Insight into TEMPO-oxidized cellulose-based composites as electrochemical sensors for dopamine assessment

Imidazole-triggered in situ fluorescence reaction system for quantitatively determination of dopamine from multiple sources

Highly selective and sensitive determination of dopamine (DA) from multiple sources remains a persistent and significant challenge. Here, we develop an imidazole-triggered in situ fluorescence reaction system for highly selective and sensitive determination of DA from various sources (human, horse, dog, rabbit, and mouse). The system operates by catalyzing the oxidation of DA with 1,5-Dihydroxynaphthalene (1,5-DHA) through a Lewis base formed by imidazole, leading to the rapid generation of yellow azamonardine fluorescent compounds (AFC). Notably, the system demonstrates minimal background noise and a high signal-to-noise ratio of up to 300-fold with a determination limit of 33.33 pM, making it 10-100 times more sensitive than conventional enzyme-linked immunosorbent assay (ELISA) methods. Moreover, selectivity tests reveal that our system can effectively distinguish between several common interfering substances, even at concentrations as low as 10 nM. The developed system shows promising results in detecting DA from diverse sources (humans, horses, dogs, rabbits, and mice), including urine samples from clinical patients, exhibiting good agreement with traditional ELISA kits. Therefore, the established in situ fluorescence reaction system holds great potential for the determination of DA-related disorders due to its impressive analytical capabilities.

Advancements in Modified Electrodes with Electrochemical Sensors for Detecting Acetaminophen and Caffeine: An Update

Acetaminophen and caffeine are analgesic or psychoactive drugs in human life that plays a major role in food and medicinal chemistry. Caffeine increases the efficacy of acetaminophen by improving its absorption, thereby prolonging analgesic action. Caffeine might exacerbate symptoms of anxiety if being prone to them. Taking these medications for a headache or migraine may cause problems for human life. Developing a sensitive, selective, easy, quick, and economical electroanalytical approach for the simultaneous detection of acetaminophen and caffeine has been a major area of research since they typically coexist in biological fluids and oxidize at overlapping potentials. Voltammetry has become one of the most commonly used and an important method amongst the other methods due to its high sensitivity and reliability. Moreover, carbon materials, metal/metal oxides/nanoparticles, and polymer-based materials have enhanced researchers' attention for the strategy and growth of electrochemical sensors for acetaminophen and caffeine. This compilation is a comprehensive effort to address the growing need for materials and their simultaneous detection of acetaminophen and caffeine. In this study, the validation parameters (electrode surface area, catalytic activity, electron transfer kinetics, potential window, sensitivity, and selectivity) were evaluated and provided a strong foundation for evaluating the effectiveness of materials and techniques. This review highlights the most widely used voltammetric methods for simultaneous electrochemical determination of acetaminophen and caffeine, and it explains the interference effect of acetaminophen and caffeine along with similar structural components. Finally, the topic has been concluded with existing challenges and prospects.

Biosensors for Early Detection of Parkinson's Disease: Principles, Applications, and Future Prospects

Parkinson's disease (PD), a neurodegenerative disorder marked by the progressive loss of dopaminergic neurons in the substantia nigra, imposes substantial economic burdens, including both direct and indirect costs. The medical community currently lacks a definitive cure for Parkinson's disease, and early detection is crucial for timely intervention and disease management. As innovative diagnostic tools, biosensors have shown great potential in detecting PD at its early stages. This review comprehensively summarizes recent advances in biosensors for the early detection of PD, with a particular focus on the detection of two key biomarkers: dopamine (DA) and α-synuclein (α-syn). Furthermore, it illustrates a variety of nanotechnology-based biosensors, including optical, electrochemical, and transistor biosensors, detailing their underlying principles, advantages, limitations, and applications in PD detection. Moreover, the review explores the challenges and prospects of advancing biosensors for early PD diagnosis.

Molecular Imprinted Polymer Decorated Electrochemical Sensors for Diabetes Biomarkers: A Critical Review

