Spectrophotometric and spectrodensitometric quantification of a new antiviral combination

Electrochemical sensor based on bio-inspired molecularly imprinted polymer for sofosbuvir detection

The electropolymerized molecularly imprinted polymers (MIP) have enabled the utilization of various functional monomers with superior selective recognition of the target analyte template. Methyldopa is an attractive synthetic dopamine analogue which has phenolic, carboxylic, and aminic functional groups. In this research, methyldopa was exploited to fabricate selective MIPs, for the detection of sofosbuvir (SFB), by a simple electropolymerization step onto a disposable pencil graphite electrode (PGE) substrate. The interaction between methyldopa, as a functional monomer, and a template has been investigated experimentally by UV spectroscopy. A polymethyldopa (PMD) polymer was electrografted onto PGE in the presence of SFB as a template. X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (ESI), and cyclic voltammetry (CV) were used for the characterization of the fabricated sensor. Differential pulse voltammetry (DPV) of a ferrocyanide/ferricyanide redox probe was employed to indirectly detect the SFB binding to the MIP cavities. The sensor shows a reproducible and linear response over a dynamic linear range from 1.0 × 10-11 M to 1.0 × 10-13 M of SFB with a limit of detection of 3.1 × 10-14 M. The sensor showed high selectivity for the target drug over structurally similar and co-administered interfering drugs, and this enabled its application to detect SFB in its pharmaceutical dosage form and in spiked human plasma samples.

Sensitive Determination of SARS-COV-2 and the Anti-hepatitis C Virus Agent Velpatasvir Enabled by Novel Metal-Organic Frameworks

Herein, we report on the electrochemical determination of velpatasvir (VLP) as the main constituent of Epclusa, a SARS-COV-2 and anti-hepatitis C virus (HCV) agent, using a novel metal-organic framework (MOF). The NH2-MIL-53(Al) MOF was successfully modified with 5-bromo-salicylaldehyde to synthesize 5-BSA=N-MIL-53(Al) MOF. The synthesized MOF has been characterized using Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The modified MOF showed higher electrochemical activity and response than the bare NH2-MIL-53(Al) MOF. Compared to the bare carbon paste electrode (CPE), the 5-BSA=N-MIL-53(Al)/CPE platform was shown to enhance the electrochemical oxidation and detection of the anti-SARS-COV-2 and anti-HCV agent. Under optimized conditions, the 5-BSA=N-MIL-53(Al)/CPE platform showed a linear range of 1.11 × 10-6 to 1.11 × 10-7 and 1.11 × 10-7 to 25.97 × 10-6 M Britton-Robinson buffer (pH 7) with a detection limit and limit of quantification of 8.776 × 10-9 and 2.924 × 10-8 M, respectively. Repeatability, storage stability, and reproducibility in addition to selectivity studies and interference studies were conducted to illustrate the superiority of the electrode material. The study also included a highly accurate platform for the determination of VLP concentrations in both urine and plasma samples with reasonable recovery.

A Review on Analytical Strategies for the Assessment of Recently Approved Direct Acting Antiviral Drugs

Human beings are in dire need of developing an efficient treatment against fierce viruses like hepatitis C virus (HCV) and Coronavirus (COVID-19). These viruses have already caused the death of over two million people all over the world. Therefore, over the last years, many direct-acting antiviral drugs (DAADs) were developed targeting nonstructural proteins of these two viruses. Among these DAADs, several drugs were found more effective and safer than the others as sofosbuvir, ledipasvir, grazoprevir, glecaprevir, voxilaprevir, velpatasvir, elbasvir, pibrentasvir and remdesivir. The last one is indicated for COVID-19, while the rest are indicated for HCV treatment. Due to the valuable impact of these DAADs, larger number of analytical methods were required to meet the needs of the clinical studies. Therefore, this review will highlight the current approaches, published in the period between 2017 to present, dealing with the determination of these drugs in two different matrices: pharmaceuticals and biological fluids with the challenges of analyzing these drugs either alone, with other drugs, in presence of interferences (pharmaceutical excipients or endogenous plasma components) or in presence of matrix impurities, degradation products and metabolites. These approaches include spectroscopic, chromatographic, capillary electrophoretic, voltametric and nuclear magnetic resonance methods that have been reported during this period. Moreover, the analytical instrumentation and methods used in determination of these DAADs will be illustrated in tabulated forms.