interpret natural phenomena and to design and facilitate drug delivery. The overarching goal of this collaborative project between Northeastern University and Harvard University is to investigate the underlying biomechanics and biochemistry of membrane and liposome fusion by coordinated experiments and theoretical modeling. Vesicles with ranges of lipids and pseudo-lipids, microstructures, and size will be fabricated using specialized microfluidic devices. Mechanical characterization and intermediate steps of fusion under physiologically relevant conditions will be performed using atomic force microscopy. A mechanistic model of vesicle fusion, including membrane properties and inter-surface forces, will be developed to reveal molecular and membrane interactions. Outcomes of this study will lead to new insights into transport processes that are ubiquitous in mammalian cells, as well as guidelines to fabricate synthetic vesicles for drug delivery. The project will involve participation of students at all academic levels. Research outputs will be incorporated into undergraduate and graduate level courses at both universities. Educational videos will be developed to demonstrate vesicle dynamics for K-12 students and for the general public.
The goal of this award is to investigate the underlying principles of fusion of similar and dissimilar lipid bilayers and vesicles and to develop a universal fusibility index by probing an extensive experimental parameter space. A wide range of known lipids relevant to drug delivery, lipids derived from healthy and diseased cell lines, and co-block polymer as pseudo lipids will be investigated. New microfluidics devices will be designed and built to manufacture homogeneous, heterogeneous, and multi-lamellar vesicles, with a wide range of diameters. Atomic force microscopy will be used to determine membrane properties of single liposomes in compression mode, as well as the energy barrier involved in hemifusion and fusion of two similar and dissimilar vesicles under physiologically relevant conditions. Hemifusion and fusion will be monitored in-situ by fluorescence microscopy, as well as a fluorescence resonance energy transfer technique. We will test the hypothesis that mechanics in terms of internal and intersurface forces, large deformation of the vesicles and associated strain energy, and statistical mechanics of surface domains plays a significant role in vesicle fusion. The fusibility index will be derived as a function of material properties of lipid membranes, vesicle geometry, interface and surface chemistry, and physiological environments, based on fundamental engineering principles.
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0.915 |
2018 — 2021 |
Weitz, David A |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Physical Approaches For Probing the Mechanical Properties of Intermediate Filaments @ Northwestern University At Chicago
Abstract Cell must support forces, must exert forces, and must respond to forces. All these behaviors are fundamentally built on mechanical properties of the cells, which are largely determined by three filamentous networks within the cytoskeleton, actin, microtubules, and intermediate filaments (IF). While actin and microtubules are widely cited as the crucial components determining the mechanical properties of the cells and are well studied, the importance of intermediate filaments is increasingly being recognized. For example, cells without vimentin intermediate filaments are much weaker and more susceptible to break up upon application of small shear forces comparable in magnitude to those encountered in blood flow; moreover, they are much less stable, with the nucleus and organelles lacking positional stability and being easier to move. The presence of vimentin IF networks mechanically stabilize cells; however, they must work in concert with the other filamentous networks. The overarching goal of this Program Project is to elucidate the roles of the vimentin IF network and how it operates in concert with other filamentous networks to determine the mechanical properties of cells. We will accomplish this through studies of reconstituted mixed networks with and without motor proteins to isolate the mechanics of the IF networks in the presence of the other networks. The results of these studies will be compared to the mechanical behavior of cells grown on flat substrates, both isolated and in confluent layers, and for cells from vimentin-related diseases. Ultimately, we will build new systems to enable studies of the properties of cells grown in three-dimensional networks that mimic environments in vivo. The knowledge gained in this study will establish foundational scientific understanding of roles of vimentin IFs in cell mechanics, which will ultimately provide guidance to the development of treatments for vimentin related diseases.
