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14 pages, 4667 KiB

Open AccessArticle

Simulation of Graphene Field-Effect Transistor Biosensors for Bacterial Detection

by Guangfu Wu, M. Meyyappan and King Wai Chiu Lai

Sensors 2018, 18(6), 1715; https://doi.org/10.3390/s18061715 - 25 May 2018

Cited by 24 | Viewed by 9364

Abstract

Foodborne illness is correlated with the existence of infectious pathogens such as bacteria in food and drinking water. Probe-modified graphene field effect transistors (G-FETs) have been shown to be suitable for Escherichia coli (E. coli) detection. Here, the G-FETs for bacterial [...] Read more.

Foodborne illness is correlated with the existence of infectious pathogens such as bacteria in food and drinking water. Probe-modified graphene field effect transistors (G-FETs) have been shown to be suitable for Escherichia coli (E. coli) detection. Here, the G-FETs for bacterial detection are modeled and simulated with COMSOL Multiphysics to understand the operation of the biosensors. The motion of E. coli cells in electrolyte and the surface charge of graphene induced by E. coli are systematically investigated. The comparison between the simulation and experimental data proves the sensing probe size to be a key parameter affecting the surface charge of graphene induced by bacteria. Finally, the relationship among the change in source-drain current (∆I_ds), graphene-bacteria distance and bacterial concentration is established. The shorter graphene-bacteria distance and higher bacterial concentration give rise to better sensing performance (larger ∆I_ds) of the G-FETs biosensors. The simulation here could serve as a guideline for the design and optimization of G-FET biosensors for various applications. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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13 pages, 3796 KiB

Open AccessArticle

A Facile Electrochemical Sensor Based on PyTS–CNTs for Simultaneous Determination of Cadmium and Lead Ions

by Ruyuan Jiang, Niantao Liu, Sanshuang Gao, Xamxikamar Mamat, Yuhong Su, Thomas Wagberg, Yongtao Li, Xun Hu and Guangzhi Hu

Sensors 2018, 18(5), 1567; https://doi.org/10.3390/s18051567 - 15 May 2018

Cited by 41 | Viewed by 5623

Abstract

A simple and easy method was implemented for the contemporary detection of cadmium (Cd²⁺) and lead (Pb²⁺) ions using 1,3,6,8-pyrenetetrasulfonic acid sodium salt-functionalized carbon nanotubes nanocomposites (PyTS–CNTs). The morphology and composition of the obtained PyTS–CNTs were characterized using scanning [...] Read more.

A simple and easy method was implemented for the contemporary detection of cadmium (Cd²⁺) and lead (Pb²⁺) ions using 1,3,6,8-pyrenetetrasulfonic acid sodium salt-functionalized carbon nanotubes nanocomposites (PyTS–CNTs). The morphology and composition of the obtained PyTS–CNTs were characterized using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results confirmed that the fabricated PyTS–CNTs exhibited good selectivity and sensitivity for metal ion-sensing owing to the insertion of sulfonic acid groups. For Cd²⁺ and Pb²⁺, some of the electrochemical sensing parameters were evaluated by varying data such as the PyTS–CNT quantity loaded on the pyrolytic graphite electrode (PGE), pH of the acetate buffer, deposition time, and deposition potential. These parameters were optimized with differential pulse anodic sweeping voltammetry (DPASV). Under the optimal condition, the stripping peak current of the PyTS–CNTs/Nafion/PGE varies linearly with the heavy metal ion concentration, ranging from 1.0 μg L⁻¹ to 90 μg L⁻¹ for Cd²⁺ and from 1.0 μg L⁻¹ to 110 μg L⁻¹ for Pb²⁺. The limits of detection were estimated to be approximately 0.8 μg L⁻¹ for Cd²⁺ and 0.02 μg L⁻¹ for Pb²⁺. The proposed PyTS–CNTs/Nafion/PGE can be used as a rapid, simple, and controllable electrochemical sensor for the determination of toxic Cd²⁺ and Pb²⁺. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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9 pages, 1312 KiB

Open AccessArticle

Rapid Iodine Sensing on Mechanically Treated Carbon Nanofibers

by Eunbyul Cho, Alexandra Perebikovsky, Olivia Benice, Sunshine Holmberg, Marc Madou and Maziar Ghazinejad

Sensors 2018, 18(5), 1486; https://doi.org/10.3390/s18051486 - 9 May 2018

Cited by 23 | Viewed by 7110

Abstract

In this work, we report on a rapid, efficient electrochemical iodine sensor based on mechanically treated carbon nanofiber (MCNF) electrodes. The electrode’s highly graphitic content, unique microstructure, and the presence of nitrogen heteroatoms in its atomic lattice contribute to increased heterogeneous electron transfer [...] Read more.

