Electrochemical Sensing of Favipiravir with an Innovative Water-Dispersible Molecularly Imprinted Polymer Based on the Bimetallic Metal-Organic Framework: Comparison of Morphological Effects

Recent Trends in Nanomaterial Based Electrochemical Sensors for Drug Detection: Considering Green Assessment

An individual's therapeutic drug exposure level is directly linked to corresponding clinical effects. Rapid, sensitive, inexpensive, portable and reliable devices are needed for diagnosis related to drug exposure, treatment, and prognosis of diseases. Electrochemical sensors are useful for drug monitoring due to their high sensitivity and fast response time. Also, they can be combined with portable signal read-out devices for point-of-care applications. In recent years, nanomaterials such as carbon-based, carbon-metal nanocomposites, noble nanomaterials have been widely used to modify electrode surfaces due to their outstanding features including catalytic abilities, conductivity, chemical stability, biocompatibility for development of electrochemical sensors. This review paper presents the most recent advances about nanomaterials-based electrochemical sensors including the use of green assessment approach for detection of drugs including anticancer, antiviral, anti-inflammatory, and antibiotics covering the period from 2019 to 2023. The sensor characteristics such as analyte interactions, fabrication, sensitivity, and selectivity are also discussed. In addition, the current challenges and potential future directions of the field are highlighted.

Bimetallic metal-organic framework as an efficient sorbent for the extraction of tacrolimus and cyclosporine from plasma before HPLC-MS/MS analysis

This study investigated the application of pores-size protocols into metal-organic frameworks that can lead to improved adsorption capacity of sorbents. A selective, fast, and sensitive analytical procedure based on dispersive solid phase extraction using a bimetallic metal organic framework named ZrZnMOF coupled with high-performance liquid chromatography-tandem mass spectrometry was established for the simultaneous quantification of tacrolimus and cyclosporine in plasma. The effects of several parameters, such as the dosage of sorbent, separation and elution times, volume and type of elution solvent, were investigated. Under optimal conditions, high extraction recovery (70 and 89 for tacrolimus and cyclosporine, respectively), low limits of detection (0.15 and 0.31 μg L-1 for tacrolimus and cyclosporine, respectively) and quantification (1.0 and 0.51 μg L-1 for tacrolimus and cyclosporine, respectively) wide linearity (1.0-1000 and 0.51-500 μg L-1 for tacrolimus and cyclosporine, respectively), and acceptable repeatability (n = 5, relative standard deviation less than 5.6 %) were attained. The validated method was successfully applied to quantify tacrolimus and cyclosporine A in plasma samples obtained from different volunteers.

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.

Preparation and Performance Analysis of 3D Thermoformed Fluidic Polymer Temperature Sensors for Aquatic and Terrestrial Applications

Employing a combination of Polyethylene terephthalate (PET) thermoforming and 3D-printed cylindrical patterns, we carefully engineer a linear resistive temperature sensor. This intricate process involves initial PET thermoforming, yielding a hollow cylindrical chamber. This chamber is then precisely infused with a composite fluid of graphite and water glue. Ensuring electrical connectivity, both ends are affixed with metal wires and securely sealed using a hot gun. This cost-effective, versatile sensor adeptly gauges temperature shifts by assessing composite fluid resistance alterations. Its PET outer surface grants immunity to water and solubility concerns, enabling application in aquatic and aerial settings without extra encapsulation. Rigorous testing reveals the sensor's linearity and stability within a 10 °C to 60 °C range, whether submerged or airborne. Beyond 65 °C, plastic deformation arises. To mitigate hysteresis, a 58 °C operational limit is recommended. Examining fluidic composite width and length effects, we ascertain a 12 Ω/°C sensitivity for these linear sensors, a hallmark of their precision. Impressive response and recovery times of 4 and 8 s, respectively, highlight their efficiency. These findings endorse thermoforming's potential for fabricating advanced temperature sensors. This cost-effective approach's adaptability underscores its viability for diverse applications.

