A novel molecularly imprinted sensing platform based on MWCNTs/AuNPs decorated 3D starfish like hollow nickel skeleton as a highly conductive nanocomposite for selective and ultrasensitive analysis of a novel pan-genotypic inhibitor velpatasvir in body fluids

Methylene blue-assisted molecularly-imprinted film modified nitrogen and sulfur co-doped molybdenum carbide for simultaneous electrochemical determination of two hepatotoxic drugs

A novel electrochemical sensor with a dual-template molecular imprinting technology was fabricated for the simultaneous detection of paracetamol (PAR) and isoniazid (INZ). The sensor was constructed using nitrogen and sulfur co-doped molybdenum carbide (N, S@Mo2C) and a thin layer of electro-polymerized methylene blue was applied onto the surface of the N, S@Mo2C. The electrochemical sensor demonstrated remarkable analytical efficiency for the concurrent PAR and INZ quantification under optimal circumstances. The system achieved an exceptionally low limit of detection (S/N = 3) of  3.7 nM for PAR, with a concentration range  of  0.013 and 140 µM.  A LOD of 7.6 nM was attained for INZ, with a linear range  between 0.025 and 140 µM. Furthermore, the platform's selectivity was evaluated using differential pulse voltammetry  (DPV). The designed platform successfully detected PAR and INZ in authentic samples with recoveries varying between 98.3% and 104.9%. The relative standard deviations (RSD) for these measurements ranged from 2.7 to 4.0%, demonstrating that the proposed sensor is extremely stable, repeatable, and reproducible. These promising results suggest that the sensor holds potential for the detection of various (bio) molecules, paving the way for future applications in sensing fields.

The Effect of Polymerization Techniques on the Creation of Molecularly Imprinted Polymer Sensors and Their Application on Pharmaceutical Compounds

Molecularly imprinted polymers (MIPs) have become more prevalent in fabricating sensor applications, particularly in medicine, pharmaceuticals, food quality monitoring, and the environment. The ease of their preparation, adaptability of templates, superior affinity and specificity, improved stability, and the possibility for downsizing are only a few benefits of these sensors. Moreover, from a medical perspective, monitoring therapeutic medications and determining pharmaceutical compounds in their pharmaceutical forms and biological systems is very important. Additionally, because medications are hazardous to the environment, effective, quick, and affordable determination in the surrounding environment is of major importance. Concerning a variety of performance criteria, including sensitivity, specificity, low detection limits, and affordability, MIP sensors outperform other published technologies for analyzing pharmaceutical drugs. MIP sensors have, therefore, been widely used as one of the most crucial techniques for analyzing pharmaceuticals. The first part of this review provides a detailed explanation of the many polymerization techniques that were employed to create high-performing MIP sensors. In the subsequent section of the review, the utilization of MIP-based sensors for quantifying the drugs in their pharmaceutical preparation, biological specimens, and environmental samples are covered in depth. Finally, a critical evaluation of the potential future research paths for MIP-based sensors clarifies the use of MIP in pharmaceutical fields.

Sonochemical synthesis of lanthanum ferrite nanoparticle-decorated carbon nanotubes for simultaneous electrochemical determination of acetaminophen and dopamine

A new nanocomposite consisting of lanthanum ferrite nanoparticles (LaFeO3 NPs) integrated with carbon nanotubes (CNTs) was fabricated via facile sonochemical approach. The engineered nanocomposite was applied to simultaneously determine acetaminophen (ACP) and dopamine (DA) in a binary mixture. The LaFeO3 NPs@CNT probe possesses several advantages such as superior conductivity, large surface area, and more active sites, improving its electrocatalytic activity towards ACP and DA. Under optimized conditions, the anodic peak currents (Ipa) linearly increased with increasing concentration of ACP and DA in the range 0.069-210 µM and 0.15-210 µM, respectively. The sensitivity of LaFeO3 NPs@CNTs/glassy carbon electrode (GCE) for detecting ACP and DA is 7.456 and 5.980 μA·μM-1·cm-2, respectively. The detection limits (S/N = 3) for ACP and DA are 0.02 μM and 0.05 μM, respectively. Advantages of LaFeO3 NPs@CNTs/GCE for the detection of ACP and DA include wide linear ranges, low-detection limits, good selectivity, and long-term stability. The as-fabricated electrode was applied to determine ACP and DA in pharmaceutical formulations and human serum samples with recoveries ranging from 97.7 to 103.3% and an RSD that did not exceed 3.7%, confirming the suitability of the proposed sensor for the determination of ACP and DA in real samples. This study not only presents promising opportunities for enhancing the sensitivity and stability of electrochemical sensors used in the detection of bioanalytes but also significantly contributes to the progress of unique and comprehensive biochemical detection methodologies.

