Efficient nanobiocatalytic systems of nuclease P₁ immobilized on PEG-NH₂ modified graphene oxide: Effects of interface property heterogeneity

The use of graphene oxide (GO) nanosheets for functional enzyme support has attracted intensive interest owing to their unique planar structure and intriguing physical and chemical properties. However, the detailed effects of the interface properties of GO and its functionalized derivatives on active biomolecules are not well understood. We immobilize nuclease P₁, a common industrial nucleic acid production enzyme, on pristine and amino poly(ethylene glycol) (PEG-NH₂) modified GO nanosheets with interface property heterogeneity using two approaches, physical adsorption and chemical crosslinking. It is demonstrated that nuclease P₁ could be stable immobilized on the surface of pristine GO by physical adsorption and on the edge of modified GO nanosheets by chemical crosslinking. The resultant loading capacity of nuclease P₁ on pristine GO is as high as 6.45 mg/mg as a consequence of strong electrostatic and hydrophobic interactions between the enzyme and carrier. However, it is determined that the acid resistance, thermal stability, reusability and degradation efficiency of the immobilized enzyme on PEG-NH₂-modified GO are obviously improved compared to those of the enzyme immobilized on pristine GO. The enhanced catalytic behavior demonstrates that GO and its derivatives have great potential in efficient biocatalytic systems.