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The strong development of mankind is inseparable from the proper use of drugs, and the electroanalytical research of drugs occupies an important position in the field of analytical chemistry. This review mainly elaborates the research progress of drugs electroanalysis based on direct electrochemical redox on various electrodes for the recent decade from 2011 to 2021. At first, we summarize some frequently used electrochemical data processing and electrochemical mechanism research derivation methods in the literature. Then, according to the drug therapeutic and application/usage purposes, the research progress of drugs electrochemical analysis is classified and discussed, where we focus on drugs electrochemical reaction mechanism. At the same time, the comparisons of electrochemical sensing performance of the drugs on various electrodes from recent studies are listed, so that readers can more intuitively compare and understand the electroanalytical sensing performance of each modified electrode for each of the drug. Finally, this review discusses the shortcomings and prospects of the drugs electroanalysis based on direct electrochemical redox research. [ABSTRACT FROM AUTHOR]

A new wearable potentiometric tattoo biosensor for real-time on-body monitoring of G-type nerve agents simulant is described. The skin-worn flexible biosensor responds rapidly and selectively to the fluorine-containing organophosphates (OP) nerve agent simulant diisopropyl fluorophosphate (DFP, a model OP analyte) in both liquid and vapor phases. The epidermal potentiometric OP biosensor relies on the pH-sensitive polyaniline (PANi) coating on a flexible printed transducer for monitoring the proton release during the enzymatic hydrolysis of DFP by enzyme organophosphate hydrolase (OPH). The sensing electrodes are screen printed on a temporary tattoo paper and are interfaced to a conformal electronic interface that provides wireless data transmission. The skin-worn OP potentiometric sensor can withstand severe mechanical strains without compromising its analytical performance. The biosensor displays a wide dynamic range, fast response and high selectivity towards DFP (including efficient discrimination against organophosphate pesticides), and good reproducibility. The attractive performance of the new wearable biosensor indicates considerable promise for on-body threat detection towards rapid warning regarding potential exposure to G-series nerve agents. [ABSTRACT FROM AUTHOR]

In this work, we report an innovative tool for heavy metal screening in water samples. This new chemiluminescent set-up screens the light generated from luminol oxidation by horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2). The pollutant concentrations in real water samples were calculated by studying the effect of metal ions on chemiluminescence signal. Owing to its simplicity, portability and low cost, this approach presents a real alternative to classical optical methods. It is constructed with simple materials: a black box containing a cuvette and a micro-camera. When the enzymatic reaction takes place, the luminescence is captured by the camera placed in upright position. The image can be saved automatically in a computer for further analysis using a MATLAB interface. The RGB diagram is then established to determine the analyte concentrations in the tested samples. This method was successfully applied for the determination of mercury (Hg), lead (Pb) and cadmium (Cd) in lake and field water samples. In these experiments, three concentrations of each analytes were tested (5, 25 and 50 µg/L). We noted a good proportionality between the analyte concentration and the chemiluminescent detection intensity. Detection of binary and tertiary combinations of heavy metals has been also investigated. The developed biosensor showed low detection limits for the tested heavy metals: 1, 0.7 and 0.02 for Hg2+, Pb2+ and Cd2+, respectively. Finally, excellent recoveries ranging from 98% to 104% were obtained for the HRP-inhibition assay. [ABSTRACT FROM AUTHOR]

Flexible epidermal tattoo and textile-based electrochemical biosensors have been developed for vapor-phase detection of organophosphorus (OP) nerve agents. These new wearable sensors, based on stretchable organophosphorus hydrolase (OPH) enzyme electrodes, are coupled with a fully integrated conformal flexible electronic interface that offers rapid and selective square-wave voltammetric detection of OP vapor threats and wireless data transmission to a mobile device. The epidermal tattoo and textile sensors display a good reproducibility (with RSD of 2.5% and 4.2%, respectively), along with good discrimination against potential interferences and linearity over the 90–300 mg/L range, with a sensitivity of 10.7 µA∙cm 3 ∙mg −1 (R 2 = 0.983) and detection limit of 12 mg/L in terms of OP air density. Stress-enduring inks, used for printing the electrode transducers, ensure resilience against mechanical deformations associated with textile and skin-based on-body sensing operations. Theoretical simulations are used to estimate the OP air density over the sensor surface. These fully integrated wearable wireless tattoo and textile-based nerve-agent vapor biosensor systems offer considerable promise for rapid warning regarding personal exposure to OP nerve-agent vapors in variety of decentralized security applications. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a flexible transdermal tattoo patch with a novel penetrative ultrasound‐triggered microballistic delivery capability toward enhanced skin penetration of its microdose payload. The new microballistic transdermal patch consists of a microporous membrane attached on an elastic temporary tattoo designed to conform to the skin surface and resist repeated common mechanical strains characteristic of epidermal wear. The porous membrane contains cylindrical micropores, which are fully loaded with a microdose of a model cargo along with a perfluorocarbon emulsion. Application of a high intensity focused ultrasound pulse vaporizes the perfluorocarbon emulsion, which serves as a propellant for the rapid ejection of the encapsulated payload and its penetration into soft adherent surfaces. The utility of the new microballistic concept and advantages over passive diffusion are illustrated using a skin‐mimicking phantom model toward enhanced drug delivery and improved nerve agent decontamination. The marriage between wearable epidermal tattoo‐patch technology and penetrative needle‐free ultrasound‐microballistic processes paves the way for new skin‐worn delivery devices for diverse therapeutic, detoxification, and skin‐care applications. [ABSTRACT FROM AUTHOR]

