Highly sensitive and selective electrochemical sensor for simultaneous determination of gallic acid, theophylline and caffeine using poly(l-proline) decorated carbon nanotubes in biological and food samples

Dual recognition electrochemical sensor for detection of gallic acid in teas, apples and grapes and derived products

Sensitive determination of gallic acid (GA) is important for food quality control due to its numerous bioactivity. This study presented an electrochemically deposited method for constructing poly(3-aminophenylboronic acid)-poly(β-cyclodextrin)/carboxylated multi-walled carbon nanotubes-chitosan (PAPBA-Poly(β-CD)/cMWCNT-CS) nanocomposites modified electrode. The cMWCNT-CS materials and PAPBA-Poly(β-CD) copolymer were utilized for signal amplification and dual recognition of GA, respectively. Electrochemical detection of GA was achieved through the peak current change of potassium ferricyanide redox probe induced by the synergistic interaction of PAPBA-Poly(β-CD) with target molecules. The proposed method exhibited an ultra-low limit of detection of 0.16 fM and ultra-wide response range of 10 fM to 10 μM for GA with the superiorities of easy construction, rapid response, good reproducibility, and excellent selectivity. This method could be employed to test GA concentration in black teas, apples, grapes, grape beverage, and wine samples, which provided an alternative method for ultrasensitive analysis of functional components in actual samples.

Development of a chemometrics-assisted electrochemical sensor applied to gallic acid quantification in food samples

Gallic acid (GA) is an abundant natural phenolic compound found in foods such as tea, fruits, and beverages. Quantifying GA remains a key research area in analytical chemistry. Traditional methods, such as liquid chromatography, are time-consuming, highlighting the need for faster and more efficient techniques to quantify GA concentration. This study proposes an approach based on the MCR-ALS algorithm to model second-order voltammetric data obtained by varying the scan rate. Data preprocessing and subsequent mathematical modeling enabled the quantification of GA with a detection limit of 5.9 mg L-1, below the stipulated concentrations for the analyte in various food matrices. Quantification was achieved even in the presence of unmodeled interferences, leveraging the second-order capabilities of multivariate calibration methods. This approach allows for accurate results to be obtained in a direct, fast, and reliable manner, representing a breakthrough in food industry quality control and opening new perspectives for food quality assessment.

Ultrasensitive electrochemical detection of gallic acid in beverages based on nitrogen-doped multi-walled carbon nanotube networks embellished with cobalt 2-methylimidazole nanoparticles

This work presents a convenient and easy-to-operate method for synthesizing the functionally integrated nanocomposite of nitrogen-doped multi walled carbon nanotube networks (N-CNTs) and cobalt 2-methylimidazole (ZIF-67) nanoparticles. The N-CNTs@ZIF-67 nanocomposite was utilized to design a novel electrochemical sensing platform for detecting gallic acid (GA). The N-CNTs@ZIF-67 modified glass carbon electrode (GCE) demonstrated high sensitivity for GA electrochemical detection (LOD: 10.17 nM, detection concentration: 0.5-20 μM). N-CNTs provided efficient electron transport channels for the GA electrochemical detection reaction, which improved the transfer rate of electrons/ions at the interface of sensing electrode/electrolyte. ZIF-67 nanoparticles with highly porous structure could adsorb GA molecules and promote the oxidation reaction. Besides that, N-CNTs provided more active sites on carbon nanotube networks by nitrogen-doping, which significantly enhanced the catalytic activity. The prepared N-CNTs@ZIF-67/GCE sensor exhibited favorable GA sensing detection performance, realizing an accurate analysis of GA in beverage samples (Recovery: 96.77-107.93 %, RSD: 1.07-4.38 %).

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.

Room-temperature fabrication of zeolitic imidazolate framework-8 nanoparticles combined with graphitized and carbonylated carbon nanotubes networks for the ultrasensitive gallic acid electrochemical detection

Gallic acid (GA) has important application value in several fields of foods, medicines, and chemical engineering. However, the excessive intake of GA may cause gastrointestinal discomfort and nerve damage. Herein, an economical room-temperature fabrication strategy was reported for the preparation of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles combined with graphitized and carbonylated carbon nanotubes (GCMCN) networks, which were used to achieve the ultrasensitive electrochemical detection of GA. The GCMCN@ZIF-8 nanocomposite modified electrode realized an accurate and rapid analysis of GA (Linear concentration range: 0.1-20 μM, LOD: 4.77 nM). GCMCN networks with graphitization and carboxylation boosted the electrical conductivity of electrode modification layer and enhanced the electrochemical interface area between sensing electrode and electrolyte. ZIF-8 nanoparticles with more active interaction sites and high porosity possessed high adsorption capacity for GA molecules. The fabricated electrochemical sensing platform exhibited good GA quantitative analysis property in food samples (Recovery: 93.88-106.73 %, RSD: 1.04-3.73).

