Hemin-graphene hybrid nanosheets with intrinsic peroxidase-like activity for label-free colorimetric detection of single-nucleotide polymorphism.

This paper demonstrated for the first time a simple wet-chemical strategy for synthesizing hemin-graphene hybrid nanosheets (H-GNs) through the π-π interactions. Significantly, this new material possesses the advantages of both hemin and graphene and exhibits three interesting properties. First, H-GNs have intrinsic peroxidase-like activity, which can catalyze the reaction of peroxidase substrate, due to the existence of hemin on the graphene surface. Second, their dispersion follow the 2D Schulze-Hardy rule, that is to say, the coagulation of H-GNs in electrolyte solution results from the interplay between van der Waals attraction and electric double-layer repulsion. Third, H-GNs exhibit the ability to differentiate ss- and ds-DNA in optimum electrolyte concentration, owing to the different affinities of ss- and ds-DNA to the H-GNs. On the basis of these unique properties of the as-prepared H-GNs, we have developed a label-free colorimetric detection system for single-nucleotide polymorphisms (SNPs) in disease-associated DNA. To our knowledge, this is the first report concerning on SNPs detection using functionalized graphene nanosheets. Owing to its easy operation and high specificity, it was expected that the proposed procedure might hold great promise in the pathogenic diagnosis and genetic diseases.