We present an electrospinning of graphene-oxide (GO) onto screen printed carbon electrodes (SPCE) for heavy metals (HMs) bio-sensing. The GO was dispersed in poly (vinyl alcohol) (PVA) diluted aqueous solution, and the mixture was electrospun into GO/PVA composite nanofibers. The morphology of GO and SPCE modified with electrospun nanofiber was studied using SEM micrographs and confirmed the uniform distribution of GO sheets in nanofibers. The Alkaline Phosphatase (ALP) was immobilized onto nanofibers grown on the SPCE and activity was checked using 1-napthyl phosphate (1-NP) by applying differential pulse voltammetry (DPV). The ALP activity was inhibited in the presence of HMs and a difference in activity was recorded after inhibition. The inhibition was calculated based on the data of pre and post inhibition current values. The inhibition of ALP was observed with mercury (Hg 2+ ), lead (Pb 2+ ) and cadmium (Cd 2+ ) with a detection limit of 0.0075, 0.015 and 0.0312 ppb respectively. The developed biosensor was also tested to evaluate the matrix suitability through recovery studies. Excellent HM recoveries were obtained in the range 94.6–99.75 with%RSD value of 3.77. [ABSTRACT FROM AUTHOR]

This manuscript describes a portable and low cost fluorescence set-up to quantify the concentrations of Ochratoxin A (OTA) in real samples using a developed system. The detection through the set up consist of an ultraviolet light at 365 nm and a CMOS sensor controlled by an executable interface designed in MATLAB, with a time consumed from acquisition to processing to image display of 20 seconds. It is reported that OTA is naturally fluorescent, so it allows the user to get a photograph of the OTA under excitation conditions and process the image in order to predict the concentrations of the sample. To capture and process the image, in an automatically manner, the system was completely based on the Red, Green and Blue (RGB) components. For each concentration of the OTA, the R, G, B coordinates were obtained and plotted to quantify the mycotoxin presented in the sample. The linearity for OTA was obtained in the concentrations range of 5–40 μg/L. Immunoaffinity columns (IAC) and molecular imprinted polymer columns (MIP) were compared. The maximum recovery of 107.76% was recorded for 2 μg/L of OTA using IAC in beer samples. The obtained results were cross validated using chromatographic method HPLC. The developed setup is easy to use, economical and portable. [ABSTRACT FROM AUTHOR]

Lysozyme (Lys) commonly presents in wines and are known to cause toxicological impact on human health. The need of highly sensitive and reliable detection methods are evident in such matrix. In this work, we developed a competitive aptamer based assay for detection of Lys by employing carboxylated magnetic beads as a support to immobilize the target molecule Lys. The used aptamer sequence was biotinylated which further binds with Streptavidin-Alkaline phosphatase (Stp-ALP) in the micro wells. Colorimetric tests were performed in order to optimize different experimental parameters. The Lys assay showed a good linearity in the range of 5–140 nM with a limit of detection (LOD) 10 nM. The mid-point value (IC 50 ) 110 nM and the analysis time (60 min) validated the developed aptasensor as a promising tool for routine use. The assay displayed good recoveries of Lys in the range 99.00–99.27% and was demonstrated for the detection of Lys in wine samples. [ABSTRACT FROM AUTHOR]

A microneedle electrochemical biosensor for the minimally invasive detection of organophosphate (OP) chemical agents is described. The new sensor relies on the coupling of the effective biocatalytic action of organophosphorus hydrolase (OPH) with a hollow-microneedle modified carbon-paste array electrode transducer, and involves rapid square-wave voltammetric (SWV) measurements of the p-nitrophenol product of the OPH enzymatic reaction in the presence of the OP substrate. The scanning-potential SWV transduction mode offers an additional dimension of selectivity compared to common fixed-potential OPH-amperometric biosensors. The microneedle device offers a highly linear response for methyl paraoxon (MPOx) over the range of 20–180 μM, high selectivity in the presence of excess co-existing ascorbic acid and uric acid and a high stability sensor upon exposure to the interstitial fluid (ISF). The OPH microneedle sensor was successfully tested ex vivo using mice skin samples exposed to MPOx, demonstrating its promise for minimally-invasive monitoring of OP agents and pesticides and as a wearable sensor for detecting toxic compounds, in general. [ABSTRACT FROM AUTHOR]

The present article describes a portable and low cost fluorescence set-up designed and characterized for in-situ screening of Ochratoxin A (OTA) in cocoa samples at field settings. The sensing module (the set up) consists of a LED with the wavelength of 370–380 nm and a color complementary metal oxide semiconductor (CMOS) micro-camera inbuilt at upright position of a black box to obtain an image of the sensing molecule. It allows the user to get an image of the sensing analytes under excitation conditions and process the image in order to predict the toxicity of the samples. The image capturing and processing of the system was based on the OTA concentration in the sample and analyzed data can be presented as RGB values. For each concentration of the OTA, the R, G, B co-ordinates were obtained and plotted to quantify actual OTA presents in the sample. Moreover, the system was tested for real sample analysis using cocoa contaminated with OTA. The system could detect OTA as low as 1.25 ng/ml with the maximum recovery of 87.5% in cocoa samples. The OTA was extracted in 1% NaHCO 3 and cleaned up using molecular imprinted polymer column (MIP). The method demonstrated a good linear range between 1.25 and 10 ng/ml. The obtained results were cross validated using chromatographic method HPLC and also compared with commercially available fluorescence instrument. The developed fluorescence setup is simple, economical, and portable with added advantages of digital image processing. The system could be deployable to cocoa fields for monitoring of OTA in quick successions. It is noteworthy to mention that this is the first report of such portable fluorescence setup where, OTA sensing was explored. [ABSTRACT FROM AUTHOR]

