About

David A. Weitz is the Mallinckrodt Professor of Physics and of Applied Physics at Harvard University. He is a member of the Kavli Institute for Bionano Science & Technology and primarily teaches in the area of Applied Physics. His research areas include applied physics, materials, soft matter, biomaterials, biophysics, bioengineering, biomechanics and motor control, cell and tissue engineering, and surface and interface science. His work focuses on understanding the fundamental properties and behaviors of soft condensed matter and materials, with particular interest in how materials respond to deformation, fracture mechanics, and the development of biomaterials. Weitz's contributions span experimental research in soft condensed matter physics and applied physics, aiming to elucidate universal mechanisms in material strength, fracture, and biological material behavior.

Research topics

• Biology
• Materials science
• Genetics
• Engineering
• Computer Science
• Nanotechnology
• Artificial Intelligence
• Mechanics
• Biophysics
• Chemistry
• Cancer research
• Data science
• Cell biology
• Computational biology
• Biological system
• Aerospace engineering
• Immunology
• Physics
• Biochemical engineering
• Geometry
• Engineering ethics

Selected publications

• Biomaterials with droplet microfluidics

  Nature Reviews Bioengineering · 2026-01-02 · 5 citations

  article
  PublisherDOI

• A droplet microfluidics-based platform for generating target-specific, natively-paired immune libraries and identifying potent and developable antibodies

  Scientific Reports · 2026-01-03

  articleOpen access

  The human antibody repertoire is a promising source for therapeutic-grade antibodies. Yet current methods for strategically mining these B cell repertoires are stymied by throughput and chain pairing considerations. This study presents advancements in fluidics and molecular biology that enable the multi-step encapsulation and capture of B cells from an immunized, humanized mouse in nanoliter sized droplets. Once singularly captured, antigen-specific B-cells can be lysed and individually manipulated via RT-PCR to splice cognate V genes and create a predominantly natively paired library. To explore the importance of these process improvements in library generation, we constructed natively-paired libraries against two therapeutically-relevant human proteins. Through deep sequencing, bioinformatics-driven screening and phage display, we selected functional, target-specific antibodies. Our findings reveal that natively paired libraries contain a higher percentage of target-specific antibodies and demonstrate enhanced potency and improved developability in both in silico and in vitro assessments relative to combinatorial library-derived antibodies. Furthermore, antibodies with native pairing show increased potency as well as improved in silico and in vitro developability compared to their randomly paired counterparts. To this end, we see this droplet microfluidic platform and its capacity to generate and facilitate the high-throughput interrogation of antigen-specific antibody repertoires as an important, orthogonal therapeutic antibody discovery approach.

  PublisherOA PDFDOI

• Implantable living materials autonomously deliver therapeutics using contained engineered bacteria

  Science · 2026-05-14 · 1 citations

  article

  Microbes are increasingly used as living therapeutics, yet their uncontrolled dissemination in the body has remained a clinical roadblock. Physical containment remains largely unattainable owing to eventual bacteria escape. In this work, we present an implantable material that encapsulates and confines bacteria, wherein synthetically engineered microbes produce therapeutic payloads from within. We developed a hydrogel scaffold with dual mechanical features: high stiffness to regulate bacterial proliferation and high toughness to resist material fracture under physiological stress. This design achieved complete bacterial containment for 6 months and withstood multiple forms of mechanical loading that otherwise caused catastrophic material failure. By genetically engineering embedded bacteria, we endowed the material with environmental sensing and on-demand therapeutic release capabilities and demonstrated autonomous treatment in a murine prosthetic joint infection model.

  PublisherDOI

• Squeaking at soft–rigid frictional interfaces

  Nature · 2026-02-25 · 3 citations

  articleOpen access
  PublisherOA PDFDOI

• Rapid fabrication of solvent-compatible NOA 81 microfluidic devices for double-emulsion microfluidics

  Lab on a Chip · 2026-01-01

  articleSenior author

  While PDMS-based microfluidic devices set the rapid prototyping standard, their application is limited by incompatibility with many non-polar solvents. This inability to tolerate organic solvents significantly restricts the types of materials that can be handled and/or synthesized. UV-curable photopolymers, such as NOA 81, present a promising solution to these challenges. NOA 81 enables simple, cost-effective device fabrication, but current limitations on proper fabrication protocols limit its full potential. Here, we present a well-defined, simple, single-step fabrication method for producing NOA 81 microfluidic devices that are compatible with organic solvents. This method allows for the rapid prototyping of devices using similar steps associated with PDMS. We report a rapid heat treatment step that enhances the chemical resistance to a wider range of organic solvents while also increasing the material's elastic modulus by nearly two orders of magnitude. We demonstrate how to control the channel wall wettability for producing water-in-oil-in-water double emulsions which serve as templates for microcapsules and amphiphilic polymer vesicles. This novel method, which we call "hard lithography", reduces the time needed to produce working prototypes to less than one day while expanding the range of solvents that can be used. It simplifies fabrication and enables the production of chemically resistant devices suitable for a wide array of applications.

