Papers by Keyword: Electrochemical Sensor

Abstract: This work reports an electrochemical sensor for the quantification of the analyte, Tyramine. The 5-Amino-1-naphthol monomer is used to modify a PGE by electropolymerisation, which is used to develop the sensor. Utilizing SEM examination, Infrared Spectroscopy, cyclic voltammetry, and EIS, the morphological and electrochemical characterizations of the modified electrode were carried out. Using differential pulse voltammetry, the oxidation peaks of Tyramine is measured at potentials of 0.596 V. The linear range for Tyramine was observed from, 100 nM to 50 μM and 50 μM to 600 μM with an LOD of 89.8 nM with high sensitivity. As a result, food sample investigations may make use of this innovative, manufactured electrode.

Abstract: In this paper, gold nanoparticles (AuPNs) and activated carbon (AC) modified electrode was used for the determination of luteolin. Porous activated carbon was made from coconut shell powder. The electrode was coated by Porous activated carbon, and then gold nanoparticles were electrodeposited on the porous carbon surface. Electrochemical behavior of luteolin was analyzed by gold nanoparticles@ activated carbon modified electrode. The results show that the detection range of luteolin is 1.8 μmol/L to 10 μmol/L (R² = 0.9863) with the detection limit of 0.1 nmol/L (3σ/slope), and the recommended method has a good recovery for the detection of luteolin in real urine.

Abstract: Portable electrochemical sensors based on noble metal nanoparticles (МеNPs) for the quantitative determination of hydrogen peroxide (H₂O₂) and sulfur-containing amino acids (cysteine, methionine, glutathione) are discussed. These sensors have high sensitivity (pM), with low sample requirements (<50 μl). This article discusses methods for producing sensors based on silver and gold nanoparticles and their application in voltammetry. It is shown that the sensitivity of H₂O₂ determination on a sensor based on silver nanoparticles (AgNPs) depends on their size. Their size is determined by the reducing agent. Sensors based on AgNPs of spherical shape with the smallest size from 0.5 to 17.5 nm have the highest sensitivity for determining H₂O₂, but a narrow range of determined concentrations. Sensors on medium-sized AgNPs have optimal metrological characteristics. Their size is from 10 to 55 nm, less sensitive, but with a wide range of determined concentrations from 0.1 to 1 nm H₂O₂. The linearity of the range of glutathione concentrations is 1.0-10.0 pM. The linearity of the range of determined concentrations of methionine is 1–26 рМ.

Abstract: In the present work, oxalic acid doped molecularly imprinted conducting polyaniline film for melamine detection was prepared by in-situ-electrochemical polymerization on the glassy carbon electrode (GCE) using melamine as template. The optimal monomer/template molar ratio was attained to be 0.2:0.1:0.01 (aniline: oxalic acid: melamine) and molecular recognition properties towards melamine were evaluated by differential pulse voltammetry. Under optimal conditions the imprinted polymer film was used to detect different concentrations of melamine in standard solutions and real milk samples. Compared with the nonimprinted polymer (NIP), the molecularly imprinted polymer (MIP) film showed higher affinity and sensitivity towards melamine with a linear range, quantification limit and detection limit of 0.5-200 nM, 1.375 nM and 0.413 nM respectively. Furthermore, the polymer blend film showed good selectivity toward melamine, stability, reproducibility and practical applications for the determination of melamine in infant formula milk with the recovery of 92.32-102.49%. The doping of the polymer with oxalic acid enhanced the conductivity and sensitivity of the sensor.

Abstract: Codeine (3-methylmorphine) is an opiate that is widely used to treat mild or moderate pain and cough suppression. It is the second predominant alkaloid in opium with a mild sedative effect. In the present study, we describe an electrochemical sensor for codeine detection by using the DNA aptamers against codeine. In the sensing protocol, a dually-labeled DNA aptamer probe was designed to be labeled at one end with HS, and at its another end with dabcyl as an electrochemical tag to produce electrochemical signal via recognization occurrence. One special electrochemical marker was prepared by modifying ZnS nanoparticle with-cyclodextrins (ab. ZnS-CDs), which employed as electrochemical signal provider and would conjunct with the codeine probe modified electrode through the host–guest recognition of CDs to dabcyl. With codeine adding, aptamer folding allows the ZnS-CDs into soultion that caused an increase of current signal. This sensor has the ability to detect 37pM codeine. Our study demonstrates that the biosensor has good specificity and stability. It can be used to detect codeine.

