Preparation of superabsorbent hydrogels from poly(aspartic acid) by chemical crosslinking

Highly Absorbent Silk Fibroin Protein Xerogel

Highly absorbent polymers have a wide range of applications in biomaterials, agriculture, physiological products of daily uses, and others. Silk fibroin, as a natural biomaterial with excellent biocompatibility and tunable mechanical properties, shows good prospects in the field of biomedicine applications. However, the dried fibroin hydrogel has very low absorbency. In this work, silk fibroin protein is used as the carrier, riboflavin as the photosensitizer, and accordingly, the hydrogel is prepared by free radical cross-linking under ultraviolet light. The fibroin in the hydrogel contains mainly the random coil structure. The covalent bond cross-linking hinders the crystallization of the silk fibroin, thereby an amorphous silk fibroin hydrogel is obtained. After drying, this xerogel can absorb water 90 times more than its own mass and assimilates a good amount of water within a minute. In vitro and in vivo rabbit ear hemostasis experiments show that this fabricated xerogel has good hemostatic properties. Therefore, this xerogel exhibits good promise for rapid hemostasis of wounds and absorbing other body exudates.

Hydrogels Based on Poly(aspartic acid): Synthesis and Applications

This review presents an overview on the recent progress in the synthesis, crosslinking, interpenetrating networks, and applications of poly(aspartic acid) (PASP)-based hydrogels. PASP is a synthetic acidic polypeptide that has drawn a great deal of attention in diverse applications due particularly to its biocompatibility and biodegradability. Facile modification of its precursor, poly(succinimide) (PSI), by primary amines has opened a wide window for the design of state-of-the-art hydrogels. Apart from pH-sensitivity, PASP hydrogels can be modified with suitable species in order to respond to the other desired stimuli such as temperature and reducing/oxidizing media as well. Strategies for fabrication of nanostructured PASP-based hydrogels in the form of particle and fiber are also discussed. Different cross-linking agents for PSI/PASP such as diamines, dopamine, cysteamine, and aminosilanes are also introduced. Finally, applications of PASP-based hydrogels in diverse areas particularly in biomedical are reviewed.

Preparation of poly(aspartic acid) superabsorbent hydrogels by solvent-free processes

Poly(aspartic acid) (PASP) hydrogel is a biodegradable and biocompatible polymer with high water absorbing ability. Traditionally, the production of PASP hydrogel consumes large amounts of organic solvents, i.e., dimethylformamide (DMF) or dimethyl sulfoxide (DMSO). This traditional approach is now considered costly, complex and environmentally unfriendly due to required used solvent disposal. The present research explores two novel methods in preparing PASP hydrogel without organic solvent, by using hydrazine hydrate and ethylene glycol diglycidyl ether (EGDGE) or poly(ethylene glycol) diglycidyl ether (PEGDGE) as the cross-linkers. Absorbent ability and other characteristics are determined. Preparing PASP hydrogel in aqueous solution is promising and finds its use in many applications.