[Recent advances in the applications of metal-organic frameworks-based molecularly imprinted materials]

Molecularly imprinted polymers have received wide attention from various fields owing to their pre-designable, recognition ability, and practicality. However, the disadvantages of the traditional embedding method, which include a slow recognition rate, uneven site recognition, low binding capacity, and incomplete template molecule elution, limit the development of molecular imprinting technology. Surface molecular imprinting techniques have been developed to effectively solve these problems, and different materials are used as carriers in the synthesis of molecularly imprinted polymers. Metal-organic frameworks (MOFs) show great potential as carriers. Because of their high porosity and specific surface area, MOFs can provide a large number of active sites for molecular imprinting, which can improve their detection sensitivity. The variable metal centers and organic ligands of MOF materials can also lead to multiple structures and functions. Numerous types of MOF materials have been synthesized, and the properties of these materials can be tailored by adjusting their pore size and introducing functional groups. MOFs and molecular imprinting technology can be combined to take full advantage of the specific adsorption of molecular imprinting technology and the large specific surface area and multiple active sites of MOFs, thereby expanding the application range of the resulting materials. In this paper, five aspects of the concept of MOF functionalization are discussed: introduction of special ligands, regulation of metal central sites, formation of MOF complexes, derivatization of MOFs, and sacrificial MOFs. The applications of MOF-based molecularly imprinted materials in catalysis, sample pretreatment, drug carriers, fluorescence sensors, and electrochemical sensors are also reviewed. Finally, the existing problems and future development of MOF-based molecularly imprinted materials are discussed and prospected.

Green synthesis of Au@g-C3N4 nanocomposite using Hyssopus officinalis extract and its sensing application for vortioxetine determination

Herein, we introduce a stable and green Au@g-C3N4 nanocomposite as a selective electrochemical sensor for vortioxetine (VOR) determination. The electrochemical behavior of VOR on the developed electrode was investigated through cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The Au@g-C3N4 nanocomposite was thoroughly observed by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and scanning electron microscopy. The Au@g-C3N4 nanocomposite had a higher conductivity and a narrower band gap than pure g-C3N4, causing higher electrochemical activity for VOR detection. Moreover, Au@g-C3N4 on the glassy carbon electrode (Au@g-C3N4/GCE) monitored a low level of VOR with high efficiency and low interference as an environmentally friendly processing approach. Interestingly, the as-fabricated sensor exhibited an ultrahigh selectivity for recognizing VOR with a detection limit (LOD) of 3.2 nM. Furthermore, the developed sensor was applied to determine VOR in pharmaceutical and biological samples, which indicated a high selectivity in the presence of interferences. This study suggests new insights into the phytosynthesis synthesis of nanomaterials with excellent biosensing applications.

Chemically engineered unzipped multiwalled carbon nanotube and rGO nanohybrid for ultrasensitive picloram detection in rice water and soil samples

Picloram (4-Amino-3,5,6-trichloro pyridine-2-carboxylic acid) is a chlorinated herbicide that has been discovered to be tenacious and relatively durable in both soil and water. It is known to have adverse and unpleasant effects on humans causing several health complications. Therefore, the determination of picloram is profoundly effective because of its bio-accumulative and persistent nature. Because of this, a sensitive, rapid, and robust detection system is essential to detect traces of this molecule. In this study, we have constructed a novel nanohybrid system comprising of an UZMWCNT and rGO decorated on AuNPs modified glassy carbon electrode (UZMWCNT + rGO/AuNPs/GCE). The synthesized nanomaterials and the developed system were characterized using techniques such as SEM, XRD, SWV, LSV, EIS, and chronoamperometry. The engineered sensor surface showed a broad linear range of 5 × 10^-2 nM to 6 × 10⁵ nM , a low limit of detection (LOD) of 2.31 ± 0.02 (RSD < 4.1%) pM and a limit of quantification (LOQ) of 7.63 ± 0.03 pM. The response time was recorded to be 0.2 s, and the efficacy of the proposed sensor system was studied using rice water and soil samples collected from the agricultural field post filtration. The calculated recovery % for picloram in rice water was found to be 88.58%-96.70% (RSD < 3.5%, n = 3) and for soil it was found to be 89.57%-93.24% (RSD < 3.5%, n = 3). In addition, the SWV responses of both the real samples have been performed and a linear plot have been obtained with a correlation coefficient of 0.97 and 0.96 for rice and soil samples, respectively. The interference studies due to the coexisting molecules that may be present in the samples have been found to be negligible. Also, the designed sensor has been evaluated for stability and found to be highly reproducible and stable towards picloram detection.

