Thermoreversible Switchlike Electrocatalytic Reduction of Tizanidine Based on a Graphene Oxide Tethered Stimuli-Responsive Smart Surface Supported Pd Catalyst.

In this work, a graphene oxide (GRO)-based temperature-sensitive smart catalytic support material was developed by tethering biodegradable and hydrophilic poly(N-vinylcaprolactam) (PVCL) on a GRO (i.e., GRO-PVCL) surface. GRO-PVCL-supported palladium catalyst (i.e., Pd/GRO-PVCL) was then prepared for tizanidine (TZN) electroreduction. The impact of a temperature-sensitive smart surface on the electrochemical and electrocatalytic properties was examined. Moreover, when the large surface area, excellent electron transfer, and electrochemical catalysis abilities of GRO were combined with the responsive characteristics of PVCL, temperature-triggered reversible electrocatalysis of TZN with enhanced sensitivity has been proved. Results designated that GRO-PVCL exposed the hydrophilic surface at 20 °C, resulting in Pd NPs highly dispersed on the GRO-PVCL surface. Subsequently, the wettability of the Pd catalyst surface arbitrarily adapted to hydrophobicity at 40 °C, which highly enhanced the TZN reduction on the catalyst in electrochemical detection. The synergistic effect amid Pd and GRO-PVCL on Pd/GRO-PVCL improved the electrocatalytic activity of TZN. The detection of TZN with the Pd/GRO-PVCL modified electrode ranged from 0.02 to 276 µM with a low detection limit of 0.0015 µM at 40 °C. The Pd/GRO-PVCL modified electrode also possesses excellent stability, reproducibility, and anti-interference ability. Lastly, the modified electrode attained good recovery results in human urine and human plasma samples for the determination of TZN and also pharmacokinetics study in rat plasma.

Ultrasonication-aided synthesis of nanoplates-like iron molybdate: Fabricated over glassy carbon electrode as an modified electrode for the selective determination of first generation antihistamine drug promethazine hydrochloride.

The innovation of novel and proficient nanostructured materials for the precise level determination of pharmaceuticals in biological fluids is quite crucial to the researchers. With this in mind, we synthesized iron molybdate nanoplates (Fe2(MoO4)3; FeMo NPs) via simple ultrasonic-assisted technique (70 kHz with a power of 100 W). The FeMo NPs were used as the efficient electrocatalyst for electrochemical oxidation of first-generation antihistamine drug- Promethazine hydrochloride (PMH). The as-synthesized FeMo NPs were characterized and confirmed by various characterization techniques such as XRD, Raman, FT-IR, FE-SEM, EDX and Elemental mapping analysis and electron impedance spectroscopy (EIS). In addition, the electrochemical characteristic features of FeMo NPs were scrutinized by electrochemical techniques like cyclic voltammetry (CV) and differential pulse voltammetry technique (DPV). Interestingly, the developed FeMo NPs modified glassy carbon electrode (FeMo NPs/GCE) discloses higher peak current with lesser anodic potential on comparing to bare GCE including wider linear range (0.01-68.65 µM), lower detection limit (0.01 µM) and greater sensitivity (0.97 µAµM-1cm-2). Moreover, the as-synthesized FeMo NPs applied for selectivity, reproducibility, repeatability and storage ability to investigate the practical viability. In the presence of interfering species like cationic, anionic and biological samples, the oxidation peak current response doesn't cause any variation results disclose good selectivity towards the detection of PMH. Additionally, the practical feasibility of the FeMo NPs/GCE was tested by real samples like, commercial tablet (Phenergan 25 mg Tablets) and lake water samples which give satisfactory recovery results. All the above consequences made clear that the proposed sensor FeMo NPs/GCE exhibits excellent electrochemical behavior for electrochemical determination towards oxidation of antihistamine drug PMH.

Structural Insights on 2D Gadolinium Tungstate Nanoflake: A Promising Electrocatalyst for Sensor and Photocatalyst for the Degradation of Postharvest Fungicide (Carbendazim).

