Direct enzyme patterning with microcontact printing and the growth of ZnO nanoparticles on the catalytic templates at room temperature

Abstract

Here we developed a microcontact printing (μCP) process to directly pattern enzymes in a single step without the loss of enzyme activity after printing. By modifying the substrate to display aldehyde groups, the direct stamping of urease enables the simultaneous patterning and covalent cross-linking of urease under the reducing agent NaCNBH₄, which does not degrade the enzyme activity. Because the enzyme was not treated by the cross-linker prior to the sampling but rather pre-assembled on the surface of the substrate, only the contact areas of the PDMS stamp reacted with the cross-linker on the substrate, minimizing the poisoning of the enzymatic sites. The exposed urease particles on the substrate, free from the cross-linker, were still catalytically active and utilized to grow crystalline ZnO nanoparticles on the enzyme patterns in ambient conditions and in aqueous solution.