Multiple signal amplification strategy using porous materials and novel controlled release self-on mode for ultrasensitive immunoassay

Abstract

Sensitivity and accuracy are key indicators for analysis, while the signal self-on/off effect is an effective means to enhance detection sensitivity. Herein, we have utilized the multiple signal amplification strategy of porous Ag/Au shell with high efficiency catalytic functionality and an aggregation-caused quenching (ACQ) elimination effect firstly. The wrapping of the Ag/Au shell eliminated the ACQ effect of rubrene (Rub), and Ag can catalyze the decomposition of the coreactant K₂S₂O₈ and lead to the formation of more SO₄˙⁻ radicals, thereby improving its electrochemiluminescence (ECL) efficiency, which promoted the application of aromatic rings as luminescence probes. Secondly, a mesoporous Fe–MOF with strong catalytic activity for the coreactants (K₂S₂O₈) was selected as a controlled release carrier to further improve the output signals of the sensor. Thirdly, the coreactants were encapsulated as functional factors, realizing controllable changes in output signals from scratch with the introduction of targets. These strategies maximize the self-on effect to more clearly display subtle changes in the concentration of the analyte, prostate-specific antigen (PSA). On this basis, the developed ECL sensor exhibited good sensitivity and accuracy for PSA detection, with a detection limit of 5.01 fg mL⁻¹, which provided an important basis for constructing efficient biosensors to better meet immunoassay needs.