Facile sonochemical synthesis of pH-responsive copper nanoclusters for selective and sensitive detection of Pb²⁺ in living cells

Abstract

A one-pot sonochemical reaction of Cu(NO3)2 with glutathione (GSH), the latter functioning as a reducing agent and a stabilizing agent, rapidly affords Cu nanoclusters (NCs). The as-prepared GSH-CuNCs possess a small size (∼2.2 ± 0.2 nm), red luminescence with quantum yield (5.3%), and water-dispersibility. Moreover, the fluorescence of the as-prepared GSH-CuNCs is responsive to pH so that the intensity of fluorescence increases rapidly with decreasing pH from 9 to 4. Besides, the GSH-CuNCs would be aggregated by Pb(2+) ions in aqueous solution which results in quenching of the fluorescence. Therefore, such GSH-CuNCs would be excellent candidates as fluorescent probes for the label-free detection of Pb(2+) with the limit of detection at 1.0 nM. Importantly, CAL-27 cells are used as models to achieve potential application as probes for monitoring Pb(2+) in living cells. Thus, these fluorescent CuNCs could work as an alternative to conventional fluorescent probes for biolabeling, sensing and other applications.

Stimuli‐Responsive Fluorescent Nanoswitches: Solvent‐Induced Emission Enhancement of Copper Nanoclusters

“…Glutathione‐capped CuNCs ( GSH‐CuNCs) were synthesized by a one‐pot method in water . First, Cu(NO 3 ) 2 ⋅ 3 H 2 O is dissolved in deionized water.…”

Fluorescent nanoprobes for sensing and imaging of metal ions: Recent advances and future perspectives

“…Furthermore, fluorescent AuNCs synthesized using BSA was also applied for the sensing of Cu 2+ in live cells [136]. In the same way, Wang et al developed a method for Pb 2+ detection in aqueous solutions and in living cells via NP aggregation by the synthesis of a pH-responsive copper NC functionalized with GSH [137]. Another smart strategy for intracellular Hg 2+ imaging was developed by Pu et al [138] in which a FRET-based hybrid complex nanoprobe using blue-fluorescent conjugated oligomer-substituted polyhedral oligomeric silsesquioxane (POSSFF) and red-fluorescent metal NCs as the energy donor and acceptor, respectively.…”

Luminescent Metal Nanoclusters for Potential Chemosensor Applications

“…In this work, upon the accumulation of Hg 2+ ions, the fluorescence of GSH-Cu NCs was quenched between the linear range from 10 nM to 10 μM with an LOD of 3.3 nM. Interestingly, the above probe with a quantum yield of 5.3% was also developed through sonochemical synthesis and consumed in fluorescent "turn-off" sensing of Pb 2+ ions with an LOD of 1.0 nM [131]. On the other hand, Bing-Yan et al represented the employment of GSH-Cu NCs in fluorescent "turn-on" recognition of Pb 2+ ions [132].…”