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0.957 |
2018 — 2021 |
Danuser, Gaudenz (co-PI) [⬀] Gelfand, Vladimir I (co-PI) [⬀] Goldman, Robert D [⬀] Janmey, Paul A (co-PI) [⬀] Ridge, Karen M (co-PI) [⬀] Weitz, David A |
P01Activity Code Description: For the support of a broadly based, multidisciplinary, often long-term research program which has a specific major objective or a basic theme. A program project generally involves the organized efforts of relatively large groups, members of which are conducting research projects designed to elucidate the various aspects or components of this objective. Each research project is usually under the leadership of an established investigator. The grant can provide support for certain basic resources used by these groups in the program, including clinical components, the sharing of which facilitates the total research effort. A program project is directed toward a range of problems having a central research focus, in contrast to the usually narrower thrust of the traditional research project. Each project supported through this mechanism should contribute or be directly related to the common theme of the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence, i.e., a system of research activities and projects directed toward a well-defined research program goal. |
Regulation and Function of Intermediate Filaments in Cell Mechanics @ Northwestern University At Chicago
The overall hypothesis of this P01 Grant is that the unique properties of vimentin intermediate filaments (VIF) play a key role in regulating cytoskeletal organization and modulate the micromechanical properties of cells as well as a diverse set of cellular activities, including cell polarization, cell migration, or tissue morphogenesis. The Project Investigators and Core Leaders are all leaders in the field of cell biology and cell mechanics. Over the past funding period collaborative studies have established unique cell reagents and assays leading to key insights into the properties and functions of VIF. These insights provide a strong foundation for this renewal application. In preparation of this application further preliminary results have been collected supporting the feasibility of each of the projects. The projects are interactive conceptually, technically and programmatically, making the aggregate of the projects much greater than the sum of its parts. In Project #1, Dr. Goldman, Northwestern University, will determine the structural interactions among VIF, microtubules (MT) and actin microfilaments (MF) using high resolution microscopic techniques; determine the role of the assembly and disassembly of VIF in wound healing and motility assays; and determine the role of VIF phosphorylation in cellular signal transduction. In Project #2, Dr. Gelfand, Northwestern University will determine the dynamic mechanisms regulating VIF-MT interactions; determine the mechanisms responsible for the dynamic interactions between VIF and MF; and determine how VIF modulate the transport and distribution of membrane-bound organelles. In Project #3, Dr. Danuser, UTSW Dallas, will examine mechanisms by which VIF control MT organization and cell polarity; investigate mechanisms by which VIF control cell traction; and examine mechanisms by which VIF respond to cell-external guidance cues. In Project #4, Dr. Weitz, Harvard University, will determine the properties of reconstituted networks of VIF as well as composite networks comprised either of VIF, MF and myosin motors, or VIF, MT and their associated motors; study the micromechanical properties of VIF networks in living cells in 3D settings and in reconstituted networks derived from these cells. In Project #5, Dr. Janmey, University of Pennsylvania, will determine the mechanisms that regulate force-dependent VIF assembly in cells; study the mechanics of VIF networks under compression in vitro; and determine how VIF regulate the response of cells and tissues to compression loading. Interactions among members of all projects and data sharing will allow for integration of physical characterizations made by different groups using methods unique to their labs that cover a wide range of time and length scales. These efforts will be supported by the Cell and Tissue Core which, under the guidance of Dr. Ridge, Northwestern University, will support all PIs by maintaining the required WT and vimentin null mouse models; by engineering tissue and cell type-specific vimentin knockout animals; by isolating primary cells from various tissues of these animals; and by analyzing gene expression patterns and providing purified proteins as required.
