Copper ion modified graphitic C3N4 nanosheets enhanced luminol-H2O2 chemiluminescence system: Toward highly selective and sensitive bioassay of H2S in human plasma

A high-efficient chemiluminescence (CL) platform for highly selective and sensitive H 2 S detection was constructed on the basis of the quenching effect of S 2 − on the copper ion modified graphitic carbon nitride nanosheets (Cu 2+ -g-C 3 N 4 NSs) enhanced luminol-H 2 O 2 system. Cu 2+ -g-C 3 N 4 NSs with horseradish peroxidase-like catalytic activity were prepared and provide a great improvement for luminol-H 2 O 2 system. The presence of S 2 − induced the formation of CuS precipitate on g-C 3 N 4 NSs surface. The precipitate can block the catalytic Cu 2+ sites on the g-C 3 N 4 NSs surface, resulting in a great CL decrease of CL system. Based on such a mechanism, a simple, highly selective and sensitive CL biosensor for H 2 S detection was designed. Under the optimized conditions, luminol-H 2 O 2 -Cu 2+ -g-C 3 N 4 NSs system gave a decrease of CL intensity with the Na 2 S concentration increasing. The CL biosensor is in a linear range of 10.0 pM–50.0 nM and the detection limit for detecting Na 2 S is as low as 2.0 pM. Moreover, the method here has enjoyed a successful application for determining H 2 S in human plasma samples and the recovery is between 95.7% and 110.0%.