Catalytic silica particles via template-directed molecular imprinting

The surfaces of silica particles were molecularly imprinted with an alpha-c hymotrypsin transition-state analogue (TSA) by utilizing the technique of t emplate-directed synthesis of mineralized materials. The resulting catalyti c particles hydrolyzed amides in an enantioselective manner. A mixture of a nonionic surfactant and the acylated chymotrypsin TSA, with the TSA acting as the headgroup at the surfactant-water interface, was used to form a mic roemulsion for silica particle formation. Incorporation of amine-, dihydroi midazole-, and carboxylate-terminated trialkoxysilanes into the particles d uring imprinting resulted in enhancement of the rates of amide hydrolysis. Acylated imprint molecules formed more effective imprints in the presence o f the functionalized silanes than noplacylated imprint molecules. Particles surface-imprinted with the chymotrypsin TSA were selective for the trypsin substrate, and particles surface-imprinted with the L-isomer of the enzyme TSA were enantioselective for the D-isomer of the substrate.