In this work, we report on a rapid, efficient electrochemical iodine sensor based on mechanically treated carbon nanofiber (MCNF) electrodes. The electrode’s highly graphitic content, unique microstructure, and the presence of nitrogen heteroatoms in its atomic lattice contribute to increased heterogeneous electron transfer and improved kinetics compared to conventional pyrolytic carbons. The electrode demonstrates selectivity for iodide ions in the presence of both interfering agents and high salt concentrations. The sensor exhibits clinically relevant limits of detection of 0.59 µM and 1.41 µM, in 1X PBS and synthetic urine, respectively, and a wide dynamic range between 5 µM and 700 µM. These results illustrate the advantages of the material’s unique electrochemical properties for iodide sensing, in addition to its simple, inexpensive fabrication. The reported iodine sensor eliminates the need for specimen processing, revealing its aptitude for applications in point-of-care diagnostics. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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12 pages, 4184 KiB

Open AccessArticle

Electrochemical Determination of Norepinephrine by Means of Modified Glassy Carbon Electrodes with Carbon Nanotubes and Magnetic Nanoparticles of Cobalt Ferrite

by Daniely Ferreira de Queiroz, Tony Rogério de Lima Dadamos, Sergio Antonio Spinola Machado and Marco Antonio Utrera Martines

Sensors 2018, 18(4), 1223; https://doi.org/10.3390/s18041223 - 16 Apr 2018

Cited by 38 | Viewed by 5800

Abstract

This study describes the electrochemical preparation of the electrocatalytic oxidation/reduction of noradrenaline in modified glassy carbon of cobalt ferrite nanoparticles and carbon nanotubes (GC/MWCNT/FCo₉₈). The cobalt ferrite powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The optimum [...] Read more.

This study describes the electrochemical preparation of the electrocatalytic oxidation/reduction of noradrenaline in modified glassy carbon of cobalt ferrite nanoparticles and carbon nanotubes (GC/MWCNT/FCo₉₈). The cobalt ferrite powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The optimum conditions found in an electrode composition were 4 μL of cobalt ferrite and 10 μL of carbon nanotubes in 0.1 mol L⁻¹ PBS at pH 7.0. The electrode displays electrochemical behavior in a wide potential range (−0.4 to 1.0 V vs. Ag/AgCl), high conductivity, and electrode stability/durability in 0.1 mol L⁻¹ PBS. Catalytic oxidation of noradrenaline was performed at the unmodified GC electrode at +0.60 V vs. Ag/AgCl and current of 0.17 μA and modified GC with cobalt ferrite nanoparticles and carbon nanotubes at +0.54 V vs. Ag/AgCl and current of 0.23 mA. With regard to the anodic peak current (I_pa) versus noradrenaline concentration by means of the amperometric method at the modified electrode, (which is linear in the 0.16 and 1.91 mmol L⁻¹ concentration range), the concentration limit was 0.76 μmol L⁻¹. In this way, the modified electrode GC/MWCNT/FCo₉₈ was found to be a promising application for the determination of this neurotransmitter in the area of neuroscience. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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13 pages, 2290 KiB

Open AccessArticle

The Effects of Graphene Stacking on the Performance of Methane Sensor: A First-Principles Study on the Adsorption, Band Gap and Doping of Graphene

by Ning Yang, Daoguo Yang, Guoqi Zhang, Liangbiao Chen, Dongjing Liu, Miao Cai and Xuejun Fan

Sensors 2018, 18(2), 422; https://doi.org/10.3390/s18020422 - 1 Feb 2018

Cited by 12 | Viewed by 5205

Abstract

The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is [...] Read more.

