In situ forming hydrogels for biomedical applications

Abstract

Hydrogels provide attractive platforms for various biomedical applications, including drug delivery and tissue engineering. Their unique blend of physical properties, such as hydrophilicity, elasticity and permeability, is ideally suited for those purposes. In addition, these properties could be controlled in an efficient manner by varying the crosslinking density of the polymeric network or hybridizing with another reinforcing materials. The crosslinking reaction to form hydrogels generally involve the use of initiators to start the process. However, these reagents often display cytotoxicity, depending on their concentrations, so their dosage must be chosen carefully to prevent the cytotoxicity while maintaining the ability to start the crosslinking reaction. Therefore, an “in situ” crosslinking reaction which occurs under mild conditions and does not involve the use of initiator would be highly favored for hydrogel fabrication. Herein, two in situ forming hydrogel systems based on Michael addition reaction are presented: (1) amine- or hydrazide-containing polyaspartamide hydrogels, and (2) poly(ethylene glycol) diacrylate (PEGDA)-polyethyleneimine (PEI) hydrogels.