Electronic Tongue Based on ZnO/ITO@glass for Electrochemical Monitoring of Spiciness Levels

Non-destructive assessment of chilling injury in red pepper powder using short-wave-infrared and XGBoost algorithm

This study aimed to evaluate red pepper powder quality by the extent of chilling injury and develop a method for detecting chilling injury-affected pepper powder. Pepper powder produced from chilling injury-affected pepper fruits exhibited increased bitter amino acids, microbial counts, and biogenic amines and decreased sweetness index and organic acid levels. These quality deteriorations indicate the need to detect chilling injury in pepper powders. The color values were insufficient to identify the occurrence of chilling injury. Therefore, hyperspectral imaging was used to detect the chilling injury. Based on the feature importance metrics results from XGBoost and correlation analysis, five key wavelengths were selected from a total of 188 wavelengths. The XGBoost model, using selected wavelengths, demonstrated higher accuracy (100 %) in discriminating the chilling injury level in pepper powder compared to that using full-wavelengths (98.0 %). These results provide insights into the rapid and non-destructive quality assessment of pepper powder.

An electrochemical bio-electronic tongue based on borophene/PPy@ITO hybrid for selective caffeine identification

Caffeine is a natural stimulant found in various plants. Some individuals are particularly sensitive to caffeine and may experience adverse effects even with minimal intake. In order to address the potential health risks associated with high caffeine use, it is imperative to establish a precise, straightforward, efficient, and cost-efficient approach for measuring caffeine levels in regularly consumed items. This article explores electrochemical techniques for monitoring bitterness induced by caffeine. The fabricated bio-electronic tongue (Bio-ET) comprised a modified electrode made of borophene/PPy@ITO, created by electropolymerizing polypyrrole (PPy) onto indium tin oxide (ITO) and subsequently decorating it with borophene sheets. Cyclic voltammetry (CV) was used to investigate the electrochemical characteristics of caffeine on borophene/PPy@ITO. The findings revealed that the Bio-ET exhibited strong electro-oxidation and reduction activity towards caffeine, indicated by the presence of distinct redox peaks. The Bio-ET demonstrated a linear range from 0.5 to 700 μM with a limit of detection (LOD) of 0.177 μM. The Bio-ET electrode was successfully employed for caffeine quantification in real samples, including coffee, black tea, and regular tea, yielding excellent electrocatalytic performance. Furthermore, the potential of the Bio-ET system could lead to the development of portable, user-friendly devices for on-site analysis, facilitating rapid testing in various settings, such as beverages and pharmaceuticals, and presenting a promising direction for both research and commercial applications.

WSe2-PPy-Based Type-II Heterostructure for Efficient Photocatalytic Removal of Nitrofurazone

The escalating concerns over water pollution and antimicrobial resistance have underscored the urgency of effective antibiotic degradation. Photocatalytic degradation offers a promising solution due to its efficiency and environmental friendliness. In this study, I synthesized a novel nanocomposite comprising WSe2 and polypyrrole (PPy) via a hydrothermal method coupled with polymerization for the degradation of nitrofurazone antibiotics. The WSe2/PPy nanocomposite demonstrated significantly higher photocatalytic degradation efficiency (94.50%) compared to pure WSe2 and PPy, with degradation efficiencies of 23.07% and 32.96%, respectively. The degradation was performed at different pH values, with acidic conditions proving the most suitable for nitrofurazone degradation. The photocatalytic degradation efficiencies at pH 2, 3, 5, 7, 9, and 11 were 98.5%, 98.3%, 85.4%, 78.02%, 61.4%, and 61%, respectively. The acidic conditions were found to be the most suitable for nitrofurazone degradation. The nanocomposite's improved efficiency was ascribed to its low recombination rate and quick charge transfer, as demonstrated by time-resolved photoluminescence (TRPL) and electrochemical impedance spectroscopy (EIS) tests, respectively. The Z-Scheme photocatalysis mechanism as proposed for the WSe2-PPy nanocomposite and supported by scavenger experiments. Moreover, the nanocomposite demonstrated excellent reusability, which enhanced its practical applicability.

