Graphene Based Electrochemical Sensors and Biosensors: A Review

Graphene, emerging as a true 2‐dimensional material, has received increasing attention due to its unique physicochemical properties (high surface area, excellent conductivity, high mechanical strength, and ease of functionalization and mass production). This article selectively reviews recent advances in graphene‐based electrochemical sensors and biosensors. In particular, graphene for direct electrochemistry of enzyme, its electrocatalytic activity toward small biomolecules (hydrogen peroxide, NADH, dopamine, etc.), and graphene‐based enzyme biosensors have been summarized in more detail; Graphene‐based DNA sensing and environmental analysis have been discussed. Future perspectives in this rapidly developing field are also discussed.     

基于多壁碳纳米管和氧化锌纳米棒复合物的葡萄糖生物传感器(英文)

利用多壁碳纳米管(MWCNTs)和氧化锌(ZnO)纳米棒复合物膜构建了一种新的电流型葡萄糖生物传感器。MWCNTs-ZnO复合物在超声协助下通过静电配位的方式产生。其中,ZnO纳米棒的存在加强了该复合物催化氧化H2O2的能力,增加了响应电流。与单一的MWCNTs和ZnO相比,这种纳米复合物显示了更为有效地电催化活性。在此基础上,我们以MWCNTs-ZnO复合物膜为基底,用戊二醛交联法固定葡萄糖氧化酶,电聚合邻苯二胺(PoPD)膜为抗干扰层,构建了抗干扰能力强,稳定性好,灵敏度高,响应快的葡萄糖传感器。在+0.8V的检测电位下,该传感器对葡萄糖响应的线性范围为5.0×10-6~5.0×10-3mol·L-1(R=0.997),检测限为3.5×10-6mol·L-1(S/N=3),响应时间小于10s的葡萄糖生物传感器,常见干扰物质如抗坏血酸和尿酸不影响测定。     

基于氧化石墨烯荧光适体传感器的胰岛素检测

采用荧光基团(FAM)标记的核酸适体作为识别元件,氧化石墨烯为淬灭剂,建立了一种高选择性、高灵敏度的核酸适体传感器.核酸适体与氧化石墨烯结合后,荧光淬灭,此时溶液无荧光;加入胰岛素后,溶液中荧光得到恢复.利用荧光分析法检测加入胰岛素前后,溶液中荧光强度的变化,获取了荧光适体传感器的线性度和灵敏度,实现对胰岛素浓度的测定.结果表明,在5×10-8 ～ 1×10-5 mol/L范围内,胰岛素的浓度与溶液中荧光强度有良好的线性关系,检出限为10 nmol/L.采用此方法检测胰岛素,操作简便,检测速度快,准确性高,选择性好,检出限低.     

Macroscopically Oriented Magnetic Core-regularized Nanomaterials for Glucose Biosensors Assisted by Self-sacrificial Label

Magnetic core-regular nanostructures composed of magnetite and regular Prussian blue was prepared by self-sacrificial macro-oriented method. Magnetic graphene oxide (MGO) was vertically oriented on the surface of home-made screen-printing electrode with the help of constant magnetic field (CMF).Then regular nanostructured Prussian blue (RPB) was realized by chemical reaction through an aerosol deposition. Finally, glucose oxidase (GOx) was immobilized by glutaraldehyde cross-linking to fabricate glucose biosensors. The linear range of CMF-RPB/MGO sensor towards glucose was 0.03∼1.35 mM, and the detection limit was 13.4 μM. The CMF-RPB/MGO sensor could apply to analyze glucose in human serum samples.     

Protein‐Directed In Situ Synthesis of Gold Nanoparticles on Reduced Graphene Oxide Modified Electrode for Nonenzymatic Glucose Sensing

A novel nonenzymatic glucose sensor was developed based on well‐dispersed gold nanoparticles, which were in situ grown under direction of protein on a reduced graphene oxide modified electrode. This electrode exhibited high electrocatalytic activity towards glucose oxidation without use of any enzyme or mediator. In application for the amperometric detection of glucose, a wide linear range of 0.02–16.6 mM, low detection limit of 5 µM and good selectivity were obtained. The attractive analytical performances of the proposed glucose sensor, coupled with the facile preparation method, provide a promising electrochemical platform for the development of effective nonenzymatic sensors.     

