Colorimetric Detection of Carcinogenic Aromatic Amine Using Layer-by-Layer Graphene Oxide/Cytochrome c Composite.

Graphene and its derivatives were found to be efficient modulators of enzymes in various systems. However, the modulating mechanism was not well discussed for long time. Inspired by the artificial enzyme-enhancing property of graphene oxide (GO) toward cytochrome c (cyt. c), we have successfully fabricated a protein/GO hybrid structure via a layer-by-layer (LbL) strategy. The obtained LbL assemblies showed great enhancement in peroxidase activity of cyt. c, as well as excellent stability, resistance to extreme environment change, and also possibility for recycling by simple centrifugation without any obvious activity loss. The LbL cyt. c/GO hybrids were expanded to a colorimetric sensing system for the detection of carcinogenic aromatic amines. The probe showed high sensitivity and selectivity for aromatic amines over various competing soluble aromatic compounds and could be determined by the naked eye or portable devices. The working mechanism was well studied through kinetic evaluation, experimental characterization, and molecular dynamics simulations. This work does not only introduce a new graphene/protein hybrid material or a rapid and sensitive visualization of carcinogenic aromatic amines, but also spread the practical application of biomolecule-graphene interface strategy and further give a better understanding of the interaction of graphene and protein.