Ultrasensitive determination of quercetin using electrochemical sensor based on nickel doping zinc-based zeolite imidazole frame with a four-point star morphology

At present, achieving the electrochemical trace detection (picomole per liter level) with high sensitivity of quercetin is rare. In this work, the nickel-doped zinc-based zeolite imidazole framework with a four-point star morphology (Ni-ZIF-8-S) was successfully prepared through simple stirring and pH adjusting at room temperature. The strategies of nickel doping and morphology control endow Ni-ZIF-8-S with a large specific surface area, a unique hierarchical pore structure comprising both micropores and mesopores, abundant active sites, and excellent electron transport ability. Therefore, under optimal conditions, the electrochemical sensor based on Ni-ZIF-8-S can detect quercetin with a very high sensitivity of 622.0 μA μM⁻¹ and a limit of detection as low as 48 pM, enabling ultra-sensitive quantitative determination of quercetin in picomole per liter level. In addition, the proposed sensor also shows other excellent analytical performances, including good reproducibility, anti-interference, and stability. Importantly, the electrochemical sensor based on Ni-ZIF-8-S can also perform quantitative detection of quercetin in complex real samples, such as urine and honey, with acceptable results. The prepared sensor has the potential to be applied in monitoring and quality control of quercetin.