Gadolinium tungstate (Gd2(WO4)3) has acquired much attention owing to its exclusive transport properties and excellent thermal and chemical stability. In this work, we demonstrate that two-dimensional (2D) gadolinium tungstate nanoflakes (GW Nfs) are synthesized by a coprecipitation method and represent novel architectures for efficient catalysis, which could be used in electrochemical sensing and photocatalytic degradation of the postharvest fungicide carbendazim (CBZ). The physicochemical properties of GW Nfs were studied by using XRD, Raman, TEM, EDX, and XPS, which show the formation of GW as a nanoflake-like structure with a well crystallized nature. The as-prepared GW Nfs revealed an admirable electrochemical response for CBZ detection with an LOD of 0.005 µM, a wide-ranging linear response of 0.02 to 40 µM, and a notable sensitivity of 0.39 µA µM-1 cm-2. Furthermore, the GW-Nf-modified electrode has a good recovery for CBZ in the study of real samples such as rice and soil washed water samples. Moreover, GW Nfs have a promising photocatalytic activity for CBZ degradation. The GW Nfs could degrade CBZ at greater than 98% efficiency and mineralize above 74% of the CBZ molecules in the presence of visible light irradiation with superior stability even after many cycles. Subsequently, the electrochemical and photocatalytic mechanisms were provided in detail.

Ultrasonication-assisted synthesis of sphere-like strontium cerate nanoparticles (SrCeO3 NPs) for the selective electrochemical detection of calcium channel antagonists nifedipine.

In this work, strontium cerate nanoparticles (SrCeO3 NPs, SC NPs) were developed through facile synthetic techniques (Ultrasound-Assisted (UA) and Stirring-Assisted (SA) synthesis) and utilized as an electrocatalyst for the selective and sensitive electrochemical detection of calcium channel blocker nifedipine (NDF). The as-prepared UASC NPs and SASC NPs were characterized using XRD, Raman, TEM, EDS, mapping, XPS and BET analysis which exposed the formation of SC NPs in the form of spherical in shape and well crystalline in nature. BET studies reveal that UASC NPs have maximum surface area than that of SASC NPs. Further, the use of the as-developed UASC NPs and SASC NPs as an electrocatalyst for the detection of NDF. Interestingly, the UASC NPs modified screen printed carbon electrode (UASC NPs/SPCE) exhibited an excellent electrocatalytic activity in terms of lower reduction potential and enhanced reduction peak current when compared to SASC NPs and unmodified SPCE. Moreover, as-prepared UASC NPs/SPCE displayed wide linear response range (LR, 0.02-174 µM), lower detection limit (LOD, 5 nM) and good sensitivity (1.31 µA µM-1 cm-2) than that of SASC NPs (LR = 0.02-157 µM, LOD = 6.4 nM, sensitivity - 1.27 µA µM-1cm-2). Furthermore, UASC NPs/SPCE showed an excellent selectivity even in the existence of potentially co-interfering compounds such as similar functional group containing drugs, pollutants, biological substances and some common cations/anions. The developed sensor was successfully employed for the determination of NDF in real lake water, commercial NDF tablet and urine samples with acceptable recovery.

Synthesis, characterization and catalytic performance of nanostructured dysprosium molybdate catalyst for selective biomolecule detection in biological and pharmaceutical samples.

The current study reports a new, simple and fast method using a flake-like dysprosium molybdate (Dy2MoO6; FL-DyM) nanostructured material to detect the antibiotic drug metronidazole (METZ). This nanocomposite material was employed on the surface of a glassy carbon electrode (GCE) to develop the electrode (FL-DyM/GCE). Further, the synthesized FL-DyM was systematically characterized by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray diffraction (EDS), elemental mapping, X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analyses. Cyclic (CV) and differential pulse voltammetry (DPV) techniques were used to study the electrochemical properties. The FL-DyM/GCE-based sensor demonstrated excellent selectivity and sensitivity for the detection of the drug METZ, which could be attributed to the strong affinity of FL-DyM towards the -NO2 group in METZ, and the good electrocatalytic activity and conductivity of FL-DyM. The fabrication and optimization of the working electrode were accomplished with CV and DPV obtained by scan rate and pH studies. Compared to the bare GCE and other rare-earth metal molybdates, the FL-DyM/GCE sensor displayed a superior electrocatalytic activity response for METZ detection. The sensor demonstrated a good linear relationship over the concentration range of 0.01-2363 µM. The quantification and detection limits were found to be 0.010 µM and 0.0030 µM, respectively. The FL-DyM/GCE sensor displayed excellent selectivity, repeatability, reproducibility, and stability for the detection of METZ in human urine and commercial METZ tablet samples, which validates the new technique for efficient drug sensing in practical applications.

3D Flower-Like Gadolinium Molybdate Catalyst for Efficient Detection and Degradation of Organophosphate Pesticide (Fenitrothion).