Overview and trends in electrochemical sensors, biosensors and cellular antioxidant assays for oxidant and antioxidant determination in food

Screening and quantifying antioxidants from food samples, their antioxidant activity, as well as the assessment of food oxidation is critical, not only for ensuring food quality and safety, but also to understand and relate these parameters to the shelf life, sensory attributes, and health aspects of food products. For this purpose, several methods have been developed and used for decades, which regardless of their effectiveness, present a certain number of drawbacks mainly related to extensive sample preparation and technical complexity, time requirements, and the use of hazardous chemicals. Electrochemical sensors and biosensors are gaining popularity in food analysis due to their high sensitivity, specificity, rapid response times, and potential for miniaturisation and portability. Furthermore, other modern methods using whole living cells such as the cellular antioxidant activity assay, the antioxidant power 1 assay, and the catalase-like assays, may interpret more realistic antioxidant results rather than just reporting the ability to scavenge free radicals in isolated systems with extrapolation to reality. This paper provides an overview of electrochemical sensors, biosensors, and cellular antioxidant assays, and reviews the latest advancements and emerging trends in these techniques for determining oxidants and antioxidants in complex food matrices. The performances of different strategies are described for each of these approaches to provide insights into the extent to which these methods can be exploited in the field and inspire new research to fill the current gaps.

Advanced chemically modified electrodes and platforms in food analysis and monitoring

Electrochemical sensors and electroanalytical techniques become emerging as effective and low-cost tools for rapid assessment of special parameters of the food quality. Chemically modified electrodes are developed to change properties and behaviour, particularly sensitivity and selectivity, of conventional electroanalytical sensors. Within this comprehensive review, novel trends in chemical modifiers material structure, electrodes construction and flow analysis platforms are described and evaluated. Numerous recent application examples for the detection of food specific analytes are presented in a form of table to stimulate further development in both, the basic research and commercial field.

Engineering carbon-based nanomaterials for the delivery of platinum compounds: An innovative cancer disarming frontier

Carbon-based nanomaterials have been frequently used as one of the most advanced and fascinating nanocarriers for drug delivery applications due to their unique physicochemical properties. Varying types of carbon nanomaterials (CNMs) including carbon nanotubes, graphene, graphene oxides, carbon nanohorns, fullerenes, carbon nanodots, and carbon nanodiamonds are promising candidates for designing novel systems to deliver platinum compounds. CNMs modification with various moieties renders vast bio-applications in the area of targeted and organelle-specific cancer therapy. This review featured an updated and concise summarizations of various types of CNMs, their synthesis, advantages and disadvantages including potential bio-toxicity for biomedical applications. The therapeutic utility of CNMs and their efficacy have been noticed and for the first time, this review addressed CNMs-focused applications on the delivery of platinum-derivatives to the cancer site. Collectively, the contents of this review will assist researchers to focus on the possible fabrication, bio-functionalization and designing methods of CNMs to the further development of their future biomedical implementations.

Highly electrochemically active Ti3C2Tx MXene/MWCNT nanocomposite for the simultaneous sensing of paracetamol, theophylline, and caffeine in human blood samples

The facile fabrication is reported of highly electrochemically active Ti3C2Tx MXene/MWCNT (3D/1D)-modified screen-printed carbon electrode (SPE) for the efficient simultaneous electrochemical detection of paracetamol, theophylline, and caffeine in human blood samples. 3D/1D Ti3C2Tx MXene/MWCNT nanocomposite was synthesized using microwave irradiation and ultrasonication processes. Then, the Ti3C2Tx/MWCNT-modified SPE electrode was fabricated and thoroughly characterized towards its physicochemical and electrochemical properties using XPS, TEM, FESEM, XRD, electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry techniques. As-constructed Ti3C2Tx-MWCNT/SPE offers excellent electrochemical sensing performance with good detection limits (0.23, 0.57, and 0.43 µM) and wide linear ranges (1.0 ~ 90.1, 2.0 ~ 62.0, and 2.0-90.9 µM) for paracetamol, caffeine, and theophylline, respectively,  in the human samples. Notably, the non-enzymatic electroactive nanocomposite-modified electrode has depicted a semicircle Nyquist plot with low charge transfer resistance (Rct∼95 Ω), leading to high ionic diffusion and facilitating an excellent electron transfer path. All the above results in efficient stability, reproducibility, repeatability, and sensitivity compared with other reported works, and thus, it claims its practical utilization in realistic clinical applications.