This study demonstrates that the enzymatic reaction rate can be increased significantly by targeted heating of the microenvironment around the enzyme, while maintaining the reaction system at environmental temperature. Enzyme molecules are covalently attached to the surface of Fe3 O4 @reduced graphite oxide (rGO). Under visible-light irradiation, the reaction rate catalyzed by the enzyme-Fe3 O4 @rGO system is clearly enhanced relative to that of the free enzyme and a mixture of free enzyme and Fe3 O4 @rGO. This local heating mechanism contributes to promotion of the enzymatic reactions of the targeted heating of the enzyme (THE) system, which has been validated by using different enzymes, including lipase, glucose oxidase, and organophosphorus hydrolase. These results indicate that targeted heating of the catalytic centers has the same effect on speeding up reactions as that of traditional heating methods, which treat the whole reaction system. As an example, it is shown that the THE system promotes the sensitivity of an enzyme screen-printed electrode by 14 times at room temperature, which implies that the THE system can be advantageous in improving enzyme efficiency, especially if heating the entire system is impossible or could lead to degradation of substrates or damage of components, such as in vitro bioanalysis of frangible molecules or in vivo diagnosis.
Keywords: biosensors; enzymes; magnetic properties; nanoparticles; photochemistry.
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