Au NBPs@ZIF-67 nanoprobe based single-particle glutathione assay by dark-field microscopy

Abnormal level of glutathione (GSH) was usually related to some physiological and pathological diseases. Thus, developing an intelligent probe for the quantification of GSH was of great significance. Here, we proposed a general, simple, and rapid in situ synthesis strategy for preparing a novel plasmonic core-shell nanoprobe gold nanobipyramids@zeolitic imidazolate framework-67 (Au NBPs@ZIF-67) to realize the quantification of GSH in human serum sample at the single particle level. Mechanism research showed that the Co2+ (the metal node of ZIF-67) would be reduced by GSH, which resulted in the breakdown of ZIF-67 in the presence of GSH, and the scattering color of the nanoprobe would change from green to red under dark-field microscopy. Tricolor (RGB) analysis exhibited that the R/G value was linearly related to the concentration of GSH in the range of 0.01-1 & mu;M (R2 = 0.999) and the detection limit was 5.7 nM. Besides, this GSH sensing strategy exhibited high selectivity, which demonstrated a satisfactory recovery in human serum sample. This work provided a general method of synthesizing a type of intelligent core-shell scattering nanoprobe and the single particle detection strategy indicated promising application under the biological milieu.