Ultra-sensitive electrochemical DNA biosensor based on signal amplification using gold nanoparticles modified with molybdenum disulfide,graphene and horseradish peroxidase

We have developed an ultra-sensitive electrochemical DNA biosensor by assembling probe ssDNA on a glassy carbon electrode modified with a composite made from molybdenum disulfide, graphene, chitosan and gold nanoparticles. A thiol-tagged DNA strand coupled to horseradish peroxidase conjugated to AuNP served as a tracer. The nanocomposite on the surface acts as relatively good electrical conductor for accelerating the electron transfer, while the enzyme tagged gold nanoparticles provide signal amplification. Hybridization with the target DNA was studied by measuring the electrochemical signal response of horseradish peroxidase using differential pulse voltammetry. The calibration plot is linear in the 5.0?×?10^?14 and 5.0?×?10^?9 M concentration range, and the limit of detection is 2.2?×?10^?15 M. The biosensor displays high selectivity and can differentiate between single-base mismatched and three-base mismatched sequences of DNA. The approach is deemed to provide a sensitive and reliable tool for highly specific detection of DNA.

基于金胶的选择性聚集实现p53基因的电化学超灵敏检测

介绍了一种利用金胶的选择性聚集实现信号扩增的超灵敏的电化学方法, 用于人类p53肿瘤抑制剂基因的检测. 在实验中, 根据p53基因的序列设计了能特异性检测p53肿瘤抑制剂基因的二段探针, 在一段探针上固定磁性颗粒以捕获并富集目标基因, 同时在另一段探针上标记金纳米颗粒作为检测信标. 另外, 通过硫代三聚氰酸和金纳米颗粒的自组装作用, 形成金纳米颗粒和硫代三聚氰酸的网状结构, 获得金纳米颗粒的选择性聚集, 实现信号扩增. 用此法检测目标p53野生型DNA, 最低检测限为2.24×10-17 mol/L, 同时进一步研究了该探针对p53野生型和一碱基错配的突变型的选择性.     

Electrochemical Determination of Tyrosine Using Graphene and Gold Nanoparticle Composite Modified Glassy Carbon Electrode

Russian Journal of Electrochemistry - A electrochemical sensor based on graphene and gold nanoparticles modified glassy carbon electrode (GCE) was developed for the determination of tyrosine (Tyr)....     

An electrochemical biosensor for direct detection of DNA using polystyrene-g-soya oil-g-imidazole graft copolymer

A label-free electrochemical DNA biosensor was developed through the attachment of polystyrene-g-soya oil-g-imidazole graft copolymer (PS-PSyIm) onto modified graphene oxide (GO) electrodeposited on glassy carbon electrode (GC). GC/GO electrode was initially functionalised via electrochemical reduction of 4-nitrobenzene diazonium salt, followed by the electrochemical reduction of NO₂ to NH₂. Subsequent to the electrochemical deposition of gold nanoparticles on modified surface, the attachment of the PS-PSyIm graft copolymer on the resulting electrode was achieved. The interaction of PS-PSyIm with DNA at the bare glassy carbon electrode was studied by cyclic voltammetry technique, and it was found that interaction predominantly takes place through intercalation mode. The selectivity of developed DNA biosensor was also explored by DPV on the basis of considering hybridisation event with non-complementary, one-base mismatched DNA and complementary target DNA sequence. Large decrease in the peak current was found upon the addition of complementary target DNA. The sensitivity of the developed DNA biosensor was also investigated, and detection limit was found to be 1.20 nmol L^?1.     

A bifunctional electrochemical aptasensor based on AuNPs-coated ERGO nanosheets for sensitive detection of adenosine and thrombin

A simple and sensitive bifunctional electrochemical aptasensor for detection of adenosine and thrombin has been developed using gold nanoparticles–electrochemically reduced graphene oxide (AuNPs-ERGO) composite film-modified electrode. Firstly, the reduced graphene oxide film and AuNPs were sequentially immobilized on glassy carbon electrode (GCE) surface. Secondly, thrombin aptamer was immobilized on the modified electrode. Finally, adenosine aptamer was hybridized with it to serve as a recognition element and methylene blue (MB) as electrochemical signal indicator. In the presence of adenosine or thrombin, the sensor recognized it and a conformational change was induced in aptamer, resulting in decrease of the peak current of MB. The linear relation between concentration of adenosine or thrombin and peak current of MB allowed quantification of them. Thanks to the special electronic characteristic of AuNPs-ERGO composite film, sensitivity of sensor was greatly improved. Under optimal conditions, the proposed aptasensor presented an excellent performance in a linear range of 25 nM to 750 nM for adenosine and 0.5 nM to 10 nM for thrombin. Detection limits were estimated to be 8.3 nM for adenosine and 0.17 nM for thrombin, respectively. Moreover, dual-analyte detection of adenosine and thrombin was achieved without potentially increasing the complexity and cost of the assay.

