Synthesis and Characterization of Photocurable Polyionic Hydrogels

In this study we describe preparation of polyionic hydrogels based on PEGylated polyamidoamine (PAMAM) dendrimers. Polyethylene glycol (PEG) with varied chain length (MW=1500, 6000, or 12000) was first conjugated to the Starburst™ G3.0 PAMAM dendrimer to form stealth dendrimers. The free hydroxyl group of PEG was further converted to an acrylate group using acrolyl chloride and triethylamine. The conjugation was characterized with 1H-NMR. The loading degree of PEG on the dendrimer surface was estimated by using both the ninhydrin assay and 1H-NMR. Hydrogel formation was realized by subjecting dendrimer-PEG acrylate to UV exposure for a brief period of time at the presence of Eosin Y, triethanolamine and 1-vinyl-2-pyrrolidinone. PEGylated G3.0 PAMAM dendrimer served as cross-linking agent to form hydrogels because of its multiple functionalities. The surface charges conferred by terminal groups on the dendrimer surface made the hydrogel polyionic with controllable charge density. This new type of hydrogel has many favorable biological properties such as non toxicity and non immunogenecity and multifunctional ties for a variety of in vivo applications. Current studies have demonstrated feasibility of chemistry and hydrogel formation