This work demonstrates the development of a folding based electrochemical aptasensor using methylene blue (MB) tagged anti-Ochratoxin A (OTA) aptamers. Different aptamer coupling strategies were tested using Hexamethylenediamine, polyethylene glycol, simple adsorption and diazonium coupling mechanism. The best sensitivity was recorded by oxidation of amines using hexamethylenediamine (HDMA) on screen printed carbon electrode (SPCE). To achieve the direct detection of OTA, aptamer conjugated redox probe was used and detection was demonstrated based on the conformational changes in aptamer structure upon OTA sensing. Signaling in this class of sensors arises from changes in electron transfer efficiency upon target-induced changes in the conformation/flexibility of the aptamer probe. These changes can be readily recorded electrochemically. The developed aptasensor is unique in its own mechanism as redox probe tagged aptamer coupling such as MB has never been tried to immobilize using long carbon chain spacers as, addition of spacers would provide more sensitive detection methods. A good dynamic range 0.01–5 ng/ml was obtained for OTA with Limit of detection (LOD) 0.01 ng/ml and Limit of quantification (LOQ) of 0.03 ng/ml respectively. The good reproducibility was recorded with RSD% of 3.75. The obtained straight line equation was y =0.4035 x +0.90311, r =0.9976. We believe that the sensor design guidelines outlined here represents a general strategy for developing new folding-based electrochemical aptasensors. The developed aptasensor was extended to screen cocoa samples for OTA contamination. The cocoa samples were extracted and purified using molecular imprinted polymer (MIP) columns. The aptasensor displayed good recovery values in the range 84–85% thus, exhibited the effectiveness of proposed aptasensor for such complex matrices. [ABSTRACT FROM AUTHOR]

Cocoa is an important ingredient for the chocolate industry and for many food products. However, it is prone to contamination by ochratoxin A (OTA), which is highly toxic and potentially carcinogenic to humans. In this work, four different extraction methods were tested and compared based on their recoveries. The best protocol was established which involves an organic solvent-free extraction method for the detection of OTA in cocoa beans using 1% sodium hydrogen carbonate (NaHCO3) in water within 30 min. The extraction method is rapid (as compared with existing methods), simple, reliable and practical to perform without complex experimental set-ups. The cocoa samples were freshly extracted and cleaned-up using immunoaffinity column (IAC) for HPLC analysis using a fluorescence detector. Under the optimised condition, the limit of detection (LOD) and limit of quantification (LOQ) for OTA were 0.62 and 1.25 ng ml–1respectively in standard solutions. The method could successfully quantify OTA in naturally contaminated samples. Moreover, good recoveries of OTA were obtained up to 86.5% in artificially spiked cocoa samples, with a maximum relative standard deviation (RSD) of 2.7%. The proposed extraction method could determine OTA at the level 1.5 µg kg–1, which surpassed the standards set by the European Union for cocoa (2 µg kg–1). In addition, an efficiency comparison of IAC and molecular imprinted polymer (MIP) column was also performed and evaluated. [ABSTRACT FROM AUTHOR]

In this work, we propose for the first time a sensitive Ochratoxin A (OTA) detection in cocoa beans using competitive aptasensor by differential pulse voltammetry (DPV). In the proposed method, biotin labeled and free OTA competed to bind with immobilized aptamer onto the surface of a screen printed carbon electrode (SPCE), and percentage binding was calculated. The detection was performed after adding avidin-ALP to perform avidin–biotin reaction; the signal was generated through a suitable substrate 1-naphthyl phosphate (1-NP), for alkaline phosphatase (ALP). The cocoa samples were extracted and purified using molecular imprinted polymer (MIP) columns specifically designed for OTA. The developed aptasensor showed a good linearity in the range 0.15–5 ng/mL with the limit of detection (LOD) 0.07 ng/mL and 3.7% relative standard deviation (RSD). The aptasensor displayed good recovery values in the range 82.1–85% with 3.87% RSD, thus, demonstrated the efficiency of proposed aptasensor for such matrices. [ABSTRACT FROM AUTHOR]

Contamination of food by mycotoxin occurs in minute/trace quantities. Nearly 92.5% of the cocoa samples present Ochratoxin A (OTA) levels at trace quantity. Hence, there is a necessity for a highly sensitive and selective device that can detect and quantify these organic toxins in various matrices such as cocoa beans. This work reports for the first time, a facile and label-free electrochemical impedimetric aptasensor for rapid detection and quantitation of OTA in cocoa beans. The developed aptasensor was constructed based on the diazonium-coupling reaction mechanism for the immobilization of anti-OTA-aptamer on screen printed carbon electrodes (SPCEs). The aptasensor exhibited a very good limit of detection (LOD) as low as 0.15 ng/mL, with added advantages of good selectivity and reproducibility. The increase in electron transfer resistance was linearly proportional to the OTA concentration in the range 0.15–2.5 ng/mL, with an acceptable recovery percentage (91–95%, RSD = 4.8%) obtained in cocoa samples. This work can facilitate a general model for the detection of OTA in cocoa beans based on the impedimetric aptasensor. The analysis can be performed onsite with pre-constructed and aptamer modified electrodes employing a portable EIS set up. [ABSTRACT FROM AUTHOR]