The application of multi-walled carbon nanotubes modified pencil graphite electrode for voltammetric determination of favipiravir used in COVID-19 treatment

This study describes the first application of an improved procedure on a pencil graphite electrode decorated with functionalized multi-walled carbon nanotubes (f-MWCNTs/PGE) for the determination of the COVID-19 antiviral drug, favipiravir (FVP). The electrochemical behavior of FVP at f-MWCNTs/PGE was examined by cyclic voltammetry and differential pulse voltammetry (DPV) methods, and it was noted that the voltammetric response significantly increased with the modification of f -MWCNTs to the surface. The linear range and limit of detection from DPV studies were determined as 1-1500 µM and 0.27 µM, respectively. In addition, the selectivity of the method was tested toward potential interferences, which can be present in pharmaceutical and biological samples, and it was found that f-MWCNTs/PGE showed high selectivity for the determination of FVP in the presence of probable interferences. The results with high accuracies and precisions from the obtained feasibility studies also revealed that the designed procedure can be used for accurate and selective voltammetric determination of FVP in real samples.

Graphical abstract

Nickel-Cobalt Salen Organometallic Complexes Encapsulated in Mesoporous NaA Nanozeolite for Electrocatalytic Quantification of Ascorbic Acid and Paracetamol

Goal of current study was fabrication of novel voltammetric nanosensor for the synchronize quantification of ascorbic acid (AA) and paracetamol (PAR) by nickel-cobalt salen complexes encapsulated in the supercages of NaA nanozeolite modified carbon paste electrode (NiCoSalenA/CPE). For this purpose, NiCoSalenA nanocomposite was firstly prepared and characterized by various methods. Also, cyclic voltammetry (CV), choronoamperometry (CHA) and differential pulse voltammetry (DPV) were utilized to evaluate performance of the modified electrodes. The effects of pH and modifier amount were considered on the electrochemical oxidation of AA and PAR on the surface of NiCoSalenA/CPE. Results from this method indicated that pH of 3.0 in phosphate buffer solution (0.1 M) and 15 wt% of NiCoSalenA nanocomposite in the modified CPE results in the maximum current density. The oxidation signals of AA and PAR was amplified affectively at NiCoSalenA/CPE versus unmodified CPE. The limit of detection (LOD) and linear dynamic range (LDR) for the simultaneous measurement of them were founds to be 0.82 and 2.73-80.70 for AA and 0.51 µM, 1.71-32.50 and 32.50-137.60 µM for PAR, respectively. The catalytic rate constants (kcat) were attained to be 3.73 × 107 and 1.27 × 107 cm3 mol-1 s-1 for AA and PAR via CHA method, respectively. Also, the amounts of diffusion coefficient (D) were found to be 1.12 × 10-7 and 1.92 × 10-7 cm2 s-1 for AA and PAR, respectively. The average value of electron transfer rate constant between NiCoSalenA/CPE and PAR was obtained to be 0.016 s-1. The NiCoSalen-A/CPE displayed worthy stability, repeatability and extraordinary recovery for simultaneous measurements of AA and PAR. Application of offered sensor was confirmed by quantifying concentrations of AA and PAR in human serum solution as a real sample.

Synchronous spectrofluorimetric determination of favipiravir and aspirin at the nano-gram scale in spiked human plasma; greenness evaluation

Favipiravir and aspirin are co-administered during COVID-19 treatment to prevent venous thromboembolism. For the first time, a spectrofluorometric method has been developed for the simultaneous analysis of favipiravir and aspirin in plasma matrix at nano-gram detection limits. The native fluorescence spectra of favipiravir and aspirin in ethanol showed overlapping emission spectra at 423 nm and 403 nm, respectively, after excitation at 368 nm and 298 nm, respectively. Direct simultaneous determination with normal fluorescence spectroscopy was difficult. The use of synchronous fluorescence spectroscopy for analyzing the studied drugs in ethanol at Δλ = 80 nm improved spectral resolution and enabled the determination of favipiravir and aspirin in the plasma matrix at 437 nm and 384 nm, respectively. The method described allowed sensitive determination of favipiravir and aspirin over a concentration range of 10-500 ng/mL and 35-1600 ng/mL, respectively. The described method was validated with respect to the ICH M10 guidelines and successfully applied for the simultaneous determination of the mentioned drugs in pure form and in the spiked plasma matrix. Moreover, the compliance of the method with the concepts of environmentally friendly analytical chemistry was evaluated using two metrics, the Green Analytical Procedure Index and the AGREE tool. The results showed that the described method was consistent with the accepted metrics for green analytical chemistry.

