Synthesis, characterization, and preparation of nickel nanoparticles decorated electrochemically reduced graphene oxide modified electrode for electrochemical sensing of diclofenac

Adsorption-Enhanced Sensitivity for Electrochemical Sensing of Diclofenac by Poly(ether sulfone)-Based Laser-Induced Graphene

Emerging contaminants are a matter of growing concern for environmental and human health and safety, requiring efficient and affordable sensing platforms. Laser-induced graphene (LIG) is a novel material with a 3D porous graphene structure that can be fabricated in a simple one-step fabrication process. However, most LIG-based works in electrochemical sensors are limited to polyimide (PI)-based platforms, thus limiting the purview of properties of LIG dependent on the substrate-laser interaction. Diclofenac (DCF), a nonsteroidal anti-inflammatory drug, is an emerging contaminant in water and wastewater that threatens aquatic and terrestrial life. Furthermore, LIG-based sensors have not been used to sense DCF. In this work, we demonstrate the spontaneous adsorption behavior of LIG toward DCF without applying any external potential. This spontaneous adsorption phenomenon can enhance the sensitivity per the characteristics of the tested water samples and permissible standards to be followed. Poly(ether sulfone)-based LIG (PES-LIG) is found to be more responsive to laser irradiation than PI-LIG due to its highly porous surface and fibrous nature, imparting more electrochemical sites and adsorption area for DCF. These characteristics lead to a higher sensitivity of 0.2774 μA μM-1 toward DCF sensing for PES-LIG with a limit of detection of 0.1 μM. The sensors were applied for DCF measurement in wastewater and tap water samples with appreciable selectivity. The specific adsorption behavior of LIG toward DCF could pave the way for new pathways in emerging contaminant sensing and removal as well as for other applications.

New approaches in antibiotics detection: The use of square wave voltammetry

Antibiotics belongs to a class of pharmaceutical compounds widely used due to their effectiveness against bacterial infections. However, if consumed or inappropriately disposed of in the environment can results in environmental and public health problems, because they are considered emerging contaminants and their residues represent damage, whether in the long or short term, to different terrestrial ecosystems, in addition to bringing potential risks to agricultural sectors, such as livestock and fish farming. For this, the development of analytical methods for low-concentration detection and identification of antibiotics in natural waters, wastewaters, soil, foods, and biological fluids is necessary. This review shows the applicability of square wave voltammetry for the analytical determination of antibiotics from different chemical classes and covers a variety of samples and working electrodes that are used as voltammetric sensors. The review involved the analysis of scientific publications from the Science Direct® and Scopus® databases, with scientific manuscripts covering the period between January 2012 and May 2023. Various manuscripts were discussed indicating the applicability of square wave voltammetry in antibiotics detection in urine, blood, natural waters, milk, among other complex samples.

Integrating thermodynamics towards bulk level synthesis of nano Ni catalysts: a green mediated sol–gel auto combustion method

Novel strategy for the environmentally benign bulk level synthesis of nickel nanoparticles.

Recent Advances in Metal Nanocomposite-Based Electrochemical (Bio)Sensors for Pharmaceutical Analysis

Rising rates of drug abuse and pharmaceutical pollution throughout the world as a consequence of increased drug production and utilization pose a serious risk to public health and to environmental integrity. It is thus critical that reliable analytical approaches to detecting drugs and their metabolites in a range of sample matrices be developed. Recent advances in the design of nanomaterial-based electrochemical sensors and biosensors have enabled promising new approaches to pharmaceutical analysis. In particular, the development of a range of novel metal nanocomposites with enhanced catalytic properties has provided a wealth of opportunities for the design of rapid and reliable platforms for the detection of specific pharmaceutical compounds. The present review provides a comprehensive overview of representative metal nanocomposites with synergistic properties and their recent (2017-2022) application in the context of electrochemical sensing as a means of detecting specific antibiotic, tuberculostatic, analgesic, antineoplastic, antipsychotic, and antihypertensive drugs. In discussing these applications, we further explore a variety of testing-related principles, fabrication approaches, characterization techniques, and parameters associated with the sensitivity and selectivity of these sensor platforms before surveying the future outlook regarding the fabrication of next-generation (bio)sensor platforms for use in pharmaceutical analysis.

Screen-Printed Graphite Electrode Modified with Graphene-Co3O4 Nanocomposite: Voltammetric Assay of Morphine in the Presence of Diclofenac in Pharmaceutical and Biological Samples

This work focuses on the development of a novel electrochemical sensor for the determination of morphine in the presence of diclofenac. The facile synthesis of graphene-Co₃O₄ nanocomposite was performed. The prepared material (graphene-Co₃O₄ nanocomposite) was analyzed by diverse microscopic and spectroscopic approaches for its crystallinity, composition, and morphology. Concerning the electrochemical determinations, after drop-casting the as-fabricated graphene-Co₃O₄ nanocomposite on the surface of a screen-printed graphite electrode (SPGE), their electrochemical performance was scrutinized towards the morphine detection. It was also found that an SPGE modified by a graphene-Co₃O₄ nanocomposite exhibited better electrocatalytic activity for morphine oxidation than unmodified electrode. Under optimal conditions, the differential pulse voltammetry (DPV) was employed to explore the present sensor (graphene-Co₃O₄/SPGE), the findings of which revealed a linear dynamic range as broad as 0.02-575.0 µM and a limit of detection (LOD) as narrow as 0.007 μM. The sensitivity was estimated to be 0.4 µM/(µA cm²). Furthermore, the graphene-Co₃O₄/SPGE sensor demonstrated good analytical efficiency for sensing morphine in the presence of diclofenac in well-spaced anodic peaks. According to the DPV results, this sensor displayed two distinct peaks for the oxidation of morphine and diclofenac with 350 mV potential difference. In addition, the graphene-Co₃O₄/SPGE was explored for voltammetric determination of diclofenac and morphine in pharmaceutical and biological specimens of morphine ampoule, diclofenac tablet, and urine, where recovery rates close to 100% were recorded for all of the samples.