The potential of carbon-based nanomaterials in hepatitis C virus treatment: a review of carbon nanotubes, dendrimers and fullerenes

HCV, hepatitis C virus, is a virus that causes damage to the liver. Both chronic infection or lack of treatment increase morbidity except if it is an acute infection, as the body clears the virus without any intervention. Also, the virus has many genotypes, and until now, there has yet to be a single treatment capable of affecting and treating all these genotypes at once. This review will discuss the main and most used old treatments, IFN-a, PEG IFN-a, Ribavirin, Celgosvir, and sofosbuvir alone and with the combination of other drugs and their drawbacks. They should be given in combination to improve the effect on the virus compared with being administrated independently, as in the case of sofosbuvir. For these reasons, the need for new treatments and diagnostic tools arises, and the rule of nanotechnology comes here. The role of carbon nanotubes, dendrimers, and fullerenes will be discussed. CNTs, carbon nanotubes, are one-dimensional structures composed of a cylindrical sheet of graphite and are mainly used for diagnostic purposes against HCV. Dendrimers, three-dimensional highly branched structures, are macromolecules that provide better drug delivery and treatment options due to their unique structure that can be modified, producing versatile types; each has unique properties. Fullerenes which are cage like structures derived and closely related to CNTs, and composed of carbon atoms that can be substituted by other atoms which in return open unlimited usage for these carbon based materials. Fullerenes rule is unique since it has two mechanisms that prevent the virus from binding and acting on the virus-replicating enzyme. However, their charge needs to be determined; otherwise, it will lead to cytotoxicity. Lastly, no review has been done on the role of nanotechnology against HCV yet.

Ratiometric sensing interface for glutathione determination based on electro-polymerized copper-coordinated molecularly imprinted layer supported on silver/porous carbon hybrid

A novel molecularly imprinted ratiometric-based sensor was designed for highly selective and ultrasensitive electrochemical detection of glutathione (GSH). The sensor consists of porous carbon co-doped with nitrogen and sulfur formed on the surface of graphite electrode (N, S@PC/GE). Silver nanoparticles (Ag) were grown on the surface of N, S@PC/GE to improve the conductivity/surface area of the sensor and represent an internal reference signal for ratiometric response. The monomer (pyrrole-4-carboxylic acid, Py-COOH) was electro-polymerized on the surface of Ag/N, S@PC/GE in the presence of Cu (II) to form Cu-MIP@Ag/N, S@PC/GE. Addition of GSH decreased the signal of Ag at 0.18 V (oxidation of Ag) due to coordination complexation, while the signal response at 0.83 V (oxidation of Ag-GSH complex) was increased. Under optimum conditions, the ratio response (I_GSH/I_Ag) was increased with increasing the concentration of GSH in the range of 0.01-500 nM with a detection limit (S/N = 3) of 0.003 nM. The electrochemical sensor exhibits many advantages including low LOD, high selectivity, good reproducibility, and satisfactory stability. The sensor was successfully applied to determine GSH in dietary supplements and human serum samples with recoveries % ranged from 97.4 to 101.8% and relative standard deviation % (RSD %) did not exceed 3.8%. This research paper introduces new information for the construction of molecular imprinted ratiometric-based electrochemical sensors for highly selective and sensitive detection of (bio) molecules.

A molecularly imprinted electrochemical sensor for specific and ultrasensitive determination of an aminoglycoside drug: the role of copper ions in the determination

Herein, a molecularly imprinted polymer (MIP) was fabricated for specific sensing of an aminoglycoside e.g. kanamycin (KANA). Carbon paste modified with a MIP specific to Cu²⁺-KANA was first introduced. Copper (Cu²⁺) as a metal ion was used as a signal tracer and an amplifier, producing a current response measured by differential pulse voltammetry (DPV). Introducing the aminoglycoside drug into the solution containing Cu²⁺ did not affect the current response of the NIP/CPE. Under the optimum conditions, the as-fabricated sensor exhibited an increase in the current response in the range of 0.55-550 nM with a good limit of detection (LOD, S/N = 3) of 161 pM. The sensor exhibited many advantages including high sensitivity and selectivity, good stability and reproducibility, and cost-effectiveness. Moreover, it was successfully applied for the determination of KANA in milk and honey samples with RSD % not more than 3.3%, suggesting the reliability of the as-designed sensor.

