Sea urchin nanostructured nickel cobaltite modified carbon cloth integrated wearable patches for the on-site detection of the immunosuppressant drug mycophenolate mofetil

Mycophenolate mofetil (MpM) is a medication used to prevent the rejection of transplanted organs, particularly in kidney, heart, and liver transplant surgeries. It is extremely important to be conscious that MpM can raise the risk of severe infections and some cancers if it exceeds the recommended dose while lower doses will result in organ rejections. So, it is essential to monitor the dosage of MpM in real time in the micromolar range. In this work, we have synthesized 3-aminopropyltriethoxysilane (APTES) functionalized nickel cobaltite (NiCo2O4) and this amino functionalization was chosen to enhance the stability and electrochemical activity of NiCo2O4. The enhanced activity of NiCo2O4 was used for developing an electrochemical sensor for the detection of MpM. APTES functionalized NiCo2O4 was coated on carbon cloth and used as the working electrode. Surface functionalization with APTES on NiCo2O4 was aimed at augmenting the adsorption/interaction of MpM due to its binding properties. The developed sensor showed a very low detection limit of 1.23 nM with linear ranges of 10-100 nM and 1-100 μM and its practical applicability was examined using artificial samples of blood serum and cerebrospinal fluid, validating its potential application in real-life scenarios.

Electrochemical sensor for simultaneous determination of antiviral favipiravir drug, paracetamol and vitamin C based on host-guest inclusion complex of β-CD/CNTs nanocomposite

Favipiravir (FVI) is extensively used as an effective medication against several diverse infectious RNA viruses. It is widely administered as an anti-influenza drug. Combination therapy formed from FVI, paracetamol (PAR) and vitamin C (VC) is needed for treating patients diseased by RNA viruses. Thus, an efficient electrochemical sensor is developed for detecting FVI in human serum samples. The sensor is fabricated by casting a thin layer of carbon nanotubes (CNTs) over a glassy carbon (GC) electrode surface followed by electrodeposition of another layer of β-cyclodextrin (β-CD). Under optimized conditions, the sensor shows excellent catalytic effect for FVI, PAR and VC oxidation in the concentration ranges (0.08 µM → 80 µM), (0.08 µM → 50 µM) and (0.8 µM → 80 µM) with low detection limits of 0.011 μM, 0.042 μM and 0.21 μM, respectively. The combined effect of host-guest interaction ability of β-CD for the drugs, and a large conductive surface area of CNTs improves the sensing performance of the electrode. The sensor exhibits stable response over 4 weeks, good reproducibility, and insignificant interference from common species present in serum samples. The reliability of using the sensor in serum samples shows good recovery of FVI, PAR and VC.

Fabrication and Characterization of Acute Myocardial Infarction Myoglobin Biomarker Based on Chromium-Doped Zinc Oxide Nanoparticles

In this article, we describe the fabrication and characterization of a sensor for acute myocardial infarction that detects myoglobin biomarkers using chromium (Cr)-doped zinc oxide (ZnO) nanoparticles (NPs). Pure and Cr-doped ZnO NPs (13 × 10¹⁷, 20 × 10¹⁷, and 32 × 10¹⁷ atoms/cm³ in the solid phase) were synthesized by a facile low-temperature sol-gel method. Synthesized NPs were examined for structure and morphological analysis using various techniques to confirm the successful formation of ZnO NPs. Zeta potential was measured in LB media at a negative value and increased with doping. XPS spectra confirmed the presence of oxygen deficiency in the synthesized material. To fabricate the sensor, synthesized NPs were screen-printed over a pre-fabricated gold-coated working electrode for electrochemical detection of myoglobin (Mb). Cr-doped ZnO NPs doped with 13 × 10¹⁷ Cr atomic/cm³ revealed the highest sensitivity of ~37.97 μA.cm⁻²nM⁻¹ and limit of detection (LOD) of 0.15 nM for Mb with a response time of ≤10 ms. The interference study was carried out with cytochrome c (Cyt-c) due to its resemblance with Mb and human serum albumin (HSA) abundance in the blood and displayed distinct oxidation potential and current values for Mb. Cr-doped ZnO NP-based Mb biosensors showed 3 times higher sensitivity as compared to pure ZnO NP-based sensors.

