In-Situ Gelling Stimuli-Sensitive PEG-Based Amphiphilic Copolymer Hydrogels

Abstract

In-situ gelling stimuli-sensitive block copolymer hydrogels exhibit sol–gel phase-transitions in response to external stimuli, due to the formation of reversible polymer networks caused by physical interactions. In-situ gelling stimuli-sensitive block copolymer hydrogels show many advantages, such as simple drug formulation and administration procedures, no organic solvent, site-specificity, a sustained drug release behavior, less systemic toxicity, and ability to delivery both hydrophilic and hydrophobic drugs. Poly(ethylene glycol)s with relatively low molecular weight are hydrophilic, nontoxic, absent of antigenicity and immunogenicity, and can be directly excreted by the kidneys. PEG-based amphiphilic copolymers have attracted extensive interest for their unique self-assembly and biocompatibility. The PEG-based amphiphilic copolymers exhibit unique changes in micellar architecture and aggregation number in response to changes near physiological temperature; therefore, in-situ gelling systems made of the PEG-based amphiphilic copolymers have received worldwide investigation. This article stresses the recent development and biomedical evaluation of the in-situ gelling stimuli-sensitive PEG-based amphiphilic copolymers that are capable of responding to changes in temperature and/or pH.