New Construction of Functionalized CuO/Al2O3 Nanocomposite-Based Polymeric Sensor for Potentiometric Estimation of Naltrexone Hydrochloride in Commercial Formulations

Electrically conductive polymeric nanocomposites with nanoparticles are adaptable types of nanomaterials that are prospective for various applications. The extraordinary features of copper oxide (CuO) and aluminium oxide (Al2O3) nanostructures, encourages extensive studies to prospect these metal oxide nanocomposites as potential electroactive materials in sensing and biosensing applications. This study suggested a new CuO/Al2O3 nanocomposite-based polymeric coated wire membrane sensor for estimating naltrexone hydrochloride (NTX) in commercial formulations. Naltrexone hydrochloride and sodium tetraphenylborate (Na-TPB) were incorporated in the presence of polymeric polyvinyl chloride (PVC) and solvent mediator o-nitrophenyloctyl ether (o-NPOE) to form naltrexone tetraphenylborate (NTX-TPB) as an electroactive material. The modified sensor using NTX-TPB-CuO/Al2O3 nanocomposite displayed high selectivity and sensitivity for the discrimination and quantification of NTX with a linearity range 1.0 × 10−9–1.0 × 10−2 mol L−1 and a regression equation EmV = (58.25 ± 0.3) log [NTX] + 754.25. Contrarily, the unmodified coated wire sensor of NTX-TPB exhibited a Nernstian response at 1.0 × 10−5–1.0 × 10−2 mol L−1 and a regression equation EmV = (52.1 ± 0.2) log [NTX] + 406.6. The suggested modified potentiometric system was validated with respect to various criteria using the methodology recommended guidelines.

Evaluation of Polytyramine Film and 6-Mercaptohexanol Self-Assembled Monolayers as the Immobilization Layers for a Capacitive DNA Sensor Chip: A Comparison

The performance of a biosensor is associated with the properties of an immobilization layer on a sensor chip. In this study, gold sensor chips were modified with two different immobilization layers, polytyramine film and 6-mercaptohexanol self-assembled monolayer. The physical, electrochemical and analytical properties of polytyramine film and mercaptohexanol self-assembled monolayer modified gold sensor chips were studied and compared. The study was conducted using atomic force microscopy, cyclic voltammetry and a capacitive DNA-sensor system (CapSenze™ Biosystem). The results obtained by atomic force microscopy and cyclic voltammetry indicate that polytyramine film on the sensor chip surface possesses better insulating properties and provides more spaces for the immobilization of the capture probe than a mercaptohexanol self-assembled monolayer. A capacitive DNA sensor hosting a polytyramine single-stranded DNA-modified sensor chip displayed higher sensitivity and larger signal amplitude than that of a mercaptohexanol single-stranded DNA-modified sensor chip. The linearity responses for polytyramine single-stranded DNA- and mercaptohexanol single-stranded DNA-modified sensor chips were obtained at log concentration ranges, equivalent to 10−12 to 10−8 M and 10−10 to 10−8 M, with detection limits of 4.0 × 10−13 M and 7.0 × 10−11 M of target complementary single-stranded DNA, respectively. Mercaptohexanol single-stranded DNA- and polytyramine single-stranded DNA-modified sensor chips exhibited a notable selectivity at an elevated hybridization temperature of 50 °C, albeit the signal amplitudes due to the hybridization of the target complementary single-stranded DNA were reduced by almost 20% and less than 5%, respectively.

Fast and Facile Voltammetric Detection of Acetaminophen at Poly (DL-phenylalanine) Modified Dysprosium-Copper Oxide Nanoparticle/Carbon Composite Paste Electrode

Introduction: The voltammetric sensing of Acetaminophen (AN) using modified Dysprosium Copper Oxide (DyCuO) Nanoparticles (NP) mixed Carbon Paste Electrode (MCPE) was successfully developed. Methods: The modification of bare NPMCPE was achieved by the polymerisation of DL-Phenylalanine (DLPA). The electroanalysis of the AN was achieved by utilizing the Cyclic voltammetry (CV) approaches. The crystallographic nature of the nanoparticle was studied via X-ray Powder Diffraction (XRD) technique. The surface morphology and electrochemical feature of the prepared electrode were evaluated by Field Emission Scanning Electron Microscopy (FE-SEM) and Electrochemical Impedance Spectroscopy (EIS) techniques. Results: The modified sensor exhibited an excellent electrocatalytic activity towards the electroanalysis of the AN. Several aspects, such as the number of polymerisation cycles, variation of pH, and the impact of scan rate were investigated in 0.2 M supporting electrolyte (pH 7) at a sweep rate of 0.1 Vs-1. The suggested sensor shows a very low detection limit (11.95×10-8 M) with a linear range of 2.0 to 50.0 µM, which exhibits excellent sensitivity. Conclusion: The stable and reusable sensor was applied for the estimation of AN in the tablet sample. Thus, P(DLPA)MNPMCPE was utilized as the most capable sensor for the voltammetric detection of AN.

