Preparation and characterization of injectable hydrogels made via Michael-type addition reaction of dithiothreitol with 3-arm acryloyl end-capped PEG

A 3-Arm PEG (M_n = 16900) was first reacted with acryloyl chloride to give rise to an acryloyl end-capped macromer. Afterthen, a kind of injectable hydrogels was prepared via Michael-type addition reaction of dithiothreitol with this macromer. The gelation time was visually determined when the mixture did not flow by inverting the vials. The hydrogel structure was characterized by using FTIR and DMA analyses as well as swelling and degradation tests. It was found that robust and transparent hydrogels were quickly formed in situ with high gel fractions. DMA measurements confirmed that the hydrogels hold intact 3D network structure. The gelation time and swelling ratio are adjustable by changing the concentration of macromer solution in PBS due to the fact that the number of reactive acrylates in unit volume is increased with the concentration of precursor solution making them more easily to be linked with DTT to form hydrogel networks. The results revealed this kind of hydrogels is injectable and degradable. Meanwhile, MTT evaluation also showed the good cell-compatibility for this kind of hydrogel material. As Michael-type addition can be smoothly carried out at physiological temperature and pH in the absence of any sensitizer or catalyst, and the reactants involved are all biocompatible, the as-prepared hydrogels have the potential to be used in the area of biomedical materials.