MXene/Hydrogel-based bioelectronic nose for the direct evaluation of food spoilage in both liquid and gas-phase environments

Various bioelectronic noses have been recently developed for mimicking human olfactory systems. However, achieving direct monitoring of gas-phase molecules remains a challenge for the development of bioelectronic noses due to the instability of receptor and the limitations of its surrounding microenvironment. Here, we report a MXene/hydrogel-based bioelectronic nose for the sensitive detection of liquid and gaseous hexanal, a signature odorant from spoiled food. In this study, a conducting MXene/hydrogel structure was formed on a sensor via physical adsorption. Then, canine olfactory receptor 5269-embedded nanodiscs (cfOR5269NDs) which could selectively recognize hexanal molecules were embedded in the three-dimensional (3D) MXene/hydrogel structures using glutaraldehyde as a linker. Our MXene/hydrogel-based bioelectronic nose exhibited a high selectivity and sensitivity for monitoring hexanal in both liquid and gas phases. The bioelectronic noses could sensitively detect liquid and gaseous hexanal down to 10-18 M and 6.9 ppm, and they had wide detection ranges of 10-18 - 10-6 M and 6.9-32.9 ppm, respectively. Moreover, our bioelectronic nose allowed us to monitor hexanal levels in fish and milk. In this respect, our MXene/hydrogel-based bioelectronic nose could be a practical strategy for versatile applications such as food spoilage assessments in both liquid and gaseous systems.

Non-Enzymatic Glucose Sensors Composed of Polyaniline Nanofibers with High Electrochemical Performance

The measurement of glucose concentration is a fundamental daily care for diabetes patients, and therefore, its detection with accuracy is of prime importance in the field of health care. In this study, the fabrication of an electrochemical sensor for glucose sensing was successfully designed. The electrode material was fabricated using polyaniline and systematically characterized using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and UV-visible spectroscopy. The polyaniline nanofiber-modified electrode showed excellent detection ability for glucose with a linear range of 10 μM to 1 mM and a detection limit of 10.6 μM. The stability of the same electrode was tested for 7 days. The electrode shows high sensitivity for glucose detection in the presence of interferences. The polyaniline-modified electrode does not affect the presence of interferences and has a low detection limit. It is also cost-effective and does not require complex sample preparation steps. This makes it a potential tool for glucose detection in pharmacy and medical diagnostics.

Hydrothermally Synthesized Z-Scheme Nanocomposite of ZIF-9 Modified MXene for Photocatalytic Degradation of 4-Chlorophenol

4-Chlorophenol (4CP) is a well-known environmental contaminant often detected in wastewater, generally arising from industrial processes such as chemical manufacture, pharmaceutical production, and pesticide formulation. 4CP is a matter of great concern since it is persistent and has the potential to have harmful impacts on both aquatic ecosystems and human health, owing to its hazardous and mutagenic properties. Hence, degradation of 4CP is of utmost significance. This research investigates the photocatalytic degradation of 4CP using a novel Z-scheme heterojunction nanocomposite composed of MXene and ZIF-9. The nanocomposite is synthesized through a two-step hydrothermal method and thoroughly characterized by using XRD, SEM, UV-visible spectroscopy, zeta potential, and electrochemical impedance spectroscopy studies, confirming successful fabrication with improved surface properties. The comparative photocatalytic degradation studies between pristine materials and the nanocomposite were performed, and significant enhancement in performance was observed. The effect of pH on the degradation efficiency is also explored and correlated with the surface charge. The Z-scheme photocatalysis mechanism is proposed, which is supported by time-resolved photoluminescence studies and scavenger experiments. The reusability of the nanocomposite is also evaluated. The study contributes to the development of efficient and sustainable photocatalysts for wastewater treatment.