Foldable micropatterned hydrogel film made from biocompatible PCL-b-PEG-b-PCL diacrylate by UV embossing.

Foldable hydrogel films with micropatterns measuring 480 microm by 45 microm by 54 microm by 2 cm (width of microchannel by width of microwall by height of wall by length of pattern) were made by UV embossing of a block copolymer of polycaprolactone (PCL) and poly(ethylene glycol) (PEG), specifically PCL-b-PEG-b-PCL-diacrylate (DA), with a polydimethylsiloxane mold. The mold was treated with Ar/CF(4) plasma to simultaneously promote microchannel filling and demolding, and the glass substrate was modified with 3-(trimethoxysilyl) propyl acrylate to promote hydrogel adhesion to avoid delamination of the gel during demolding. The micropatterned hydrogel film was detached from the glass substrate by freeze-drying. As the films were demolded, the microstructured pattern was well replicated in the hydrogel. The gel pattern dimensions shrank with freeze-drying and increased with water swelling, but under both conditions, the gel micropattern morphology was perfectly preserved. PCL-b-PEG-b-PCL-DA hydrogel was found to have good biocompatibility compared with PEGDA hydrogel. A micropattern with a smaller microchannel width of 50 microm was also made. Micropatterned foldable and biocompatible hydrogel films have potential applications in the construction of tissue-engineering scaffolds.