PdPtRu trimetallic nanozymes and application to electrochemical immunosensor for sensitive SARS-COV-2 antigen detection

Herein, a ternary PdPtRu nanodendrite as novel trimetallic nanozyme was reported, which possessed excellent peroxidase-like activity as well as electro-catalytic activity on account of the synergistic effect between the three metals. Based on the excellent electro-catalytic activity of trimetallic PdPtRu nanozyme toward the reduction of H₂O₂, the trimetallic nanozyme was applied to construct a brief electrochemical immunosensor for SARS-COV-2 antigen detection. Concretely, trimetallic PdPtRu nanodendrite was used to modify electrode surface, which not only generated high reduction current of H₂O₂ for signal amplification, but also provided massive active sites for capture antibody (Ab₁) immobilization to construct immunosensor. In the presence of target SARS-COV-2 antigen, SiO₂ nanosphere labeled detection antibody (Ab₂) composites were introduced on the electrode surface according sandwich immuno-reaction. Due to the inhibitory effect of SiO₂ nanosphere on the current signal, the current signal was decreased with the increasing target SARS-COV-2 antigen concentration. As a result, the proposed electrochemical immunosensor presented sensitive detection of SARS-COV-2 antigen with linear range from 1.0 pg/mL to 1.0 μg/mL and limit of detection down to 51.74 fg/mL. The proposed immunosensor provide a brief but sensitive antigen detection tool for rapid diagnosis of COVID-19.

An innovative wireless electrochemical card sensor for field-deployable diagnostics of Hepatitis B surface antigen

A wireless-based detection utilizing an innovative electrochemical card (eCard) sensor controlled by a smartphone was developed for targeting Hepatitis B surface antigen (HBsAg). A simple label-free electrochemical platform allows a convenient operation for point-of-care diagnosis. A disposable screen-printed carbon electrode was modified straightforwardly layer-by-layer with chitosan followed by glutaraldehyde, allowing a simple but effective, reproducible, and stable method for covalently immobilizing antibodies. The modification and immobilization processes were verified by electrochemical impedance spectroscopy and cyclic voltammetry. The smartphone-based eCard sensor was used to quantify HBsAg by measuring the change in current response of the [Fe(CN)₆]^3-/4- redox couple before and after the presence of HBsAg. Under the optimal conditions, the linear calibration curve for HBsAg was found to be 10-100,000 IU/mL with a detection limit of 9.55 IU/mL. The HBsAg eCard sensor was successfully applied to detect 500 chronic HBV-infected serum samples with satisfactory results, demonstrating the excellent applicability of this system. The sensitivity and specificity of this sensing platform were found to be 97.75% and 93%, respectively. As illustrated, the proposed eCard immunosensor offered a rapid, sensitive, selective, and easy-to-use platform for healthcare providers to rapidly determine the infection status of HBV patients.

Synergistic effect of gold nanoparticles anchored on conductive carbon black as an efficient electrochemical sensor for sensitive detection of anti-COVID-19 drug Favipiravir in absence and presence of co-administered drug Paracetamol

Favipiravir (FVP) is introduced as a promising newly developed antiviral drug against the coronavirus disease 2019 (COVID-19). Therefore, the accurate determination of FVP is of great significance for quality assessment and clinical diagnosis. Herein, a novel electrochemical sensing platform for FVP based on gold nanoparticles anchored conductive carbon black (Au@CCB) modified graphite nanopowder flakes paste electrode (GNFPE) was constructed. Morphological and nanostructure properties of Au@CCB have been investigated by TEM, HRTEM, and EDX methods. The morphology and electrochemical properties of Au@CCB/GNFPE were characterized by SEM, cyclic voltammetry (CV), and EIS. The Au@CCB nanostructured modified GNFPE exhibited strong electro-catalytic ability towards the oxidation of FVP. The performance of the fabricated Au@CCB/GNFPE was examined by monitoring FVP concentrations in the absence and presence of co-administered drug paracetamol (PCT) by AdS-SWV. It was demonstrated that the proposed sensor exhibited superior sensitivity, stability, and anti-interference capability for the detection of FVP. The simultaneous determination of a binary mixture containing FVP and the co-administered drug PCT using Au@CCB/GNFPE sensor is reported for the first time. Under optimized conditions, the developed sensor exhibited sensitive voltammetric responses to FVP and PCT with low detection limits of 7.5 nM and 4.3 nM, respectively. The sensing electrode was successfully used to determine FVP and PCT simultaneously in spiked human plasma and pharmaceutical preparations, and the findings were satisfactory. Finally, the fabricated sensor exhibited high sensitivity for simultaneous detection of FVP and PCT in the presence of ascorbic acid in a real sample.