Fabrication of a nanostructure thin film on the gold electrode using continuous pulsed-potential technique and its application for the electrocatalytic determination of metronidazole

Recent Advances in Bimetallic Nanoporous Gold Electrodes for Electrochemical Sensing

Bimetallic nanocomposites and nanoparticles have received tremendous interest recently because they often exhibit better properties than single-component materials. Improved electron transfer rates and the synergistic interactions between individual metals are two of the most beneficial attributes of these materials. In this review, we focus on bimetallic nanoporous gold (NPG) because of its importance in the field of electrochemical sensing coupled with the ease with which it can be made. NPG is a particularly important scaffold because of its unique properties, including biofouling resistance and ease of modification. In this review, several different methods to synthesize NPG, along with varying modification approaches are described. These include the use of ternary alloys, immersion-reduction (chemical, electrochemical, hybrid), co-electrodeposition-annealing, and under-potential deposition coupled with surface-limited redox replacement of NPG with different metal nanoparticles (e.g., Pt, Cu, Pd, Ni, Co, Fe, etc.). The review also describes the importance of fully characterizing these bimetallic nanocomposites and critically analyzing their structure, surface morphology, surface composition, and application in electrochemical sensing of chemical and biochemical species. The authors attempt to highlight the most recent and advanced techniques for designing non-enzymatic bimetallic electrochemical nanosensors. The review opens up a window for readers to obtain detailed knowledge about the formation and structure of bimetallic electrodes and their applications in electrochemical sensing.

Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry

Nanoporous gold (NPG) is characterized by a bicontinuous network of nanometer-sized metallic struts and interconnected pores formed spontaneously by oxidative dissolution of the less noble element from gold alloys. The resulting material exhibits decent catalytic activity for low-temperature, aerobic total as well as partial oxidation reactions, the oxidative coupling of methanol to methyl formate being the prototypical example. This review not only provides a critical discussion of ways to tune the morphology and composition of this material and its implication for catalysis and electrocatalysis, but will also exemplarily review the current mechanistic understanding of the partial oxidation of methanol using information from quantum chemical studies, model studies on single-crystal surfaces, gas phase catalysis, aerobic liquid phase oxidation, and electrocatalysis. In this respect, a particular focus will be on mechanistic aspects not well understood, yet. Apart from the mechanistic aspects of catalysis, best practice examples with respect to material preparation and characterization will be discussed. These can improve the reproducibility of the materials property such as the catalytic activity and selectivity as well as the scope of reactions being identified as the main challenges for a broader application of NPG in target-oriented organic synthesis.

One-step hydrothermal synthesis of nitrogen-doped carbon dots as a super selective and sensitive probe for sensing metronidazole in multiple samples

A reliable, super selective and sensitive nitrogen-doped carbon dots (N-CDs) nanoprobe that can quantitatively and quickly detect the concentration of metronidazole (MTZ) in multiple samples was built. We first prepared the N-CDs using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC·HCl) as the precursor via a green, facile one-step hydrothermal method. The as-synthesized N-CDs were characterized by a variety of analytical and spectroscopic techniques, which revealed excitation-dependent fluorescence behavior with the maximum excitation and emission wavelengths being 335 and 370 nm, respectively. Significantly, the fluorescence emission of N-CDs underwent initial quenching upon the addition of MTZ via the inner filter effect (IFE), indicating a prospective detection method for MTZ. The linear range for MTZ detection was 0.1-250 μM, and the corresponding limit of detection (LOD) and limit of quantification (LOQ) were calculated to be only 70 nM and 233.33 nM, respectively. Moreover, due to the negligible cytotoxicity and superior biocompatibility, the fabricated N-CDs show a promising prospect for detecting MTZ in living cells. In general, our proposed N-CDs-based fluorescence sensing platform possesses super low LOD and LOQ values, wide linear range, and satisfactory selectivity, and can be applied to the detection of MTZ in multiple real samples.

