Preparation and characterization of hydrogels based on acryloyl end-capped four-arm star-shaped poly(ethylene glycol)-branched-oligo(l-lactide) via Michael-type addition reaction

An acryloyl end-capped four-arm star-shaped poly(ethylene glycol)-branched-oligo(l-lactide) (4A-PEG-PLA) macromer was firstly prepared. A novel kind of hydrogels was synthesized via the Michael-type addition reaction between (2S,3S)-1,4-bis-sulfanylbutane-2,3-diol (dithiothreitol) and this macromer. Gelation time was determined visually as the time when the precursor solution did not flow on inverting the vials. Hydrogel structure was characterized by FTIR analysis, swelling and degradation tests. It was found that colorless and transparent hydrogels were quickly generated in situ. The gelation time, swelling and degradation behaviors of this kind of hydrogels could be adjusted by changing the concentration of the macromer solution in PBS buffer (pH 7.4). This novel hydrogel is expected to be used as a biomedical material.