Preparation of surface-modified electrode of copper(ii) oxide mixed with the molecularly imprinted polymer for enhancement of melamine detection with photoelectrochemical technique

Non-enzymatic electrochemical detection of melamine in dairy products by using CuO decorated carbon nanotubes nanocomposites

Melamine, a typical nitrogen enriched organic compound exhibiting great potential in the industrial sector, is exploited as an adulterant to inflate protein levels in dairy products, can pose serious threats to humans and therefore necessitates its swift detection and precise quantification at its first exposure. In this investigation, sensitive and reliable sensor probes were fabricated using CuO nanoparticles and its nanocomposites (NCs) with carbon nanotubes (CNTs), carbon black (CB), and graphene oxide (GO) to promptly quantify melamine in dairy products. The optical, morphological, and structural characteristics of the CuO-CNT NCs were achieved using diverse instrumental techniques including UV-visible spectroscopy, transmission electron microscopy, X- ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy and etc. The fabrication of glassy carbon electrodes (GCE) was accomplished by coating CuO-CNT NCs through a binder (5 % nafion). These sensor probes demonstrated outstanding electrochemical sensor performance with CuO-CNT NCs/Nafion/GCE sensor probe in terms of very low limit of detection (0.27 nM), good linearity range (0.05-0.5 nM), and relatively high sensitivity (93.924 µA µM-1 m-2) for melamine under optimized experimental conditions. Furthermore, the performance of CuO-CNT NCs/Nafion/GCE coated sensor probes was practically validated for the selective melamine detection in the real sample analysis of commercially available milk brands, which revealed significant figures of merit in a very short response time of 10 s. From the results, it was concluded that the current study might be helpful in the development of an efficient commercial sensor based on ultra-sensitive transition metal oxides in the field of health care monitoring, food stuffs in a broader scale as well as food applications.

Enhancement in Sensitivity and Selectivity of Electrochemical Technique with CuO/g-C3N4 Nanocomposite Combined with Molecularly Imprinted Polymer for Melamine Detection

This study focused on enhancing the sensitivity and selectivity to detect melamine by utilizing a photoelectrochemical method. This was achieved by combining a melamine-imprinted polymer with a CuO/g-C3N4 nanocomposite, which was synthesized through chemical precipitation and calcination. The resulting nanocomposite exhibits improved carrier mobility and photoelectrochemical properties. A molecularly imprinted receptor for selective detection was created through bulk polymerization with methacrylic acid and a melamine template. The characterization of the nanocomposite was performed using X-ray photoelectron spectroscopy for the chemical oxidation state, X-ray diffraction patterns for the crystalline structure, and ultraviolet/visible/near-infrared spectroscopy for optical properties. The CuO/g-C3N4 nanocomposite exhibits photoactivity under visible light. The modified electrode, incorporating the CuO/g-C3N4 nanocomposite and melamine-imprinted polymer, demonstrates a linear detection range of 2.5 to 50 nM, a sensitivity of 4.172 nA/nM for melamine, and a low detection limit of 0.42 nM. It shows good reproducibility and high selectivity to melamine, proving effective against interferences and real samples, showcasing the benefits of the molecularly imprinted polymer.

Using the photo-enhanced barrier effect on electrochemical response for highly sensitive detection of melamine

Melamine added to milk powder can lead to kidney injury and even death, but rapid detection is still hard due to the strong interference of milk powder solution. Herein, the CC/CeO2/CNPs mesh was constructed to detect melamine by using the photo-enhanced barrier effects on electrochemical response. Schottky barrier was regulated effectively to produce electrochemical response to melamine by photo-induced electrostatic interaction, which exhibited strong resistance to interference in milk powder solution. Sensitivity was enhanced by nearly 5 times and the lowest detection limit was reduced as low as 0.274 nM. The obtained high recovery (100%-104%) and good stability in milk powder solution indicated the good potential for practical applications. It provides a new opportunity for achieving strong resistance to interference by using the photo-enhanced barrier driving effect on electrochemical response.

Recent Progress in Photoelectrochemical Sensing of Pesticides in Food and Environmental Samples: Photoactive Materials and Signaling Mechanisms

Pesticides have become an integral part of modern agricultural practices, but their widespread use poses a significant threat to human health. As such, there is a pressing need to develop effective methods for detecting pesticides in food and environmental samples. Traditional chromatography methods and common rapid detection methods cannot satisfy accuracy, portability, long storage time, and solution stability at the same time. In recent years, photoelectrochemical (PEC) sensing technology has gained attention as a promising approach for detecting various pesticides due to its salient advantages, including high sensitivity, low cost, simple operation, fast response, and easy miniaturization, thus becoming a competitive candidate for real-time and on-site monitoring of pesticide levels. This review provides an overview of the recent advancements in PEC methods for pesticide detection and their applications in ensuring food and environmental safety, with a focus on the categories of photoactive materials, from single semiconductor to semiconductor-semiconductor heterojunction, and signaling mechanisms of PEC sensing platforms, including oxidation of pesticides, steric hindrance, generation/decrease in sacrificial agents, and introduction/release of photoactive materials. Additionally, this review will offer insights into future prospects and confrontations, thereby contributing novel perspectives to this evolving domain.