Enhanced chemiluminescence with sub-1 nanometer CuO-PMA nanosheets for the sensitive detection of quercetin.

Background: Chemiluminescence (CL) analysis, characterized by its simple instrumentation, high signal-to-noise ratio, wide linear range, and minimal background interference, has garnered increasing attention from researchers. Nanomaterials (NMs) have been explored to enhance CL intensity. Notably, sub-1 nanometer scale NMs are considered to hold significant untapped potential due to their size effects. The application of these sub-1 nanometer NMs in enhancing CL is anticipated to yield favorable results. Additionally, the low water solubility and bioavailability of quercetin glycosides lead to their presence in bodily fluids at only trace levels, highlighting the urgent need for efficient and rapid detection methods.

Results: In this work, phosphomolybdic acid (PMA) was incorporated into CuO to synthesize sub-1 nanometer CuO-PMA nanosheets (SNSs) using a cluster-core co-assembly strategy. Conformational and structural characterization confirmed the successful synthesis of these nanosheets. The CuO-PMA SNSs were employed to enhance the CL emission of the luminol-HO system, resulting in an increase of over 1000 times. The catalytic properties of CuO-PMA SNSs significantly facilitated the decomposition of HO, leading to an enhanced production of reactive oxygen species, which in turn induced the CL enhancement. Given that the antioxidant effect of quercetin would consume the reactive oxygen species generated during the catalysis, a decrease in CL intensity was anticipated. A CL sensor for quercetin detection was developed based on the CuO-PMA SNSs-luminol-HO system, demonstrating a strong linear relationship (R = 0.9969) and a low detection limit of 0.31 nM.

Significance: This research provides a strategy to enhance the CL intensity of the luminol-HO system by using CuO-PMA SNSs, offering a highly sensitive assay for detecting quercetin concentrations. The method is characterized as a simple and cost-effective analytical strategy making CL analysis very attractive for chemical analysts.