     

Selective Electrochemical Determination of Salicylic Acid in Wheat Using Molecular Imprinted Polymers

Salicylic acid is a phytohormone, playing crucial roles in signal transduction, crop growth, and development, and defense to environmental challenges. In this study, a highly selective electrochemical sensor was designed and used to determine salicylic acid using molecularly imprinted polymers for recognition. The electrochemical sensor was fabricated via stepwise modification of gold nanoparticle–graphene–chitosan and molecularly imprinted polymers on a glassy carbon electrode. With electrochemical deposition, a gold nanoparticle–graphene–chitosan film was deposited on the glassy carbon electrode and enhanced the sensitivity. Molecularly imprinted polymers with adsorbed template salicylic acid were added to the surface of the modified electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the modified electrodes. Salicylic acid in wheat was quantified by the sensor using the molecularly imprinted polymer/gold nanoparticle–graphene–chitosan/glassy carbon electrode. Concentrations of salicylic acid from 5?×?10^?10 to 5?×?10^?5?mol?L^?1 were determined showing that the developed sensor was suitable for the analysis of food.     

Evaluation of Electrochemically Reduced Gold Nanoparticle—Graphene Nanocomposites for the Determination of Dopamine

Two gold nanoparticle-graphene nanocomposites were electrochemically obtained by the one-step constant potential coreduction of graphene oxide and gold ions or the electrodeposition of gold nanoparticles on graphene oxide followed by electrochemical reduction of graphene oxide. The surface morphology, electron transfer rate, and electrocatalytic activity toward the oxidation of dopamine on these nanocomposites were systematically studied. The results showed that both preparations synthesized gold nanoparticle-graphene nanocomposites. The nanocomposite obtained by the one-step synthesis showed higher electron transfer kinetics and electrocatalytic activity toward dopamine than the material obtained by the two-step synthesis. Consequently, the one-step nanocomposite was used to modify a glassy carbon electrode to form a dopamine sensor. Differential pulse voltammetry was used to detect dopamine with a detection limit of 0.1 micromolar and a linear dynamic range from 0.2 to 20 micromolar. The sensor displayed good stability, high reproducibility, and was used for the determination of dopamine in human urine.     

Voltammetric Determination of Metol on a Gold Nanoparticle Modified Carbon Molecular Wire Electrode

A carbon molecular wire electrode was fabricated using diphenylacetylene as the modifier and gold nanoparticles were electrodeposited on the surface. The morphology and electrochemical properties of this modified electrode were investigated by scanning electron microscopy and electrochemical impedance spectroscopy. Two well-defined peaks for metol appeared using this gold nanoparticle-modified carbon molecular wire electrode by cyclic voltammetry with a high current response. These results demonstrate a synergistic effect between the gold nanoparticles and the carbon molecular wire electrode resulting in a rapid electrochemical reaction. The electrochemical conditions for metol were optimized on the modified electrode and a detection limit of 0.64?µmol/L and a linear dynamic range between 2.0 to 800.0?µmol/L were obtained. This modified electrode provided good selectivity, high sensitivity, and acceptable reproducibility, demonstrating promise for the determination of metol in the water.     

Reduced Graphene Oxide/Carbon Nanotube/Gold Nanoparticles Nanocomposite Functionalized Screen‐Printed Electrode for Sensitive Electrochemical Detection of Endocrine Disruptor Bisphenol A

We fabricated a highly sensitive electrochemical sensor for the determination of bisphenol A (BPA) in aqueous solution by using reduced graphene oxide (RGO), carbon nanotubes (CNT), and gold nanoparticles (AuNPs)‐modified screen‐printed electrode (SPE). GO/CNT nanocomposite was directly reduced to RGO/CNT on SPE at room temperature. AuNPs were then electrochemically deposited in situ on RGO/CNT‐modified SPE. Under optimized conditions, differential pulse voltammetry (DPV) produced linear current responses for BPA concentrations of 1.45 to 20 and 20 to 1,490 nM, with a calculated detection limit of an ultralow 800 pM. The sensor response was unaffected by the presence of interferents such as phenol, p‐nitrophenol, pyrocatechol, 2,4‐dinitrophenol, and hydroquinone.     

