Fabrication of block-shaped Sb2O3 and flower-shaped CoNPs nanocomposites for ultrasensitive antioxidant quercetin sensing and its electrooxidation mechanism

Quercetin (Qu) is a natural pentahydroxyflavone that is thought to counteract oxidative cell damage by acting as an effective free radical scavenger, exhibits estrogenic and anticancer activities. Therefore, it is important to detect the content of Qu and study its electrooxidation mechanism. Here, we prepared Sb 2 O 3 @MWCNTs/GCE sensors based on block-shaped antimony oxide (Sb 2 O 3 ) and multi-walled carbon nanotubes (MWCNTs), and Pyrrole/CoNPs/GCE sensors with pyrrole and flower-shaped cobalt nanoparticles (CoNPs), respectively, for ultrasensitive detection of Qu, as these modified nanocomposites have excellent catalytic effect towards Qu. In contrast, the second sensor allowed ultrasensitive detection of Qu and had a wider linear range (0.10–100.00 μmol·L −1 ), a detection limit of 0.033 μmol·L −1 and a sensitivity of 8.98 µA·μmol·L −1 ·cm −1 . In addition, both sensors showed good repeatability, stability and selectivity. The recoveries of antioxidant Qu in ginkgo biloba by these two sensors ranged from 95.50 to 103.86 %, and the Qu accounted for 35.60 % and 39.57 % of the flavonol glycosides (19.20 mg) in the tablets. These studies demonstrate the potential application of both sensors in practical assays.