An innovative dual recognition aptasensor for specific detection of Staphylococcus aureus based on Au/Fe3O4 binary hybrid

Pathogenic bacteria cause disease outbreaks and threaten human health, prompting the research on advanced detection assays. Herein, we developed a selective molecular imprinted aptasensor for sensitive and prompt quantitation of Staphylococcus aureus (S. aureus) bacteria. The aptasensor was constructed by immobilization of aptamer on gold nanoparticles modified magnetic nanoparticles (apt-AuNPs@ Fe₃O₄). A functional monomer (o-phenylenediamine, o-phen) was electro-polymerized on the surface of the as-synthesized nanocomposite in the presence of a template (S. aureus). After removing S. aureus, the formed imprinted sites were available to extract pathogenic bacteria from complicated matrices. The surface morphology of the as-fabricated nanocomposites was characterized using different spectroscopic and electrochemical methods. Moreover, we thoroughly evaluated factors affecting the synthesis and determination procedures. The molecular imprinted aptasensor exhibited a wide linear range of 10¹–10⁷ CFU mL⁻¹ with a Limit of Detection, LOD (signal to noise = 3) of 1 CFU mL⁻¹. The aptasensor detected S. aureus in milk, conduit water, and apple juice samples with good recoveries % and satisfactory relative standard deviations (RSDs %) values.

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.

Biomimetic Sensors to Detect Bioanalytes in Real-Life Samples Using Molecularly Imprinted Polymers: A Review

Molecularly imprinted polymers (MIPs) come with the promise to be highly versatile, useful artificial receptors for sensing a wide variety of analytes. Despite a very large body of literature on imprinting, the number of papers addressing real-life biological samples and analytes is somewhat limited. Furthermore, the topic of MIP-based sensor design is still, rather, in the research stage and lacks wide-spread commercialization. This review summarizes recent advances of MIP-based sensors targeting biological species. It covers systems that are potentially interesting in medical applications/diagnostics, in detecting illicit substances, environmental analysis, and in the quality control of food. The main emphasis is placed on work that demonstrates application in real-life matrices, including those that are diluted in a reasonable manner. Hence, it does not restrict itself to the transducer type, but focusses on both materials and analytical tasks.

Analytical Methods for Determination of Antiviral Drugs in Different Matrices: Recent Advances and Trends

Viruses are the main pathogenic substances that cause severe diseases in humans and other living things. They are among the most common microorganisms, and consequently, antiviral drugs have emerged to prevent and treat viral infections. Antiviral drugs are an essential drug group considering their prescription and consumption rates for different diseases and indications. Therefore, it is crucial to develop accurate and precise analytical methods to detect antiviral drugs in various matrices. Chromatographic techniques are used frequently for the quantification purpose since they allow simultaneous determination of antivirals. Electrochemical methods have also gained importance since the analysis can be performed quickly without the need for pretreatment. Spectrophotometric and spectrofluorimetric methods are used because they are simple, inexpensive, and less time-consuming methods. The purpose of this review is to present an overview of the analysis of currently used antiviral drugs from 2010 to 2021. Since studies on antiviral drugs are numerous, selected publications were reviewed in this article. The analysis of antiviral drugs was divided into three main groups: chromatographic, spectrometric, and electrochemical methods which were applied to different matrices, including pharmaceutical, biological, and environmental samples.

Nitrogen doped graphene quantum dots based on host guest interaction for selective dual readout of dopamine

Herein, yellow emissive nitrogen doped graphene quantum dots (N@GQDs) were prepared by a novel advanced thermal driven oxidation. The N@GQDs was functionalized with β-cyclodextrin (β-CD) to improve its catalytic performance towards dopamine (DA) detection. The β-CD/N@GQDs exhibited strong fluorescence at λ_em. = 550 nm after excitation at 460 nm with a quantum yield of 38.6%. The β-CD/N@GQDs showed good peroxidase like activity via catalyzing the oxidation of tetramethylbenzidine (TMB) in presence of H₂O₂ to form blue colored product at λ_max = 652 nm. In the colorimetric assay of DA, the detection based on the oxidation of TMB by H₂O₂ in presence of β-CD/N@GQDs as a catalyst. Then, the color of the blue oxidized TMB (oxTMB) product was reduced by addition of DA. While the fluorometric detection of DA based on the "inner filter effect" of the overlapped emission spectrum of β-CD/N@GQDs with the absorption spectrum of oxTMB, where, addition of DA reduces oxTMB to TMB and restores the fluorescence intensity of β-CD/N@GQDs. Under the optimized conditions, the colorimetric method achieved linearity range of 0.12-7.5 µM and LOD (S/N = 3) of 0.04 µM, while the fluorometric method achieved linearity range of 0.028-1.5 µM and LOD (S/N = 3) of 0.009 µM. The peroxidase like activity of β-CD/N@GQDs was used to detect DA in human plasma and serum samples with good % recoveries. The colorimetric and fluorometric methods exhibited good sensitivity and selectivity toward DA detection.