The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is found that the zigzag graphene with Bernal stacking has the largest adsorption energy on methane, while the armchair graphene with Order stacking is opposite. In addition, both the Order and Bernal stacked graphenes possess a positive linear relationship between adsorption energy and layer number. Furthermore, they always have larger adsorption energy in zigzag graphene. For electronic properties, the results show that the stacking effects on band gap are significant, but it does not cause big changes to band structure and density of states. In the comparison of distance, the average interlamellar spacing of the Order stacked graphene is the largest. Moreover, the adsorption effect is the result of the interactions between graphene and methane combined with the change of graphene’s structure. Lastly, the armchair graphene with Order stacking possesses the lowest formation energy in these five dopants. It could be the best choice for doping to improve the methane adsorption. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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12 pages, 4971 KiB

Open AccessArticle

A New Strategy Involving the Use of Peptides and Graphene Oxide for Fluorescence Turn-on Detection of Proteins

by Huan Shi, Bibo Zhang, Shuwen Liu, Chunyan Tan, Ying Tan and Yuyang Jiang

Sensors 2018, 18(2), 385; https://doi.org/10.3390/s18020385 - 29 Jan 2018

Cited by 7 | Viewed by 3975

Abstract

The detection of proteins is of great biological significance as disease biomarkers in early diagnosis, prognosis tracking and therapeutic evaluation. Thus, we developed a simple, sensitive and universal protein-sensing platform based on peptide and graphene oxide (GO). The design consists of a fluorophore [...] Read more.

The detection of proteins is of great biological significance as disease biomarkers in early diagnosis, prognosis tracking and therapeutic evaluation. Thus, we developed a simple, sensitive and universal protein-sensing platform based on peptide and graphene oxide (GO). The design consists of a fluorophore (TAMRA, TAM), a peptide containing eight arginines and peptide ligand that could recognize the target protein, and GO used as a quencher. To demonstrate the feasible use of the sensor for target detection, Bcl-xL was evaluated as the model target. The sensor was proved to be sensitive and applied for the detection of the target proteins in buffer, 2% serum and living cells. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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1824 KiB

Open AccessArticle

Sulfophenyl-Functionalized Reduced Graphene Oxide Networks on Electrospun 3D Scaffold for Ultrasensitive NO₂ Gas Sensor

by Bin Zou, Yunlong Guo, Nannan Shen, Anshan Xiao, Mingjun Li, Liang Zhu, Pengbo Wan and Xiaoming Sun

Sensors 2017, 17(12), 2954; https://doi.org/10.3390/s17122954 - 19 Dec 2017

Cited by 19 | Viewed by 6511

Abstract

Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or [...] Read more.

Ultrasensitive room temperature real-time NO₂ sensors are highly desirable due to potential threats on environmental security and personal respiratory. Traditional NO₂ gas sensors with highly operated temperatures (200–600 °C) and limited reversibility are mainly constructed from semiconducting oxide-deposited ceramic tubes or inter-finger probes. Herein, we report the functionalized graphene network film sensors assembled on an electrospun three-dimensional (3D) nanonetwork skeleton for ultrasensitive NO₂ sensing. The functional 3D scaffold was prepared by electrospinning interconnected polyacrylonitrile (PAN) nanofibers onto a nylon window screen to provide a 3D nanonetwork skeleton. Then, the sulfophenyl-functionalized reduced graphene oxide (SFRGO) was assembled on the electrospun 3D nanonetwork skeleton to form SFRGO network films. The assembled functionalized graphene network film sensors exhibit excellent NO₂ sensing performance (10 ppb to 20 ppm) at room temperature, reliable reversibility, good selectivity, and better sensing cycle stability. These improvements can be ascribed to the functionalization of graphene with electron-withdrawing sulfophenyl groups, the high surface-to-volume ratio, and the effective sensing channels from SFRGO wrapping onto the interconnected 3D scaffold. The SFRGO network-sensing film has the advantages of simple preparation, low cost, good processability, and ultrasensitive NO₂ sensing, all advantages that can be utilized for potential integration into smart windows and wearable electronic devices for real-time household gas sensors. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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2459 KiB

Open AccessArticle

Silver Nanoparticle Modified Electrode Covered by Graphene Oxide for the Enhanced Electrochemical Detection of Dopamine

by Jae-Wook Shin, Kyeong-Jun Kim, Jinho Yoon, Jinhee Jo, Waleed Ahmed El-Said and Jeong-Woo Choi

Sensors 2017, 17(12), 2771; https://doi.org/10.3390/s17122771 - 29 Nov 2017

Cited by 68 | Viewed by 8656

Abstract

Several neurological disorders such as Alzheimer’s disease and Parkinson’s disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold [...] Read more.