Antibacterial and in vivo toxicological studies of Bi2O3/CuO/GO nanocomposite synthesized via cost effective methods

In this research work, Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposites have been synthesized via an eco-friendly green synthesis technique, solgel route and co-precipitation method respectively for the assessment of antibacterial activity as well as in vivo toxicity. The XRD patterns confirm the formation of Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposites showing monoclinic structures. Crystallite size and lattice strain are calculated by Scherrer equation, Scherrer plot and Willimson Hall plot methods. Average crystallite size measured for Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposites by Scherrer equation, Scherrer plot and WH-plot methods are (5.1, 13.9, 11.5)nm, (5.4, 14.2, 11.3)nm and (5.2, 13.5, 12.0)nm respectively. Optical properties such as absorption peaks and band-gap energies are studied by UV-vis spectroscopy. The FTIR peaks at 513 cm-1, 553 cm-1 and 855 cm-1 confirms the successful synthesis of Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposites. The antibacterial activity of synthesized Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposites is examined against two gram-negative (Escherichia coli and pseudomonas) as well as gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) at dose 25 mg/kg and 40 mg/kg by disk diffusion technique. Zone of inhibition for Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO at dose 40 mg/kg against E. coli (gram - ve) are 12 mm, 17 mm and 18 mm respectively and against Pseudomonas (gram - ve) are 28 mm, 19 mm and 21 mm respectively. While the zone of inhibition for Bi2O3/GO and Bi2O3/CuO/GO at dose 40 mg/kg against B. cereus (gram + ve) are 8 mm and 8.5 mm respectively and against S. aureus (gram + ve) are 5 mm and 10.5 mm respectively. These amazing results reveal that Bi2O3, Bi2O3/GO and Bi2O3/CuO/GO nanocomposite as a kind of antibacterial content, have enormous potential for biomedical applications. In addition, the in vivo toxicity of synthesized Bi2O3/CuO/GO nanocomposite is investigated on Swiss Albino mice at dose of 20 mg/kg by evaluating immune response, hematology and biochemistry at the time period of 2, 7, 14 and 30 days. No severe damage is observed in mice during whole treatment. The p value calculated by statistical analysis of hematological and biochemistry tests is nonsignificant which ensures that synthesized nanocomposites are safe and non-toxic as they do not affect mice significantly. This study proves that Bi2O3/CuO/GO nanocomposites are biocompatible and can be explored further for different biomedical applications.

Simultaneous Analysis of Paracetamol and Diclofenac Using MWCNTs-COOH Modified Screen-Printed Carbon Electrode and Pulsed Potential Accumulation

A differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure with the use of pulsed potential accumulation and carboxyl functionalized multiwalled carbon nanotubes modified screen-printed carbon electrode (SPCE/MWCNTs-COOH) was delineated for simultaneous analysis of paracetamol (PA) and diclofenac (DF). The use of carboxyl functionalized MWCNTs and pulsed potential accumulation improves the analytical signals of PA and DF, and minimizes interferences from surfactants. After optimization of analytical conditions for this sensor, the peak currents of the two compounds were found to increase linearly with the increase in their concentration (5.0 × 10^-9-5.0 × 10^-6 mol L^-1 with a detection limit of 1.4 × 10^-9 mol L^-1 for PA, and 1.0 × 10^-10-2.0 × 10^-8 mol L^-1 with a detection limit of 3.0 × 10^-11 mol L^-1 for DF). For the first time, the electrochemical sensor allows simultaneous determination of PA and DF at concentrations of 24.3 ± 0.5 nmol L^-1 and 3.7 ± 0.7 nmol L^-1, respectively, in wastewater samples purified in a sewage treatment plant.

First Electrochemical Sensor (Screen-Printed Carbon Electrode Modified with Carboxyl Functionalized Multiwalled Carbon Nanotubes) for Ultratrace Determination of Diclofenac

A simple, sensitive and time-saving differential-pulse adsorptive stripping voltammetric (DPAdSV) procedure using a screen-printed carbon electrode modified with carboxyl functionalized multiwalled carbon nanotubes (SPCE/MWCNTs-COOH) for the determination of diclofenac (DF) is presented. The sensor was characterized using optical profilometry, SEM, and cyclic voltammetry (CV). The use of carboxyl functionalized MWCNTs as a SPCE modifier improved the electron transfer process and the active surface area of sensor. Under optimum conditions, very sensitive results were obtained with a linear range of 0.1–10.0 nmol L⁻¹ and a limit of detection value of 0.028 nmol L⁻¹. The SPCE/MWCNTs-COOH also exhibited satisfactory repeatability, reproducibility, and selectivity towards potential interferences. Moreover, for the first time, the electrochemical sensor allows determining the real concentrations of DF in environmental water samples without sample pretreatment steps.