Three-dimensional (3D) nanostructured materials have received enormous attention in energy and environment remediation applications. Herein, we developed a novel 3D flower-like gadolinium molybdate (Gd2MoO6; GdM) and used as a bifunctional catalyst for the electrochemical detection and photocatalytic degradation of organophosphate pesticide fenitrothion (FNT). The flower-like GdM catalyst was prepared via a simple sol-gel technique with the assistance of urea and ethylene glycol. The properties of GdM were confirmed by various spectroscopic and analytical techniques. The GdM catalyst played a significant role in electrochemical reduction of FNT and results in a very low detection limit (5 nM), wide linear ranges (0.02-123; 173-1823 µM), and good sensitivity (1.36 µA µM-1 cm-2). Interestingly, the GdM electrocatalyst had good recoveries to FNT in soil and water sample analysis. In addition to trace level detection, the flower-like GdM was used as the photocatalyst which portrayed an excellent photocatalytic degradation behavior to eliminate the FNT in the aqueous system. The GdM photocatalyst could degrade above 99% of FNT under UV light irradiation with good stability even after five cycles.

Investigation on the Electrocatalytic Determination and Photocatalytic Degradation of Neurotoxicity Drug Clioquinol by Sn(MoO4)2 Nanoplates.

Transition-metal molybdates have concerned enormous curiosity as supercapacitors, photocatalysts, and electrocatalysts. These materials are the best alternatives to noble-metal-based catalysts, which are generally show a limited photocatalytic and electrocatalytic activity. In addition, the antiprotozoal drug can usually pollute the environment through improper disposable and incomplete metabolism, and it is very dangerous to humans as well as aquatic animals. Therefore, here, we have studied the electrochemical determination and photodegradation of neurotoxicity clioquinol (CQL) by nanoplate-like tin molybdate (Sn(MoO4)2, denoted as SnM), which is used as both an electro- and a photocatalyst. The as-prepared catalyst delivered a highly efficient activity toward the detection and degradation of CQL. The proposed nanoplate-like SnM was prepared through a simple wet-chemical route, and its physicochemical properties were characterized by various spectroscopic and analytical techniques. As an electrochemical sensor, the SnM electrocatalyst exhibited tremendous activity for the detection of CQL in terms of lower potential and enhanced anodic peak current. In addition, it showed high selectivity, a wide linear concentration range, a lower detection limit, and good sensitivity. From the UV-vis spectroscopy study, the SnM photocatalyst delivered an excellent photocatalytic activity toward the degradation of CQL in terms of increasing contact time and reducing CQL concentration, resulting in the increasing of the degradation efficiency about 98% within 70 min under visible light irradiation and showing an appreciable stability by observation of the reusability of the catalyst.

A Study of Electrocatalytic and Photocatalytic Activity of Cerium Molybdate Nanocubes Decorated Graphene Oxide for the Sensing and Degradation of Antibiotic Drug Chloramphenicol.

In this present work, "killing two birds with one stone" strategy was performed for the electrochemical trace level detection and photocatalytic degradation of antibiotic drug chloramphenicol (CAP) using Ce(MoO4)2 nanocubes/graphene oxide (CeM/GO) composite for the first time. The CeM/GO composite was synthesized via simple hydrothermal treatment followed by sonication process. The successful formation of CeM/GO composite was confirmed by several analytical and spectroscopic techniques. The CeM/GO composite modified glassy carbon electrode (GCE) showed excellent electrocatalytic activity toward the reduction of CAP in terms of decrease the potential and increase the cathodic peak current in comparison with different modified and unmodified electrodes. The electrocatalytic reduction of CAP based on the CeM/GO modified GCE exhibited high selectivity, wide linear ranges, lower detection limit, and good sensitivity of 0.012-20 and 26-272 µM, 2 nM ,and 1.8085 µA µM-1 cm-2, respectively. Besides, when CeM/GO/GCE was used to analyze the CAP in real samples, such as honey and milk, the satisfactory recovery results were obtained. On the other hand, the CeM/GO composite played excellent catalyst toward the photodegradation of CAP. The obtained results from the UV-vis spectroscopy clearly suggested that CeM/GO composite had high photocatalytic activity compared to pristine Ce(MoO4)2 nanocubes. The degradation efficiency of CeM/GO toward CAP is observed about 99% within 50 min under visible irradiation and it shows a good stability by observing the reusability of the catalyst. The enhanced photocatalytic performance was attributed to the increased migration efficiency of photoinduced electrons and holes.