MnO₂ coated Au nanoparticles advance SERS detection of cellular glutathione

Glutathione, referred to as GSH, abnormal physiologic level of GSH is an indication to some neurodegenerative diseases and cancers. A measurement of cellular GSH calls for rapid, sensitive, and selective methods. In this work, we rationally design and prepare Au@MnO₂ core-shell composite nanoparticles combining with tetramethylbenzidine (TMB) molecules to determine intracellular GSH by Surface enhanced Raman scattering (SERS) technique. MnO₂ plays multifunctional roles in the method, including the participation in catalyzing TMB to molecules form dimer charge-transfer complex (CTC) which own a great SERS signal reporter. With the addition of GSH, the MnO₂ will be dissolving detaching CTC molecules from the surface of Au@MnO₂ and resulting in a signal-off off SERS response and indirect and sensitive detection of GSH could be realized. The limit of detection of GSH by SERS method is as low as 0.1 μmol/L and a good linear relationship of GSH is found in the range from 0.5 to 30 μmol/L. Au@MnO₂-SERS assay is successfully applied to detect cellular GSH, which is validated by using Enzyme-linked-immunoassay-based Kit. The Au@MnO₂-SERS protocol has promising potential for clinical application.