scholarly journals A Brief Description of Cyclic Voltammetry Transducer-Based Non-Enzymatic Glucose Biosensor Using Synthesized Graphene Electrodes

2020 ◽  
Vol 3 (3) ◽  
pp. 32
Author(s):  
Mohamed Husien Fahmy Taha ◽  
Hager Ashraf ◽  
Wahyu Caesarendra
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Properties ◽  
High Performance ◽  
Ph Value ◽  
Limit Of Detection ◽  
Low Cost ◽  
Synthesis Method ◽  
Glucose Biosensor ◽  
Glucose Sensors ◽  
Fourth Generation

The essential disadvantages of conventional glucose enzymatic biosensors such as high fabrication cost, poor stability of enzymes, pH value-dependent, and dedicated limitations, have been increasing the attraction of non-enzymatic glucose sensors research. Beneficially, patients with diabetes could use this type of sensor as a fourth-generation of glucose sensors with a very low cost and high performance. We demonstrate the most common acceptable transducer for a non-enzymatic glucose biosensor with a brief description of how it works. The review describes the utilization of graphene and its composites as new materials for high-performance non-enzymatic glucose biosensors. The electrochemical properties of graphene and the electrochemical characterization using the cyclic voltammetry (CV) technique of electrocatalysis electrodes towards glucose oxidation have been summarized. A recent synthesis method of the graphene-based electrodes for non-enzymatic glucose sensors have been introduced along with this study. Finally, the electrochemical properties such as linearity, sensitivity, and the limit of detection (LOD) for each sensor are introduced with a comparison with each other to figure out their strengths and weaknesses.

scholarly journals Regeneration and Reuse of Immunoaffinity Column for Highly Efficient Clean-Up and Economic Detection of Ochratoxin A in Malt and Ginger

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 462 ◽  
Author(s):  
Xi Liu ◽  
Xiaofei Liu ◽  
Pinxuan Huang ◽  
Fang Wei ◽  
Guangyao Ying ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
High Performance ◽  
Ph Value ◽  
Low Cost ◽  
Herbal Medicines ◽  
Preparation Procedure ◽  
Preservation Solution ◽  
Traditional Procedure ◽  
Sample Extraction ◽  
Sample Preparation Procedure

Immunoaffinity columns (IACs) are most popularly used for mycotoxin clean-up in complex matrices prior to chromatographic analysis. But, their high cost has limited their wide application and the regeneration of IACs for multiple instances of reuse is important. This study aimed to investigate the feasibility of regeneration and reuse of IACs for purification of ochratoxin A (OTA) in spiked raw malt and dried ginger samples followed by high performance liquid chromatography-fluorescence detection. After each use, the IACs were filled with phosphate buffer saline (PBS) as the preservation solution and stored at 8 °C overnight for regeneration and reuse until the recovery rate was <70%. The results showed that matrix type, preparation procedure, and pH value of sample extraction exhibited major effects on the reuse of IACs for OTA clean-up. While, after modifying the sample preparation procedure using water as the diluent and the solution at a pH of 7 to 8, the IACs could be used eight and three times for the spiked raw malt and dried ginger samples with OTA after regeneration. Regarding the traditional procedure recommended in Chinese Pharmacopoeia (2015 edition), the IACs could be used for three and two times for the spiked raw malt and dried ginger samples with OTA, respectively. Therefore, the corresponding experimental cost could be reduced to one-eighth and one-third of the original cost. This is the first study on the regeneration and reuse of IACs for OTA clean-up in complex Chinese herbal medicines, providing a green and economical tool for a large number of samples analysis with low cost.

scholarly journals A Facile Fabrication of a Potentiometric Arrayed Glucose Biosensor Based on Nafion-GOx/GO/AZO

