A highly selective fluorescent probe for sulfide ions based on aggregation of Cu nanocluster induced emission enhancement

Abstract

In this study, S²⁻ ions were found to enhance the fluorescence of cysteine-capped Cu nanoclusters (Cu NCs). High resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) measurements, zeta potential and X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the S²⁻ ion-induced aggregation of the Cu NCs contributed to the fluorescence enhancement of the dispersed Cu NCs. Based on these findings, a highly selective fluorescent probe was developed for the determination of H₂S using the S²⁻ ion-enhanced fluorescence of the as-prepared Cu NCs. The relative fluorescence intensity was proportional to the concentration of S²⁻ in the range from 0.2 to 50 μM. The detection limit (S/N = 3) was 42 nM. The proposed method has been successfully applied to determine H₂S produced from toys called “Fart Bomb” with recoveries of 97.6–101.8%. The results of the proposed method were in good agreement with those determined by a standard methylene blue method. This work is not only of importance for a better understanding of the aggregation induced emission (AIE) properties of the Cu NCs but also of great potential to find extensive biological applications for H₂S.