background: the excellent biocompatibility, biodegradability and biological properties of the hydrogels, fabricated using natural polymers, especially polysaccharides, are very advantageous for biomedical applications. gum tragacanth (gt) is a heterogeneous highly branched anionic polysaccharide, which has been used extensively in food and pharmaceutical industries. despite,  its desirable prop...

Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation that exploits an inbuilt switch: the increase in pH after an induction period in the urease-catalyzed hydrolysis of urea was used to trigger the base-catalyzed Michael addition of a water-soluble trithiol to a polyethylene glyco...

Background: The excellent biocompatibility, biodegradability and biological properties of the hydrogels, fabricated using natural polymers, especially polysaccharides, are very advantageous for biomedical applications. Gum tragacanth (GT) is a heterogeneous highly branched anionic polysaccharide, which has been used extensively in food and pharmaceutical industries. Despite,  its desirable prop...

We experimentally and theoretically investigate the size effect of gelation using Resorcinol-Formaldehyde aerogels. We find a clear dependence of gelation time on the sample size under mild shear conditions. We developed a theoretical model based on Smoluchowski’s aggregation model adding, however, a growth term which accounts for the continuous growth of the colloidal particles while clusterin...

We monitored the cell-free solubilization of extracellular matrix and fibronectin gels, catalyzed by exogenous proteinases. The corresponding measurements could not be interpreted according to usual proteinase kinetics. The observation that this experimental system did not consist in surface but in bulk degradation and appeared specific to gel substrates, incited us to use gelation-related appr...

A new and versatile, crown ether appended, chiral supergelator has been designed and synthesized based on the bis-urea motif. The introduction of a stereogenic center improved its gelation ability significantly relative to its achiral analogue. This low-molecular-weight gelator forms supramolecular gels in a variety of organic solvents. It is sensitive to multiple chemical stimuli and the sol-g...

The bioinspired strategy of triggered release of Ca2+ from liposomal compartments was used to induce rapid gelation of polysaccharide and protein-based hydrogels. Thermally triggerable liposomes were designed by entrapping CaCl2 within liposomes constructed of 90% dipalmitoylphosphatidylcholine and 10% dimyristoylphosphatidylcholine. These liposomes released greater than 90% of entrapped Ca2+ w...

A novel, high hydrolysis ratio sol-gel route for the biocompatible production of macroporous silica gels is presented. This route exploits the two step nature of the gelation reaction to remove undesired alcohol by-products from an acidic aqueous sol prior to gelation. These alcohol-free sols will gel when the pH is raised to the physiologic range in a two-step, acid/base catalyzed process. Fur...

A one-pot, enzyme-catalyzed bulk polymerization method for direct production of highly branched polyesters has been developed as an alternative to currently used industrial procedures. Bio-based feed components in the form of glycerol, pentaerythritol, azelaic acid, and tall oil fatty acid (TOFA) were polymerized using an immobilized Candida antarctica lipase B (CALB) and the potential for an e...