Modulation of inner filter effect between plasmonic Cu2−xSySe1−y and rhodamine 6G for detection of biothiols

Abstract

Synthesis and engineering of nanostructures with multiple components for the acceptable biosensing platform is a hot topic research. Herein, flower-like nonstoichiometric copper chalcogenides nanocrystals (Cu2−xSySe1−y NCs) loaded with rhodamine 6G (R6G) were used as a selective and sensitive off-on fluorescent probe for biothiols based on inner filter effect (IFE). The Cu2−xSySe1−y showed the strong interband transition band in the UV–vis region and broad localized surface plasmon resonance (LSPR) in the near-infrared region which exhibited good light-harvesting features, and thus can show sufficient absorption of the excitation or emission light of fluorescent R6G with high fluorescence quenching ability. When the biothiols (glutathione, homocysteine and cysteine) were added, the interband transition bands of Cu2−xSySe1−y NCs were suppressed, resulting in the fluorescence of R6G switched on. There was a good linear relationship between fluorescent recovery of R6G and the concentrations of glutathione, homocysteine and cysteine over the range of 1.0–150 μM, 1.0–200 μM, 1.0–150 μM with a detection limit of 32.0 nM, 34.0 nM and 31.0 nM, respectively. The established strategy exhibited the selective response to biothiol compounds and was also been applied for detecting biothiols in the human serum samples.