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0.957 |
2020 |
Liu, Jia (co-PI) [⬀] Ramanathan, Sharad [⬀] Weitz, David A |
RF1Activity Code Description: To support a discrete, specific, circumscribed project to be performed by the named investigator(s) in an area representing specific interest and competencies based on the mission of the agency, using standard peer review criteria. This is the multi-year funded equivalent of the R01 but can be used also for multi-year funding of other research project grants such as R03, R21 as appropriate. |
'Building a Robust Organoid Platform to Study the Developmental Potential and Physiology of Human Specific Cortical Cell Types'
Abstract The goal of this proposal is to develop robust in vitro human cell-derived microphysical systems which faithfully represent key features of the developing human neocortex in vivo. Our work addresses three key challenges that have limited the development of these systems to date: (1) Building robust and reproducible organoids at high throughput. To obtain meaningful, statistically significant results from genetic and non-genetic perturbations, it is necessary to develop organoid systems which are robust and can be reproducibly assayed in large numbers. (2) Determining in vivo relevance to human neocortex. The utility of organoid systems is defined by the degree to which they reproduce key aspects of human brain development that are not recapitulated by model organisms. (3) Monitoring and perturbing activity longitudinally in situ. To address fundamental questions about cerebral cortex development in either health or disease, it is necessary to capture and experimentally influence the trajectories of cellular activity across the three-dimensional volume of developing organoids through chronic recordings and perturbations. We overcome these challenges by merging three research teams whose expertise spans microfluidics and microelectromechanical systems, bioengineering and stem cell biology, computational and systems biology, and theoretical physics. We exploit novel technologies we have developed independently including: (1) microprinting, droplet encapsulation and microfluidic-based sorting methods to build and enrich for organoids with the selected cell types and geometry at high throughput, (2) in situ single cell RNA sequencing and computational mapping methods to determine the robustness of cell type composition and in vivo relevance against previously obtained in vivo fetal tissue data, and (3) 3D embedded soft microelectrode technology that grows and stretches with the developing tissue to chronically monitor and perturb electrical activity over the course of development. Here, we propose to integrate, employ, and build upon these inventions to further conduct basic research on a unique aspect of human brain development. The cerebral cortex is dramatically expanded and gyrated in humans versus other closely related species. Outer radial glial (oRG) progenitors have been implicated in this expansion. We have previously identified molecular markers that define these cell types, built and tested a reporter human embryonic stem cell line that drives GFP in these cell types, and developed a novel viral barcoded library that allows us to establish lineage relationships using single-cell sequencing. Here, we will determine the developmental potential of these human-specific oRG cells. Specifically, we will determine the contribution of the differentiated oRG progeny to cerebral cortex architecture, cell types, circuit connectivity, and developmental trajectory. The success of this proposal will result in a robust reproducible pipeline to build organoids that will be invaluable in the study of human neocortical development and disease.
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1 |
2021 — 2024 |
Weitz, David |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Collaborative Research: Droplet-Based Selection to Improve Aflatoxin Detoxification
Fungi are microorganisms that can grow naturally on cereals and fruits. When fungi grow, some can produce toxins that can damage our nervous system, liver, and urinary tract when consumed. Fungal contamination thus poses considerable economic burdens on agriculture, as there are no cost-effective approaches to removing the toxins they produce. Some species of bacteria called ‘detoxifiers’ have been identified that can degrade these toxins. However, naturally occurring detoxifiers are not efficient enough to address this problem. The aim of this research is to understand how detoxifiers degrade fungal toxins with the ultimate goal of protecting the food supply. This goal will be achieved using a highly novel single droplet sorting platform. Detoxifiers will be mutated from the original strains and tested for the ability to degrade fungal toxins in the droplet. By monitoring and sorting large numbers of droplets, detoxifier variants will be rapidly identified that work best. These strains will be investigated to understand the toxin degradation process. Successful completion of this research will lead to new strategies for addressing fungal toxin treatment. It will also lead to the development of a novel systematic method for enriching bacterial detoxifiers for a range of applications. This project will improve the Nation’s STEM workforce through the training of future researchers in environmental engineering and will also increase scientific literacy through public education and outreach on food safety and contamination.
The goal of this project is to understand the mechanisms bacteria use to detoxify harmful fungal toxins that contaminate our food. A high-throughput droplet-based platform will be used to characterize and sort bacterial cells that carry detoxification enzymes focusing on aflatoxin—a ubiquitous, harmful toxin that contaminates many food and feed resources. The research design exploits the natural fluorescence of aflatoxin for high throughput sensing to create a library of detoxifier mutants. These mutants will be screened in subsequent genomic and transcriptomic studies to identify genes involved in the detoxification process. This collaborative project combines quantitative biology, droplet-based sorting technology, and genomic and transcriptomic tools to offer a streamlined strategy for uncovering the mechanisms of aflatoxin degradation. This information is critical to develop solutions for protecting the food supply from this toxic compound. Knowledge gained from this research holds promise to open up new avenues for systematic engineering of improved detoxifying strains. This project will contribute to the training and education of interdisciplinary experts at the interface of science and engineering, thus improving the Nation’s STEM workforce. The findings, methods, and tools will be disseminated to the scientific community, as well as the general public through outreach on public health and economic impact of food contamination, thus improving scientific literacy.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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0.915 |