About

Ayusman Sen is the Verne M. Willaman Professor of Chemistry and a Distinguished Professor of Chemistry at Pennsylvania State University. His research focuses on the development of self-powered nano and micromotors and pumps, aiming to create dynamic, multifunctional, and highly responsive materials that can remodel themselves and transform their environment. His work emphasizes the design of rationally-engineered dynamic materials capable of minimizing waste, improving performance, and performing collective tasks through emergent behaviors similar to biological systems. Sen's approach leverages chemical control at the molecular level, biomimetic catalytic energy harvesting, rapid and reversible assembly processes, and communication capabilities inspired by microorganisms. His goal is to establish a new paradigm for molecular-level engineering of functional materials that are entirely synthetic and capable of autonomous operation, sensing, and environmental response. His contributions have advanced the understanding of chemically propelled molecules and machines, enzyme-driven motion, and active colloids, positioning him as a leading figure in the field of dynamic and intelligent material systems.

Research topics

• Nanotechnology
• Materials science
• Thermodynamics
• Chemistry
• Chemical physics
• Biochemical engineering
• Biology
• Physics
• Engineering
• Composite material
• Ecology
• Biophysics
• Organic chemistry
• Biochemistry
• Optics
• Mechanics
• Cell biology
• Computational biology

Selected publications

• Emergent Nonlinearity in Active Molecular Chemotaxis

  ACS Nano · 2026-05-13

  articleOpen access

  Understanding chemotaxis at the molecular level is challenging, as individual enzyme molecules cannot sense chemical gradients across their nanometer-sized bodies. Typical theoretical models encompass chemotaxis under constant, externally imposed gradients; however, this overlooks a critical feedback loop, where the active enzymes themselves reshape the imposed gradients through catalysis. In this work, we investigate the principles of active molecular chemotaxis using a Fokker-Planck model for an ATP-driven kinase-phosphatase system. Using experimentally relevant enzyme concentration ranges (∼nM), we demonstrate that the chemotactic velocity of enzymes does not simply respond linearly to chemical gradients, as commonly observed in microscale systems driven by diffusiophoresis. Instead, it emerges from a nonlinear coupling between the enzyme's spatial distribution, its conformational state (free/bound-state ratio), and chemical gradients modulated by catalytic reactions. As a result, the spatial profile of chemotactic velocity transitions between monotonic and nonmonotonic regimes, depending on substrate availability. Furthermore, we find that high catalyst concentrations can amplify the effective interaction between enzymes, forming a cascade that is critical for collective assemblies such as metabolon formation. To understand these complex interactions, we construct chemotactic velocity maps as a function of enzyme concentration, energy, and substrate availability, offering a set of design principles. This work clarifies the distinct roles of energy, gradients, and enzyme free/bound states in molecular motion, highlighting a fundamental difference between nano and microscale systems, and provides a theoretical framework for designing advanced autonomous active molecular systems.

  PublisherDOI

• Chemotaxis of ATPase-Powered Nanoparticles up Extra- and Intracellular ATP Gradients

  Nano Letters · 2026-05-05

  articleOpen access

  Guiding synthetic nanomaterials toward specific cells and subcellular organelles remains a critical challenge for targeted therapeutics. Here, we report that ATPase-functionalized nanoparticles harness enzymatic turnover to autonomously navigate extracellular and intracellular ATP gradients, accumulating near cell surfaces, experiencing enhanced uptake, and once endocytosed, localizing selectively to mitochondria in both primary human aortic endothelial cells and HeLa cells. ATP depletion or ATPase inhibition abolishes accumulation and disrupts mitochondrial targeting, confirming the requirement for active enzymatic turnover. This targeting mechanism is preserved across particle types, including lipid-based vesicles, indicating broad applicability. This work establishes enzyme-powered chemotaxis as a route to pericellular accumulation, enhanced endocytosis, and organelle-specific delivery, providing a foundation for responsive nanomedicines targeting metabolically active disease environments. The strategy shifts the paradigm from passive, receptor-based delivery to dynamic, energy-responsive targeting.

