Khan_2018_Methods.Enzymol_609_83

The unexpected discovery of graphene and especially the follow-up explosion of interest in its properties and applications marked the beginning of a new carbon era. Graphene-based nanostructured materials are highly useful because they show great promise in the field of biotechnology and biomedicine. Owing to their unique structural features, exceptional chemical, electrical, and mechanical properties, and their ability to affect the microenvironment of biomolecules, graphene-armored nanomaterials are suitable for use in various applications, such as immobilization of enzymes, field-effect transistors, photovoltaic devices, and biosensors, which in turn is extremely vital to the development of biomedical instruments, clinical diagnosis, and disease treatment. In this chapter, we present our recently reported work to armor hydrolytic enzymes on graphene-based nanomaterial in order to develop novel scaffolds to build robust nanobiocatalysts. Synthesized graphene-Fe3O4 and polyaniline-coated silver graphene nanocomposite have been used to immobilize beta-galactosidase and lipase, using noncovalent and covalent strategies, respectively. Herein, the methodologies of both techniques have been discussed in detail. Owing to the large surface area offered by the honeycomb like structure of graphene, very high amount of enzyme has been loaded on small amounts of the nanocomposite. The stability and reusability of the fabricated nanobiocatalysts have been compared with their free forms. Nanographene-armored enzymes demonstrated high catalytic stability and easy recovery from the reaction medium and can be applied in various biotechnological applications. Lastly, future prospects and possible challenges in this rapidly developing area have also been discussed.