Biophysical Society Thematic Meeting | Riga 2026

Active and Responsive Soft Matter: From Biological to Engineered Systems

Tuesday Speaker Abstracts

MECHANICAL PHASE TRANSITIONS AND THE NONLINEAR RESPONSE OF BIOPOLYMER MATRICES Fred C. MacKintosh ; 1 Rice University, Chemical and Biomolecular Engineering, Houston, TX, USA The mechanics of cells and tissues are largely governed by scaffolds of filamentous proteins. Particularly common examples of these are the collagen fiber networks of extracellular matrices. There is now increasing evidence that the mechanics of such fibrous structures are governed by underlying mechanical phase transitions reminiscent of the rigidity transition identified by Maxwell for macroscopic engineering structures: networks of struts or springs exhibit a continuous, second-order phase transition at the isostatic point, where the number of constraints imposed by connectivity just equals the number of mechanical degrees of freedom. By contrast, fibrous networks in 3D exhibit a line of critical transitions as a function of strain rather than connectivity. These transitions have shown remarkable richness, including non-mean-field critical behavior. We will present recent theoretical predictions and experimental evidence for such strain-controlled mechanical phase transitions in biopolymer networks, as well as some of the resulting elastic and viscoelastic signatures and anomalies such as an unexpectedly large Poisson ratio, slow stress relaxation and a divergent viscosity. DIRECTING REGENERATION THROUGH FIBER-BASED PHYSICAL CUES Treena Arinzeh 1 ; 1 Columbia University, Biomedical Engineering, New York, NY, USA The field of tissue engineering has expanded rapidly through the convergence of stem cell biology, emerging bioactive therapeutics, and the development of biomaterials capable of modulating cellular behavior. This talk will describe recent work investigating the physical properties of fibrous matrices, namely topographical cues and an understudied phenomena of electromechanical behavior or piezoelectricity, and how they drive changes in cell behavior. Piezoelectric fibrous scaffolds offer a biomaterials-based approach to couple mechanical deformation with localized electrical signaling, enabling dynamic regulation of cellular behavior. Our work demonstrates that piezoelectric fibers can direct stem and progenitor cell differentiation and organization in the absence of externally applied electrical fields. Through the integration of fiber architecture and electromechanical properties, these scaffolds provide multiscale physical cues that influence lineage specification and tissue formation. More recently, we have extended this platform through functionalization strategies, including the complexation of lipid nanoparticles for immune engineering applications. Interestingly, transient functionalization can be achieved without compromising the intrinsic piezoelectric properties of the scaffold, positioning piezoelectric fibrous scaffolds as modular systems for integrating bioelectric and biochemical signals in regenerative medicine.

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