Synthesis and characterization of peptide granted porous polymer microstructures

A scanning laser system has been used to generate three-dimensional trimethylolpropane trimethacrylate (TRIM) cross-linked poly(2-hydroxylethyl methacrylate) polymer microstructures through azo-bis(isobutyro)nitrile (AIBN) photopolymerization using a 20 × 0.5 NA microscope objective and 365 nm laser excitation. Macropores are observed to form without the use of porogens in regions of highest light flux. This is attributed to phase separation, which results from differences in monomer reactivity and miscibility. The microstructures were aminated and then protected with the photolabile protective group 6-nitroveratryloxycarbonyl (NVOC). This made it possible to selectively modify the microstructures with the same scanning laser system that was used to fabricate them, resulting in peptide grafted three-dimensional porous microstructures. On the basis of the absorbance of the dibenzofulvene-piperidine, these structures have an amine site density of ∼0.1 nmol/feature. MALDI-TOF MS was used to characterize peptide photografted microstructures. N-Tris(2,4,6-trimethoxyphenyl)phosphonium (TMPP) labeling of the peptides greatly enhanced detection and allowed post-source decay sequencing of the peptides from the microstructures. The techniques described could be used to generate three-dimensional peptide grafted porous scaffolds for tissue engineering applications.