Ultrasensitive and selective molecularly imprinted electrochemical oxaliplatin sensor based on a novel nitrogen-doped carbon nanotubes/Ag@cu MOF as a signal enhancer and reporter nanohybrid

A sensitive and selective molecular imprinted polymeric network (MIP) electrochemical sensor is proposed for the determination of anti-cancer drug oxaliplatin (OXAL). The polymeric network [poly(pyrrole)] was electrodeposited on a glassy carbon electrode (GCE) modified with silver nanoparticles (Ag) functionalized Cu-metal organic framework (Cu-BDC) and nitrogen-doped carbon nanotubes (N-CNTs). The MIP-Ag@Cu-BDC /N-CNTs/GCE showed an observable reduction peak at -0.14 V, which corresponds to the Cu-BDC reduction. This peak increased and decreased by eluting and rebinding of OXAL, respectively. The binding constant between OXAL and Cu-BDC was calculated to be 3.5 ± 0.1 × 10⁷ mol^-1 L. The electrochemical signal (∆i) increased with increasing OXAL concentration in the range 0.056-200 ng mL^-1 with a limit of detection (LOD, S/N = 3) of 0.016 ng mL^-1. The combination of N-CNTs and Ag@Cu-BDC improves both the conductivity and the anchoring sites for binding the polymer film on the surface of the electrode. The MIP-based electrochemical sensor offered outstanding sensitivity, selectivity, reproducibility, and stability. The MIP-Ag@Cu-BDC /N-CNTs/GCE was applied to determine OXAL in pharmaceutical injections, human plasma, and urine samples with good recoveries (97.5-105%) and acceptable relative standard deviations (RSDs = 1.8-3.2%). Factors affecting fabrication of MIP and OXAL determination were optimized using standard orthogonal design using L₂₅ (5⁶) matrix. This MIP based electrochemical sensor opens a new venue for the fabrication of other similar  sensors and biosensors.

Facile one pot sonochemical synthesis of layered nanostructure of ZnS NPs/rGO nanosheets for simultaneous analysis of daclatasvir and hydroxychloroquine

In this study, zinc sulfide nanoparticles were loaded on reduced graphene oxide (ZnS NPs/rGO) using simple sonochemical method. The nanocomposite was characterized using different morphological and electrochemical techniques such as TEM, SEM, PXRD, EDX, Raman spectroscopy, FTIR, N₂-adsorption-desorption, CV, and EIS. The ZnS NPs/rGO modified glassy carbon electrode (GCE) was used to simultaneously estimate hydroxychloroquine (HCQ) and daclatasvir (DAC) in a binary mixture for the first time. The modified nanocomposite exhibited good catalytic activity towards HCQ and DAC detection. In addition, it showed higher sensitivity, good selectivity and stability; and high reproducibility towards HCQ and DAC analysis. The activity of the modified electrode was noticeably improved due to synergism between ZnS NPs and rGO. Under optimum conditions of DPV measurements, the anodic peak currents (Ipa) were obviously increased with the increase of HCQ and DAC amounts with linear ranges of 5.0-65.0 and 7.0-65.0 nM with LODs of 0.456 and 0.498 nM for HCQ and DAC, respectively. The ZnS NPs/ rGO modified GCE was used to quantify HCQ and DAC in biological fluids with recoveries of 98.7-102.7% and 96.9-104.5% and RSDs of 1.89-3.57% and 1.91-3.70%, respectively.