This work presents an application of automatic flow based biosensor to detect binary (chlorpyriphos-oxon (CPO) and malaoxon (MO)) organophosphate (OP) mixtures in milk, based on artificial neural network (ANN). Genetically modified acetylcholinesterase (AChE) B394 and B4 were used as a biological recognition element for sensor development. AChE binds with OPs irreversibly, creating an anionic phosphonyl species. The enzymes were coupled on screen printed electrodes (SPEs) and inserted in a flow cell connected to the potentiostat and syringe pump. In order to model the combined response of CPO and MO, a total set of 19 mixtures were prepared using ANN. The modeling was validated with an external test of 6 milk samples spiked with CPO and MO mixtures. The spiked concentrations of CPO and MO were ranged from 5 × 10 −10 to 5 × 10 −12 M and 1.01 × 10 −10 to 9.17 × 10 −11 M, respectively. These concentrations were determined using factorial designing (FD) method and the obtained and expected recovery values in milk showed good co-relation. The average % recovery yields for CPO and MO are 109.53 and 100.66, respectively. [ABSTRACT FROM AUTHOR]

An analytical chemical method has been developed for determination of β-hydroxymyristic acid (β-HMA), a component of lipopolysaccharides (LPSs/endotoxins) in dialysis water. In our investigation, the β-HMA component was used as a chemical marker for endotoxin presence in dialysis water because it is available in the molecular subunit (lipid A) and responsible for toxicity. It is the most abundant saturated fatty acid in that subunit. The developed method is based on fluorescence derivatization with 4-nitro-7-piperazino-2,1,3-benzoxadiazole (NBD–PZ). A high-performance liquid chromatographic separation of the β-HMA derivative was achieved using an octadecyl silica column in gradient elution. A wide dynamic range of β-HMA was tested and a calibration curve was constructed with accuracy of 90% and variability of less than 10%. The limits of detection and quantification obtained were 2 and 5 μM, respectively. The developed method was applied to detect endotoxins in dialysis water by alkaline hydrolysis of LPS using NaOH (0.25 M) at 60 °C for 2 h. After hydrolysis, free acid was detected as its NBD–PZ derivative using high-performance liquid chromatography/mass spectrometry (HPLC/MS). Good recovery rates ranging from 98 to 105% were obtained for β-HMA in dialysis water. [ABSTRACT FROM AUTHOR]

Abstract: Among known pesticide groups, organophosphates (OPs) have grasped attention due to their hazardous nature and their applications as pesticides and chemical weapons. This work presents the development of cost-effective column based biosensor for detoxification of OPs in water and milk. Enzyme phosphotriesterase (PTE) was immobilized on an activated Sepharose 4B via covalent coupling using an Omnifit glass column. Three different OPs, ethyl paraoxon (EPOx), malaoxon (MAO) and chlorpyriphos-oxon (CPO) were spiked in water and milk to test the detoxification of OPs. Mixtures of these pesticides were also tested to check the cumulative detoxification in the real samples. The efficiency of detoxification was evaluated using a highly sensitive acetylcholinesterase (AChE) B394 biosensor based flow system. The column conditions were optimized for the detoxification studied. The method was shown to be promising when we tested real milk samples spiked with OPs. Detoxification obtained in milk was up to 86% whereas in water, 100% detoxification was obtained. [Copyright &y& Elsevier]

Abstract: This work describes the development of an automated flow-based biosensor that employs genetically modified acetylcholinesterase (AChE) enzymes B394, B4 and wild type B131. The biosensor was based on a screen printed carbon electrode (SPE) that was integrated into a flow cell. Enzymes were immobilised on cobalt (II) phthalocyanine (CoPC) modified electrodes by entrapment in a photocrosslinkable polymer (PVA-AWP). The automated flow-based biosensor was successfully used to quantify three organophosphate pesticides (OPs) in milk samples. The OPs used were chlorpyriphos-oxon (CPO), ethyl paraoxon (EPOx) and malaoxon (MOx). The total analysis time for the assay was less than 15min. Initially, the biosensor performance was tested in phosphate buffer solution (PBS) using B394, B131 and B4 biosensors. The best detection limits were obtained with B394; therefore, this biosensor was used to produce calibration data in milk with three OPs in the concentration range of 5×10−6 M to 5×10−12 M. The limit of detection (LOD) obtained in milk for CPO, EPOx and MOx were 5×10−12 M, 5×10−9 M and 5×10−10 M, respectively, with a correlation coefficient R 2 =0.9910. The automated flow-based biosensor successfully quantified the OPs in different fat-containing milk samples. There were no false positives or false negatives observed for the analytical figures of merit for the constructed biosensors. This method is inexpensive, sensitive, portable, non-invasive and provides real-time results. This analytical system can provide rapid detection of highly toxic OPs in food matrices such as milk. [Copyright &y& Elsevier]

Abstract: Urea in adulterated milk is one of the major health concern, it is especially harmful to pregnant women, children, and the sick. A sophisticated and reliable detection system is needed to replace current diagnostic tools for the urea in the milk. In this work, we report a flow injection analysis-enzyme thermistor (FIA-ET) bio-sensing system for monitoring of urea in adulterated milk. This biosensor was made of the covalently immobilized enzyme urease (Jack bean) on controlled pore glass (CPG) and packed into a column inside thermistor, which selectively hydrolysed the urea present in the sample. The specific heat registered from the hydrolysis of urea was found proportional to the concentration of urea present in the milk sample. The biosensor showed a linear range 1–200mM, with % R.S.D. 0.96 for urea in 100mM phosphate buffer, pH 7.2. Good recoveries were obtained (97.56–108.7%) for urea up to 200mM in the spiked milk samples with % R.S.D. 0.95. In the adulterated milk, a simple filtration strategy and matrix matching technique was used to analyse urea. The response time of the sensor was evaluated for urea, which was 2min, and it gives satisfactory output. A good comparison was observed between the urea concentrations measured through FIA-ET and the colorimetric method. These results indicate that utilizing this system could be very effective to detect low and high level of urea in adulterated milk. The immobilized urease column exhibited a good operational stability up to 180 days when used continuously at room temperature. [ABSTRACT FROM AUTHOR]