Low potential detection of antiprotozoal drug metronidazole with aid of novel dysprosium vanadate incorporated oxidized carbon nanofiber modified disposable screen-printed electrode

In this work, we designed tetragonal nanogravel structured dysprosium vanadate Dy(VO₄) nanoparticles unified with oxidized carbon nanofiber (f-CNF) denoted as Dy(VO₄)/f-CNF nanocomposite for the low potential determination of antiprotozoal drug metronidazole (MEZ). The physicochemical properties of novel Dy(VO₄)/f-CNF nanocomposite were analyzed through microscopic and spectroscopic techniques and obtained results express nanocomposite formed with desired surface morphology, crystalline phase, atomic vibrational modes, and preferred elemental compositions. The electrocatalytic activity of Dy(VO₄)/f-CNF nanocomposite was examined with a disposable screen-printed electrode (SPCE) via cyclic voltammetry (CV) and linear sweep voltammetry technique (LSV) with a conventional three-electrode system. Dy(VO₄)/f-CNF/SPCE delivers a higher active surface area recommends superior electrocatalytic activity which is favorable for the MEZ sensor. Electrocatalytic reduction of MEZ occurred with lower reduction potential (-0.55 V) with dynamic linear range (1.5-1036.9 µM), lower detection limit (6 nm), LOQ (0.022 µM), and higher sensitivity (1.12 μA μM^-1 cm²). The anti-interference studies retain its actual current without any shift in cathodic potential. Besides, the practical feasibility outcomes with higher cathodic current with the higher recovery rate and RSD in human blood sample, urine sample, and lake water as a real samples. Thus, Dy(VO₄)/f-CNF nanocomposite modified SPCE considers being a potential candidate for the MEZ sensor.

Electrochemical determination of chloramphenicol and metronidazole by using a glassy carbon electrode modified with iron, nitrogen co-doped nanoporous carbon derived from a metal-organic framework (type Fe/ZIF-8)

In this study, an iron-doped metal-organic framework (MOF) Fe/ZIF-8 was synthesized from ZIF-8 at room temperature. Direct carbonization of Fe/ZIF-8 under a nitrogen atmosphere produced nanoporous nitrogen doped carbon nanoparticles decorated with Fe component (Fe/NC). The Fe/NC exhibited a large surface area (1221.185 m² g^-1) and narrow pore-size distribution (3-5 nm). The nanoporous Fe/NC components along with Nafion were used to modify a glassy carbon electrode for the electrochemical determination of chloramphenicol and metronidazole via linear sweep voltammetry. Under optimal conditions, the reduction peak currents (observed at -0.237 V and -0.071 V vs. Ag/AgCl) of these analytes increased linearly with increasing chloramphenicol and metronidazole concentrations in the range of 0.1-100 μM and 0.5-30 μM, with the detection limits estimated to be 31 nM and 165 nM, respectively. This result was attributed to the large surface area, porous structure, high nitrogen content, and as well as the electrocatalytic effect of Fe atoms embeded in the carbon support. The proposed sensor was used for chloramphenicol and metronidazole analysis in samples, providing satisfactory results.

Technological development of mucoadhesive film containing poloxamer 407, polyvinyl alcohol and polyvinylpyrrolidone for buccal metronidazole delivery

Aim: This work aimed to develop a mucoadhesive film composed of a triblock copolymer (poloxamer 407), polyvinyl alcohol and polyvinylpyrrolidone for buccal modified delivery of metronidazole. Materials & methods: Three film formulations containing different polymer amounts were prepared by solvent casting. They were characterized as physicochemical, mechanical and mucoadhesive properties, and in vitro metronidazole release profiles. Results: Films displayed physicochemical, mechanical and mucoadhesive characteristics dependent of polymeric composition and drug presence. They could rapidly swell and promote the fast drug release (80% in 20 min) that was governed by Fickian diffusion. The films showed total disintegration in less than 90 s and total drug release in 30 min. Conclusion: Therefore, the formulations represent a promising alternative for modifying of buccal metronidazole delivery for pharmaceutical applications.

