Development of biosensors using ordered nanoporous carbon

Abstract

A mesocellular carbon foam, MSU-F-C, was synthesized and used as a host for enzyme immobilization, and then employed for biosensor fabrication. The unique structural properties of MSU-F-C, such as large surface area and pore volume, large mesopores with uniform size, and small particle size (< 500 nm), enabled an efficient immobilization of a large enzyme, glucose oxidase (GOx), thereby resulting in a high enzyme loading. The loading in MSU-F-C was significantly higher than those in other porous carbons, including another type of mesoporous carbon, CMK-3, and in mesoporous silica. Furthermore, the resulting MSU-F-C/GOx composite exhibited excellent stability of the catalytic activity. A glucose biosensor was constructed by coating the surface of a glassy carbon electrode with MSU-F-C/GOx using Nafion membrane. The resulting glucose biosensor exhibited high sensitivity to glucose, due to the high enzyme density on electrode and the large effective electrode surface area provided by the electrically conductive MSU-F-C. Based on these results, a magnetically controllable electrochemical biosensing system using immobilized enzymes was developed. As a suitable enzyme carrier for this system, a mesoporous carbon with incorporated magnetic nanoparticles (MNPs) was synthesized by a simplified approach, based on the in situgeneration of MNPs during the synthesis of the mesocellular carbon. The resulting Mag-MCF-C has many desirable characteristics for preparation of immobilized enzymes for magnetically controllable electrochemical biosensing system: large pore size and volume, the ability to be positioned with a magnet, and good electron conductivity. The Mag-MCF-C was found to possess large interconnected pores and well-dispersed MNPs on the exterior carbon surface. As a result, Mag-MCF-C showed high loading and fast immobilization kinetics for GOx. By taking advantage of unique pore structure of Mag-MCF-C, in combination with cross-linking agent, the immobilized enzym...