An Ultra-sensitive Kaempferol Electrochemical Sensor Based on Flower-like ZIF-8 Pyrolysis-derived ZnWO4/Porous Nanocarbon Composites

Green and Low-temperature Synthesis of Carbon Dots for Simple Detection of Kaempferol

As a common flavonols, kaempferol (Kae) has a broad market as health food and medicine for its anti-inflammatory, anti-oxidation, and anti-cancer properties. In this study, a novel convenient and simple fluorescent sensor based on carbon dots (CDs) for the detection of Kae was developed. The fluorescent CDs, with excellent photo-luminescence (PL) and up-conversion luminescence (UCPL) properties, were successfully prepared by low-temperature oil bath reaction based on ascorbic acid as carbon source at 90 °C in one pot. Under the optimal conditions, the fluorescence (FL) intensity of CDs was gradually quenched by the increasing addition of Kae with a linear relationship between F0/F and Kae concentration in a wide range from 5 µM to 100 µM with a detection limit of 0.38 µM. And this designed sensor was favourably applied for the detection of Kae in actual sample (xin-da-kang tablets). Moreover, the proposed CDs has great application prospects as a drug-sensor for detecting Kae due to its simple operation, economical and green materials, low equipment requirement, and rapid detection.

A Sandwich-Type Electrochemical Immunosensor for Insulin Detection Based on Au-Adhered Cu5 Zn8 Hollow Porous Carbon Nanocubes and AuNP Deposited Nitrogen-Doped Holey Graphene

Rapid, accurate, and sensitive insulin detection is crucial for managing and treating diabetes. A simple sandwich-type electrochemical immunosensor is engineered using gold nanoparticle (AuNP)-adhered metal-organic framework-derived copper-zinc hollow porous carbon nanocubes (Au@Cu₅ Zn₈ /HPCNC) and AuNP-deposited nitrogen-doped holey graphene (NHG) are used as a dual functional label and sensing platform. The results show that identical morphology and size of Au@Cu₅ Zn₈ /HPCNC enhance the electrocatalytic active sites, conductivity, and surface area to immobilize the detection antibodies (Ab₂ ). In addition, AuNP/NHG has the requisite biocompatibility and electrical conductivity, which facilitates electron transport and increases the surface area of the capture antibody (Ab₁ ). Significantly, Cu₅ Zn₈ /HPCNC exhibits necessary catalytic activity and sensitivity for the electrochemical reduction of H₂ O₂ using (i-t) amperometry and improves the electrochemical response in differential pulse voltammetry. Under optimal conditions, the immunosensor for insulin demonstrates a wide linear range with a low detection limit and viable specificity, stability, and reproducibility. The platform's practicality is evaluated by detecting insulin in human serum samples. All these characteristics indicate that the Cu₅ Zn₈ /HPCNC-based biosensing strategy may be used for the point-of-care assay of diverse biomarkers.