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 964
Author(s):  
Jung-Chuan Chou ◽  
Si-Hong Lin ◽  
Tsu-Yang Lai ◽  
Po-Yu Kuo ◽  
Chih-Hsien Lai ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Low Cost ◽  
Glucose Biosensor ◽  
Average Sensitivity ◽  
Glucose Biosensors ◽  
Coating Method ◽  
Aluminum Doped Zinc Oxide ◽  
Screen Printing Technology

In this study, the potentiometric arrayed glucose biosensors, which were based on zinc oxide (ZnO) or aluminum-doped zinc oxide (AZO) sensing membranes, were fabricated by using screen-printing technology and a sputtering system, and graphene oxide (GO) and Nafion-glucose oxidase (GOx) were used to modify sensing membranes by using the drop-coating method. Next, the material properties were characterized by using a Raman spectrometer, a field-emission scanning electron microscope (FE-SEM), and a scanning probe microscope (SPM). The sensing characteristics of the glucose biosensors were measured by using the voltage–time (V-T) measurement system. Finally, electrochemical impedance spectroscopy (EIS) was conducted to analyze their charge transfer abilities. The results indicated that the average sensitivity of the glucose biosensor based on Nafion-GOx/GO/AZO was apparently higher than that of the glucose biosensor based on Nafion-GOx/GO/ZnO. In addition, the glucose biosensor based on Nafion-GOx/GO/AZO exhibited an excellent average sensitivity of 15.44 mV/mM and linearity of 0.997 over a narrow range of glucose concentration range, a response time of 26 s, a limit of detection (LOD) of 1.89 mM, and good reproducibility. In terms of the reversibility and stability, the hysteresis voltages (VH) were 3.96 mV and 2.42 mV. Additionally, the glucose biosensor also showed good anti-inference ability and reproducibility. According to these results, it is demonstrated that AZO is a promising material, which could be used to develop a reliable, simple, and low-cost potentiometric glucose biosensor.

scholarly journals Glucose Biosensor Based on Disposable Activated Carbon Electrodes Modified with Platinum Nanoparticles Electrodeposited on Poly(Azure A)

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4489 ◽  
Author(s):  
Francisco Jiménez-Fiérrez ◽  
María Isabel González-Sánchez ◽  
Rebeca Jiménez-Pérez ◽  
Jesús Iniesta ◽  
Edelmira Valero
Keyword(s):  
Platinum Nanoparticles ◽  
High Performance ◽  
Electrochemical Biosensor ◽  
Limit Of Detection ◽  
Electrochemical Measurement ◽  
Glucose Biosensor ◽  
Carbon Electrodes ◽  
Real Samples ◽  
Glucose Determination ◽  
Azure A

Herein, a novel electrochemical glucose biosensor based on glucose oxidase (GOx) immobilized on a surface containing platinum nanoparticles (PtNPs) electrodeposited on poly(Azure A) (PAA) previously electropolymerized on activated screen-printed carbon electrodes (GOx-PtNPs-PAA-aSPCEs) is reported. The resulting electrochemical biosensor was validated towards glucose oxidation in real samples and further electrochemical measurement associated with the generated H2O2. The electrochemical biosensor showed an excellent sensitivity (42.7 μA mM−1 cm−2), limit of detection (7.6 μM), linear range (20 μM–2.3 mM), and good selectivity towards glucose determination. Furthermore, and most importantly, the detection of glucose was performed at a low potential (0.2 V vs. Ag). The high performance of the electrochemical biosensor was explained through surface exploration using field emission SEM, XPS, and impedance measurements. The electrochemical biosensor was successfully applied to glucose quantification in several real samples (commercial juices and a plant cell culture medium), exhibiting a high accuracy when compared with a classical spectrophotometric method. This electrochemical biosensor can be easily prepared and opens up a good alternative in the development of new sensitive glucose sensors.

scholarly journals Improved Mechanical and Electrochemical Properties of XNBR Dielectric Elastomer Actuator by Poly(dopamine) Functionalized Graphene Nano-Sheets