Electrochemical synthesis of a graphene sheet and gold nanoparticle-based nanocomposite, and its application to amperometric sensing of dopamine

We describe a simple, green and controllable approach for electrochemical synthesis of a nanocomposite made up from electrochemically reduced graphene oxide (ERGO) and gold nanoparticles. This material possesses the specific features of both gold nanoparticles and graphene. Its morphology was characterized by scanning electron microscopy which reveals a homogeneous distribution of gold nanoparticles on the graphene sheets. Cyclic voltammetry was used to evaluate the electrochemical properties of this nanocomposite towards dopamine by modification of it on surface of glassy carbon electrode (GCE). Compared to the bare GCE, the electrode modified with gold nanoparticles, and the electrode modified with ERGO, the one modified with the nanocomposite displays better electrocatalytic activity. Its oxidation peak current is linearly proportional to the concentration of dopamine (DA) in the range from 0.1 to 10?μM, with a detection limit of 0.04?μM (at S/N?=?3). The modified electrode also displays good storage stability, reproducibility, and selectivity.

Electrochemical Determination of Hydrogen Peroxide Using a Glassy Carbon Electrode Modified with Three-Dimensional Copper Hydroxide Nanosupercages and Electrochemically Reduced Graphene Oxide

Three-dimensional copper hydroxide nanosupercages and electrochemically reduced graphene oxide were used to modify the glassy carbon electrode for the selective determination of hydrogen peroxide. The morphology and electrochemistry properties of copper hydroxide nanosupercage/electrochemically reduced graphene oxide/glassy carbon electrode were characterized using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, Raman spectra, cyclic voltammetry, and electrochemical impedance spectroscopy. The resulting copper hydroxide nanosupercage/electrochemically reduced graphene oxide/glassy carbon electrode showed favorable performance for the electrocatalytic reduction of hydrogen peroxide. The amperometric current–time curve of the electrochemical sensor exhibited a wide linear range from 0.5 to 1030?µM with a limit of detection of 0.23?µM at a signal-to-noise ratio of three. Moreover, the sensor provided favorable selectivity, reproducibility, and stability and was used for the determination of H₂O₂ in tap water.     

纳米金放大计时库仑法的PML/RARα融合基因检测

应用恒电位在金基底表面电化学沉积纳米金,通过Au—S键将巯基修饰DNA探针固定在纳米金表面,与互补靶序列杂交,构建计时库仑电化学DNA传感器,并检测急性早幼粒细胞白血病(APL)PML/RARα融合基因.采用扫描电子显微术(SEM)与电化学交流阻抗技术(EIS)观察纳米金和表征DNA传感器的构筑过程.以氯化六氨合钌([Ru(NH3)6]Cl3,RuHex)作电化学杂交指示剂,由计时库仑法检测人工合成APL的PML/RARα融合基因.结果表明,纳米金能放大RuHex检测信号,杂交前后电量差值(ΔQ)与靶标链DNA浓度的对数(lgC)值在1.0×10-13～1.0×10-9mol.L-1范围内呈线性关系,检出下限3.7×10-14mol.L-1(S/N=3).该法操作简便、特异性好,有望用于实际样品的检测.     

Electrochemical Detection of Para‐nitrophenol using Copper Metal Nanoparticles Modified Gold Electrode

para‐Nitrophenol (p‐NP) is a high priority environmental pollutant. For the sake of safety, sensitive detection of its presence in water resources and food is highly important. The present article describes the use of copper metal nanoparticles for selective and sensitive electrochemical detection of p‐NP in pure and real sample. For this the gold electrode was fabricated by polyvenylpyrrolidone stabilized copper metal nanoparticles (ca . 4 nm d.) via self‐assembled 4,4′‐bipyridine monolayer and characterized by microscopic and electrochemical techniques. The newly developed sensor permits for sensitive detection of p‐NP in a linear concentration range of 1–500 μM with lowest detection limit of 0.34 nM and high sensitivities 247.1 μA cm⁻² μM⁻¹. The sensor electrode exhibited high stability, reproducibility, good selectivity in the presence of potential interfering agents and had an excellent capability for the selective determination of p‐NP in river water without preliminary treatments.     

