Nanostructured TiO₂ Carbon Paste Based Sensor for Determination of Methyldopa

Synthesis of New Azo Compounds and Their Application for a Simple Spectrophotometric Determination of Methyldopa Drug Using Anthranilic Acid and 2-Aminopyrimidine as Reagents

The goal of the current work is to synthesize methyldopa derivatives. Based on these reactions, two easy, speedy, accurate, inexpensive, and sensitive spectrophotometric approaches have been established for determining methyldopa (MED) in both pure and pharmaceutical forms. The proposed azo-coupling method depends on forming an azo compound between methyldopa drug and 2-AMPY or ANTH to produce two compounds of MED-2AMPY and MED-ANTH in the alkaline medium. The characterization of synthesized compounds utilizing UV-Visible and FT-IR spectra. FT-IR spectra of 2AMPY-MED confirm the existence of OH, C-Hor, C-Hal, NH, N=N, C=O, and C=C vibration at 3455, 3059, 2973, 3100, 1476,1692, and 1560 cm-1, and FT-IR spectra of ANTH-MED confirm the existence of OH, C-Hor, NH, C=O and N=N vibration at 3490, 3050, 3100, 1701 and 1462 cm-1, correspondingly. The obtained color of azo compounds is spectrophotometrically measured for the previously mentioned azo compounds at 450 and 455 nm, respectively. Under perfect conditions, the azo compound solutions exhibited molar absorptivities of 1563.0058 and 2091.0285 L.mol-1.cm-1, Sandell's sensitivity of 0.135 and 0.10 µg.cm-1, and Beer-Lambert's law are obeyed over the ranges 6.25- 62.5 mg. L-1 for the two developed procedures, respectively.

Recent Prospects of Carbonaceous Nanomaterials-Based Laccase Biosensor for Electrochemical Detection of Phenolic Compounds

Phenolic compounds (PhCs) are ubiquitously distributed phytochemicals found in many plants, body fluids, food items, medicines, pesticides, dyes, etc. Many PhCs are priority pollutants that are highly toxic, teratogenic, and carcinogenic. Some of these are present in body fluids and affect metabolism, while others possess numerous bioactive properties such as retaining antioxidant and antimicrobial activity in plants and food products. Therefore, there is an urgency for developing an effective, rapid, sensitive, and reliable tool for the analysis of these PhCs to address their environmental and health concern. In this context, carbonaceous nanomaterials have emerged as a promising material for the fabrication of electrochemical biosensors as they provide remarkable characteristics such as lightweight, high surface: volume, excellent conductivity, extraordinary tensile strength, and biocompatibility. This review outlines the current status of the applications of carbonaceous nanomaterials (CNTs, graphene, etc.) based enzymatic electrochemical biosensors for the detection of PhCs. Efforts have also been made to discuss the mechanism of action of the laccase enzyme for the detection of PhCs. The limitations, advanced emerging carbon-based material, current state of artificial intelligence in PhCs detection, and future scopes have also been summarized.

Development and characterization of electrochemical sensors based on carbon modified with TiO2 nanoparticles

The aim of this study is the development and characterization of a carbon-based electrochemical sensor, modified with TiO2 nanoparticles for potential application in electroanalytical techniques. The influence of binder and modifier contents on morphological, physicochemical and electrochemical characteristics of the electrode material was investigated in order to determine the optimal ratio of the carbon material/binder/modifier. Carbon pastes were prepared from mixtures containing graphite powder, TiO2 nanoparticles and liquid hydrocarbons. Scanning electron microscopy showed that the electrode material becomes more compact with the addition and the increase in the binder material content, while increasing the proportion of TiO2 nanoparticles did not have any significant effect on the material morphology showing fairly homogeneous nanoparticle distribution in the graphite electrode material. The test results indicate that the modified carbon paste with 40 vol.% paraffin oil (PO) and 6-8 wt.% TiO2 nanoparticles is characterized by the lowest value of specific resistance. By applying cyclic voltammetry, the most pronounced degree of reversibility was obtained in relation to the standard reversible redox system ([Fe (CN)]-3/-4) for the electrode material with 30-40 vol.% PO and 8-10 wt.% TiO2 nanoparticles. Characterization of the electrode material based on carbon modified with TiO2 nanoparticles indicated that the optimal composition contains 40 vol.% PO and 6-8 wt.% TiO2 nanoparticles, which is important for application in electroanalytical techniques.