Simultaneous electrochemical detection of azithromycin and hydroxychloroquine based on VS2 QDs embedded N, S @graphene aerogel/cCNTs 3D nanostructure

In this research paper, an innovative electrochemical sensor was suggested for simultaneous voltammetric analysis of azithromycin (AZM) and hydroxychloroquine (HCQ) for the first time. The sensor based on hydrothermal synthesis of vanadium disulfide quantum dots (VS₂ QDs) and insertion within 3D N, S graphene aerogel (3D N, S @ GNA) and carbon nanotubes nanaostructure as a new and widely group of carbon nanomaterials. The nanocomposites were characterized morphologically using different techniques. In addition, the nanomaterials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The proposed electrochemical sensor showed wide dynamic linear ranges of 0.28–30 × 10⁻⁸ M and 0.84–22.5 × 10⁻⁸ M for analysis of AZM and HCQ, respectively. The limits of detection (LODs) based on signal to noise (S/N) 3:1 were found to be 0.091 × 10⁻⁸ M and 0.277 × 10⁻⁸ M for AZM and HCQ, respectively. Briefly, the electrochemical sensor had good stability, selectivity, reproducibility and feasibility for simultaneous detection of AZM and HCQ in presence of different interfering species.

Silver nanoparticles conjugated MnFe-based Prussian blue analogue for voltammetric and impedimetric bioaptasensing of amifostine (ethyol)

A novel bioaptasensing-based electrochemical method for determination of amifostine (AMF) is proposed. The electrochemical aptasensor is based on modification of a glassy carbon electrode with a nanocomposite consisting of silver nanoparticles @ MnFe Prussian blue analogue nanospheres (AgNPs@MnFePBA NS), followed by immobilization of aptamer via Ag-N bonds (aptamer/AgNPs@MnFePBA NS/GCE). Experimental parameters including pH, incubation time, and aptamer concentrations were optimized. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetric (DPV) techniques were utilized to quantify AMF. The anodic peak current (∆Ipa) and charge transfer resistance (∆Rct) differences increase in the presence of AMF. Under the optimal conditions, using the redox probe, the electrochemical aptasensor exhibited linear ranges of 0.34-45 nmol L^-1 and 0.69-45 nmol L^-1 with LODs of 0.11 nmol L^-1 and 0.23 nmol L^-1 for EIS and DPV, respectively. The aptasensor was used to determine AMF in human plasma and in the presence of interfering species with recoveries and RSDs in the range 97.8-103.2% and 2.2-4.2%, respectively. Graphical abstract.

Synthesis of three-dimensional nickel ferrite nanospheres decorated activated graphite nanoplatelets for electrochemical detection of vortioxetine with pharmacokinetic insights in human volunteers

An innovative electrochemical nanoprobe was developed for determination of vortioxetine (VORT), a serotonergic antidepressant drug, for the first time. The fabrication of the nanoprobe is based on decoration of a glassy carbon electrode with three-dimensional nickel ferrite nanospheres modified activated graphite nanoplatelets (3D NiFe₂O₄ NS/AGNP/GCE). The morphological characterization of the nanoprobe was carried out via scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDS), N₂-adsorption-desorption isotherm, and powder X-ray spectroscopy (PXRD). In addition, the electrochemical behavior of the nanoprobe was described using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). A well-defined and irreversible peak at 0.82 V was seen at the surface of 3D NiFe₂O₄ NS/AGNP/GCE. The proposed nanoprobe exhibited outstanding electro-catalytic activity towards VORT oxidation. Under the optimized conditions, the anodic oxidation currents were linearly proportional to VORT concentration at the working range 1.8-90 nM with a LOD of 0.55 nM. The nanoprobe was used to determine VORT in pharmaceutical tablets and human plasma samples. Satisfactory recoveries and RSD percentages were obtained in the range 103.8-107.7% (RSD% = 2.7-3.1%) and 101.4-105.3% (RSD % = 2.8-3.4%) for tablets and plasma samples, respectively. Moreover, the method was used to monitor VORT during a pharmacokinetic study in human volunteers with satisfactory results. The 3D NiFe₂O₄ NS/AGNP/GCE shows excellent sensitivity, reproducibility, and selectivity towards VORT detection. The proposed electrode could be utilized as simple, rapid, and inexpensive sensing tool for routine analysis and during pharmacokinetic/pharmacodynamic investigations. Graphical abstract.

