Electrochemiluminescence resonance energy transfer between luminol and black phosphorus nanosheets for detection of trypsin via “off-on-off” switch mode
In this work, electrochemiluminescence (ECL) behavior of luminol-H2O2 system was studied on a black phosphorus nanosheets (BPNs) modified electrode. A quenching effect of BPNs on luminol ECL was obtained based on ECL resonance energy transfer (ECL-RET) with the excited state luminol as energy donor while BPNs as energy acceptor. Protamine could bind on the surface of BPNs through electrostatic interactions, which can cut off the energy transfer route between luminol and BPNs to restore the ECL signal. The immobilized protamine could be hydrolyzed by trypsin, as a result, the BPNs surface was exposed and the RET occurred again, resulting in the decreased ECL intensity instantly. The reduced ECL signals varied linearly with trypin concentrations, and could be indirectly used in the sensitive detection of trypsin in the range of 100 ng mL-1 to 5 μg mL-1. The detection limit of the biosensor was calculated at levels down to 6.33×10–8 g mL-1 (3σ). The proposed ECL sensor had been successfully used in the detection of trypsin in serum samples. The results reveal novel quenching effect of BP nanomaterials on ECL, which will further expand its application in ECL biosensing for protein.