Application of a Conducting Poly-Methionine/Gold Nanoparticles-Modified Sensor for the Electrochemical Detection of Paroxetine

This work demonstrates a facile electropolymerization of a dl-methionine (dl-met) conducting polymeric film on a gold nanoparticle (AuNPs)-modified glassy carbon electrode (GCE). The resulting sensor was successfully applied for the sensitive detection of paroxetine·HCl (PRX), a selective serotonin (5-HT) reuptake inhibitor (SSRIs), in its pharmaceutical formulations. The sensor was characterized morphologically using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) and electrochemical techniques such as differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed sensor, poly (dl-met)/AuNPs-GCE, exhibited a linear response range from 5 × 10−11 to 5 × 10−8 M and from 5 × 10−8 to 1 × 10−4 M using DPV with lowest limit of detection (LOD = 1 × 10−11 M) based on (S/N = 3). The poly (dl-met)/AuNPs-GCE sensor was successfully applied for PRX determination in three different pharmaceutical formulations with percent recoveries between 96.29% and 103.40% ± SD (±0.02 and ±0.58, respectively).

2D/3D Copper-Based Metal-Organic Frameworks for Electrochemical Detection of Hydrogen Peroxide

Metal-organic frameworks (MOFs) have been extensively used as modified materials of electrochemical sensors in the food industry and agricultural system. In this work, two kinds of copper-based MOFs (Cu-MOFs) with a two dimensional (2D) sheet-like structure and three dimensional (3D) octahedral structure for H2O2 detection were synthesized and compared. The synthesized 2D and 3D Cu-MOFs were modified on the glassy carbon electrode to fabricate electrochemical sensors, respectively. The sensor with 3D Cu-MOF modification (HKUST-1/GCE) presented better electrocatalytic performance than the 2D Cu-MOF modified sensor in H2O2 reduction. Under optimal conditions, the prepared sensor displayed two wide linear ranges of 2 μM–3 mM and 3–25 mM and a low detection limit of 0.68 μM. In addition, the 3D Cu-MOF sensor exhibited good selectivity and stability. Furthermore, the prepared HKUST-1/GCE was used for the detection of H2O2 in milk samples with a high recovery rate, indicating great potential and applicability for the detection of substances in food samples. This work provides a convenient, practical, and low-cost route for analysis and extends the application range of MOFs in the food industry, agricultural and environmental systems, and even in the medical field.

Development of Polypyrrole Modified Screen-Printed Carbon Electrode Based Sensors for Determination of L-Tyrosine in Pharmaceutical Products

Good health, of vital importance in order to carry out our daily routine, consists of both physical and mental health. Tyrosine (Tyr) deficiency as well as its excess are issues that can affect mental health and can generate disorders such as depression, anxiety, or stress. Tyr is the amino acid (AA) responsible for maintaining good mental health, and for this reason, the present research presents the development of new electrochemical sensors modified with polypyrrole (PPy) doped with different doping agents such as potassium hexacyanoferrate (II) (FeCN), sodium nitroprusside (NP), and sodium dodecyl sulfate (SDS) for a selective and sensitive detection of Tyr. The development of the sensors was carried out by chronoamperometry (CA) and the electrochemical characterization was carried out by cyclic voltammetry (CV). The detection limits (LOD) obtained with each modified sensor were 8.2 × 10−8 M in the case of PPy /FeCN-SPCE, 4.3 × 10−7 M in the case of PPy/NP-SPCE, and of 3.51 × 10−7 M in the case of PPy/SDS-SPCE, thus demonstrating a good sensitivity of these sensors detecting L-Tyr. The validation of sensors was carried out through quantification of L-Tyr from three pharmaceutical products by the standard addition method with recoveries in the range 99.92–103.97%. Thus, the sensors present adequate selectivity and can be used in the pharmaceutical and medical fields.