Formation of Microchannels in Poly(ethylene glycol) Hydrogels by Selective Degradation of Patterned Microstructures

A technique for constructing microchannels within three-dimensional hydrogels is described. The method depends on the use of two photopolymerizable macromers with different degradation kinetics. Poly(ethylene glycol)-diacrylate (PEG-DA) and poly(ethylene glycol)- co ( L -lactide) diacrylate (PEG-PLLA-DA) were synthesized and characterized by 1 HNMR and FTIR. PEG-PLLA (but not PEG-DA) gels degrade rapidly via hydrolysis. Gels were formed via bulk photopolymerization of the macromers by exposure to ultraviolet light in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPA) as an initiator. Patterns of PEG-PLLA-DA were generated within multilayer PEG hydrogels by noncontact photolithography. When the hydrogels were exposed to high pH conditions, the patterned PEG-PLLA-DA structures degraded rapidly, resulting in channels within the PEG-DA hydrogels. Single and multilayered channels were formed and their structure examined by phase contrast and confocal microscopy.