Ionophore-based nanospheres enable selective and sensitive fluorescence detection of copper ions

A novel ionophore-based fluorescent nanosensor has been successfully fabricated for the sensitive and selective detection of Cu²⁺ ions. The nanosensor was constructed through self-assembly of amphiphilic block copolymers, incorporating elesclomol as a Cu²⁺ ionophore and long-chain dialkylcarbocyanines (DiD) as a fluorescent dye. This design exhibits an "ON/OFF" fluorescence response, where Cu²⁺ ions are selectively sequestered within the nanosensors, resulting in fluorescence quenching of DiD. This strategy enables rapid and highly selective Cu²⁺ sensing with remarkable fluorescence quenching efficiency (up to 93.5 %) and an exceptionally low detection limit of 28.6 nM. The linear detection range extends over two orders of magnitude (0.05-10 μM). Furthermore, the feasibility of this nanosensor for practical applications was confirmed through successful determination of Cu²⁺ in real water and beer samples, with excellent recovery rates. This nanosensor offers advantages of simplicity, rapidity, and cost-effectiveness, holding significant potential for sensitive and selective Cu²⁺ detection in various biological and environmental samples.