scholarly journals Mesoporous CoOx/C Nanocomposites Functionalized Electrochemical Sensor for Rapid and Continuous Detection of Nitrite

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 596
Author(s):  
Xuhua Dong ◽  
Siqi Xie ◽  
Jingyang Zhu ◽  
Haiquan Liu ◽  
Yong Zhao ◽  
...  
Keyword(s):  
Electrochemical Sensor ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Electrochemical Sensors ◽  
Meat Products ◽  
Inorganic Ions ◽  
Cobalt Nitrate ◽  
Detection Range ◽  
Current Time ◽  
And Control

Nitrite is widespread in the environment, and is frequently used as an additive to extend the shelf life of meat products. However, the excess intake of nitrite can be harmful to human health. Hence, it is very important to know and control the content of nitrite in foodstuffs. In this work, by the means of self-assembly induced by solvent evaporation, we used the amphiphilic PEO-b-PS diblock copolymers resol and cobalt nitrate as a template to synthesize ordered mesoporous CoOx/C nanocomposites. Then, the CoOx/C nanocomposites were modified on a glassy carbon electrode (GCE), which showed excellent sensitivity, good selectivity, and a wide detection range for nitrite. Through cyclic voltammetry and current–time techniques, the electrochemical performance of the GCE modified with CoOx/C nanocomposites was analyzed. Under the optimized conditions, we found that anodic currents were linearly related to nitrite concentrations with a regression equation of lp (µA) = 0.36388 + 0.01616C (R2 = 0.9987) from 0.2 µM to 2500 µM, and the detection limit was 0.05 µM. Furthermore, the electrochemical sensor behaved with high reproducibility and anti-interference ability towards various organic and inorganic ions, such as NO3−, SO42−, Cl−, COOH− (Ac−), Na+, K+, Mg2+, and NH4+. Our results indicated that these CoOx/C nanocomposites could be applied in electrochemical sensors for the rapid and sensitive detection of the food preservative nitrite.

scholarly journals An Electrochemical Sensor Based on Gold-Nanocluster-Modified Graphene Screen-Printed Electrodes for the Detection of β-Lactoglobulin in Milk

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3956
Author(s):  
Jingyi Hong ◽  
Yuxian Wang ◽  
Liying Zhu ◽  
Ling Jiang
Keyword(s):  
Electrochemical Sensor ◽  
Electrochemical Sensors ◽  
Limit Of Detection ◽  
Gold Nanoclusters ◽  
Enzyme Linked Immunosorbent Assay ◽  
Gold Nanocluster ◽  
Detection Range ◽  
Screen Printed Electrodes ◽  
Β Lactoglobulin ◽  
Screen Printed

A simple and low-cost electrochemical sensor based on multimodified screen-printed electrodes (SPEs) was successfully synthesized for the sensitive detection of β-lactoglobulin (β-Lg). The surface treatment of SPEs was accomplished by a simple drip coating method using polyethyleneimine (PEI), reduced graphene oxide (rGO), and gold nanoclusters (AuNCs), and the treated SPEs showed excellent electrical conductivity. The modified SPEs were then characterized with UV-Vis, SEM, TEM, and FTIR to analyze the morphology and composition of the AuNCs and the rGO. An anti-β-Lg antibody was then immobilized on the composite material obtained by modifying rGO with PEI and AuNCs (PEI-rGO-AuNCs), leading to the remarkable reduction in conductivity of the SPEs due to the reaction between antigen and antibody. The sensor obtained using this novel approach enabled a limit of detection (LOD) of 0.08 ng/mL and a detection range from 0.01 to 100 ng/mL for β-Lg. Furthermore, pure milk samples from four milk brands were measured using electrochemical sensors, and the results were in excellent agreement with those from commercial enzyme-linked immunosorbent assay (ELISA) methods.

Self-assembly of photoswitchable diblock copolymers: salt-induced micellization and the influence of UV irradiation

2015 ◽  
Vol 17 (18) ◽  
pp. 12215-12221 ◽  
Author(s):  
Jing Zhang ◽  
Yue Zhang ◽  
Feiyang Chen ◽  
Weiyao Zhang ◽  
Hanying Zhao
Keyword(s):  
Complex Formation ◽  
Uv Irradiation ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Inorganic Ions ◽  
The Self ◽  
Inorganic Salts ◽  
Water Mixture ◽  
Assembly Process

Inorganic salts are able to induce micellization of PEG-b-PSPMA in a 10 : 1 DMF/water mixture upon UV irradiation. The complex formation between inorganic ions and MC isomers plays a key role in the self-assembly process.