Diabetes is a chronic illness marked by high blood sugar or hyperglycemia, which can be caused by deficiencies in the action or secretion of insulin, or both. A prolonged period of elevated blood glucose levels can cause several tissues to malfunction. To avoid or postpone the onset of problems associated with diabetes, early diagnosis, and effective care are essential. Biomarkers and biosensors have become potential tools for monitoring and managing diabetes. Glucose, glycated hemoglobin, and other relevant biomarkers of diabetes can be detected using various biosensors, including enzymatic, electrochemical, and optical types. The molecular imprinting technique is an emerging electroanalytical method, that creates cavities in the polymer matrix with an affinity for a selected template molecule, known as molecularly imprinted polymer (MIP). Typically, the procedure involves the polymerization of monomers in the presence of a template molecule, which is then removed to leave behind imprinting sites. These polymers have been employed in molecular sensors, chemical separations, and catalysis due to their affinity for the original molecule. With special attention to their mechanisms of action, clinical applications, limitations, and the potential of emerging technologies, such as wearables and nano-biosensors, these can be used for continuous and real-time diabetes monitoring. This critical review focuses on the role of nanomaterials and conducting polymer-decorated molecularly imprinted sensors for tracking diabetes biomarkers. Additionally, this paper discusses the difficulties in developing and implementing biosensors, including selectivity, sensitivity, and real-time monitoring of glucose levels.

Cobalt vanadate intertwined in carboxylated multiple-walled carbon nanotubes for simultaneous electrochemical detection of ascorbic acid, dopamine and uric acid

Low-cost transition metal vanadate-based electrochemical sensors have attracted a lot of attention recently. A cobalt vanadate and carboxylated multi-walled carbon nanotube composite (CoV/MWCNTs-COOH) was prepared by an ultrasonic-assisted assembly method. The uniform and dense MWCNTs-COOH attached to the surface of CoV not only combines the large surface area and superior conductivity of MWCNTs-COOH with the excellent electrochemical activity of CoV, but also enhances the redox reaction between CoV/MWCNTs-COOH composite and the analyte through synergistic effect of hydrogen bonding and electrostatic interaction. The electrochemical behaviors of CoV/MWCNTs-COOH composite modified glassy carbon electrode (CoV/MWCNTs-COOH/GCE) were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The simultaneous electrochemical sensing of ascorbic acid (AA), dopamine (DA) and uric acid (UA) on CoV/MWCNTs-COOH/GCE possesses good peak current signals with well-defined peak potentials. The linear ranges of AA, DA, and UA at CoV/MWCNTs-COOH/GCE are 1.0-100.0 μM, and the limits of detection (LODs; S/N = 3) are 0.4 μM, 0.03 μM, and 0.1 μM, respectively. The practicality of the designed sensor was further confirmed by the good recoveries obtained in the simultaneous measurement of actual samples including fetal bovine serum, human serum, urine, and Vitamin C tablets. Overall, the developed electrochemical sensor shows potential therapeutic applications for simultaneous determination of AA, DA and UA in biological fluids.

Eco-friendly anti-corrosion performance of chitosan modified with fused heterocyclic compound on mild steel in acidic medium

This study aims to explore the prevention of chitosan modified with a fused heterocyclic compound as a sustainable corrosion inhibitor for mild steel in 1 M HCl. Electrochemical instruments, including potentiodynamic polarization techniques, and electrochemical impedance spectroscopy (EIS), were employed to evaluate the corrosion protection performance. The outcomes showed that the chitosan modified with a fused heterocyclic compound has outstanding inhibition performance, with an inhibition effectiveness of 98.25 % at 100 ppm. The anti-corrosion features of modified chitosan were ascribed to the presence of hetero atoms in modified chitosan composite which leads to the creation of a protective layer, The modified chitosan composite behaved as mixed-typed inhibitors, as shown by the PDP results. The modified chitosan composite adsorbs on mild steel in the investigated corrosive media via chemisorption interactions, and its adsorption followed the Langmuir adsorption model. Furthermore, increasing the temperature from 303 to 333 K enhanced the corrosion rate, most likely due to the desorption of the inhibitor agent from the steel surface.

From Self-Assembly of Colloidal Crystals toward Ordered Porous Layer Interferometry

Interferometry-based, reflectometric, label-free biosensors have made significant progress in the analysis of molecular interactions after years of development. The design of interference substrates is a key research topic for these biosensors, and many studies have focused on porous films prepared by top-down methods such as porous silicon and anodic aluminum oxide. Lately, more research has been conducted on ordered porous layer interferometry (OPLI), which uses ordered porous colloidal crystal films as interference substrates. These films are made using self-assembly techniques, which is the bottom-up approach. They also offer several advantages for biosensing applications, such as budget cost, adjustable porosity, and high structural consistency. This review will briefly explain the fundamental components of self-assembled materials and thoroughly discuss various self-assembly techniques in depth. We will also summarize the latest studies that used the OPLI technique for label-free biosensing applications and divide them into several aspects for further discussion. Then, we will comprehensively evaluate the strengths and weaknesses of self-assembly techniques and discuss possible future research directions. Finally, we will outlook the upcoming challenges and opportunities for label-free biosensing using the OPLI technique.