Several neurological disorders such as Alzheimer’s disease and Parkinson’s disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold and platinum, are widely used in this electrochemical detection method; however, low sensitivity and linearity at low dopamine concentrations limit the use of these materials. To overcome these limitations, a silver nanoparticle (SNP) modified electrode covered by graphene oxide for the detection of dopamine was newly developed in this study. For the first time, the surface of an indium tin oxide (ITO) electrode was modified using SNPs and graphene oxide sequentially through the electrochemical deposition method. The developed biosensor provided electrochemical signal enhancement at low dopamine concentrations in comparison with previous biosensors. Therefore, our newly developed SNP modified electrode covered by graphene oxide can be used to monitor neurological diseases through electrochemical signal enhancement at low dopamine concentrations. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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2481 KiB

Open AccessArticle

Binding Affinity of a Highly Sensitive Au/Ag/Au/Chitosan-Graphene Oxide Sensor Based on Direct Detection of Pb²⁺ and Hg²⁺ Ions

by Nur Hasiba Kamaruddin, Ahmad Ashrif A. Bakar, Nadhratun Naiim Mobarak, Mohd Saiful Dzulkefly Zan and Norhana Arsad

Sensors 2017, 17(10), 2277; https://doi.org/10.3390/s17102277 - 6 Oct 2017

Cited by 58 | Viewed by 6975

Abstract

The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, [...] Read more.

The study of binding affinity is essential in surface plasmon resonance (SPR) sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, K, for Pb²⁺ and Hg²⁺ ions according to their SPR response using a gold/silver/gold/chitosan–graphene oxide (Au/Ag/Au/CS–GO) sensor for the concentration range of 0.1–5 ppm. The higher affinity of Pb²⁺ to binding with the CS–GO sensor explains the outstanding sensitivity of 2.05 °ppm⁻¹ against 1.66 °ppm⁻¹ of Hg²⁺. The maximum signal-to-noise ratio (SNR) upon detection of Pb²⁺ is 1.53, and exceeds the suggested logical criterion of an SNR. The Au/Ag/Au/CS–GO SPR sensor also exhibits excellent repeatability in Pb²⁺ due to the strong bond between its functional groups and this cation. The adsorption data of Pb²⁺ and Hg²⁺ on the CS–GO sensor fits well with the Langmuir isotherm model where the affinity constant, K, of Pb²⁺ and Hg²⁺ ions is computed. The affinity of Pb²⁺ ions to the Au/Ag/Au/CS–GO sensor is significantly higher than that of Hg²⁺ based on the value of K, 7 × 10⁵ M⁻¹ and 4 × 10⁵ M⁻¹, respectively. The higher shift in SPR angles due to Pb²⁺ and Hg²⁺ compared to Cr³⁺, Cu²⁺ and Zn²⁺ ions also reveals the greater affinity of the CS–GO SPR sensor to them, thus supporting the rationale for obtaining K for these two heavy metals. This study provides a better understanding on the sensing performance of such sensors in detecting heavy metal ions. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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4234 KiB

Open AccessArticle

One-Step Facile Synthesis of Aptamer-Modified Graphene Oxide for Highly Specific Enrichment of Human A-Thrombin in Plasma

by Yuan Xu, Siyuan Tan, Qionglin Liang and Mingyu Ding

Sensors 2017, 17(9), 1986; https://doi.org/10.3390/s17091986 - 13 Sep 2017

Cited by 5 | Viewed by 5660

Abstract

The enrichment of low-abundance proteins in complex biological samples plays an important role in clinical diagnostics and biomedical research. This work reports a novel one-step method for the synthesis of aptamer-modified graphene oxide (GO/Apt) nanocomposites, without introducing the use of gold, for the [...] Read more.

