scholarly journals Highly Sensitive Amperometric Detection of Hydrogen Peroxide in Saliva Based on N-Doped Graphene Nanoribbons and MnO2 Modified Carbon Paste Electrodes

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8301
Author(s):  
Ema Gričar ◽  
Kurt Kalcher ◽  
Boštjan Genorio ◽  
Mitja Kolar
Keyword(s):  
Hydrogen Peroxide ◽  
Limit Of Detection ◽  
Graphene Nanoribbons ◽  
Amperometric Detection ◽  
High Sensitivity ◽  
Pharmaceutical Product ◽  
Carbon Paste ◽  
Real Sample Analysis ◽  
Starting Point ◽  
Highly Sensitive

Four different graphene-based nanomaterials (htGO, N-htGO, htGONR, and N-htGONR) were synthesized, characterized, and used as a modifier of carbon paste electrode (CPE) in order to produce a reliable, precise, and highly sensitive non-enzymatic amperometric hydrogen peroxide sensor for complex matrices. CPE, with their robustness, reliability, and ease of modification, present a convenient starting point for the development of new sensors. Modification of CPE was optimized by systematically changing the type and concentration of materials in the modifier and studying the prepared electrode surface by cyclic voltammetry. N-htGONR in combination with manganese dioxide (1:1 ratio) proved to be the most appropriate material for detection of hydrogen peroxide in pharmaceutical and saliva matrices. The developed sensor exhibited a wide linear range (1.0–300 µM) and an excellent limit of detection (0.08 µM) and reproducibility, as well as high sensitivity and stability. The sensor was successfully applied to real sample analysis, where the recovery values for a commercially obtained pharmaceutical product were between 94.3% and 98.0%. Saliva samples of a user of the pharmaceutical product were also successfully analyzed.

scholarly journals Functionalized Carbon Nanotubes with Gold Nanoparticles to Fabricate a Sensor for Hydrogen Peroxide Determination

2012 ◽  
Vol 9 (4) ◽  
pp. 2540-2549 ◽  
Author(s):  
Halimeh Rajabzade ◽  
Parandis Daneshgar ◽  
Elham Tazikeh ◽  
Ramin Zafar Mehrabian
Keyword(s):  
Hydrogen Peroxide ◽  
Gold Nanoparticles ◽  
Ionic Liquid ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Applied Potential ◽  
Carbon Paste ◽  
Experimental Conditions ◽  
Highly Sensitive ◽  
The Matrix

A highly sensitive electrode was prepared based on gold nanoparticles/nanotubes/ionic liquid for measurement of Hydrogen peroxide. Gold nanoparticles of 20–25 nm were synthesized on a nanotube carbon paste electrode by cyclic voltammetry technique while the coverage was controlled by applied potential and time. The gold nanoparticles were modified to form a monolayer on CNT, followed by decoration with ionic liquid for determination of hydrogen peroxide. The experimental conditions, applied potential and pH, for hydrogen peroxide monitoring were optimized, and hydrogen peroxide was determined amperometrically at 0.3 V vs. SCE at pH 7.0. Electrocatalytic effects of gold deposited CNT were observed with respect to unmodified one. The sensitivity obtained was 5 times higher for modified one. The presence of Au particles in the matrix of CNTs provides an environment for the enhanced electrocatalytic activities. The sensor has a high sensitivity, quickly response to H2O2and good stability. The synergistic influence of MWNT, Au particles and IL contributes to the excellent performance for the sensor. The sensor responds to H2O2in the linear range from 0.02 µM to 0.3 mM. The detection limit was down to 0.4 µM when the signal to noise ratio is 3.

scholarly journals Electro-Polymerized Titan Yellow Modified Carbon Paste Electrode for the Analysis of Curcumin

Surfaces ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 191-204
Author(s):  
Edwin S. D’Souza ◽  
Jamballi G. Manjunatha ◽  
Chenthattil Raril ◽  
Girish Tigari ◽  
Huligerepura J. Arpitha ◽  
...  
Keyword(s):  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Solution Ph ◽  
Real Sample Analysis ◽  
Titan Yellow ◽  
Paste Electrode