Electrochemical Behavior and Direct Quantitative Determination of Paclitaxel

The electrochemical behavior and direct quantitative determination of paclitaxel, a poorly soluble drug made into microemulsion, were researched by cyclic voltammetry in acetate buffer solutions (pH = 4.0) at a glassy carbon electrode. The results show that the oxidation process is irreversible and controlled by diffusion. Moreover, the effects of anodic peak current (Ipa), anodic peak potential, scan rate, pH, and the electrochemical redox mechanism have been studied. The anodic peak current varied linearly with paclitaxel concentration in the range of 5 × 10-5 mol/L to 5 × 10-4 mol/L, and the detection limit was 9.15 × 10-8 mol/L. The results of RSD (0.90%) and recovery (99.22%-101.69%) were obtained. Additionally, it has been proved that one electron and one proton are involved in the electrochemical redox process. The present research has been successfully used to determine paclitaxel in pure and real samples, which further supported the electrochemical behavior investigation of paclitaxel and direct determination of micro-emulsion.

Square-wave Adsorptive Anodic Stripping Voltammetric Determination of Antidiabetic Drug Linagliptin in Pharmaceutical Formulations and Biological Fluids Using a Pencil Graphite Electrode

A simple, sensitive, low-cost, quick and reliable square-wave anodic stripping voltammetric method is described for the determination of the antidiabetic drug Linagliptin (LNG) in pure form, tablets, and spiked human urine and plasma samples. Using a pencil graphite electrode (PGE), cyclic voltammetry (CV) was applied to study the electrochemical behavior of LNG. In a Teorell-Stenhagen buffer (pH 5.5) containing 0.1 M NaClO₄ as a supporting electrolyte, the LNG yields an irreversible well-defined oxidation peak at about 1.2 V vs. Ag/AgCl electrode. The various affecting factors, such as the pH, buffer type, supporting electrolyte, accumulation potential, scan rate and accumulation time, were tested and optimized. Also, square-wave adsorptive anodic stripping voltammetric (SWAdASV) studies show that the peak current various linearly over the LNG concentration range of 0.24 - 5.20 μg mL^-1 (R² = 0.9994). The detection and quantification limits were calculated to be 0.10 and 0.33 μg mL^-1, respectively. The proposed procedure exhibits a good precision, selectivity, and stability and was applied successfully to determine the LNG in pharmaceutical formulations (tablets) and biological fluids (spiked human urine and plasma samples).

Electrochemical Determination of Mycophenolate Mofetil in Drug Samples Using Carbon Paste Electrode Modified with 1-methyl-3-butylimidazolium Bromide and NiO/SWCNTs Nanocomposite

Background:

The mycophenolate mofetil is an immunosuppressant drug with wide application in the treatment of cancer and prevent rejection in organ transplantation. This drug showed many sides effects for pregnant women and determination of this drug is very important in the human body.

Objective:

A new electrochemical strategy was described for analysis of Mycophenolate Mofetil (MMF) using novel voltammetric sensor. The sensor was fabricated using NiO/SWCNTs and 1-methyl- 3-butylimidazolium bromide as two conductive mediators for modification of carbon paste electrode (NiO/SWCNTs/MBBr/CPE). The NiO/SWCNTs/MBBr/CPE can be used for analysis of MMF in aqueous buffer solution in the concentration range of 0.08-900 µM. In addition, the NiO/SWCNTs/ MBBr/CPE reduced oxidation over-potential of MMF ~ 80 mV and increased the oxidation current of MMF ~ 2.85 times. In the final step, NiO/SWCNTs/MBBr/CPE was used for determination of MMF in pharmaceutical serum and tablet samples.

