Samya Sen, Ph.D.

All Publications

• Highly Extensible Physically Crosslinked Hydrogels for High-Speed 3D Bioprinting. Advanced healthcare materials Song, Y. E., Eckman, N., Sen, S., Jons, C. K., Saouaf, O. M., Appel, E. A. 2025: e2404988

  Abstract

  Hydrogels have emerged as promising materials for bioprinting and many other biomedical applications due to their high degree of biocompatibility and ability to support and/or modulate cell viability and function. Yet, many hydrogel bioinks have suffered from low efficiency due to limitations on accessible printing speeds, often limiting cell viability and/or the constructs which can be generated. In this study, a highly extensible bioink system created by modulating the rheology of physically crosslinked hydrogels comprising hydrophobically-modified cellulosics and either surfactants or cyclodextrins is reported. It is demonstrated that these hydrogels are highly shear-thinning with broadly tunable viscoelasticity and stress-relaxation through simple modulation of the composition. Rheological experiments demonstrate that increasing concentration of rheology-modifying additives yields hydrogel materials exhibiting extensional strain-to-break values up to 2000%, which is amongst the most extensible examples of physically crosslinked hydrogels of this type. The potential of these hydrogels for use as bioinks is demonstrated by evaluating the relationship between extensibility and printability, demonstrating that greater hydrogel extensibility enables faster print speeds and smaller print features. The findings suggest that optimizing hydrogel extensibility can enhance high-speed 3D bioprinting capabilities, reporting over 5000 fold enhancement in speed index compared to existing works reported for hydrogel-based bioinks in extrusion-based printing.

  View details for DOI 10.1002/adhm.202404988

  View details for PubMedID 39955737

• A thiol-ene click-based strategy to customize injectable polymer-nanoparticle hydrogel properties for therapeutic delivery. Biomaterials science Bailey, S. J., Eckman, N., Brunel, E. S., Jons, C. K., Sen, S., Appel, E. A. 2025

  Abstract

  Polymer-nanoparticle (PNP) hydrogels are a promising injectable biomaterial platform that has been used for a wide range of biomedical applications including adhesion prevention, adoptive cell delivery, and controlled drug release. By tuning the chemical, mechanical, and erosion properties of injected hydrogel depots, additional control over cell compatibility and pharmaceutical release kinetics may be realized. Here, we employ thiol-ene click chemistry to prepare a library of modified hydroxypropylmethylcellulose (HPMC) derivatives for subsequent use in PNP hydrogel applications. When combined with poly(ethylene glycol)-b-poly(lactic acid) nanoparticles, we demonstrate that systematically altering the hydrophobic, steric, or pi stacking character of HPMC modifications can readily tailor the mechanical properties of PNP hydrogels. Additionally, we highlight the compatibility of the synthetic platform for the incorporation of cysteine-bearing peptides to access PNP hydrogels with improved bioactivity. Finally, through leveraging the tunable physical properties afforded by this method, we show hydrogel retention time in vivo can be dramatically altered without sacrificing mesh size or cargo diffusion rates. This work offers a route to optimize PNP hydrogels for a variety of translational applications and holds promise in the highly tunable delivery of pharmaceuticals and adoptive cells.

  View details for DOI 10.1039/d4bm01315h

  View details for PubMedID 39898598

  View details for PubMedCentralID PMC11789556

• Water-Enhancing Gels Exhibiting Heat-Activated Formation of Silica Aerogels for Protection of Critical Infrastructure During Catastrophic Wildfire. Advanced materials (Deerfield Beach, Fla.) Dong, C., d'Aquino, A. I., Sen, S., Hall, I. A., Yu, A. C., Crane, G. B., Acosta, J. D., Appel, E. A. 2024: e2407375

  Abstract

  A promising strategy to address the pressing challenges with wildfire, particularly in the wildland-urban interface (WUI), involves developing new approaches for preventing and controlling wildfire within wildlands. Among sprayable fire-retardant materials, water-enhancing gels have emerged as exceptionally effective for protecting civil infrastructure. They possess favorable wetting and viscoelastic properties that reduce the likelihood of ignition, maintaining strong adherence to a wide array of surfaces after application. Although current water-enhancing hydrogels effectively maintain surface wetness by creating a barricade, they rapidly desiccate and lose efficacy under high heat and wind typical of wildfire conditions. To address this limitation, unique biomimetic hydrogel materials from sustainable cellulosic polymers crosslinked by colloidal silica particles are developed that exhibit ideal viscoelastic properties and facile manufacturing. Under heat activation, the hydrogel transitions into a highly porous and thermally insulative silica aerogel coating in situ, providing a robust protective layer against ignition of substrates, even when the hydrogel fire suppressant becomes completely desiccated. By confirming the mechanical properties, substrate adherence, and enhanced substrate protection against fire, these heat-activatable biomimetic hydrogels emerge as promising candidates for next-generation water-enhancing fire suppressants. These advancements have the potential to dramatically improve the ability to protect homes and critical infrastructure during wildfire.