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

2018 ◽  
Author(s):  
Dominic Bara ◽  
Claire Wilson ◽  
Max Mörtel ◽  
Marat M. Khusniyarov ◽  
ben slater ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Areas ◽  
Metal Precursors ◽  
Additional Coordination ◽  
Fine Control ◽  
Multiple Alternative ◽  
Metal Organic ◽  
Dft Simulations ◽  
High Valent ◽  
And Control

Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.<br><br>

scholarly journals Electrochemical Determination of Capsaicinoids Content in Soy Sauce and Pot-Roast Meat Products Based on Glassy Carbon Electrode Modified with Β-Cyclodextrin/Carboxylated Multi-Wall Carbon Nanotubes

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1743
Author(s):  
Qianhui Gu ◽  
Chaoqun Lu ◽  
Kangwen Chen ◽  
Xingguang Chen ◽  
Pengfei Ma ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Sensor ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Meat Products ◽  
Soy Sauce ◽  
Relative Dispersion ◽  
Carbon Electrode ◽  
Trace Detection ◽  
Multi Wall Carbon Nanotubes

The rapid quantification of capsaicinoids content is very important for the standardization of pungent taste degree and flavor control of soy sauce and pot-roast meat products. To rapidly quantify the capsaicinoids content in soy sauce and pot-roast meat products, an electrochemical sensor based on β-cyclodextrin/carboxylated multi-wall carbon nanotubes was constructed and the adsorptive stripping voltammetry method was used to enrich samples in this study. The results showed that the excellent performance of the established electrochemical sensor was mostly because β-cyclodextrin caused the relative dispersion of carboxylated multi-wall carbon nanotubes on the glassy carbon electrode surface. Capsaicin and dihydrocapsaicin had similar electrochemical behavior, so the proposed method could determine the total content of capsaicinoids. The linearity of capsaicinoids content was from 0.5 to 100 μmol/L and the detection limit was 0.27 μmol/L. The recovery rates of different capsaicinoids content were between 83.20% and 136.26%, indicating the proposed sensor could realize trace detection of capsaicinoids content in sauce and pot-roast meat products. This work provides a research basis for pungent taste degree standardization and flavor control in the food industry.

scholarly journals Guided Self-Assembly and Control of Vortices in Ensembles of Active Magnetic Rollers

Langmuir ◽  
2019 ◽  
Vol 36 (25) ◽  
pp. 6957-6962 ◽  
Author(s):  
Gašper Kokot ◽  
Andrey Sokolov ◽  
Alexey Snezhko
Keyword(s):  
Self Assembly ◽  
And Control

scholarly journals MnO2@Reduced Graphene Oxide Nanocomposite-Based Electrochemical Sensor for the Simultaneous Determination of Trace Cd(II), Zn(II) and Cu(II) in Water Samples

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 517
Author(s):  
Siyamthanda Hope Mnyipika ◽  
Tshimangadzo Saddam Munonde ◽  
Philiswa Nosizo Nomngongo
Keyword(s):  
Heavy Metals ◽  
Electrochemical Sensor ◽  
Simultaneous Determination ◽  
Rapid Detection ◽  
Electrochemical Sensors ◽  
Simultaneous Detection ◽  
Cyclic Voltammograms ◽  
Current Response ◽  
Mno2 Nanoparticles

The rapid detection of trace metals is one of the most important aspect in achieving environmental monitoring and protection. Electrochemical sensors remain a key solution for rapid detection of heavy metals in environmental water matrices. This paper reports the fabrication of an electrochemical sensor obtained by the simultaneous electrodeposition of MnO2 nanoparticles and RGO nanosheets on the surface of a glassy carbon electrode. The successful electrodeposition was confirmed by the enhanced current response on the cyclic voltammograms. The XRD, HR-SEM/EDX, TEM, FTIR, and BET characterization confirmed the successful synthesis of MnO2 nanoparticles, RGO nanosheets, and MnO2@RGO nanocomposite. The electrochemical studies results revealed that MnO2@RGO@GCE nanocomposite considerably improved the current response on the detection of Zn(II), Cd(II) and Cu(II) ions in surface water. These remarkable improvements were due to the interaction between MnO2 nanomaterials and RGO nanosheets. Moreover, the modified sensor electrode portrayed high sensitivity, reproducibility, and stability on the simultaneous determination of Zn(II), Cd(II), and Cu(II) ions. The detection limits of (S/N = 3) ranged from 0.002–0.015 μg L−1 for the simultaneous detection of Zn(II), Cd(II), and Cu(II) ions. The results show that MnO2@RGO nanocomposite can be successfully used for the early detection of heavy metals with higher sensitivity in water sample analysis.

Highly sensitive real-time detection of intracellular oxidative stress and application in mycotoxin toxicity evaluation based on living single-cell electrochemical sensors

The Analyst ◽  
2021 ◽  
Author(s):  
Lu Gao ◽  
Jiadi Sun ◽  
Liping Wang ◽  
Qigao Fan ◽  
Gaowen Zhu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Electrochemical Sensor ◽  
Single Cell ◽  
Real Time ◽  
Electrochemical Sensors ◽  
Living Cells ◽  
Selective Detection ◽  
Toxicity Evaluation ◽  
Highly Sensitive ◽  
Intracellular Oxidative Stress

Single-cell electrochemical sensor is used in the local selective detection of living cells because of its high spatial–temporal resolution and sensitivity, as well as its ability to obtain comprehensive cellular physiological states and processes.

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