基于分子印迹聚合物掺杂氧化石墨烯膜的利巴韦林电位传感器

以利巴韦林为模板分子,甲基丙烯酸为功能单体,采用沉淀聚合法制备利巴韦林分子印迹聚合物(MIP).以利巴韦林分子印迹聚合物掺杂氧化石墨烯(GO)为离子载体,聚氯乙烯为基质,癸二酸二辛酯为增塑剂制备电极敏感膜.结果表明,敏感膜组成为100.8 mg MIP、14.7 mg GO、450.8 mg聚氯乙烯和901.6 mg癸二酸二辛酯,内充液组成为0.1 mol/L NaCl+0.05 mol/L NaAc-0.05 mol/L HAc缓冲溶液+ 1.0×10.-5 mol/L利巴韦林,电极的响应性能最好.此电极的能斯特响应斜率为45.565 mV/decade,线性范围为1.0×10.-6~1.0×10.-4 mol/L, 检出限为1.0×10.-7 mol/L(S/N=3),工作pH范围为3~5,响应时间小于3 min.此电极对利巴韦林具有高选择性,可用于检测饲料和注射液中利巴韦林含量,加标回收率为90%~110%,RSD为3.0%~7.9%.     

Electrochemiluminescence Biosensor for Glucose Based on Graphene/Nafion/GOD Film Modified Glassy Carbon Electrode

Glucose oxidase(GOD) was encapsulated in the Graphene/Nafion film modified glassy carbon electrode(GCE) and used as an ECL sensor for glucose. The GOD retains its bioactivity after being immobilized into the composite film. The sensor gives a linear response for glucose in the range of 2.0×10^?6–1.0×10^?4 mol/L with a detection limit of 1.0×10^?6 mol/L. The sensor showed good stability, the RSD for continuous scanning for 5.0×10^?5 mol/L glucose was 4.21 % (n=5). After being stored in 0.05 mol/L pH 7.4 PBS in 4 °C for two weeks, the modified electrode maintains 80 % of its initial activity. The glucose sensor provides new opportunity for clinical diagnosis applications.     

Reduced Graphene Oxide/Pt Nanoparticles/Zn‐MOF‐74 Nanomaterial for a Glucose Biosensor Construction

In this study, a new glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on platinum nanoparticles (Pt NPs) decorated reduced graphene oxide (rGO)/Zn‐MOF‐74 hybrid nanomaterial. Herein, the biosensor fused the advantages of rGO with those of porous Zn‐MOF and conductive Pt NPs. This has not only enlarged the surface area and porosity for the efficient GOx immobilization and faster mass transport, but also provided favorable electrochemical features such as high current density, remarkable electron mobility through metal nanoparticles, and improved electron transfer between the components. The GOx‐rGO/Pt NPs@Zn‐MOF‐74 coated electrode displayed a linear measurement range for glucose from 0.006 to 6 mM, with a detection limit of 1.8 μM (S/N: 3) and sensitivity of 64.51 μA mM^?1 cm^?2. The amperometric response of the enzyme biosensor demonstrated the typical behavior of Michaelis‐Menten kinetics. The obtained satisfying sensitivity and measurement range enabled fast and accurate glucose measurement in cherry juice using the fabricated biosensor. The water‐stable Zn‐MOF‐74 demonstrated higher enzyme loading capacity and can be potent supporting material for biosensor construction.     