  PublisherDOI

• Engineering the biophysical properties of lipid nanostructures for drug delivery

  Communications Materials · 2026-01-24 · 3 citations

  articleOpen access

  The physical properties of drug delivery vehicles are important for the development of effective and targeted treatment options for human disease. In this review, we elucidate the role of the fundamental physical properties such as size, charge, elasticity, curvature, fluidity, and asymmetry in optimizing lipid-based drug delivery systems. These properties significantly influence the performance of such drug delivery vehicles in overcoming biological barriers, minimizing clearance, and improving cellular uptake. The optimization of physical properties is important in bridging the translational gap and achieving consistent clinical outcomes. By focusing on the fundamental physical properties, we also provide a comprehensive review that identifies remaining knowledge gaps and guides future development of lipid-based nanocarriers. This Review explores the role of fundamental physical properties, such as size, charge, elasticity, curvature, fluidity, and asymmetry, on optimizing lipid-based drug delivery systems. Knowledge gaps and guidance for the future development of lipid-based nanocarriers are also discussed.

  PublisherOA PDFDOI

• BPS2026 – Liquid-liquid phase separation modulates protein pathological aggregation

  Biophysical Journal · 2026-02-01

  article
  PublisherDOI

• Single-Cell Microgel Microrobot for Targeted and Imaging-Guided Cell Therapy

  CCS Chemistry · 2025-07-14 · 2 citations

  articleOpen accessSenior author
  PublisherDOI

• Tough Hybrid Hydrogels with Exceptional Swollen-State Mechanical Robustness via Nanocrystalline Domain Engineering

  Macromolecules · 2025-07-11 · 2 citations

  article

  Hydrogels often suffer from weak mechanical properties when fully swollen due to reduced polymer chain density, leading to stress concentration and failure under mechanical loads. To address this, we propose an electron-interaction-induced phase separation strategy for synthesizing tough hybrid hydrogels. Introducing Zr4+ ions during preparation forms nanocrystalline domains via chelation with acid-group monomers, while flexible domains arise from other monomers. This dual-domain structure enhances toughness through efficient energy dissipation and ensures durability. The hybrid hydrogels exhibit a swelling ratio of 15.7 in 10,000 g/L NaCl at 80 °C for 30 days, with a compressive modulus of over 18 kPa and a compressive strength of 0.11 MPa. They maintain integrity after 40 fatigue cycles and show a dissipation energy ratio of ∼44%. Hydrogel particles with the same formula, prepared via inverse emulsion polymerization, demonstrate a compressive modulus of 49.50 MPa and a shear modulus of 13 MPa in the swollen state, retaining structure after navigating capillaries three times smaller than their diameter. This one-step strategy creates hybrid hydrogels with nanocrystalline and flexible domains, providing exceptional toughness and resilience under extreme conditions and offering substantial potential for applications in challenging aquatic environments characterized by high salinity and elevated temperatures.

  PublisherDOI

• Ion-Triggered Reconfigurable Hydrogel with Salt-Enhanced Mechanical and Swelling Properties via Network Topological Adaptation

  Research Square · 2025-11-28

  preprintOpen accessSenior author
  PublisherOA PDFDOI

Recent grants

• Materials Research Science and Engineering Center

  NSF · $12.2M · 2008–2016

• NIH Grant P01HL120839

  NIH · $24.5M · 2019

• Collaborative Research: Mechanics of fusion of dissimilar lipid bilayers and multi-lamellar vesicles

  NSF · $217k · 2017–2020

• NIH Grant R01EB014703

  NIH · $3.1M · 2016

• Collaborative Proposal: Instrumental Development of Microfluidics-Based Fluorescence Activated Cell Sorting Device for Research and Education

  NSF · $378k · 2007–2010

Frequent coauthors

• Dong Chen

  University of Chinese Academy of Sciences

  75 shared

• F. Spaepen

  Harvard University

  66 shared

• Lizhi Xiao

  China University of Petroleum, Beijing

  62 shared

• Shmuel M. Rubinstein

  Hebrew University of Jerusalem

  61 shared

• Thomas Cochard

  Harvard University

  55 shared

• Congcong Yuan

  Planetary Science Institute

  55 shared

• Ilya Svetlizky

  Harvard University

  54 shared

• Robert C. Viesca

  Tufts University

  50 shared

Labs

• Weitz LabPI

Education

• PhD, Physics

  Harvard University

  1976

• A.M., Physics

  Harvard University

  1975

• B.Sc., Honors Physics

  University of Waterloo

  1973