Mycophenolate mofetil sensor based on molecularly imprinted polymer/multi-walled carbon nanotubes modified carbon paste electrode

Using square wave voltammetry, a carbon paste electrode modified by molecularly imprinted polymer (MIP) as a recognition element of mycophenolate mofetil (MMF) and multi-walled carbon nanotubes was used for MMF monitoring To investigate the electrode during modification, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were utilized. After optimization of the effective parameters, the anodic peak current of MMF was utilized for dynamic range study which was linear in 9.9 nM-87 μM range. The detection limit of the sensor was 7.0 nM. The capture ability of MIP to target was compared with that of non-imprinted polymer (NIP). The practical application of the sensor in biological fluid samples analysis demonstrates its selectivity, sensitivity, and stability.

Eco-friendly reduced graphene oxide for the determination of mycophenolate mofetil in pharmaceutical formulations

Graphene oxide (GO) was synthesized and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). GO was then electrochemically reduced and used for electrochemical study of mycophenolate mofetil (MMF). The electrochemically reduced graphene oxide (ERGO) film on glassy carbon electrode (GCE) showed enhanced peak current for electrooxidation of MMF. MMF exhibited two irreversible oxidation peaks at 0.84 V (peak a₁) and 1.1 V (peak a₂). Effects of accumulation time, pH and scan rate were studied and various electrochemical parameters were calculated. A differential pulse voltammetric method was developed for the determination of MMF in bulk samples and pharmaceutical formulations. Linear relationship was observed between the peak current and concentration of MMF in the range of 40 nM-15 μM with a limit of detection of 11.3 nM. The proposed method is simple, sensitive and inexpensive and, hence, could be readily adopted in clinical and quality control laboratories.

Monitoring of microbial cell viability using nanostructured electrodes modified with Graphene/Alumina nanocomposite

Microbial infections are rapidly increasing; however most of the existing microbiological and molecular detection methods are time consuming and/or cannot differentiate between the viable and dead cells which may overestimate the risk of infections. Therefore, a bioelectrochemical sensing platform with a high potential to the microbial-electrode interactions was designed based on decorated graphene oxide (GO) sheet with alumina (Al₂O₃) nanocrystals. GO-Al₂O₃ nanocomposite was synthesized using self-assembly of GO and Al₂O₃ and characterized using the scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Raman-spectroscopy, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Enhancement of electrocatalytic activity of the composite-modified electrode was demonstrated. Thus, using the GO-Al₂O₃ nanocomposite modified electrode, the cell viability was determined by monitoring the bioelectrochemical response of the living microbial cells (bacteria and yeast) upon stimulation with carbon source. The bioelectrochemical assay was optimized to obtain high sensitivity and the method was applied to monitor cell viability and screen susceptibility of metabolically active cells (E. coli, B. subtilis, Enterococcus, P. aeruginosa and Salmonella typhi) to antibiotics such as ampicillin and kanamycin. Therefore, the developed assay is suitable for cell proliferation and cytotoxicity testing.

Core-shell hyperbranched chitosan nanostructure as a novel electrode modifier

The present study reports, for the first time, the development and use of core-shell amino-terminated chitosan (Cs) hyperbranched nanoparticles (HBCs-NH₂ NPs) as a novel natural polymer-based electrode modifier for efficient electrochemical systems. The electrochemical activity of the developed HBCs-NH₂ NPs as compared to Cs NPs was identified by standard oxidation-reduction reactions of ferricyanide. The oxidation-reduction peaks height was about twofold higher than the response of Cs-modified electrode. On the other hand, NADH oxidation at the nanostructured surfaces confirmed the electrocatalytic activity where the oxidation of NADH appeared at a lower overpotential (from 805mV to 635mV vs Ag/AgCl). Eventually, a diffusion-controlled process was confirmed from the scan rate effect.