The enrichment of low-abundance proteins in complex biological samples plays an important role in clinical diagnostics and biomedical research. This work reports a novel one-step method for the synthesis of aptamer-modified graphene oxide (GO/Apt) nanocomposites, without introducing the use of gold, for the rapid and specific separation and enrichment of human α-thrombin from buffer solutions with highly concentrated interferences. The obtained GO/Apt nanocomposites had remarkable aptamer immobilization, up to 44.8 nmol/mg. Furthermore, GO/Apt nanocomposites exhibited significant specific enrichment efficiency for human α-thrombin (>90%), even under the presence of 3000-fold interference proteins, which was better than the performance of other nanomaterials. Finally, the GO/Apt nanocomposites were applied in the specific capturing of human α-thrombin in highly concentrated human plasma solutions with negligible nonspecific binding of other proteins, which demonstrated their prospects in rare protein analysis and biosensing applications. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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5680 KiB

Open AccessArticle

Simultaneous Voltammetric Detection of Carbaryl and Paraquat Pesticides on Graphene-Modified Boron-Doped Diamond Electrode

by Aniela Pop, Florica Manea, Adriana Flueras and Joop Schoonman

Sensors 2017, 17(9), 2033; https://doi.org/10.3390/s17092033 - 6 Sep 2017

Cited by 41 | Viewed by 7012

Abstract

Monitoring of pesticide residues in food, beverages, and the environment requires fast, versatile, and sensitive analyzing methods. Direct electrochemical detection of pesticides could represent an efficient solution. Adequate electrode material, electrochemical technique, and optimal operation parameters define the detection method for practical application. [...] Read more.

Monitoring of pesticide residues in food, beverages, and the environment requires fast, versatile, and sensitive analyzing methods. Direct electrochemical detection of pesticides could represent an efficient solution. Adequate electrode material, electrochemical technique, and optimal operation parameters define the detection method for practical application. In this study, cyclic voltammetric and differential pulse voltammetric techniques were used in order to individually and simultaneously detect two pesticides, i.e., carbaryl (CR) and paraquat (PQ), from an acetate buffer solution and also from natural apple juice. A graphene-modified boron-doped diamond electrode, denoted BDDGR, was obtained and successfully applied in the simultaneous detection of CR and PQ pesticides, using the differential pulse voltammetric technique with remarkable electroanalytical parameters in terms of sensitivity: 33.27 μA μM⁻¹ cm⁻² for CR and 31.83 μA μM⁻¹ cm⁻² for PQ. These outstanding results obtained in the acetate buffer supporting electrolyte allowed us to simultaneously detect the targeted pesticides in natural apple juice. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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Review

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21 pages, 4290 KiB

Open AccessReview

3D Architectured Graphene/Metal Oxide Hybrids for Gas Sensors: A Review

by Yi Xia, Ran Li, Ruosong Chen, Jing Wang and Lan Xiang

Sensors 2018, 18(5), 1456; https://doi.org/10.3390/s18051456 - 7 May 2018

Cited by 88 | Viewed by 9062

Abstract

Graphene/metal oxide-based materials have been demonstrated as promising candidates for gas sensing applications due to the enhanced sensing performance and synergetic effects of the two components. Plenty of metal oxides such as SnO₂, ZnO, WO₃, etc. have been hybridized [...] Read more.

Graphene/metal oxide-based materials have been demonstrated as promising candidates for gas sensing applications due to the enhanced sensing performance and synergetic effects of the two components. Plenty of metal oxides such as SnO₂, ZnO, WO₃, etc. have been hybridized with graphene to improve the gas sensing properties. However, graphene/metal oxide nanohybrid- based gas sensors still have several limitations in practical application such as the insufficient sensitivity and response rate, and long recovery time in some cases. To achieve higher sensing performances of graphene/metal oxides nanocomposites, many recent efforts have been devoted to the controllable synthesis of 3D graphene/metal oxides architectures owing to their large surface area and well-organized structure for the enhanced gas adsorption/diffusion on sensing films. This review summarizes recent advances in the synthesis, assembly, and applications of 3D architectured graphene/metal oxide hybrids for gas sensing. Full article

(This article belongs to the Special Issue Carbon Materials Based Sensors and the Application)

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