Graphene–hemin hybrid nanosheets as a label-free colorimetric platform for DNA and small molecule assays

Abstract

Here we report a novel label-free colorimetric biosensing strategy based on graphene–hemin hybrid nanosheets (GHs) for DNA and small molecule assays. GHs were synthesized by a simple wet-chemical method and they possess excellent properties from both graphene and hemin. When mixed with ssDNA, GHs exhibited enhanced catalytic activity in the presence of ABTS and H₂O₂. In contrast, the GHs mixed with dsDNA had lower catalytic activity than those mixed with ssDNA. On the basis of this property of the GHs, a novel universal label-free colorimetric method was proposed. This simple strategy has advantages over conventional assays because of its label-free design, extreme operational simplicity and low cost. DNA and cocaine were studied as model cases and the results revealed that the developed method had potential for becoming a universal platform for detection of a wide range of analytes.