Magnetic graphene oxide-supported hemin as peroxidase probe for sensitive detection of thiols in extracts of cancer cells

Magnetic graphene oxide (GO)–hemin probes containing disulfide bonds are simply and effectively synthesized through amide reaction to covalently link magnetic particles to GO surface and π – π stacking interaction between hemin and GO to immobilize hemin on GO. Based on the strong nucleophilicity of sulfhydry, we have developed a colorimetric detection system for thiols by using glutathione (GSH) as a model analyte . Upon the introduction of GSH to the fabricated magnetic particle (MP)-GO–hemin probes, the disulfides can be readily reduced by thiols, resulting in the release of GO–hemin hybrids to solution. Due to the existence of hemin on GO surface, the released GO–hemin that has the intrinsic peroxidase-like activity can catalyze the oxidation of ABTS 2− by H 2 O 2 to form the colored radical product ABTS ·− . A broad linear dynamic range of 10 −10   M to 10 −6   M GSH is achieved with a detection limit of 8.2×10 −11   M (3 σ ). Moreover, the new probe is successfully applied to the detection of non-protein thiols and protein thiols in the extracts of Ramos cells, which shows favorable correlationship with the results obtained by electrochemical method . In addition, the MP-GO–hemin probe can detect non-protein thiols in Ramos extracts as low as 500 cells. In this assay, the prepared MP-GO–hemin conjugates are thoroughly characterized by SEM , AFM , UV–Vis, FT-IR, and Raman spectroscopy.