CuO Nanospheres Based Nonenzymatic Glucose Sensor

CuO nanospheres, synthesized by a simple one‐step hydrothermal method, have been applied to modify the glassy carbon (GC) electrode for sensitive nonenzymatic glucose detection. The CuO nanospheres modified electrode, compared to the Nafion modified GC electrode, exhibits an enhanced electrocatalytic property for direct glucose oxidation and shows a fast response and a high sensitivity for the amperometric detection of glucose. It has been determined that the dissolved oxygen is not involved in glucose oxidation and the high concentration of NaCl does not poison the electrode. These results also indicate that CuO nanospheres have great potential application in electrochemical detection.     

碳纳米管负载铂-二氧化钌纳米颗粒用于葡萄糖传感器的研究

建立了多壁碳纳米管(MWNTs)负载铂二二氧化钌纳米颗粒的液相化学还原法.以Nafion为固定剂,将Pt-RuO2/MWNTs复合材料修饰于玻碳电极的表面,制备了一种无酶型葡萄糖传感器.实验表明:复合材料修饰的电极对葡萄糖响应电流明显,并且受抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)的干扰小.本实验采用安培法测定葡萄糖,线性范围为2 0×10 3～1.0×10-2 mol/L(R～0.9965);灵敏度为119.26 μA cm-2(mmol/L)-1;检出限为1.25×10 -5 mol/L(信噪比为3);响应时间为4.8 s.PtRuO2/MWNTs修饰电极可作为性能良好的无酶型葡萄糖传感器.     

Amperometric Glucose Biosensors Based on Composite Polymeric Structures to Prevent Interferences

ABSTRACT

High sensitive glucose biosensors were realised by oxidative polymerisation of amphiphilic pyrrole monomer-glucose oxidase mixtures, previously adsorbed on platinum electrodes. These sensors, based on H₂O₂ electrooxidation at 0.5V vs SCE, exhibited marked interferences due to electrooxidisable endogenous (ascorbate and urate) and exogenous (paracetamol) compounds. Bilayer structures, combining the preceding polymer film as an outer layer and electrogenerated poly(phenylene diamine), overoxidised polypyrrolic films or Nafion as an inner layer, were fabricated in order to minimise interferences. Finally, the use of Nafion as a semipermeable barrier appeared to be more efficient than the electrogenerated films. The Nafion-based biosensor exhibited glucose sensitivity of 0.4 mA.M^?1; .cm^?2, while interference of ascorbate, urate and paracetamol was negligible.     

Amperometric Biosensors for Tyramine Determination Based on Graphene Oxide and Polyvinylferrocene Modified Screen‐printed Electrodes

A comparison of the analytical characteristics of two tyramine biosensors, based on graphene oxide (GRO) and polyvinylferrocene (PVF) modified screen‐printed carbon electrodes (SPCE), is reported. Diamine oxidase (DAOx) or monoamine oxidase (MAOx) was immobilized onto the PVF/GRO modified SPCE to fabricate the biosensors. Surface characteristics and electrochemical behaviour of the modified SPCEs were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX) and cyclic voltammetry (CV). Electrode surface composition and experimental variables such as pH and working potential were optimized in order to ensure a high performance. Under optimum experimental conditions, both DAOx/PVF/GRO/SPCE and MAOx/PVF/GRO/SPCE biosensors exhibited wide linear dynamic ranges for tyramine from 9.9×10^?7 to 1.2×10^?4 M and from 9.9×10^?7 to 1.1×10^?4 M, respectively. MAOx/PVF/GRO/SPCE biosensor showed higher sensitivity (11.98 μA mM^?1) for tyramine determination than the DAOx/PVF/GRO/SPCE biosensor (7.99 μA mM^?1). The substrate specifity of the biosensors to other biogenic amines namely histamine, putrescine, spermine, spermidine, tryptamine, β‐phenylethylamine and cadaverine was also investigated. The developed biosensors were successfully used for tyramine determination in cheese sample.     