Development and Optimization of Solanum Lycocarpum Polyphenol Oxidase-Based Biosensor and Application towards Paracetamol Detection

Purpose: The development biosensing technologies capable of delivering fast and reliable analysis is a growing trend in drug quality control. Considering the emerging use of plant-based polyphenol oxidases (PPO) as biological component of electrochemical biosensors, this work reports the first Solanum lycocarpum PPO biosensor and its use in the pharmaceutical analysis of paracetamol in tablet formulations.

Methods: The biosensor was optimized regarding fruit maturation (immature and mature-ripe), vegetal extract volume to be used in biosensor construction as well as optimal pH of electrochemical cell fluid.

Results: Results evidenced that the extract which rendered the biosensor with best analytical performance was from immature fruits, and the biosensor produced using 100 µL of crude plant extract promoted better faradaic signal gathering. Moreover, when neutral pH media was used in the electrochemical cell, the biosensor showcased best faradaic signal output from the used redox probe (catechol), suggesting thence that the method presents high sensibility for phenolic compounds detection. Furthermore, the biosensor was able to quantify paracetamol in a linear range from 50 to 300 μM, showcasing LoD and LoQ of 3 μM and 10 μM, respectively.

Conclusion: after careful evaluation, this biosensor might be a low-cost alternative for conventional pharmaceutical quality control methods.

Nano-sized Metal and Metal Oxide Modified Electrodes for Pharmaceuticals Analysis

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The electrochemical analysis offers a number of important advantages such as providing information on pharmaceuticals analysis and their in vivo redox processes and pharmacological activity. The interest in developing electrochemical sensing devices for use in clinical assays is growing rapidly. Metallic nanoparticles can be synthesized and modified with various chemical functional groups, which allow them to be conjugated with antibodies, ligands, and drugs of interest.

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In this article, the novel developments to enhance the performance of sensor modified with metal nanoparticles of pharmaceuticals were reviewed. A discussion of the properties of metal nanostructures and their application in drug analysis is presented. Their application as a modifier agent in determining low levels of drugs in pharmaceutical dosage forms and biological samples is discussed. It has been found that the electrocatalytic effect of the electrode, sensitivity and selectivity were increased using various working electrodes modified with nano-sized metal, metal oxide and metal/metal oxide particles.

Preparation of A Magnetic Nanosensor Based on Cobalt Ferrite Nanoparticles for The Electrochemical Determination of Methyldopa in The Presence of Uric Acid

AIM AND OBJECTIVE

Methyldopa is one of the medications that is used for the treatment of hypertension. Therefore, the determination of methyldopa in the presence of other biological components is essential. In this work, a promising electrochemical sensor based on CoFe₂O₄ magnetic nanoparticles modified glassy carbon electrode (CoFe₂O₄/GCE) was developed for electrochemical determination of methyldopa in the presence of uric acid. Cobalt ferrite nanoparticles were synthesized via chemical method.

MATERIALS AND METHODS

Characterizing the CoFe₂O₄ was investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), and cyclic voltammetry techniques.

RESULTS

Under the optimal experimental conditions, the current response of the electrochemical sensor obtained with differential pulse voltammetry was increased linearly in the concentration range from 1.45 to 15.1 μmol L^-1 with the detection limit of 1.07 μmol L^-1 for methyldopa. Also, by using the proposed method, methyldopa and uric acid could be analyzed in a mixture independently. The difference in peak potential for analytes is about 150 mV.

CONCLUSION

The present sensor was successfully applied for the determination of methyldopa in the presence of uric acid in biological samples and the pharmaceutical samples with satisfactory results.