Experimental Investigation of Enzymatic Stability on Graphene

Studies attaching proteins to graphene have shown modulation of its electrical characteristics, however the effect of graphene surface on the biomolecular stability has not been studied. This poster shows how immobilizing enzymes such as horseradish peroxidase (HRP) and glucose oxidase (GOx) on graphene affects its stability when compared to free enzymes in solution. This study is conducted on mono-/bilayer graphene, which has gained importance in developing field-effect biosensors. This study shows that HRP and GOx stability is not changed significantly by tethering them to graphene, which is contrary to present literature reports. HRP stability on graphene lasts barely 24 hours, while GOx is found to be stable past 10 days. Through modeling of enzyme deactivation as a single reaction, the overall rate order is found to be first order in case of HRP and GOx. The deactivation rate constants for both enzymes are calculated and the activation energy leading to the deactivation has been calculated. These answers are key to realizing and testing graphene based biosensors in laboratories.