A rapid, high-sensitivity, chemiluminescence (CL) enzyme assay for the determination of organophosphate (OP) residues in milk is presented. The assay for quantification of OP residues in milk is based on the inhibition of enzyme butyrylcholinesterase (BuChE). BuChE was stabilized and preloaded in 384 well plates at 30 °C. The assay permits rapid determination of OPs in milk within 12 min including an incubation step. The enzyme assay was tested for individual and mixtures of OPs such as methyl paraoxon (MPOx), methyl parathion (MP) and malathion (MT) in milk to evaluate their synergistic effect on BuChE inhibition. Good linearity was obtained in the range 0.005-50 μg·L-1 for MPOx and 0.5-1,000 μg·L-1 for MP as well as MT in milk. Mean recovery of 93.2%-98.6% was obtained for MPOx spiked milk samples with 0.99%-1.67% reproducibility (RSD). The proposed method facilitated rapid screening of milk samples in 384 well plate formats with further miniaturization presented in 1,536 well plates. [ABSTRACT FROM AUTHOR]

A highly sensitive and specific enzyme inhibition assay based on alcohol oxidase (AlOx) and horseradish peroxidase (HRP) for determination of mercury Hg(II) in water samples has been presented. This article describes the optimization and miniaturization of an enzymatic assay using a chemiluminescence reaction. The analytical performance and detection limit for determination of Hg(II) was optimized in 96 well plates and further extended to 384 well plates with a 10-fold reduction in assay volume. Inhibition of the enzyme activity by dissolved Hg(II) was found to be linear in the range 5-500 pg·mL-1 with 3% CV in inter-batch assay. Due to miniaturization of assay in 384 well plates, Hg(II) was measurable as low as 1 pg·mL-1 within 15 min. About 10-fold more specificity of the developed assay for Hg(II) analysis was confirmed by challenging with interfering divalent metal ions such as cadmium Cd(II) and lead Pb(II). Using the proposed assay we could successfully demonstrate that in a composite mixture of Hg(II), Cd(II) and Pb(II), inhibition by each metal ion is significantly enhanced in the presence of the others. Applicability of the proposed assay for the determination of the Hg(II) in spiked drinking and sea water resulted in recoveries ranging from 100-110.52%. [ABSTRACT FROM AUTHOR]

Driving under the influence of cannabis and alcohol represents a major safety concern due to the synergistic or additive effect of these substances of abuse. Hence, rapid road-site testing of these substances is highly desired to reduce risks of fatal accidents. Here we describe a wearable electrochemical sensing device for the simultaneous direct, decentralized, detection of salivary THC and alcohol. The new ring-based sensing platform contains a voltammetric THC sensor and an amperometric alcohol biosensor on the ring cap, along with the wireless electronics embedded within the ring case. Rapid replacement of the disposable sensing-electrode ring cap following each saliva assay is accomplished by aligning spring-loaded pins, mounted on the electronic board (PCB), with the current collectors of the sensing electrodes. The printed dual-analyte sensor ring cover is based on a MWCNT/carbon electrode for the THC detection along with a Prussian-blue transducer, coated with alcohol oxidase/chitosan reagent layer, for the biosensing of alcohol. THC and alcohol can thus be detected simultaneously in the same diluted saliva sample within 3 min, with no cross talk and no interferences from the saliva matrix. The new wearable ring sensor platform should enable law enforcement personnel to screen drivers in a single traffic stop and offers considerable promise for addressing growing concerns of drug-impaired driving. Image 1 • Wearable Electrochemical Ring Sensor for rapid road-site testing of alcohol and THC. • Electrochemical sensor to quantify salivary alcohol and THC with SWV and amperometry. • Ring sensor containing electronic board enables wireless data transmission. • Simultaneous detection of salivary THC and alcohol with no apparent cross talk. [ABSTRACT FROM AUTHOR]

• Field screening of opioids with a wearable glove-based electrochemical sensor. • Rapid "swipe, scan, and detect" operating procedure. • Progress towards a complete forensic "Lab-on-Glove". Rapid, on-site detection of fentanyl is of critical importance, as it is an extremely potent synthetic opioid that is prone to abuse. Here we describe a wearable glove-based sensor that can detect fentanyl electrochemically on the fingertips towards decentralized testing for opioids. The glove-based sensor consists of flexible screen-printed carbon electrodes modified with a mixture of multiwalled carbon nanotubes and a room temperature ionic liquid, 4-(3-butyl-1-imidazolio)-1-butanesulfonate. The sensor shows direct oxidation of fentanyl in both liquid and powder forms with a detection limit of 10 μM using square-wave voltammetry. The "Lab-on-a-Glove" sensors, combined with a portable electrochemical analyzer, provide wireless transmission of the measured data to a smartphone or tablet for further analysis. The integrated sampling and sensing methodology on the thumb and index fingers, respectively, enables rapid screening of fentanyl in the presence of a mixture of cutting agents and offers considerable promise for timely point-of-need screening for first responders. Such a glove-based "swipe, scan, sense, and alert" strategy brings chemical analytics directly to the user's fingertips and opens new possibilities for detecting substances of abuse in emergency situations. [ABSTRACT FROM AUTHOR]

