Signal-off electrochemiluminescence immunosensor based on Mn-Eumelanin coordination nanoparticles quenching PtCo-CuFe2O4-reduced graphene oxide enhanced luminol

Herein, a facile one-pot intrapolymerization strategy to synthesize manganese-eumelanin coordination nanocomposites (Mn-Eu) was introduced to quench the electrochemiluminescence (ECL) behavior of luminol/H2O2 system. Bimetallic PtCo and CuFe2O4 nanoparticles decorated with reduced graphene oxide was prepared to combine with luminol via electrostatic attractions (Lu-PtCo-CuFe2O4-rGO) which possessed excellent ECL signals. PtCo-CuFe2O4-rGO not only exhibited well electrocatalytic activity toward the electrooxidation reactions of luminol and H2O2, but also facilitated the electroreduction of H2O2 producing more reactive oxygen species (ROSs) which can further enhance the ECL intensity of luminol. To sensitively detect pmcalcitonin, Mn-Eu labeled-secondary antibodies were employed to specific recognize antigen which incubated with primary antibodies/Lu-PtCo-CuFe2O4-rGO. The quenching mechanism may be via the synergistic effect between Mn-Eu inhibiting the electrooxidation of H2O2 and ECL resonance energy transfer (ECL-RET) from ECL donor luminol to ECL acceptor Mn-Eu. Under optimal experiments, the ECL immunosensor for detecting procalcitonin with a wider linear range from 0.005 pg/mL to 100 pg/mL and a detection limit of 0.0021 pg/mL (S/N = 3) was obtained. The suggested strategy possessed great potential in bioanalysis and will broaden the application of Mn-Eu.