Sensitive and Selective Electrochemical Sensor Based on Molecularly Imprinted Polypyrrole Hybrid Nanocomposites for Tetrabromobisphenol A Detection

Abstract

A sensitive and selective electrochemical sensor based on electropolymerized molecularly imprinted polypyrrole and gold nanoparticles–multiwalled carbon nanotubes (AuNPs–MWCNTs) hybrid nanocomposites was developed for the determination of tetrabromobisphenol A (TBBPA). A glassy carbon electrode (GCE) was modified with MWCNTs, and the AuNPs–MWCNTs/GCE was prepared by an electrodeposition method in HAuCl₄ solution. The AuNPs–MWCNTs nanocomposite showed high electrocatalytic activity, good conductivity, and sufficient reactive sites for the direct electro-oxidation of TBBPA. The molecularly imprinted polymers (MIPs) as recognition elements were synthesized through in situ electro-polymerization of pyrrole as functional monomers in the presence of the TBBPA template molecules. Under the optimal conditions, the developed sensor exhibited good selectivity towards TBBPA compared with structural analogs, high sensitivity, and excellent producibility. The electrochemical responses of the sensor toward TBBPA were obtained in the linear range from 0.5?nM to 1?μM with a limit of detection equal to 0.24?nM at a signal-to-noise ratio of 3.     

Amplified Electrochemical DNA Sensor Based on Polyaniline Film and Gold Nanoparticles

In this work, an electrochemical DNA biosensor, based on a dual signal amplified strategy by employing a polyaniline film and gold nanoparticles as a sensor platform and enzyme‐linked as a label, for sensitive detection is presented. Firstly, polyaniline film and gold nanoparticles were progressively grown on graphite screen‐printed electrode surface via electropolymerization and electrochemical deposition, respectively. The sensor was characterized by scanning electron microscopy (SEM), cyclic voltammetry and impedance measurements. The polyaniline‐gold nanocomposite modified electrodes were firstly modified with a mixed monolayer of a 17‐mer thiol‐tethered DNA probe and a spacer thiol, 6‐mercapto‐1‐hexanol (MCH). An enzyme‐amplified detection scheme, based on the coupling of a streptavidin‐alkaline phosphatase conjugate and biotinylated target sequences was then applied. The enzyme catalyzed the hydrolysis of the electroinactive α‐naphthyl phosphate to α‐naphthol; this product is electroactive and has been detected by means of differential pulse voltammetry. In this way, the sensor coupled the unique electrical properties of polyaniline and gold nanoparticles (high surface area, fast heterogeneous electron transfer, chemical stability, and ease of miniaturisation) and enzymatic amplification. A linear response was obtained over a concentration range (0.2–10 nM). A detection limit of 0.1 nM was achieved.     

Determination of melamine in food contact materials using an electrode modified with gold nanoparticles and reduced graphene oxide

We describe an electrochemical sensor for melamine based on a glassy carbon electrode (GCE) modified with reduced graphene oxide that was decorated with gold nanoparticles (AuNP/rGO). The AuNPs/rGO nanocomposite was synthesized by co-reduction of Au(III) and graphene oxide and characterized by transmission electron microscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The response of the modified GCE to melamine was investigated by using hexacyanoferrate as an electrochemical reporter. It is found that the electrochemical response to hexacyanoferrate is increasingly suppressed by increasing concentration of melamine. This is attributed to competitive adsorption of melamine at the AuNP/rGO composite through the interaction between the amino groups of melamine and the AuNPs. The presence of rGO, in turn, provides a platform for a more uniform distribution of the AuNPs and enhances the electron transfer rate of the redox reaction. The findings were used to develop a sensitive method for the determination of melamine. Under optimized conditions, the redox peak current of hexacyanoferrate at a working voltage of 171 mV (vs. SCE) is linearly related to the concentration of melamine in 5.0 to 50 nM range. The method was successfully applied to the determination of melamine in food contact materials.

A simple electrochemical sensor based on gold nanoparticles decorated reduced graphene oxide was developed for highly sensitive measurement of melamine in food contact materials.