A modest, efficient, and sensitive chemically modified electrode was fabricated for sensing curcumin (CRC) through an electrochemically polymerized titan yellow (TY) modified carbon paste electrode (PTYMCPE) in phosphate buffer solution (pH 7.0). Cyclic voltammetry (CV) linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) approaches were used for CRC detection. PTYMCPE interaction with CRC suggests that the electrode exhibits admirable electrochemical response as compared to bare carbon paste electrode (BCPE). Under the optimized circumstances, a linear response of the electrode was observed for CRC in the concentration range 2 × 10−6 M to 10 × 10−6 M with a limit of detection (LOD) of 10.94 × 10−7 M. Moreover, the effort explains that the PTYMCPE electrode has a hopeful approach for the electrochemical resolution of biologically significant compounds. Additionally, the proposed electrode has demonstrated many advantages such as easy preparation, elevated sensitivity, stability, and enhanced catalytic activity, and can be successfully applied in real sample analysis.

scholarly journals Assay of Phospholipase D Activity by an Amperometric Choline Oxidase Biosensor

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1304 ◽  
Author(s):  
Rosanna Ciriello ◽  
Antonio Guerrieri
Keyword(s):  
Phospholipase D ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Fast Response ◽  
Borate Buffer ◽  
Choline Oxidase ◽  
Linear Calibration ◽  
Real Sample Analysis ◽  
Polypyrrole Film ◽  
Overoxidized Polypyrrole

A novel electrochemical method to assay phospholipase D (PLD) activity is proposed based on the employment of a choline biosensor realized by immobilizing choline oxidase through co-crosslinking on an overoxidized polypyrrole film previously deposited on a platinum electrode. To perform the assay, an aliquot of a PLD standard solution is typically added to borate buffer containing phosphatidylcholine at a certain concentration and the oxidation current of hydrogen peroxide is then measured at the rotating modified electrode by applying a detection potential of +0.7 V vs. SCE. Various experimental parameters influencing the assay were studied and optimized. The employment of 0.75% (v/v) Triton X-100, 0.2 mM calcium chloride, 5 mM phosphatidylcholine, and borate buffer at pH 8.0, ionic strength (I) 0.05 M allowed to achieve considerable current responses. In order to assure a controlled mass transport and, at the same time, high sensitivity, an electrode rotation rate of 200 rpm was selected. The proposed method showed a sensitivity of 24 (nA/s)⋅(IU/mL)−1, a wide linear range up to 0.33 IU/mL, fast response time and appreciable long-term stability. The limit of detection, evaluated from the linear calibration curve, was 0.005 IU/mL (S/N = 3). Finally, due to the presence of overoxidized polypyrrole film characterized by notable rejection properties towards electroactive compounds, a practical application to real sample analysis can be envisaged.

scholarly journals A Highly Sensitive Cell-Based TLR Reporter Platform for the Specific Detection of Bacterial TLR Ligands

2022 ◽  
Vol 12 ◽  
Author(s):  
Katharina Radakovics ◽  
Claire Battin ◽  
Judith Leitner ◽  
Sabine Geiselhart ◽  
Wolfgang Paster ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Ectopic Expression ◽  
High Sensitivity ◽  
High Specificity ◽  
Reporter System ◽  
Specificity And Sensitivity ◽  
Highly Sensitive ◽  
Definition Of ◽  
The Individual ◽  
Allergen Extracts

Toll-like receptors (TLRs) are primary pattern recognition receptors (PRRs), which recognize conserved microbial components. They play important roles in innate immunity but also in the initiation of adaptive immune responses. Impurities containing TLR ligands are a frequent problem in research but also for the production of therapeutics since TLR ligands can exert strong immunomodulatory properties even in minute amounts. Consequently, there is a need for sensitive tools to detect TLR ligands with high sensitivity and specificity. Here we describe the development of a platform based on a highly sensitive NF-κB::eGFP reporter Jurkat JE6-1 T cell line for the detection of TLR ligands. Ectopic expression of TLRs and their coreceptors and CRISPR/Cas9-mediated deletion of endogenously expressed TLRs was deployed to generate reporter cell lines selectively expressing functional human TLR2/1, TLR2/6, TLR4 or TLR5 complexes. Using well-defined agonists for the respective TLR complexes we could demonstrate high specificity and sensitivity of the individual reporter lines. The limit of detection for LPS was below 1 pg/mL and ligands for TLR2/1 (Pam3CSK4), TLR2/6 (Fsl-1) and TLR5 (flagellin) were detected at concentrations as low as 1.0 ng/mL, 0.2 ng/mL and 10 pg/mL, respectively. We showed that the JE6-1 TLR reporter cells have the utility to characterize different commercially available TLR ligands as well as more complex samples like bacterially expressed proteins or allergen extracts. Impurities in preparations of microbial compounds as well as the lack of specificity of detection systems can lead to erroneous results and currently there is no consensus regarding the involvement of TLRs in the recognition of several molecules with proposed immunostimulatory functions. This reporter system represents a highly suitable tool for the definition of structural requirements for agonists of distinct TLR complexes.

