Peptide-capped functionalized Ag/Au bimetal nanoclusters with enhanced red fluorescence for lysosome-targeted imaging of hypochlorite in living cells

Highlights

• The peptide functionalized nanoclusters were rationally designed and had good cell penetrating ability.

• The probe has lysosome-targeting capability for monitoring ClO⁻ level in living cells.

• The probe has good selectivity and sensitivity towards ClO⁻ over other species commonly present in biological matrices.

Abstract

Bioimaging probes for monitoring intracellular reactive oxygen species have important implications for cell biology research. Herein, we developed peptide-capped silver/gold nanoclusters (peptide@Ag/Au NCs) for lysosome-targeted imaging of hypochlorite (ClO⁻). The peptide@Ag/Au NCs were synthesized via a one-pot method using peptide as both a template and a reducing agent. The fluorescence intensity and absolute quantum yield of peptide@Ag/Au NCs were much higher than those of peptide-capped gold nanoclusters and silver nanoclusters. In the presence of ClO⁻, the fluorescence of peptide@Ag/Au NCs was quenched, accompanied by a redshift due to ClO⁻-induced oxidation of the peptide ligand and decreased Ag content in Ag/Au NCs. The relative fluorescence intensity F₀/F had favourable linearity for ClO⁻ concentrations in the range 0.1–100 μmol/L (R² = 0.9954), with a detection limit (LOD) of 80 nmol/L. The lysosome-targeted peptide@Ag/Au NCs were applied to detect ClO⁻ in lysosomes in living cells via fluorescence imaging.