Study on the interaction between HIV reverse transcriptase and its non-nucleoside inhibitor nevirapine by capillary electrophoresis

TiO2 Nanoparticles Decorated Graphene Nanoribbons for Voltammetric Determination of an Anti-HIV Drug Nevirapine

In the present study, electrochemical behavior of nevirapine on a glassy carbon electrode (GCE) modified with TiO2 nanoparticles decorated graphene nanoribbons was investigated. Characterization of different components used for modifications was achieved using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The electrochemical behavior of nevirapine on the modified electrodes was examined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and differential pulse voltammetry (DPV). A considerable oxidation potential decrease of +352 mV for nevirapine in 0.1 M phosphate-buffered saline (PBS), pH 11.0, was achieved due to synergy offered by graphene nanoribbons and TiO2 compared to graphene nanoribbons (+252 mV) and TiO2 (−37 mV), all with respect to the glassy carbon electrode. Under optimized conditions, DPV gave linear calibrations over the range of 0.020–0.14 µM. The detection limit was calculated as 0.043 µM. The developed sensor was used for determination of nevirapine in a pharmaceutical formulation successfully.

A novel voltammetric sensor for nevirapine, based on modified graphite electrode by MWCNs/poly(methylene blue)/gold nanoparticle

In the present study, a graphite electrode (GE) modified by conductive film (containing functionalized multi-walled carbon nanotubes (f-MWCNTs), poly methylene blue p(MB) and gold nanoparticles (AuNPs)) was introduced for determination of nevirapine (NVP) as an anti-HIV drug by applying the differential pulse anodic stripping voltammetry (DPASV) technique. Modification of the electrode was investigated by scanning electron microscopy (SEM) and impedance electrochemical spectroscopy (EIS). All electrochemical effective parameters on detection of NVP were optimized and the oxidation peak current of drug was used for its monitoring. The obtained results confirmed that the oxidation peak currents increased linearly by increasing in NVP concentrations in the range of 0.1-50 μM and a detection limit of 53 nM was achieved. The proposed sensor (AuNPs/p(MB)/f-MWCNTs/GE) was successfully applied for the determination of NVP in blood serum and pharmaceutical samples. It revealed the excellent stability, repeatability and reproducibility as well.

Capillary electrophoresis based on nucleic acid detection for diagnosing human infectious disease

Rapid transmission, high morbidity, and mortality are the features of human infectious diseases caused by microorganisms, such as bacteria, fungi, and viruses. These diseases may lead within a short period of time to great personal and property losses, especially in regions where sanitation is poor. Thus, rapid diagnoses are vital for the prevention and therapeutic intervention of human infectious diseases. Several conventional methods are often used to diagnose infectious diseases, e.g. methods based on cultures or morphology, or biochemical tests based on metabonomics. Although traditional methods are considered gold standards and are used most frequently, they are laborious, time consuming, and tedious and cannot meet the demand for rapid diagnoses. Disease diagnosis using capillary electrophoresis methods has the advantages of high efficiency, high throughput, and high speed, and coupled with the different nucleic acid detection strategies overcomes the drawbacks of traditional identification methods, precluding many types of false positive and negative results. Therefore, this review focuses on the application of capillary electrophoresis based on nucleic detection to the diagnosis of human infectious diseases, and offers an introduction to the limitations, advantages, and future developments of this approach.

Protein-mediated antagonism between HIV reverse transcriptase ligands nevirapine and MgATP

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) play a central role in the treatment of AIDS, but their mechanisms of action are incompletely understood. The interaction of the NNRTI nevirapine (NVP) with HIV-1 reverse transcriptase (RT) is characterized by a preference for the open conformation of the fingers/thumb subdomains, and a reported variation of three orders of magnitude between the binding affinity of NVP for RT in the presence or absence of primer/template DNA. To investigate the relationship between conformation and ligand binding, we evaluated the use of methionine NMR probes positioned near the tip of the fingers or thumb subdomains. Such probes would be expected to be sensitive to changes in the local environment depending on the fractions of open and closed RT. Comparisons of the NMR spectra of three conservative mutations, I63M, L74M, and L289M, indicated that M63 showed the greatest shift sensitivity to the addition of NVP. The exchange kinetics of the M63 resonance are fast on the chemical shift timescale, but become slow in the presence of NVP due to the slow binding of RT with the inhibitor. The simplest model consistent with this behavior involves a rapid open/closed equilibrium coupled with a slow interaction of the inhibitor with the open conformation. Studies of RT in the presence of both NVP and MgATP indicate a strong negative cooperativity. Binding of MgATP reduces the fraction of RT bound to NVP, as indicated by the intensity of the NVP-perturbed M230 resonance, and enhances the dissociation rate constant of the NVP, resulting in an increase of the open/closed interconversion rate, so that the M63 resonance moves into the fast/intermediate-exchange regime. Protein-mediated interactions appear to explain most of the affinity variation of NVP for RT.