Surface Immobilization of Metalloenzymes Usinga Pyrene-Modified Hydrogel

Pyrene-modified hydrogels are useful materials for preparing thin enzyme-containing polymer coatings on solid surfaces. Cross-linked films of pyrene-modified linear poly(ethylenimine) (pyrene-LPEI) contain a network of ionic bonds and π-π interactions. The hydrogels are uniformly thin (~1 μm) and porous, allowing fast diffusion of small molecule substrates, making these materials ideal for applications in catalysis. Pyrene-LPEI has been particularly useful to promote bioelectrocatalysis in several different metalloenzymes, including laccase (reduction of O₂ to H₂O) and nitrogenase (reduction of N₂ to NH₃). When used to immobilize redox-active enzymes onto an electrode surface, pyrene-LPEI promotes efficient electron transfer between the enzymatic redox active site and electrode surface without the need for an additional electron mediator. This material facilitates a rapid method for determining the electrochemical potential of redox-active cofactors using exceptionally small amounts of the protein of interest.