scholarly journals Rapid-Response and Highly Sensitive Boronate Derivative-Based Fluorescence Probe for Detecting H2O2 in Living Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Muthusamy Selvaraj ◽  
Kanagaraj Rajalakshmi ◽  
Yun-Sik Nam ◽  
Yeonhee Lee ◽  
Byoung Chan Kim ◽  
...  
Keyword(s):  
Functional Group ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Rapid Identification ◽  
Oxygen Species ◽  
Human Breast ◽  
Highly Sensitive ◽  
Whatman Paper ◽  
Mcf 7

Intracellular H2O2 monitoring is important and has driven researchers to pursue advancements for the rapid identification of H2O2, since H2O2 is short-lived in cell lines. An arylboronate derivative has been investigated as a chemospecific fluorescence recognition agent for H2O2. Triphenylimidazoleoxadiazolephenyl (TPIOP) boronate was contrived as a novel candidate for the rapid and sensitive recognition of H2O2. The probe was conjugated using the TPIOP functional group acting as an excellent fluorescent enhancer. The TPIOP group stimulated the polarization of C–B bond due to its extended π-conjugation, which included heteroatoms, and induced the production of rapid signal because of the highly polar C–B bond along with the corresponding boronate unit. While H2O2 reacts with TPIOP boronate, its nucleophilic addition to the boron generates a charged tetrahedral boronate complex, and then the C–B bond migrates toward one of the electrophilic peroxide oxygen atoms. The resulting boronate ester is then hydrolyzed by water into a phenol, which significantly enhances fluorescence through aggregation-induced emission. The TPIOP boronate probe responded to H2O2 rapidly, within 2 min, and exhibited high sensitivity with a limit of detection of 8 nM and a 1000-fold selectivity in the presence of other reactive oxygen species. Therefore, the developed TPIOP boronate chemodosimeter was successfully utilized to visualize and quantify intracellular H2O2 from human breast cancer (MCF-7) cells, as well as gaseous and aqueous H2O2 from environmental samples using Whatman paper strips coated with TPIOP boronate.

scholarly journals Determination of cyanide in bamboo shoots by microdiffusion combined with ion chromatography–pulsed amperometric detection

2018 ◽  
Vol 5 (4) ◽  
pp. 172128 ◽  
Author(s):  
Ming Ding ◽  
Kailiang Wang
Keyword(s):  
Ion Chromatography ◽  
Limit Of Detection ◽  
Correlation Coefficients ◽  
Amperometric Detection ◽  
High Sensitivity ◽  
Practical Method ◽  
Pulsed Amperometric Detection ◽  
Bamboo Shoots ◽  
Relative Standard

A practical method for the determination of cyanide in bamboo shoots has been developed using microdiffusion preparation integrated with ion chromatography–pulsed amperometric detection (IC-PAD). Cyanide was released from bamboo shoots after Conway cell microdiffusion, and then analysed by IC-PAD. In comparison with the previously reported methods, derivatization and ion-pairing agent addition were not required in this proposed microdiffusion combined with IC-PAD method. The microdiffusion parameters were optimized including hydrolysis systems, temperature, time, and so on. Under the optimum conditions, the linear range of the calibration curve for cyanide was 0.2–200.0 µg kg −1 with satisfactory correlation coefficients of 0.9996 and the limit of detection was 0.2 µg kg −1 ( S/N  = 3). The spiked recovery range was from 92.8 to 98.6%. The intra-day and inter-day relative standard deviations of cyanide were 2.7–14.9% and 3.0–18.3%, respectively. This method was proved to be convenient in operation with high sensitivity, precision and accuracy, and was successfully applied in the determination of cyanide in bamboo shoot samples.

scholarly journals Flexible and Highly Sensitive Pressure Sensors Based on Microstructured Carbon Nanowalls Electrodes

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 496 ◽  
Author(s):  
Xi Zhou ◽  
Yongna Zhang ◽  
Jun Yang ◽  
Jialu Li ◽  
Shi Luo ◽  
...  
Keyword(s):  
Pressure Sensor ◽  
High Performance ◽  
Limit Of Detection ◽  
Pressure Sensors ◽  
High Sensitivity ◽  
Physiological Signals ◽  
Healthcare Applications ◽  
Highly Sensitive ◽  
Carbon Nanowalls ◽  
Pressure Regime

