Poly(N-isopropylacrylamide) microgel (NMG) has been developed by adding various functional groups to control surface charges, hydrophobicity, pKa and protein adsorption capacity. Here, we focused on the protonation/deprotonation of NMG's functional groups and present the NMG in anchoring potential functional groups as a polymeric catalyst, to possess the amidase activity at the optimized conditions. Various concentrations of microgels and functional groups were evaluated for efficient amidase activity on p-nitroaniline-based substrate via the colorimetric assay. At higher functional group concentrations, the distance between functional groups was reduced, consequently increasing the amidase activity of the NMG. The pH of the reaction environment is crucial to create a balance between neutral and deprotonated species of functional group to enhance the catalytic efficiency of NMGs. We proposed the amidase activity mechanism and the theoretical average distance based on the pH and functional group concentration studies, using NMG bearing functional group of 1-vinylimidazole as the study model. The results of substrate specificity evaluation showed that the efficient turnover rate was greatly affected by the factors of substrate bulkiness and electrostatic interaction between NMGs and substrates. Also, amidase activity was inhibited by a transition-state protease inhibitor, which suggested an enzyme-like amidolytic catalysis and confirmed the proposed NMG reaction model. These results provide an insight into the strategies to functionalize hydrogels through an enzyme-mimic approach for future robust bio- and chemical conversions as well as therapeutic utilities.

Enzyme-like amidolytic catalysis from optimized poly(<i>N</i>-isopropylacrylamide) microgel

248th National Meeting (2014)

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Enzyme-like amidolytic catalysis from optimized poly(N-isopropylacrylamide) microgel