Syneresis of Colloidal Gels: Endogenous Stress and Interfacial Mobility Drive Compaction

Phase mechanics of colloidal gels: osmotic pressure drives non-equilibrium phase separation

“…41 Other explanations of syneresis have sometimes described syneresis as resulting from internal stresses within the gel generated during gelation, but the microscopic origin of these stresses and the reason for their relaxation are typically not described, leaving open the mechanistic explanation for the phenomenon of syneresis. 42 To our knowledge, such models have focused on low-coordination number gels where single strands stretch and bend; while food-based gels have been the primary focus of gel syneresis, we are not aware of studies of model-system studies of dense, highly-bonded or reversibly-bonded model gels. Syneresis has some parallels to the present work, but here condensation of a reversibly bonded dense gel is shown to emerge from relaxation of bonds and where we provide a microscopic mechanistic explanation: negative osmotic pressure acts to reduce the free energy, advancing phase separation.…”

FITC-Dextran Release from Cell-Embedded Fibrin Hydrogels

“…It is widely known that cells have the capability to exert traction forces (e.g., fibroblasts) and often contract the surrounding gel matrix, locally and globally. Our initial assumption that had motivated this research was that cellular traction forces in fibrin gels will cause higher release profiles of drugs compared to the release from acellular gels, as forces are expected to cause gel global shrinkage [49] and induce the extraction or expulsion of liquid from the gel (i.e., syneresis) [50][51][52]. During active syneresis, we expected advection to occur, i.e., directed transport of molecules/drugs out of the gel and therefore faster and higher release profiles.…”

Microscopic interactions and emerging elasticity in model soft particulate gels

“…There is evidence of these phenomena from confocal microscopy images in experiments, showing that local coordination of particulate gels can be limited to 2-4 contacts even when there is not a clear fractal characteristics of the gel structure. Optical tweezers experiments have proven that strands of aggregated colloidal particles can sustain finite torques, and it has been recently shown that the mechanical contacts between colloidal particles can be solid-on-solid contacts, which stiffen over time [3,4,[42][43][44][45].…”