  View details for DOI 10.1002/adma.202407375

  View details for PubMedID 39169738

• Biomimetic Non-ergodic Aging by Dynamic-to-covalent Transitions in Physical Hydrogels. ACS applied materials & interfaces Sen, S., Dong, C., D'Aquino, A. I., Yu, A. C., Appel, E. A. 2024

  Abstract

  Hydrogels are soft materials engineered to suit a multitude of applications that exploit their tunable mechanochemical properties. Dynamic hydrogels employing noncovalent, physically cross-linked networks dominated by either enthalpic or entropic interactions enable unique rheological and stimuli-responsive characteristics. In contrast to enthalpy-driven interactions that soften with increasing temperature, entropic interactions result in largely temperature-independent mechanical properties. By engineering interfacial polymer-particle interactions, we can induce a dynamic-to-covalent transition in entropic hydrogels that leads to biomimetic non-ergodic aging in the microstructure without altering the network mesh size. This transition is tuned by varying temperature and formulation conditions such as pH, which allows for multivalent tunability in properties. These hydrogels can thus be designed to exhibit either temperature-independent metastable dynamic cross-linking or time-dependent stiffening based on formulation and storage conditions, all while maintaining structural features critical for controlling mass transport, akin to many biological tissues. Such robust materials with versatile and adaptable properties can be utilized in applications such as wildfire suppression, surgical adhesives, and depot-forming injectable drug delivery systems.

  View details for DOI 10.1021/acsami.4c03303

  View details for PubMedID 38862125

• Soft glassy materials with tunable extensibility. Soft matter Sen, S., Fernandes, R. R., Ewoldt, R. H. 2023

  Abstract

  Extensibility is beyond the paradigm of classical soft glassy materials, and more broadly, yield-stress fluids. Recently, model yield-stress fluids with significant extensibility have been designed by adding polymeric phases to classically viscoplastic dispersions [Nelson et al., J. Rheol., 2018, 62, 357; Nelson et al., Curr. Opin. Solid State Mater. Sci., 2019, 23, 100758; Dekker et al., J. Non-Newtonian Fluid Mech., 2022, 310, 104938]. However, fundamental questions remain about the design of and coupling between the shear and extensional rheology of such systems. In this work, we propose a model material, a mixture of soft glassy microgels and solutions of high molecular weight linear polymers. We establish systematic criteria for the design and thorough rheological characterization of such systems, in both shear and extension. Using our material, we show that it is possible to dramatically change the behavior in extension with minimal change in the shear yield stress and elastic modulus, thus enabling applications that exploit orthogonal modulation of shear and extensional material properties.

  View details for DOI 10.1039/d3sm01150j

  View details for PubMedID 38078477

• Thixotropic spectra and Ashby-style charts for thixotropy JOURNAL OF RHEOLOGY Sen, S., Ewoldt, R. H. 2022; 66 (5): 1041-1053

  View details for DOI 10.1122/8.0000446

  View details for Web of Science ID 000848363100002

• Thixotropy in viscoplastic drop impact on thin films PHYSICAL REVIEW FLUIDS Sen, S., Morales, A. G., Ewoldt, R. H. 2021; 6 (4)

  View details for DOI 10.1103/PhysRevFluids.6.043301

  View details for Web of Science ID 000652861500001

• Rheology of fibre suspension flows in the pipeline hydro-transport of biomass feedstock BIOSYSTEMS ENGINEERING Faghani, A., Sen, S., Vaezi, M., Kumar, A. 2020; 200: 284-297

  View details for DOI 10.1016/j.biosystemseng.2020.10.009

  View details for Web of Science ID 000598489200007

• Viscoplastic drop impact on thin films JOURNAL OF FLUID MECHANICS Sen, S., Morales, A. G., Ewoldt, R. H. 2020; 891

  View details for DOI 10.1017/jfm.2020.147

  View details for Web of Science ID 000524939800001

• Base-triggered self-amplifying degradable polyurethanes with the ability to translate local stimulation to continuous long-range degradation CHEMICAL SCIENCE Xu, Y., Sen, S., Wu, Q., Zhong, X., Ewoldt, R. H., Zimmerman, S. C. 2020; 11 (12): 3326-3331

  Abstract

  A new type of base-triggered self-amplifying degradable polyurethane is reported that degrades under mild conditions, with the release of increasing amounts of amine product leading to self-amplified degradation. The polymer incorporates a base-sensitive Fmoc-derivative into every repeating unit to enable highly sensitive amine amplified degradation. A sigmoidal degradation curve for the linear polymer was observed consistent with a self-amplifying degradation mechanism. An analogous cross-linked polyurethane gel was prepared and also found to undergo amplified breakdown. In this case, a trace amount of localized base initiates the degradation, which in turn propagates through the material in an amplified manner. The results demonstrate the potential utility of these new generation polyurethanes in enhanced disposability and as stimuli responsive materials.

  View details for DOI 10.1039/c9sc06582b

  View details for Web of Science ID 000528663000021

  View details for PubMedID 34122840

  View details for PubMedCentralID PMC8152679

• Acid-Triggered, Acid-Generating, and Self-Amplifying Degradable Polymers JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Miller, K. A., Morado, E. G., Samanta, S. R., Walker, B. A., Nelson, A. Z., Sen, S., Tran, D. T., Whitaker, D. J., Ewoldt, R. H., Braun, P. V., Zimmerman, S. C. 2019; 141 (7): 2838-2842

  Abstract

  We describe the 3-iodopropyl acetal moiety as a simple cleavable unit that undergoes acid catalyzed hydrolysis to liberate HI (p Ka ∼ -10) and acrolein stoichiometrically. Integrating this unit into linear and network polymers gives a class of macromolecules that undergo a new mechanism of degradation with an acid amplified, sigmoidal rate. This trigger-responsive self-amplified degradable polymer undergoes accelerated rate of degradation and agent release.

  View details for DOI 10.1021/jacs.8b07705

  View details for Web of Science ID 000459642000009

  View details for PubMedID 30698426