Abstract: Hydrogels have been a topic of extensive research because of their unique bulk and surface properties. They play a vital role in development of controlled release drug delivery systems. Polysulfone hydrogels are hydrophilic porous materials, which provide the advantage of biocompatibility and effective orientation of biomolecule in the design of the novel biosensors [1-2]. Polysulfone hydrogels may be prepared as water swellable powders or drop cast as thin films on screen printed carbon electrodes (SPCE). Polysulfone hydrogels produce electroactive thin films, characterized by 2 well resolved redox peaks, with a formal potential of 0.0867 V and diffusion coefficient in aqueous medium of 9.06e^-9 Cm²/s. In this paper we report on the initial speciation studies and analytical performance of Selenium and Vanadium at the hydrogel electrodes, as evaluated by using cyclic voltammetry in a range of -0.7 V to +0.0 V versus Ag/AgCl. The morphology, adsorption and thin film integrity was evaluated using High resolution scanning electron microscopy (HR-SEM), UV-Vis and Raman spectroscopy.

Abstract: Polyaromatic hydrocarbons (PAHs) are typically present in environmental samples at very low concentrations. Therefore, extensive sample preparation is necessary to enhance the signal for analytical determination of these compounds by classical methods based on chromatography or spectroscopy. In this study an electrochemical sensor for anthracene based on polyamic acid- graphene oxide (PAA-GO) nanocomposite electrode was prepared for application in the direct analysis of small volumes of samples with minimal pre-treatment steps. Polyamic acid and graphene oxide (GO) are materials with well-defined electrochemistry of their own and both are readily synthesised under ambient laboratory conditions. The sensor was prepared by cyclic voltammetric co-deposition of PAA and GO onto a commercial screen printed carbon electrode (SPCE) in five voltammetric cycles with initial and switch potentials of -1000 mV and +1000 mV, respectively, at a potential scan rate of 50 mV/s. The sensor materials (GO, PAA and PAA-GO) were characterised by Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (HRSEM) and cyclic voltammetry (CV), while their corresponding screen printed electrode systems (GO/SPCE, PAA/SPCE and PAA-GO/SPCE) were evaluated as possible chemical sensors for anthracene.

Abstract: The way of the graphite electrodes production, modified by polymeric composition, containing nanoparticles of gold or mercury, for determination of metals’ ions by the method of stripping voltammetry is offered. The influence of copolymer’s structure, nature of solvent, concentration of metal-modifier, viscosity of composition, film’s thickness and conditions of its formation on electrochemical and mechanical characteristics of sensor systems was studied. The approbation of electrodes was carried out using the certified techniques with help of the method of stripping voltammetry during determination of zinc, cadmium, lead, copper, mercury, arsenic, selenium.

Abstract: Micro-analytical based sensors with complex biomatrices such as blood, urine, or saliva are of increasing interest in health-care sector because of their sensitivity, selectively and simplicity. A modified carbon electrode with hydroxyapatite (HAp) and Bismuth (II) was developed to detect Pb²⁺ concentration in blood sera from healthy persons. Square wave anodic stripping voltammetry was used for the detection of Pb²⁺ by the interacting capability of the Bi film and HAp on the electrode surface with the optimised parameters of deposition time 240sec, deposition potential –1.0 V in 0.1M acetate buffer followed by square wave potential scan from-1.0 V to-0.2V. Bi film deposited HAp-CME showed attractive electrochemical characteristics with high sensitivity for Pb²⁺. Clear current peaks for different Pb²⁺ concentrations were observed around-0.55V, with favourable signal-to-background ratio, and comparatively free from oxygen interferences.

Abstract: Increasing contamination of water by trace levels of heavy metals has become major environmental threats leading to an increased demand for the detection and monitoring of metal contaminants. In this work, modification of carbon electrode with cellulose was reported to enhance Pb²⁺ detection. The interacting ability of cellulose on the electrode surface was evaluated for Pb²⁺ by using square wave anodic stripping voltammetry. The deposition potential of –1.0 V in 0.1M acetate buffer for 240 sec, followed by square wave potential scan from-1.0 V to-0.2V were used. Stripping voltammogram showed current peaks corresponding to Pb²⁺. The sensitivity and selectivity of the modified electrodes for Pb²⁺ were also determined.