Wearable pressure sensors have attracted widespread attention in recent years because of their great potential in human healthcare applications such as physiological signals monitoring. A desirable pressure sensor should possess the advantages of high sensitivity, a simple manufacturing process, and good stability. Here, we present a highly sensitive, simply fabricated wearable resistive pressure sensor based on three-dimensional microstructured carbon nanowalls (CNWs) embedded in a polydimethylsiloxane (PDMS) substrate. The method of using unpolished silicon wafers as templates provides an easy approach to fabricate the irregular microstructure of CNWs/PDMS electrodes, which plays a significant role in increasing the sensitivity and stability of resistive pressure sensors. The sensitivity of the CNWs/PDMS pressure sensor with irregular microstructures is as high as 6.64 kPa−1 in the low-pressure regime, and remains fairly high (0.15 kPa−1) in the high-pressure regime (~10 kPa). Both the relatively short response time of ~30 ms and good reproducibility over 1000 cycles of pressure loading and unloading tests illustrate the high performance of the proposed device. Our pressure sensor exhibits a superior minimal limit of detection of 0.6 Pa, which shows promising potential in detecting human physiological signals such as heart rate. Moreover, it can be turned into an 8 × 8 pixels array to map spatial pressure distribution and realize array sensing imaging.

An Amperometric Biosensor Based on a Multi-Nanoporous SnO2/HRP/Chitosan for Detection of Hydrogen Peroxide in Human Urine Samples

2019 ◽  
Vol 17 (10) ◽  
pp. 769-776
Author(s):  
Samiul Alim ◽  
Rajan Jose ◽  
Mashitah M. Yusoff ◽  
A. K. M. Kafi
Keyword(s):  
Hydrogen Peroxide ◽  
Horseradish Peroxidase ◽  
Glassy Carbon ◽  
Human Urine ◽  
Limit Of Detection ◽  
Amperometric Biosensor ◽  
Carbon Electrode ◽  
Sample Analysis ◽  
Real Sample Analysis ◽  
Effects Of Ph

A new amperometric biosensor fabricated from a multi-nanoporous SnO2 and HRP was trialled. The multiporous SnO2 nanofiber was fabricated in the research lab. Horseradish peroxidase was co-immobilized on a glassy carbon electrode with the multiporous SnO2 nanofiber and chitosan. The FESEM and EDX analysis were used to study the nanostructure and composition details of the nanofiber. Electrochemical results established that the immobilized HRP exhibited direct electrochemical behavior toward hydrogen peroxide (H2O2). The effects of pH, and applied potentials on the biosensor were also investigated. The limit of detection which was found to be 5 × 10–7 M with the linear range being between 5 × 10–6 M to 1.2 × 10–4 M of H2O2. For real sample analysis, this biosensor showed that the H2O2 concentration in the human urine can be monitored conveniently, where the interference is noted to be negligible.

scholarly journals Novel Highly Sensitive Protein Sensors Based on Tapered Optical Fibres Modified with Au-Based Nanocoatings

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Aitor Urrutia ◽  
Kartheka Bojan ◽  
Leonel Marques ◽  
Kevin Mullaney ◽  
Javier Goicoechea ◽  
...  
Keyword(s):  
Binding Constant ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Optical Fibres ◽  
Layer By Layer ◽  
Measured Concentration ◽  
Au Nps ◽  
Layer Deposition ◽  
Highly Sensitive ◽  
Protein Sensors

Novel protein sensors based on tapered optical fibres modified with Au coatings deposited using two different procedures are proposed. Au-based coatings are deposited onto a nonadiabatic tapered optical fibre using (i) a novel facile method composed of layer-by-layer deposition consisting of polycation (poly(allylamine hydrochloride), PAH) and negatively charged SiO2nanoparticles (NPs) followed by the deposition of the charged Au NPs and (ii) the sputtering technique. The Au NPs and Au thin film surfaces are then modified with biotin in order to bind streptavidin (SV) molecules and detect them. The sensing principle is based on the sensitivity of the transmission spectrum of the device to changes in the refractive index of the coatings induced by the SV binding to the biotin. Both sensors showed high sensitivity to SV, with the lowest measured concentration levels below 2.5 nM. The calculated binding constant for the biotin-SV pair was2.2×10-11 M−1when a tapered fibre modified with the LbL method was used, with a limit of detection (LoD) of 271 pM. The sensor formed using sputtering had a binding constant of1.01×10-10 M−1with a LoD of 806 pM. These new structures and their simple fabrication technique could be used to develop other biosensors.

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