A novel copper-based nanozyme: fabrication and application for colorimetric detection of resveratrol

A novel nanozyme (urea@Cu-NF) was synthesized by self-assembly of urea and copper phosphate with urea as plasticizer. Urea@Cu-NF exhibited excellent peroxidase-like activity with the ability to oxidize TMB in the presence of H2O2. However, its peroxidase-like activity could be inhibited by resveratrol, leading to an absorption decrease in the intensity of oxTMB. Based on this phenomenon, a colorimetric method was designed for resveratrol detection. The colorimetric reaction could be completed within 20 min with a linear range of 1-120 μM. The limit of detection (LOD) of resveratrol is 0.43 μM. Our experimental results demonstrate that urea@Cu-NF has enormous potential to function as a cheap and accurate quality detection tool.

Trans-resveratrol electrochemical detection using portable device based on unmodified screen-printed electrode

Trans-resveratrol (t-RESV) is an important and natural polyphenolic antioxidant generally found in grapes and in its derivatives such as red wine and grape juices. The t-RESV has been explored in the pharmaceutical industry for its anti-inflammatory, anti-cancer, and neuroprotective properties. The t-RESV electrochemical determination has basically been carried out using modified electrodes-based sensors. Although these devices show good analytical performance, the electrode preparation can be laborious, and the devices may lack reproducibility. In this sense, it was proposed here a new methodology for the t-RESV electrochemical detection using unmodified screen-printed electrodes and differential pulse voltammetry (DPV). The response of the anodic signal has optimized varying the most important parameters of DPV (pulse time, pulse potential, and pulse step) using the response surface methodology. We showed based on analysis of variance that the new mathematical model developed can predict responses for the t-RESV using DPV. Furthermore, the new analytical method was validated from the limits of detection and quantification. We have still shown that t-RESV can be quantified in commercial drug using DPV with the optimized parameters. The selectivity test also showed that the sensor can be used to determine the antioxidant in other more complex matrices. Additionally, the proposed electrochemical system is completely portable and can work with its own energy, which facilitates point-of-care analysis.

Ultrasonic synthesis of nano-PrO1.8 as nanozyme for colorimetric determination of trans-resveratrol

In this study, nano-PrO1.8 were synthesized successfully in ionic liquids (ILs) as template assisted ultrasonic irradiation method. Various precipitating agents and different types of ILs were investigated to determine their respective effects on the morphology of the end products. Using hydrazine hydrate as a precipitating agent and 1-carboxymethyl-3-methylimidazolium chloride as a template, spherical structure with an average diameter of 250 nm was obtained. It is worth noting that the prepared material exhibits high peroxidase-like activity and weak oxidase activity. Then, the catalytic oxidation capacity of the nano-PrO1.8 was evaluated by the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB). The colorless of TMB can be converted into blue oxidized TMB (oxTMB) in the presence of nano-PrO1.8, but trans-resveratrol inhibited its peroxidase-like activity and weakened the blue color. Hence, we developed a sensitive, selective and simple colorimetric method for trans-resveratrol detection using nano-PrO1.8 as peroxidase-like enzyme. A linear relationship was found in the range of 0.30 µM-16 µM trans-resveratrol with the detection limit of 0.29 µM. Satisfactory results were achieved when the method was submitted to the determination of trans-resveratrol in white wine samples.