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 218 ◽  
Author(s):  
Dan Yang ◽  
Xinxin Kong ◽  
Yufeng Ni ◽  
Mengnan Ruan ◽  
Shuo Huang ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
High Performance ◽  
Low Cost ◽  
Dielectric Strength ◽  
Dielectric Elastomer ◽  
Hydroxyl Groups ◽  
Butadiene Rubber ◽  
Functionalized Graphene ◽  
Filler Dispersion ◽  
Phenolic Hydroxyl Groups

In this work, graphene nano-sheets (GNS) functionalized with poly(dopamine) (PDA) (denoted as GNS-PDA) were dispersed in a carboxylated nitrile butadiene rubber (XNBR) matrix to obtain excellent dielectric composites via latex mixing. Because hydrogen bonds were formed between –COOH groups of XNBR and phenolic hydroxyl groups of PDA, the encapsulation of GNS-PDA around XNBR latex particles was achieved, and led to a segregated network structure of filler formed in the GNS-PDA/XNBR composite. Thus, the XNBR composite filled with GNS-PDA showed improved filler dispersion, enhanced dielectric constant and dielectric strength, and decreased conductivity compared with the XNBR composite filled with pristine GNS. Finally, the GNS-PDA/XNBR composite displayed an actuated strain of 2.4% at 18 kV/mm, and this actuated strain was much larger than that of pure XNBR (1.3%) at the same electric field. This simple, environmentally friendly, low-cost, and effective method provides a promising route for obtaining a high-performance dielectric elastomer with improved mechanical and electrochemical properties.

scholarly journals Electrochemical Properties of Screen-Printed Carbon Nano-Onion Electrodes

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3884
Author(s):  
Loanda R. Cumba ◽  
Adalberto Camisasca ◽  
Silvia Giordani ◽  
Robert J. Forster
Keyword(s):  
High Performance ◽  
Electrode Materials ◽  
Limit Of Detection ◽  
Low Cost ◽  
Analytical Sensitivity ◽  
High Performing ◽  
Carbon Particles ◽  
Screen Printed Electrodes ◽  
Ink Formulation ◽  
Screen Printed

The properties of carbon nano-onions (CNOs) make them attractive electrode materials/additives for the development of low-cost, simple to use and highly sensitive Screen Printed Electrodes (SPEs). Here, we report the development of the first CNO-based ink for the fabrication of low-cost and disposable electrodes, leading to high-performance sensors. Achieving a true dispersion of CNOs is intrinsically challenging and a key aspect of the ink formulation. The screen-printing ink formulation is achieved by carefully selecting and optimising the conductive materials (graphite (GRT) and CNOs), the polymer binder, the organic solvent and the plasticiser. Our CNO/GRT-based screen-printed electrodes consist of an interconnected network of conducting carbon particles with a uniform distribution. Electrochemical studies show a heterogeneous electron transfer rate constant of 1.3 ± 0.7 × 10−3 cm·s−1 and a higher current density than the ferrocene/ferrocenium coupled to a commercial graphite SPEs. In addition, the CNO/GRT SPE can detect dopamine in the concentration range of 10.0–99.9 µM with a limit of detection of 0.92 µM (N = 3). They exhibit a higher analytical sensitivity than the commercial graphite-based SPE, with a 4-fold improvement observed. These results open up the possibility of using high-performing CNO-based SPEs for electrochemical applications including sensors, battery electrodes and electrocatalysis.

scholarly journals Electrochemical detection of ascorbic acid in artificial sweat using a flexible alginate/CuO-modified electrode

2020 ◽  
Vol 187 (9) ◽  
Author(s):  
Bergoi Ibarlucea ◽  
Arnau Pérez Roig ◽  
Dmitry Belyaev ◽  
Larysa Baraban ◽  
Gianaurelio Cuniberti
Keyword(s):  
Ascorbic Acid ◽  
Cyclic Voltammetry ◽  
Electrochemical Detection ◽  
Limit Of Detection ◽  
Low Cost ◽  
Reference Electrode ◽  
Single Step ◽  
Repeated Measurements ◽  
Relative Standard ◽  
Artificial Sweat

