The combination of highly efficient resonance energy transfer in one nanocomposite and ferrocene-quenching for ultrasensitive electrochemiluminescence bioanalysis

Sensitive and accurate detection of prostate-specific antigen (PSA) is of great significance since it is regarded as a biomarker for prostate diseases. Herein, a facile strategy for the design of highly efficient electrochemiluminescence (ECL) sensor was proposed for PSA assay. Carboxylated graphitic carbon nitride (g-C3N4) nanosheet (CCN) and tris (2, 2'-Bipyridyl) ruthenium (II) (Ru(bpy)32+) encapsulated in silica nanospheres (RuSi NPs) were employed as the donor and acceptor, respectively. CCN and RuSi NPs were covalently bound within one nanocomposite (CCN@RuSi) through the amide bond, which greatly shortened the electron-transfer path. Thus, the resonance energy transfer (RET) efficiency was remarkably increased, providing a high initial ECL intensity for the ECL assay. After the successive introducing of aptamer, PSA, and ferroceneboronic acid (FcBA) on the surface of CCN@RuSi modified electrode, the ECL signal remarkably decreased, which was caused by the steric hindrance of PSA and electron transfer quenching between Fc+ and excited-state Ru(bpy)32+*. Therefore, a highly efficient ECL platform was constructed, which achieved the ultrasensitive detection of PSA with a linear range and a limit of detection of 100 fg/mL - 50 ng/mL and 1.2 fg/mL, respectively. Furthermore, the dual-affinity of the aptamer and FcBA to PSA endowed the sensor with a high selectivity for the determination of PSA in human serum samples. The present work provides an important reference for the integration of RET and quenching strategy in the ECL study with rapid, ultrasensitive, and highly selective detection performances.