Dual-recognition molecularly imprinted aptasensor based on gold nanoparticles decorated carboxylated carbon nanotubes for highly selective and sensitive determination of histamine in different matrices

In this study, an electrochemical aptamer based sensor (aptasensor) was proposed for specific recognition of histamine (HIS). The electrochemical aptasensor based on fabrication of glassy carbon electrode (GCE) with molecular imprinted polymer (MIP) and DNA aptamers on gold nanoparticles (AuNPs) and carboxylated carbon nanotubes (cCNTs) (MIP-apta/AuNPs/cCNTs/GCE). The aptasensor exhibits high selectivity towards HIS detection as it has two recognition elements which are MIP cavities and aptamer interaction. Upon exposure of MIP-apt/AuNPs/cCNTs/GCE to HIS, the current of redox probe was decreased that depends on the template (HIS) concentration. The effects of aptamer concentration, incubation time, pH and AuNPs electro-deposition time were optimized. Differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques were used to analyze HIS in complicated matrices. Favorable performance of MIP-apt/AuNPs/cCNTs/GCE was achieved with linearity ranges of 0.46-35 nmol L^-1 and 0.35-35 nmol L^-1 with limits of detection (LODs, S/N = 3) of 0.15 nmol L^-1 and 0.11 nmol L^-1 using DPV and EIS, respectively. The fabricated aptasensor displayed high selectivity, desirable reproducibility and stability. The MIP-apt/AuNPs/cCNTs/GCE was used to detect HIS in human plasma and canned tuna samples with good recoveries % and RSDs %.

Optimization of a sensitive and robust strategy for micellar electrokinetic chromatographic analysis of sofosbuvir in combination with its co-formulated hepatitis C antiviral drugs

Based on our previous work with "pseudostationary-ion exchanger sweeping", we use this strategy to develop a sensitive, reliable and robust method for the analysis of the newly-FDA approved hepatitis C antiviral drugs namely; sofosbuvir (SOV), daclatasvir (DAC), ledipasvir (LED) and velpatasvir (VEP) in their pure forms and co-formulated pharmaceutical dosage forms using micellar electrokinetic chromatography (MEKC) as a separation method. For the first time, a successful separation of all the investigated compounds was achieved in less than 8 min using a basic background electrolyte (BGE) composed of 25 mmol L^-1 SDS + 20% (v/v) ACN (acetonitrile) in 10 mmol L^-1 disodium tetraborate buffer (final apparent pH is 9.90). A special focus was given to optimize the composition of the sample matrix to maintain the solubility of the analytes within the sample zone while gaining additional benefits regarding analyte zone focusing. It was found that replacing phosphoric acid (as a sample matrix) with a zwitterionic/isoelectric buffering compound (L-glutamic acid) has a substantial positive impact on the obtained enrichment efficiency. The interplay of other enrichment principles such as the retention factor gradient effect (RFGE) is also discussed. A full validation study is performed based on the pharmacopeial and ICH guidelines. The obtained limits of detection and quantitation are as low as 0.63 and 1.3 μg mL^-1; respectively for SOV and DAC and 1.3 and 2.5 μg mL^-1; respectively for LED and VEP using UV-DAD as a detection method. The selectivity of the developed method for determination of the studied compounds in their pharmaceutical dosage forms or in the presence of ribavirin (RIB) or elbasvir (ELB), which are other prescribed medications in the treatment regimen of patients with hepatitis C virus infection, is demonstrated. It is shown that with acidic sample matrix and basic BGE, an efficient and precise approach was designed in which analyte adsorption on the capillary wall was minimized while keeping repeatable peak height, peak area and migration time together with the highest possible enrichment efficiency.

Modification of N,S co-doped graphene quantum dots with p-aminothiophenol-functionalized gold nanoparticles for molecular imprint-based voltammetric determination of the antiviral drug sofosbuvir

A molecularly imprinted polymer (MIP) was developed for the electrochemical determination of the antiviral drug sofosbuvir (SOF). The MIP was obtained by polymerization of p-aminothiophenol (p-ATP) on N,S co-doped graphene quantum dots (N,S@GQDs) in the presence of gold nanoparticles to form gold-sulfur covalent network. The presence of quantum dots improves the electron transfer rate, enhances surface activity and amplifies the signal. The nanocomposites were characterized by FTIR, TEM, EDX, and SEM. The electrochemical performance of the electrode was investigated by differential pulse voltammetry and cyclic voltammetry. The sensor uses hexacyanoferrate as the redox probe and is best operated at a potential of around 0.36 V vs. Ag/AgCl. It has a linear response over the concentration range of 1-400 nM SOF, with a detection limit of 0.36 nM. Other features include high selectivity, good reproducibility and temporal stability. The sensor was applied to the determination of SOF in spiked human plasma. Graphical abstract Novel sofosbuvir imprinted p-ATP polymer was synthesized by the aid of gold nanoparticles on N,S co-doped graphene quantum dots as a good conductive support. The imprinted polymer was used for detection of sofosbuvir in real samples by using the ferri/ferrocyanide redox probe.