Abstract A flexible sensor is presented for electrochemical detection of ascorbic acid in sweat based on single-step modified gold microelectrodes. The modification consists of electrodeposition of alginate membrane with trapped CuO nanoparticles. The electrodes are fabricated at a thin polyimide support and the soft nature of the membrane can withstand mechanical stress beyond requirements for skin monitoring. After characterization of the membrane via optical and scanning electron microscopy and cyclic voltammetry, the oxidative properties of CuO are exploited toward ascorbic acid for amperometric measurement at micromolar levels in neutral buffer and acidic artificial sweat, at ultralow applied potential (− 5 mV vs. Au pseudo-reference electrode). Alternatively, measurement of the horizontal shift of redox peaks by cyclic voltammetry is also possible. Obtaining a limit of detection of 1.97 μM, sensitivity of 0.103 V log (μM)−1 of peak shift, and linear range of 10–150 μM, the effect of possible interfering species present in sweat is minimized, with no observable cross-reaction, thus maintaining a high degree of selectivity despite the absence of enzymes in the fabrication scheme. With a lateral flow approach for sample delivery, repeated measurements show recovery in few seconds, with relative standard deviation of about 20%, which can serve to detect increased loss or absence of vitamin, and yet be improved in future by optimized device designs. This sensor is envisioned as a promising component of wearable devices for e.g. non-invasive monitoring of micronutrient loss through sweat, comprising features of light weight, low cost, and easy fabrication needed for such application.

scholarly journals Incorporating N Atoms into SnO2 Nanostructure as an Approach to Enhance Gas Sensing Property for Acetone

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 445 ◽  
Author(s):  
Xiangfeng Guan ◽  
Yongjing Wang ◽  
Peihui Luo ◽  
Yunlong Yu ◽  
Dagui Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Gas Sensing ◽  
Diffuse Reflectance Spectroscopy ◽  
Limit Of Detection ◽  
Low Cost ◽  
X Ray ◽  
Sno2 Nanostructure

The development of high-performance acetone gas sensor is of great significance for environmental protection and personal safety. SnO2 has been intensively applied in chemical sensing areas, because of its low cost, high mobility of electrons, and good chemical stability. Herein, we incorporated nitrogen atoms into the SnO2 nanostructure by simple solvothermal and subsequent calcination to improve gas sensing property for acetone. The crystallization, morphology, element composition, and microstructure of as-prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), Raman spectroscopy, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and the Brunauer–Emmett–Teller (BET) method. It has been found that N-incorporating resulted in decreased crystallite size, reduced band-gap width, increased surface oxygen vacancies, enlarged surface area, and narrowed pore size distribution. When evaluated as gas sensor, nitrogen-incorporated SnO2 nanostructure exhibited excellent sensitivity for acetone gas at the optimal operating temperature of 300 °C with high sensor response (Rair/Rgas − 1 = 357) and low limit of detection (7 ppb). The nitrogen-incorporated SnO2 gas sensor shows a good selectivity to acetone in the interfering gases of benzene, toluene, ethylbenzene, hydrogen, and methane. Furthermore, the possible gas-sensing mechanism of N-incorporated SnO2 toward acetone has been carefully discussed.

