Graphene nanoplatelets like structures formed on ionic liquid modified carbon-ceramic electrode: As a sensing platform for simultaneous determination of dopamine and acetaminophen

Paper-Based Electrodes Decorated with Silver and Zinc Oxide Nanocomposite for Electro-Chemical Sensing of Methamphetamine

We present the development of an electrochemical paper-based analytical device (ePAD) for the detection of methamphetamine. Methamphetamine is a stimulant that young people use as an addictive narcotic, and it must be detected quickly since it may be hazardous. The suggested ePAD has the advantages of being simple, affordable, and recyclable. This ePAD was developed by immobilizing a methamphetamine-binding aptamer onto Ag-ZnO nanocomposite electrodes. The Ag-ZnO nanocomposites were synthesized via a chemical method and were further characterized via scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-vis spectrometry in terms of their size, shape, and colloidal activity. The developed sensor showed a limit of detection of about 0.1 μg/mL, with an optimum response time of about 25 s, and its extensive linear range was between 0.01 and 6 μg/mL. The application of the sensor was recognized by spiking different beverages with methamphetamine. The developed sensor has a shelf life of about 30 days. This cost-effective and portable platform might prove to be highly successful in forensic diagnostic applications and will benefit those who cannot afford expensive medical tests.

SU8/glass microchip capillary electrophoresis integrated with Pt electrodes for separation and simultaneous detection of phenylephrine and acetaminophen

Introduction: A new microfluidic-based method with electrochemical detection was developed for the simultaneous quantification of acetaminophen (AP) and phenylephrine (PHE) pharmaceuticals in the human blood and pharmaceuticals (e.g. tablet and drop).

Methods: The separation was achieved on a SU8/glass microchip with a 100 µm Pt working electrode that was positioned out of the channel and 2-(N-morpholino) ethanesulfonic acid was used as a running buffer (pH 7, 10 mM). Home designed modulated high voltage power supply and dual time switcher was used for controlling the injection and separation of the analytes in the unpinched injection mode.

Results: The injection was carried out using +750 V for 7 seconds, and the separation and detection voltages were set at +1000 V and +0.9 V, respectively. Critical parameters such as detection potential, buffer concentration, injection, and separation voltage were studied in terms of their effects on the resolution, peak height, and migration times. For each analyte, the correlation coefficients were over 0.99 (n = 6). The developed microchip was able to detect AP and phenylephrine simultaneously with the limit of detection of 7.9 and 5.2 (µg/mL) respectively for PHE and AP and excellent linear range of 10-200 (µg/mL). The recovery of the drugs ranged from 96% to 103%, while the repeatability of the method through inter- and intra-day was lower than 7%.

Conclusion: The developed method offers several advantages, including easy sample pretreatment process, simplicity, very fast analysis compared to other typical chromatographic methods. Thus, the proposed microfluidic-based method is proposed to be used as a time- and cost-effective monitoring method for the analysis of AP and PHE.

Room Temperature Ionic Liquids-Based Electrochemical Sensors: An Overview on Paracetamol Detection

Paracetamol (PAR) is an effective antipyretic and analgesic drug utilized worldwide, safer at therapeutic levels but over-dosing and the chronic usage of PAR results in accumulation of toxic metabolites, which leads to kidney and liver damages. Hence, a simple, rapid, cost-effective, and sensitive analytical technique is needed for the accurate determination of PAR in pharmaceutical and biological samples. Though numerous techniques have been reported for PAR detection, electrochemical methods are being receiving more interest due to their advantages. Moreover, in the past few decades, room temperature ionic liquids (RTILs) have been utilized in electrochemical sensors due to their attractive properties. In this present review, authors gathered research findings available for the determination of PAR using RTIL-based electrochemical sensors and discussed. The advantages and limitations in these systems as well as the future research directions are summarized.

Chemically modified carbon-based electrodes for the determination of paracetamol in drugs and biological samples

Paracetamol is a non-steroidal, anti-inflammatory drug widely used in pharmaceutical applications for its sturdy, antipyretic and analgesic action. However, an overdose of paracetamol can cause fulminant hepatic necrosis and other toxic effects. Thus, the development of advantageous analytical tools to detect and determine paracetamol is required. Due to simplicity, higher sensitivity and selectivity as well as costefficiency, electrochemical sensors were fully investigated in last decades. This review describes the advancements made in the development of electrochemical sensors for the paracetamol detection and quantification in pharmaceutical and biological samples. The progress made in electrochemical sensors for the selective detection of paracetamol in the last 10 years was examined, with a special focus on highly innovative features introduced by nanotechnology. As the literature is rather extensive, we tried to simplify this work by summarizing and grouping electrochemical sensors according to the by which manner their substrates were chemically modified and the analytical performances obtained.

An ultrasensitive immunosensor based on manganese dioxide-graphene nanoplatelets and core shell Fe3O4@Au nanoparticles for label-free detection of carcinoembryonic antigen

A novel electrochemical immunosensor was developed for label-free detection of carcinoembryonic antigen (CEA) as a cancer biomarker. The designed immunosensor was based on CEA antibody (anti-CEA) anchored with core shell Fe₃O₄@Au nanoparticles which were immobilized on a screen-printed carbon electrode modified with manganese dioxide decorating on graphene nanoplatelets (SPCE/GNP-MnO₂/Fe₃O₄@Au-antiCEA). The SPCE was placed onto a home-made electrode holder for easy handling. The approach was based on direct binding of CEA to a fixed amount of anti-CEA on the modified electrode for the specific detection using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) monitored in a solution containing 5 mM [Fe(CN)₆^3-/4-] prepared in 0.1 M phosphate buffer at pH 7.4. The difference in signal response owing to the redox reaction of [Fe(CN)₆]^3-/4- before and after interaction with CEA was regarded as the immunosensor response corresponding directly to the CEA concentration. Under optimized conditions, the linear range of 0.001-100 ng/mL, and the detection limits of 0.10 pg/mL (LSV) and 0.30 pg/mL (EIS) were evaluated. The applicability of the immunosensor was verified by well-corresponding determination of CEA in diluted human serum samples by electrochemiluminescence (ECL) immunoassay. Therefore, the proposed immunosensor could be suitable enough for a real sample analysis of CEA.

Latest Trends in Electrochemical Sensors for Neurotransmitters: A Review

Neurotransmitters are endogenous chemical messengers which play an important role in many of the brain functions, abnormal levels being correlated with physical, psychotic and neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's disease. Therefore, their sensitive and robust detection is of great clinical significance. Electrochemical methods have been intensively used in the last decades for neurotransmitter detection, outclassing more complicated analytical techniques such as conventional spectrophotometry, chromatography, fluorescence, flow injection, and capillary electrophoresis. In this manuscript, the most successful and promising electrochemical enzyme-free and enzymatic sensors for neurotransmitter detection are reviewed. Focusing on the activity of worldwide researchers mainly during the last ten years (2010-2019), without pretending to be exhaustive, we present an overview of the progress made in sensing strategies during this time. Particular emphasis is placed on nanostructured-based sensors, which show a substantial improvement of the analytical performances. This review also examines the progress made in biosensors for neurotransmitter measurements in vitro, in vivo and ex vivo.