Time-dependent study of graphene oxide-trypsin adsorption interface and visualization of nano-protein corona

Understanding of interactions of nanomaterialswith biomolecules (especially proteins) is of great importance to the area of nanobiotechnology. Graphene and its derivative such as graphene oxide (GO), are two-dimensional (2-D) nanomaterials with remarkable physical and chemical properties and have been broadly explored in biotechnology and biomedical application. Here, we have reported the nature of adsorption of trypsin on theGOsurface, considering its biomedical implications. A simple incubation of trypsin on GO surface exhibits varying resistance to autolysis. The structural morphology of trypsin on the GO surface was studied by using atomic force microscopy (AFM), circular dichroism (CD), fluorescence, and total internal reflection fluorescence (TIRF) microscopies. Results suggest that the trypsin follows the Freundlich Isotherm. By the Langmuirmodel, the maximum adsorption capacity was found to be 100 mg/g. Fromprotein assay results we have concluded that the native trypsin exhibits the highest catalytic efficiency (33.97*10(4) L mol(-1) min(-1)) in comparison to other Trp-GO constructs. We have further visualized morphological change on GO-trypsin interface throughout the adsorption process by taking samples at definite time intervals, which suggests that the interaction of trypsin with GO is an example of the soft corona. Our findings may be implicated in enzyme engineering as well as enzyme-based biosensing applications. (C) 2020 Published by Elsevier B.V.