Electrochemical Fabrication of Cu2O Photocathode for Photoelectrochemical Hydrogen Evolution Reaction

2015 ◽  
Vol 659 ◽  
pp. 226-230 ◽  
Author(s):  
Pattranit Thongthep ◽  
Somporn Moonmangmee ◽  
Chatchai Ponchio
Keyword(s):  
Cyclic Voltammetry ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Ph Value ◽  
Low Cost ◽  
Previous Method ◽  
Mixed Solution ◽  
Deposition Method ◽  
Electro Deposition ◽  
Excellent Method

In this study, we can fabricate Cu2O on F-doped SnO2coated glass (FTO) substrates as photocathode for hydrogen evolution reaction by electro-deposition techniques. Cyclic voltammetry as a new deposition method was studied to fabricate Cu2O photocathode in a mixed solution of Cu (NO3)2and KNO3under a condition of low temperature and without pH value adjustment. Amperometry as a previous method was used to compare for Cu2O electrode fabrication under the situation of pH adjustment and higher temperature condition. A photocurrent from hydrogen evolution reaction was performed by keep potential at-0.2 V in 0.1 M Na2SO4under visible irradiation comparing with both fabricated method. The Cu2O photocathode from cyclic voltammetry deposition method presents photoelectrocatalytic activity higher than that of amperometry deposition method with the optimum conditions. This electro-deposition technique represents the excellent method with simple, fast and low cost of Cu2O photocathode fabrication for photoelectrochemical hydrogen evolution reaction.

scholarly journals Extraction of soluble sugars from green coffee beans using hot water and quantification by a chromatographic method without an organic solvent

2020 ◽  
Vol 32 (4) ◽  
pp. 242-246 ◽  
Author(s):  
Leonel Vinicius Constantino ◽  
Douglas Mariani Zeffa ◽  
Alessandra Koltun ◽  
Mariana Ragassi Urbano ◽  
Alisson Wilson Santos Sanzovo ◽  
...  
Keyword(s):  
High Performance ◽  
Chromatographic Method ◽  
Limit Of Detection ◽  
Low Cost ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Hot Water ◽  
Green Coffee ◽  
Limit Of Quantification ◽  
Assisted Extraction

An optimal condition for extraction of soluble sugars from green coffee using water and a validated chromatographic method for its separation and quantification were proposed in this research. An orbital incubator shaker (OIS) and microwave-assisted extraction (MAE) were the 2 techniques used to extract soluble sugars. In such experiments, the variables: sample amount (300, 400, and 500 mg), time (30, 60, and 90 min), and temperature (30, 45, and 60 °C) were tested. The separation of sugars was performed in a chromatographic system (high-performance liquid chromatography refractive index detector [HPLC-RID]), which presented the selectivity for the analytes, a limit of detection of 0.020 g/L, a limit of quantification of 0.0625 g/L, and recovery rates greater than 95%. The repeatability and inter-day precision had low dispersion, RSD < 2.0% and < 3.0%, respectively. Sucrose content ranged from 0.65 to 2.39 g/L using an OIS and from 1.19 to 2.72 g/L by MAE, while glucose and fructose concentration varied from 0.08 to 0.12 g/L using both methods. The OIS technique is preferably indicated for extraction of soluble sugars at the following conditions: 500 mg of grounded green coffee, 90 min, and 60 °C. The proposed method for soluble sugar extraction and quantification may be applied in research laboratories and food industries since it is a low-cost and environment-friendly technique.

Fabrication and evaluation of Ni-based air-cathode

2020 ◽  
Vol 64 (1-4) ◽  
pp. 65-71
Author(s):  
Yuhei Tsuji ◽  
Dang-Trang Nguyen ◽  
Kozo Taguchi
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Synthesis Method ◽  
Ozone Treatment ◽  
Air Cathode ◽  
Carbon Sheet ◽  
Air Battery ◽  
Temperature And Pressure ◽  
Materials Used ◽  
Uv Ozone

This study focused on investigating low-cost but high-performance catalyst materials used for the air cathode of the aluminum-air battery. Nickel, in the form of Ni(OH)2, was used as the catalyst because it is abundant and low-cost. The activated carbon sheet was used as the substrate to load the catalyst. The solvothermal synthesis method was used to synthesize the catalyst. The advantage of the solvothermal method is that the particle size can be reduced under high temperature and pressure conditions. The operation of some types of air-cathodes was examined. UV-ozone treatment of the air-cathode has also been investigated to enhance the performance of the battery.

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