This work presents a simple method to fabricate an octahedral cuprous oxide (Cu2O) decorated two‐dimensional (2D) flexible rGOP electrode with filtration and electrodeposition strategies. The characteristic of the Cu2O/rGOP electrodes was recorded by SEM, EDX, XPS, XRD, and Raman spectroscopy. The results clearly showed that Cu2O was successfully electrodeposited on the surface of rGOP by controlling the electrodeposition potential without the introduction of any template or surfactant. The electrochemical characterizations of the Cu2O/rGOP exhibited high electrocatalytic activity toward the reduction of H2O2. The linear detection range for the Cu2O/rGOP flexible sensor was 5.0 μM to 5.5 mM, with a limit of detection of 1.27 μΜ. Subsequently, the developed flexible rGOP sensor was extended for H2O2 detection in milk samples for avoiding milk spoilage. Such judicial preparation of rGOP as a sensing device will certainly pave the way for various other sensing applications including environmental and biomedical applications. [ABSTRACT FROM AUTHOR]

The present work describes an attractive skin-worn microneedle sensing device for the minimally invasive electrochemical monitoring of subcutaneous alcohol. The device consists of an assembly of pyramidal microneedle structures integrated with Pt and Ag wires, each with a microcavity opening. The microneedle aperture was modified by electropolymerizing o-phenylene diamine onto the Pt wire microtransducer, followed by the immobilization of alcohol oxidase (AOx) in an intermediate chitosan layer, along with an outer Nafion layer. The resulting microneedle-based enzyme electrode displays an interference-free ethanol detection in artificial interstitial fluid without compromising its sensitivity, stability and response time. The skin penetration ability and the efficaciousness of the biosensor performance towards subcutaneous alcohol monitoring was substantiated by the ex vivo mice skin model analysis. Our results reveal that the new microneedle sensor holds considerable promise for continuous non-invasive alcohol monitoring in real-life situations. [ABSTRACT FROM AUTHOR]

Herein, we reported a titanium oxide (TiO2) modified activated carbon nanocomposite that showed advantageous characteristics in terms of electro-conductivity, catalytic activity and surface area. The designed nanocomposite was employed to modify the screen printed carbon electrode transducer surface in the construction of an electrochemical sensor. The electrode surface modification was characterised by cyclic voltammetry and impedimetric studies. The modified transducer surface was subsequently used for the detection of four phenolic endocrine disruptors,p-nitrophenol, hydroquinone, catechol and 1-naphtol. Under optimal conditions, TiO2modified activated carbon sensor was evaluated by differential pulse voltammetry showing a good linearity with correlation coefficients higher than 0.99. It showed, in parallel, a high sensitivity where the detection limits were 348 ng/L, 110.1 ng/L, 3.3 ng/L and 7.2 µg/L for the respective studied compounds (S/N = 3). Finally, we validated the method with river water samples, and good recovery values were obtained showing the potential application of the reported biosensor. [ABSTRACT FROM PUBLISHER]

This work presents a comparison of two different aptamers (Apts) (COX and TRAN) for the detection of a ubiquitous protein Lysozyme (Lys) using Apt-based biosensors. The detection is based on the specific recognition by the Apt immobilized on screen printed carbon electrodes (SPCEs) via diazonium coupling reaction. The quantitative detection of Lys protein was achieved by electrochemical impedance spectroscopy (EIS). A very good linearity and detection limits for the quantitation of Lys were obtained from 0.1 to 0.8 μM and 100 nM using Apt COX and from 0.025 to 0.8 μM and 25 nM using Apt TRAN respectively. The obtained results showed that the developed aptasensors exhibit good specificity, stability and reproducibility for Lys detection. For real application, the aptasensors were tested in wine samples and good recovery rates were recorded in the range from 94.2 to 102% for Lys detection. The obtained recovery rates confirm the reliability and suitability of the developed method in wine matrix. The developed method could be a useful and promising platform for detection of Lys in different applications. [ABSTRACT FROM AUTHOR]

We demonstrate for the first time, the development of titanium dioxide nanoparticles (TiO2) quenching based aptasensing platform for detection of target molecules. TiO2 quench the fluorescence of FAM-labeled aptamer (fluorescein labeled aptamer) upon the non-covalent adsorption of fluorescent labeled aptamer on TiO2 surface. When OTA interacts with the aptamer, it induced aptamer G-quadruplex complex formation, weakens the interaction between FAM-labeled aptamer and TiO2, resulting in fluorescence recovery. As a proof of concept, an assay was employed for detection of Ochratoxin A (OTA). At optimized experimental condition, the obtained limit of detection (LOD) was 1.5 nM with a good linearity in the range 1.5 nM to 1.0 μM for OTA. The obtained results showed the high selectivity of assay towards OTA without interference to structurally similar analogue Ochratoxin B (OTB). The developed aptamer assay was evaluated for detection of OTA in beer sample and recoveries were recorded in the range from 94.30%-99.20%. Analytical figures of the merits of the developed aptasensing platform confirmed its applicability to real samples analysis. However, this is a generic aptasensing platform and can be extended for detection of other toxins or target analyte. [ABSTRACT FROM AUTHOR]

The thermal decomposition of the third-generation beta-blocker nebivolol (NEB) was investigated using thermogravimetric analysis (TG) under isothermal and non-isothermal environments, revealing important steadiness performance for the dispensation in the pharma manufacturing, expecting shelf life, and appropriate storing features. Kinetic analysis was carried out using Kissinger–Akahira–Sunose, Friedman, Flynn–Wall–Ozawa, and Starink methods. The analysis reveals that the activation energy estimated from the disintegration reactions via different techniques is unswerving with each other. Furthermore, the thermodynamic constraints (ΔH, ΔS, and ΔG) of the decomposition reaction were also estimated. A correlation between the mass spectrometry and thermal behavior of NEB has also been investigated. The study provides valuable stability data, expected shelf life, and optimal storing conditions that would help drug design and manufacturing. Density functional theory was also employed to study the possible thermodynamic dissociation channels of NEB. [ABSTRACT FROM AUTHOR]

