Detection of urokinase based on ECL resonance energy transfer between block copolymers encapsulated iridium complex and ReS2 nanosheets

The encapsulation of water insoluble iridium complex in SiO2 nanoparticles can be used to fabricate aqueous electrochemiluminescence (ECL) sensor, however, the ECL signal is greatly reduced. It is urgent to explore more suitable method to encapsulate iridium complex and improve its ECL efficiency. Pluronic block copolymers has good biocompatibility and high load capacity, which might be used to encapsulate iridium complex. In the present work, one kind of concentric nanospheres were assembled by encapsulating iridium complexes into block copolymers using poly (styrene-co-maleicanhydride) (PSMA@Ir). Strong anodic ECL signal was obtained at PSMA@Ir nanospheres modified electrode without additional coreactant. The light absorption character of ReS2 nanosheets (ReS2NS) endowed it the ability to accept energy from PSMA@Ir ECL. As a result, a novel ECL resonance energy transfer (ECL-RET) system was constructed with PSMA@Ir as energy donor while ReS2NS as energy acceptor. Based on the above results, an ECL aptasensor was designed to detect urokinase (UPA). The ECL intensity changed linearly with the logarithm of UPA concentration in the range of 1.0 × 10−16–1.0 × 10−12 mol/L with a detection limit of 2.95 × 10−17 mol/L. The prepared sensor owned high sensitivity and selectivity, and provided new avenue for the application of water insoluble iridium complex in ECL sensing.