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.

Cerium doped magnetite nanoparticles for highly sensitive detection of metronidazole via chemiluminescence assay

Cerium doped magnetite nanoparticle (CDM) was synthesized via a co-precipitation method and used as the co-reactant of luminol-K₃Fe(CN)₆ chemiluminescent system. The physical-chemical features of CDM were studied by XPS, XRD, HRTEM, FESEM, VSM, BET, and FTIR analyses. This simple and highly sensitive nanoprobe enabled the determination of minor concentrations of metronidazole (MNZ). Owing to the quenching efficacy of MNZ in the studied chemiluminescence system, a linear range of 3.47 × 10^-6-9.37 × 10^-5 mol/L was obtained with a limit of detection of 3.91 × 10^-7 mol/L. This biosensor was used for MNZ detection in human serum samples, which was highly efficient. The outcomes of this study give credit to the proposed biosensor to be applied for detection of MNZ in biological samples.

Biocompatible chitosan-pectin polyelectrolyte complex for simultaneous electrochemical determination of metronidazole and metribuzin

Development of novel biocompatible sensor material suitable for modest, cost-effective, and rapid practical application is a demanding research interest in the field of electroanalytical chemistry. In this context, for the first time, we utilized biocompatible chitosan-pectin biopolyelectrolyte (CS-PC BPE) complex for the simultaneous electroreduction of an important antibiotic drug (metronidazole-MNZ) and herbicide (metribuzin-MTZ). This sensor reveals an attractive welfares such as simplicity, biocompatibility, and low production cost. Under optimized experimental conditions, the electroanalytical investigation confirmed that CS-PC BPE modified glassy carbon electrode (CS-PC BPE/GCE) was found to sense MNZ and MTZ in the nanomolar range. Moreover, as-prepared CS-PC BPE/GCE exhibited prominent selectivity, stability, and reproducibility. Additionally, the possible MNZ and MTZ sensing mechanism of CS-PC BPE/GCE have been discussed in detail. Lastly, real sample analysis was also carried out and revealed from several investigations that the CS-PC BPE/GCE is a good electrochemical sensor system for the detection of targeted analytes.

A highly sensitive metronidazole sensor based on a Pt nanospheres/polyfurfural film modified electrode

A sensitively electrochemical metronidazole sensor basing on a Pt nanospheres/polyfurfural modified glassy carbon electrode.

A zeolite modified carbon paste electrode based on copper exchanged clinoptilolite nanoparticles for voltammetric determination of metronidazole

Modified carbonpaste elelctrode with Cu(ii)-exchanged clinoptilolite nanoparticles showed increased peak current in the presence of metronidazole.

Petal-like graphene–Ag composites with highly exposed active edge sites were designed and constructed for electrochemical determination of metronidazole

The petal-like graphene–Ag composites with highly exposed active edge sites were constructed, which served as both the electrocatalyst and the current amplifier for electrochemical detection of metronidazole.

Electrochemistry of raloxifene on glassy carbon electrode and its determination in pharmaceutical formulations and human plasma

The electrochemical behavior of raloxifene (RLX) on the surface of a glassy carbon electrode (GCE) has been studied by cyclic voltammetry (CV). The CV studies were performed in various supporting electrolytes, wide range of potential scan rates, and pHs. The results showed an adsorption-controlled and quasi-reversible process for the electrochemical reaction of RLX, and a probable redox mechanism was suggested. Under the optimum conditions, differential pulse voltammetry (DPV) was applied for quantitative determination of the RLX in pharmaceutical formulations. The DPV measurements showed that the anodic peak current of the RLX was linear to its concentration in the range of 0.2-50.0μM with a detection limit of 0.0750μM, relative standard deviation (RSD %) below 3.0%, and a good sensitivity. The proposed method was successfully applied for determination of the RLX in pharmaceutical and human plasma samples with a good selectivity and suitable recovery.