     

Electrochemical deoxyribonucleic acid biosensor based on the self-assembly film with nanogold decorated on ionic liquid modified carbon paste electrode

An electrochemical DNA biosensor was fabricated by self-assembling probe single-stranded DNA (ssDNA) with a nanogold decorated on ionic liquid modified carbon paste electrode (IL-CPE). IL-CPE was fabricated using 1-butylpyridinium hexafluorophosphate as the binder and the gold nanoparticles were electrodeposited on the surface of IL-CPE (Au/IL-CPE). Then mercaptoacetic acid was self-assembled on the Au/IL-CPE to obtain a layer of modified film, and the ssDNA probe was further covalently-linked with mercaptoacetic acid by the formation of carboxylate ester with the help of N-(3-dimethylamino-propyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. The hybridization reaction with the target ssDNA was monitored with methylene blue (MB) as the electrochemical indicator. Under the optimal conditions, differential pulse voltammetric responses of MB was proportional to the specific ssDNA arachis sequences in the concentration range from 1.0×10(-11) to 1.0×10(-6) mol L(-1) with the detection limit as 1.5×10(-12) mol L(-1) (3σ). This electrochemical DNA sensor exhibited good stability and selectivity with the discrimination ability of the one-base and three-base mismatched ssDNA sequences. The polymerase chain reaction product of arachis Arabinose operon D gene was successfully detected by the proposed method, which indicated that the electrochemical DNA sensor designed in this paper could be further used for the detection of specific ssDNA sequence.     

The morphology modulation of graphene to produce wrinkles and folds for effective electrochemical determination of Hg(II)

A highly efficient electrode material, three-dimensional reduced graphene oxide with varying wrinkles and folds (WRGO), applicable for electrochemical determination of Hg(II) was obtained by treating graphene oxide (GO) with KOH aqueous solution. After alkaline etching, the relatively flat graphene was altered and its self-aggregation was significantly alleviated, producing more wrinkles and folds, which provided more active adsorption sites for heavy metal ions. WRGO-5 modified electrode system herein offers a highest sensitivity of (31.83 μAμM⁻¹) and a lowest LOD of (16.28 nM). Moreover, the electrode sensor possesses good stability and reproducibility.     

Lable‐Free Electrochemical DNA Sensor Based on Gold Nanoparticles/Poly(neutral red) Modified Electrode

We present a new strategy for the label‐free electrochemical detection of DNA hybridization based on gold nanoparticles (AuNPs)/poly(neutral red) (PNR) modified electrode. Probe oligonucledotides with thiol groups at the 5‐end were covalently linked onto the surface of AuNPs/PNR modified electrode via S‐Au binding. The hybridization event was monitored by using differential pulse voltammetry (DPV) upon hybridization generates electrochemical changes at the PNR‐solution interface. A significant decrease in the peak current was observed upon hybridization of probe with complementary target ssDNA, whereas no obvious change was observed with noncomplementary target ssDNA. And the DNA sensor also showed a high selectivity for detecting one‐mismatched and three‐mismatched target ssDNA and a high sensitivity for detecting complementary target ssDNA, the detection limit is 4.2×10^?12 M for complementary target ssDNA. In addition, the DNA biosensor showed an excellent reproducibility and stability under the DNA‐hybridization conditions.     

布洛芬在石墨烯/DNA/纳米金修饰电极上的电化学行为及测定

利用石墨烯/DNA/纳米金(Gr/DNA/GNPs)修饰电极对布洛芬(IB)的电化学行为进行了研究。分别采用紫外-可见分光光度法和扫描电镜成像技术对Gr/DNA/GNPs复合材料进行了表征。比较了不同修饰电极的检测效果并考察了缓冲体系及修饰量等对测定的影响。实验结果表明,IB在Gr/DNA/GNPs复合材料修饰电极上的电化学信号较为明显,在0.1 mol·L-1PBS缓冲溶液(pH 6.8)中,IB于0.83 V处可观察到1个灵敏的氧化峰。在最佳实验条件下对IB进行检测,其线性范围为7.2×10-7~4.9×10-5mol·L-1,检出限为1.5×10-7mol·L-1。干扰实验和重复实验的结果表明,该修饰电极选择性及重现性良好。用于实际样品的检测,结果满意。