The majority of existing medical diagnosis depends on the blood analysis in centralized sophisticated laboratories having bulky, complex, and time-consuming clinical instruments. Blood test involves invasive sample collection followed by plasma separation via centrifugation, and chemical analyses. This may prevent persons in need of urgent medical diagnosis and prompt medical attention. Wearable biosensor offers non-invasive monitoring of physiologically relevant biomarkers from biofluids and continuous tracking of real-time health status. Recent advances are much focused on electrochemical monitoring of various biomarkers from sweat samples. Such skin-interfaced sweat sensors require flexibility, stretchability and self-healing ability to match with the mechanical properties of the epidermis. The multiplexed sweat analysis coupled with wireless signal transduction provides vital information about health and fitness level of the wearer. This review focuses on the challenges, perspectives, recent advances and the technological aspects in the progress of wearable electrochemical sweat sensors. • Wearable sweat sensors offer non-invasive monitoring of real-time health information. • Wearable sensors require skin-like flexibility, stretchability and self-healing ability. • Microfluidic integration facilitates real-time sample transport and eliminates dilution. • Multiplexed sweat analysis enables timely diagnosis and prompt clinical therapy. [ABSTRACT FROM AUTHOR]

We report on a wearable tear bioelectronic platform, integrating a microfluidic electrochemical detector into an eyeglasses nose-bridge pad, for non-invasive monitoring of key tear biomarkers. The alcohol-oxidase (AOx) biosensing fluidic system allowed real-time tear collection and direct alcohol measurements in stimulated tears, leading to the first wearable platform for tear alcohol monitoring. Placed outside the eye region this fully wearable tear-sensing platform addresses drawbacks of sensor systems involving direct contact with the eye as the contact lenses platform. Integrating the wireless electronic circuitry into the eyeglasses frame thus yielded a fully portable, convenient-to-use fashionable sensing device. The tear alcohol sensing concept was demonstrated for monitoring of alcohol intake in human subjects over multiple drinking courses, displaying good correlation to parallel BAC measurements. We also demonstrate for the first time the ability to monitor tear glucose outside the eye and the utility of wearable devices for monitoring vitamin nutrients in connection to enzymatic flow detector and rapid voltammetric scanning, respectively. These developments pave the way to build an effective eyeglasses system capable of chemical tear analysis. Image 1 • Wearable fluidic tears biosensor and wireless circuitry integrated into eyeglasses for non-invasive biomarker monitoring. • Wearable tear sensing platform placed outside the eye region mitigates drawbacks of systems requiring direct eye contact. • Real-time collection and direct measurements of stimulated tears allow the first wearable tear alcohol monitoring platform. [ABSTRACT FROM AUTHOR]

In this work, we have developed for the first time a carboxylic group riched graphene oxide based disposable electrochemical immunosensor for cancer biomarker detection using methylene blue (MB). The developed immunosensor is highly sensitive for detection of biomarker Mucin1 (MUC1) in human serum samples. Development of this disposable electrochemical immunosensor was premeditated by applying specific monoclonal antibodies against MUC1. In this method, we explored highly conductive surface of carboxylic group (-COOH-) rich graphene oxide (GO) on screen-printed carbon electrodes (SPCE). This modified GO-COOH-SPCE was employed for the detection of MUC1 protein based on the reaction with methylene blue (MB) redox probe using differential pulse voltammetry (DPV) technique. Developed immunosensor exhibited good detection range for MUC1 with excellent linearity (0.1 U/mL- 2 U/mL), with a limit of detection of 0.04 U/mL. Upon potential application of developed biosensor, good recoveries were recorded in the range of 96–96.67% with % R.S.D 4.2. Analytical performance of the developed immunosensor assures the applicability in clinical diagnostic applications. [ABSTRACT FROM AUTHOR]