  PublisherDOI

• Chemically powered active particle colonies

  Nature Chemical Engineering · 2026-03-25

  articleSenior authorCorresponding
  PublisherDOI

• Nonequilibrium surfactant partitioning into microdroplets generates local phase inversion conditions and interfacial instability

  Soft Matter · 2026-01-01

  articleOpen access

  Droplets far from equilibrium experience different compositions and local environments compared with bulk oil and water phases at equilibrium. Understanding the pathways involved in emulsion progression towards equilibrium is valuable for designing complex fluids for many purposes including coatings, food, chemical separations, active matter, and enhanced oil recovery. Here we report how microscale oil droplets, which partition nonionic surfactants and also solubilize, can follow an unexpected pathway wherein a spherical droplet transitions through an interfacial instability and dissociates. This process depends on the oil hydrophobicity, the concentration and ethylene oxide number of the surfactant, the initial droplet diameter, and the presence of neighboring droplets. We propose a mechanism based on local phase inversion that explains both the visual appearance of the droplet dissociation behavior as well as the trends in its counterintuitive dependence on specific conditions like oil and surfactant chemical structure and surfactant concentration.

  PublisherOA PDFDOI

• Swarming intelligence in self-propelled micromotors and nanomotors

  Nature Reviews Materials · 2025-06-13 · 16 citations

  reviewCorresponding
  PublisherDOI

• Nanomotors: 20 years anniversary and future roadmap

  ChemRxiv · 2025-02-17 · 4 citations

  preprintOpen access

  Since their discovery in 2004, there has been remarkable progress in research on nanomotors starting with the elucidation of different propulsion mechanisms to the study of their collective behavior, culminating in investigations into their applications in biomedicine and environmental remediation. This perspective reviews this evolution in nanomotors research and discusses the key challenges ahead, including the development of advanced characterization techniques, precise motion control, materials innovation, theory and modelling, and in vivo applications. These challenges not only highlight the current limitations of synthetic nanomotors but also point to exciting future opportunities to revolutionize theranostics, and the creation of ‘living’ hybrid systems. Thus, this perspective aims to inspire future generations of researchers in advancing both fundamental understanding and practical breakthroughs, thereby engineering a paradigm shift in nanomotors research.

  PublisherOA PDFDOI

• H₂O₂-sensitized single-component TiO₂ micromotors: blue-light-driven propulsion and collective cell manipulation

  Chemical Communications · 2025-01-01 · 1 citations

  articleSenior author

  H 2 O 2 -sensitized TiO 2 micromotors achieve visible-light propulsion and collective cell manipulation at ultralow fuel concentrations.

  PublisherDOI

• Ionic gradients in flow to control transport of emissive ions

  Chemical Communications · 2025-01-01 · 2 citations

  articleOpen access

  Concentration gradients of simple salts in microfluidic channels control the transport of a common photoredox catalyst.

  PublisherOA PDFDOI

• A roadmap for next-generation nanomotors

  Nature Nanotechnology · 2025-08-01 · 26 citations

  reviewOpen access
  PublisherOA PDFDOI

• Technology Roadmap of Micro/Nanorobots

  ACS Nano · 2025-06-27 · 68 citations

  reviewOpen access

  , the field of micro/nanorobots has evolved from science fiction to reality, with significant advancements in biomedical and environmental applications. Despite the rapid progress, the deployment of functional micro/nanorobots remains limited. This review of the technology roadmap identifies key challenges hindering their widespread use, focusing on propulsion mechanisms, fundamental theoretical aspects, collective behavior, material design, and embodied intelligence. We explore the current state of micro/nanorobot technology, with an emphasis on applications in biomedicine, environmental remediation, analytical sensing, and other industrial technological aspects. Additionally, we analyze issues related to scaling up production, commercialization, and regulatory frameworks that are crucial for transitioning from research to practical applications. We also emphasize the need for interdisciplinary collaboration to address both technical and nontechnical challenges, such as sustainability, ethics, and business considerations. Finally, we propose a roadmap for future research to accelerate the development of micro/nanorobots, positioning them as essential tools for addressing grand challenges and enhancing the quality of life.

  PublisherDOI

Recent grants

• NIRT: Nanoscale Motors Powered by Catalytic Reactions

  NSF · $1.0M · 2005–2009

Frequent coauthors

• Arthur C. Reber

  Virginia Commonwealth University

  53 shared

• Thomas E. Mallouk

  47 shared

• Shiv N. Khanna

  45 shared

• Meichun Qian

  Virginia Commonwealth University

  42 shared

• Paul S. Weiss

  California NanoSystems Institute

  38 shared

• Anna C. Balazs

  University of Pittsburgh

  37 shared

• Sachin Borkar

  32 shared

• Arnold L. Rheingold

  University of California, San Diego

  29 shared

Awards & honors

• Langmuir Lecture Award, American Chemical Society
• Humboldt Prize, Alexander von Humboldt Foundation
• Elected Fellow, Royal Society of Chemistry
• Medal, Chemical Research Society of India (CRSI)
• Elected Fellow, American Association for the Advancement of…