Facile preparation of solid gelatin foams by a water-lean batch foaming process.

Existing polystyrenic and polyolefinic packaging foams are non-biodegradable, and persist in the environment for hundreds of years. Gelatin foams are an interesting alternative, given their biodegradability, biocompatibility, solution-based processability, low cost, and non-toxicity. However, current methods for preparing gelatin foams, such as freeze-drying, microfluidic foaming, and batch foaming, are not suitable for high-volume production.

Microwave-assisted synthesis of crosslinked ureido chitosan for hemostatic applications.

In this study, we present a facile method for introducing hydrophilic ureido groups (NH-CO-NH-) into chitosan using a microwave-assisted reaction with molten urea, with the aim of enhancing chitosan's interaction with blood components for improved hemostasis. The formation of the ureido groups through nucleophilic addition reaction between the amine groups in chitosan and in situ generated isocyanic acid was confirmed by FTIR, CP/TOSS C NMR, and CP/MAS N NMR spectroscopic techniques. However, in stark contrast to the glucans, the said modification introduced extensive crosslinking in chitosan.

Solvent-less carboxymethylation-induced electrostatic crosslinking of chitosan.

The successful N-carboxymethylation and concomitant crosslinking of solid chitosan upon heating its mixture with solid monochloroacetic acid, without the use of solvents or catalysts, is reported. The N-carboxymethylation was confirmed through the analysis of the partially depolymerized product using NMR spectroscopy, as well as a control reaction with lysine. This transformation was facilitated by the nucleophilic nature of the free amine group in the repeating unit of chitosan, which possesses lone pair of electrons capable of attacking the carbon center bearing the leaving group and displacing the leaving group in a concerted manner.

Facile, shear-induced, rapid formation of stable gels of chitosan through in situ generation of colloidal metal salts.

A novel method of preparing chitosan gels using in situ generated negatively-charged colloidal salts of a variety of metal ions is described. Their potential as scaffolds for tissue-engineering and as recoverable catalysts in aza-Michael addition is demonstrated here. Given their wide range of properties, they have broad scope for applications.