Infectious diseases caused by viruses can elevate up to undesired pandemic conditions affecting the global population and normal life function. These in turn impact the established world economy, create jobless situations, physical, mental, emotional stress, and challenge the human survival. Therefore, timely detection, treatment, isolation and prevention of spreading the pandemic infectious diseases not beyond the originated town is critical to avoid global impairment of life (e.g., Corona virus disease - 2019, COVID-19). The objective of this review article is to emphasize the recent advancements in the electrochemical diagnostics of twelve life-threatening viruses namely - COVID-19, Middle east respiratory syndrome (MERS), Severe acute respiratory syndrome (SARS), Influenza, Hepatitis, Human immunodeficiency virus (HIV), Human papilloma virus (HPV), Zika virus, Herpes simplex virus, Chikungunya, Dengue, and Rotavirus. This review describes the design, principle, underlying rationale, receptor, and mechanistic aspects of sensor systems reported for such viruses. Electrochemical sensor systems which comprised either antibody or aptamers or direct/mediated electron transfer in the recognition matrix were explicitly segregated into separate sub-sections for critical comparison. This review emphasizes the current challenges involved in translating laboratory research to real-world device applications, future prospects and commercialization aspects of electrochemical diagnostic devices for virus detection. The background and overall progress provided in this review are expected to be insightful to the researchers in sensor field and facilitate the design and fabrication of electrochemical sensors for life-threatening viruses with broader applicability to any desired pathogens. [Display omitted] • Comprehensive overview of virus diagnosis by analytical/electrochemical approaches. • Summary of electrochemical biosensors for coronaviruses (COVID-19, MERS, SARS). • Rapid POC screening of Influenza, Hepatitis, HIV, HPV, Zika, Dengue and Rotavirus. • Infectious virus detection by immuno/apta/CRISPR based electrochemical sensors. • Perspectives on biofouling, selectivity, multiplex sensing and wireless devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • First electrochemical sensor was used for determination of AMS in the presence of co-administered drugs. • All the system parameters were optimized. • Ruthenium nanoparticles (Ru) and Safranin (Saf) improved the detection power of the method. • The calibration curve for AMS was AMS (9.8 × 10−8–7.0 × 10−5 M) with LOD of 8.80 × 10−9 M. A wholly new electroanalytical protocol for the sensitive determination of Amisulpride (AMS) has been developed. AMS is an antipsychotic and antiemetic medicine that is prescribed at lower dosages intravenously to stop and cure vomiting and postoperative nausea; and at higher orally dosages and intramuscularly for treatment of schizophrenia and serious psychotic seizures. AMS detection is proposed here for the first-time using Ruthenium nanoparticles (Ru) and Safranin (Saf) as a modifier through carbon paste electrochemical sensor platform. The Ruthenium - Safranin sensor was found to possess good electrocatalytic activity and selectivity for simultaneous determination of AMS in the presence of co-administered drug citalopram (CIT). The Ru-Saf/CPE modified sensor exhibited a wide linear response range for electrochemical sensing of AMS (9.8 × 10−8–7.0 × 10−5 M) with LOD of 8.80 × 10−9 M. [ABSTRACT FROM AUTHOR]

• Development of a solid-contact fluoride ion-selective electrode by comparing different fluoride ionophores. • Solid-contact fluoride electrode displayed near-Nernstian behavior at neutral pH, high selectivity and reproducibility. • Field detection of G-type nerve agent simulant via combining OPAA reaction with recognition of the liberated fluoride ion. • Fast, sensitive and selective DFP detection over a wide dynamic range of 250–3000 μM. • Selective OPAA-based biocatalytic hydrolysis of G-type nerve agents to discriminate against common OP pesticides. Sensor technology, particularly disposable, field-deployable devices offer considerable promise for addressing major security demands, in general, and in particular the urgent needs for selective and rapid field detection of highly toxic G-type organophosphate (OP) nerve agents. Herein, we report on the first example of a disposable electrochemical biosensor chip for decentralized field detection of diisopropyl fluorophosphate (DFP), as the simulant compound of G-type nerve agents (e.g., Sarin and Soman), based on the integration of an all-solid-state fluoride potentiometric transducer with the enzyme organophosphorus acid anhydrolase (OPAA) in connection to a hand-held potentiometric analyzer. Such solid-contact fluoride ion-selective electrodes were realized by comparing different fluoride ionophores to select the bis(fluorodioctylstannyl)methane molecule, along with systematic optimization of the experimental parameters. This first solid-contact fluoride detection chip displayed a favorable analytical performance, with near-Nernstian behavior at neutral pH in different buffers, high selectivity against various anions along with excellent reproducibility. Combining such desirable merits of the new fluoride sensor with the selective biocatalytic hydrolysis via an immobilized OPAA, to break the P F bond of G-type neurotoxins and release detectable fluoride ions, thereby enabled an attractive analytical performance. Both the fluoride and the nerve-agent recognition layers have thus been systematically optimized. The resulting biosensor chip thus displays a fast, sensitive and selective response towards DFP (including efficient discrimination against OP pesticides), along with a wide dynamic range of 250–3000 μM. Key challenges towards developing the nerve-agent detection chip were carefully addressed, including the pH incompatibility of the enzymatic and detection processes. By providing effective discrimination against common OP pesticides and minimizing related false alarms, the resultant disposable potentiometric biochip platform is expected to provide an instantaneous reliable warning of chemical attack and exposure towards a timely countermeasure action, and hence, would dramatically advance the protection of our military personnel. [ABSTRACT FROM AUTHOR]

Aptamers are synthetic bio-receptors of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) origin selected by the systematic evolution of ligands (SELEX) process that bind a broad range of target analytes with high affinity and specificity. So far, electrochemical biosensors have come up as a simple and sensitive method to utilize aptamers as a bio-recognition element. Numerous aptamer based sensors have been developed for clinical diagnostics, food, and environmental monitoring and several other applications are under development. Aptasensors are capable of extending the limits of current analytical techniques in clinical diagnostics, food, and environmental sample analysis. However, the potential applications of aptamer based electrochemical biosensors are unlimited; current applications are observed in the areas of food toxins, clinical biomarkers, and pesticide detection. This review attempts to enumerate the most representative examples of research progress in aptamer based electrochemical biosensing principles that have been developed in recent years. Additionally, this account will discuss various current developments on aptamer-based sensors toward heavy metal detection, for various cardiac biomarkers, antibiotics detection, and also on how the aptamers can be deployed to couple with antibody-based assays as a hybrid sensing platform. Aptamers can be used in various applications, however, this account will focus on the recent advancements made toward food, environmental, and clinical diagnostic application. This review paper compares various electrochemical aptamer based sensor detection strategies that have been applied so far and used as a state of the art. As illustrated in the literature, aptamers have been utilized extensively for environmental, cancer biomarker, biomedical application, and antibiotic detection and thus have been extensively discussed in this article. [ABSTRACT FROM AUTHOR]