Ultrasensitive competitive electrochemiluminescence immunosensor based on luminol-AuNPs@Mo2C and upconversion nanoparticles for detection of diethylstilbestrol

Abstract

A competitive electrochemiluminescence (ECL) immunosensor for sensitive detection of diethylstilbestrol (DES) was successfully fabricated. Initially, molybdenum carbides (Mo2C) with excellent conductivity and large surface area were applied as the ECL reagent nanocarriers of luminol-capped Au nanoparticles (luminol-AuNPs). ECL performance of luminol-AuNPs with Mo2C (lumino-AuNPs@Mo2C) hybrid get enhanced in comparison with individual luminol-AuNPs due to facilitated electron transfer process. To carry out successful fabrication of competitive immunosensor, the label was constructed by encapsulating upconversion nanoparticles (UCNPs) functionalized by platinium into metal-organic frameworks (UCNPs-Pt@MOF). The synthesized UCNPs-Pt@MOF firmly anchored DES-antigen (Ag) by covalent bonding and was able to convert longer wavelength irradiation to shorter wavelength emission. In addition, UCNPs-Pt@MOF has been used as signal amplification mediator and it exhibited high catalytic activity towards hydrogen peroxide. Under optimal experimental condition, reliable and successful determination of DES was done within linear range of 0.1 pg/mL to 30 ng/mL with detection limit of 3.8 fg/mL (S/N = 3). The ECL immunosensor exhibited acceptable selectivity, good sensitivity and high repeatability. Moreover, the proposed competitive ECL immunosensor was evaluated by detecting DES in real water samples with satisfactory results. Therefore, this immunosensor has potential application values for detecting DES and other environmental pollutants.