Enhanced pattern resolution, swelling-behaviour and biocompatibility of bioimprinted casein microdevices
This work introduces casein microstructures with surface features as a biodegradable biomedical platform technology for enhancing tissue-engineering applications. An optimized fabrication process is presented to reduce the hydrophobicity of intermediate polydimethylsiloxane (PDMS) molds and to transfer high-resolution regular and biomimetic features onto the surface of casein devices. Four different cross-linking reagents, glutaraldehyde, formaldehyde, citric acid and transglutaminase(TG) were investigated to increase the degradation time of casein and their inﬂuence on swelling and biocompatibility of the ﬁlms was studied. TG was found to be the only cross-linker to effectively increase the degradation time and show reduced ﬁlm swelling after immersion into media, while remaining compatible with cell-culture. The maximum expansion of the ﬁlms cross-linked via TG was 33% after 24 hours of immersion in cell-culture media. C2C12 cells were successfully cultured on the patterned ﬁlms for up to 72 hours. The patterned biodegradable casein substrates presented here have promising applications in stem-cell engineering, regenerative medicine, and implantable devices.