Nanomaterials as catalysts for the sensitive and selective determination of diclofenac.

Background and purpose: Diclofenac (DCF) is a non-steroidal anti-inflammatory drug possessing analgesic and antipyretic properties. It is used for the treatment of rheumatoid arthritis pain, osteoarthritis, and acute muscle pain conditions and can be administrated orally, topically or intravenously. Because of its widespread use, hydrophilicity, stability and poor degradation (bioaccumulation in the food chain), DCF is an emerging chemical contaminant that can cause adverse effects in the ecosystems. Taking into account the consumption of DCF in pharmaceutical formulations and its negative impact on the environment, the development of new sensitive, selective, cheap, fast, and online capable analytical devices is needed for on-site applications. Experimental approach: This brief review attempts to cover the recent developments related to the use of nanomaterials as catalysts for electrochemical determination of DCF in pharmaceutical formulations, biological fluids and environmental samples. Key results: The article aims to prove how electrochemical sensors represent reliable alternatives to conventional methods for DCF analysis. Conclusion: The manuscript highlights the progress in the development of electrochemical sensors for DCF detection. We have analyzed numerous recent papers (mainly since 2019) on sensors developed for the quantitative determination of DCF, indicating the limit of detection, linear range, stability, reproducibility, and analytical applications. Current challenges related to the sensor design and future perspectives are outlined.

Recent advances in electrochemical determination of anticancer drug 5-fluorouracil.

Reliable, rapid, highly selective and sensitive analytical methods for the determination of antineoplastic agent 5-fluorouracil (5-FU) in human body fluids (blood serum/plasma and urine) are required to improve the chemotherapy regimen to reduce its toxicity and improve efficacy. Nowadays, electrochemical techniques provide a powerful analytical tool for 5-FU detection systems. This comprehensive review covers the advances in the development of electrochemical sensors for the quantitative determination of 5-FU, mainly focused on original studies reported from 2015 to date. We have summarized recent trends in the electrochemical sensor systems applied for the analysis of 5-FU in pharmaceutical formulations and biological samples, and critically evaluated the key performance metrics of these sensors (limit of detection, linear range, stability and recovery). Challenges and future outlooks in this field have also been discussed.

A Review on Electrochemical Microsensors for Ascorbic Acid Detection: Clinical, Pharmaceutical, and Food Safety Applications.

Nowadays, micro-sized sensors have become a hot topic in electroanalysis. Because of their excellent analytical features, microelectrodes are well-accepted tools for clinical, pharmaceutical, food safety, and environmental applications. In this brief review, we highlight the state-of-art electrochemical non-enzymatic microsensors for quantitative detection of ascorbic acid (also known as vitamin C). Ascorbic acid is a naturally occurring water-soluble organic compound with antioxidant properties and its quantitative determination in biological fluids, foods, cosmetics, etc., using electrochemical microsensors is of wide interest. Various electrochemical techniques have been applied to detect ascorbic acid with extremely high sensitivity, selectivity, reproducibility, and reliability, and apply to in vivo measurements. This review paper aims to give readers a clear view of advances in areas of electrode modification, successful strategies for signal amplification, and miniaturization techniques used in the electroanalytical devices for ascorbic acid. In conclusion, current challenges related to the microelectrodes design, and future perspectives are outlined.

Ruthenium Oxide Hexacyanoferrate as an Effective Electrode Modifier for Amperometric Detection of Iodate and Hydrogen Peroxide.

Ruthenium oxide hexacyanoferrate (RuOHCF) film was electrochemically deposited on to a glassy carbon (GC) surfaceusing consecutive cyclic voltammetry as a facile and green synthetic strategy. The electrochemical behaviour and electrocatalytic properties of the modified electrode Ru?HCF/GC were evaluated with regards to electroreduction of hydrogen peroxide and iodate in a strong acidic medium (pHs 1.0-2.0) by using different electrochemical techniques, including cyclic voltammetry and amperometry at a constant potential. Electrochemical studies indicated that Ru?HCF/GC possess a high catalytic activity in both studied reactions, fast response and good reproducibility of the current signal. The Ru?HCF/GC exhibits enhanced electrocatalytic behaviour compared with other modified electrodes reported before. The simple and reproducible procedure for electrode fabrication, the wide linear range, anti-interference performance and long-time stability of the Ru?HCF/GC make it a promising sensing material for practical quantitative determination of hydrogen peroxide and iodate. Remarkably, the reported modified.

Amperometric Biosensors for Glucose and Lactate with Applications in Food Analysis: A Brief Review.

Over the past two decades, electrochemical biosensor devices have received great attention in the field of food analysis owing to their attractive performances. In the food industry the quality control during manufacturing process and final products requires quick and reliable analytical methods. A promising alternative to the traditional analytical techniques are the electrochemical enzymatic biosensors - devices that combine the robustness of electrochemical techniques with the specificity of biological recognition processes and offer great advantages due to size, cost, sensitivity, selectivity, and fast response. This brief review has attempted to summarise the literature on the recent progress in the development of enzyme biosensors with amperometric detection for quantitative analysis of glucose and lactate in various food samples. The review concludes with an outlook on the future challenges and perspectives in this area.

An Electrochemical Sensing Platform Based on Iridium Oxide for Highly Sensitive and Selective Detection of Nitrite and Ascorbic Acid.

Iridium oxide (IrOx) was electrodeposited onto glassy carbon electrode applying two-step potential cycling procedure. The electrocatalytic properties of the modified electrode IrOx/GC were evaluated with regards to electrochemical oxidation of nitrite and ascorbic acid (AA). The developed electrode-catalyst have been extensively studied by various electrochemical techniques. Differential pulse voltammetry (DPV) experiments indicated that the modified electrode possesses excellent electrocatalytic activity towards the oxidation of both nitrite and AA in neutral medium and offers simultaneous quantification of these substances. Constant potential amperometry studies also were performed - the IrOx/GC showed sensitive response to nitrite (159.7 µA mM-1 cm-2) with a wide linear range from 0.002 to 10 mM at 0.77 V (vs. Ag/AgCl, 3 M KCl), and to AA (96.2 µA mM-1cm-2) with a linear range from 0.01 to 3 mM at 0.025 V. The detection limit was 0.63 µM nitrite and 4 µM AA, respectively, and both of them had fast response within 5 s. Considering the simple and rapid electrodeposition procedure for preparation, IrOx/GC is a new electrode-catalyst for sensitive and selective quantitative detection of nitrite and AA. The wide linear range, good selectivity, reproducibility of the amperometric response and long-time stability of the IrOx/GC make it a promising sensing material for practical nonenzymatic quantitative detection of nitrite and AA.

Modified graphites: application to the development of enzyme-based amperometric biosensors.

For a series of graphite electrodes, modified with microquantities of Pd+Pt mixture in varied proportions, surface morphology of the catalytically active phase was studied with scanning electron microscopy (SEM), while the catalytic activity was examined at electrochemical reduction of hydrogen peroxide by means of steady-state polarization curves and constant potential amperometry. It was proven that the graphite, exhibiting the highest electrocatalytic activity (modified with Pd+Pt mixed in the ratio 70%:30% at t(deposit)=10 s) is distinguished with the smallest average size of the microformations. The operational characteristics of the same electrode and graphite modified with microquantities of Pd+Au mixed in the same ratio (70%:30%; t(deposit)=10 s) were compared. The application of these electrodes as basic transducers in highly selective biosensors for glucose and xanthine was demonstrated.