Nonenzymatic Electrochemical Glucose Sensor Based on Pt Nanoparticles/Mesoporous Carbon Matrix

A nonenzymatic amperometric sensor for sensitive and selective detection of glucose has been constructed by using highly dispersed Pt nanoparticles supported onto mesoporous carbons (MCs). The Pt nanoparticles/mesoporous carbons (Pt/MCs) composites modified electrode displayed high electrocatalytic activity towards the oxidation of glucose. At an applied potential of 0.1 V, the Pt/MCs electrode has a linear dependence (R=0.996) in the glucose concentration up to 7.5 mM with a sensitivity of 8.52 mA M^?1 cm^?2. The Pt/MCs electrode has also shown highly resistant toward poisoning by chloride ions and without interference from the oxidation of common interfering species.     

A New Electrochemical Biosensor for Determination of Hydrogen Peroxide in Food Based on Well‐Dispersive Gold Nanoparticles on Graphene Oxide

Herein, we describe a new method for the detection of hydrogen peroxide (H₂O₂) in food by using an electrochemical biosensor. Initially, ultrafine gold nanoparticles dispersed on graphene oxide (AuNP‐GO) were synthesized by the redox reaction between AuCl₄^? and GO, and thionine‐catalase conjugates were then assembled onto the AuNP‐GO surface on a glassy carbon electrode. With the aid of the AuNP‐GO, the as‐prepared biosensor exhibited good electrocatalytic efficiency toward the reduction of H₂O₂ in pH 5.8 acetic acid buffer. Under optimal conditions, the dynamic responses of the biosensor toward H₂O₂ were achieved in the range from 0.1 µM to 2.3 mM, and the detection limit (LOD) was 0.01 µM at 3s_B. The Michaelis–Menten constant was measured to be 0.98 mM. In addition, the repeatability, reproducibility, selectivity and stability of the biosensor were investigated and evaluated in detail. Finally, the method was applied for sensing H₂O₂ in spiked or naturally contaminated samples including sterilized milk, apple juices, watermelon juice, coconut milk, and mango juice, receiving good correspondence with the results from the permanganate titration method. The disposable biosensor could offer a great potential for rapid, cost‐effective and on‐field analysis of H₂O₂ in foodstuff.     

青霉素酶-氧化苏木精修饰Au/ZnO/石墨烯基青霉素电化学传感器的研制

采用均匀沉淀法合成ZnO纳米颗粒( ZnO NPs),以ZnO NPs为种子,制备水溶性Au/ZnO异质结构。将Au/ZnO异质结构附着于离子液体功能化石墨烯( GN)复合膜上,形成一种新颖的负载型石墨烯复合材料(Au/ZnO/GN)。所构建的青霉素酶-氧化苏木精修饰Au/ZnO/GN(PH-AZG)传感器在PBS水溶液(pH=7.0)中对青霉素钠检测线性范围为2.5×10-14~3.3×10-6 mol/L,检出限达到1.5×10-14 mol/L (S/N≥3)。在相同条件下制备5根PH-AZG电极,其响应电流的相对标准偏差(RSD)小于3.2%。同时,在实际牛奶制品中,本方法的检测线性范围为5×10-14~5×10-7 mol/L,加标回收率为99.7%~101.4%,RSD 为2.3%~3.5%(n=5)。结果表明,本方法对实际牛奶制品中低浓度青霉素钠的检测具有可行性。     

基于聚对苯二甲酸乙二醇酯薄膜的石墨烯/金纳米粒子/葡萄糖氧化酶柔性电极的制备及检测葡萄糖

采用化学气相沉积法生长多晶石墨烯(Graphene, G),转移至聚对苯二甲酸乙二醇酯(PET)薄膜表面,通过控制金溶胶蒸发速率,在多晶石墨烯表面组装均匀分布的亚单层金纳米粒子(AuNPs);然后修饰巯基乙酸,通过共价交联反应将葡萄糖氧化酶固定于AuNPs表面,构建基于PET膜的石墨烯/金纳米粒子/葡萄糖氧化酶(G/AuNPs/GOD)柔性电极.此电极在工作电位0.6 V(vs.SCE电极)、pH 7.0磷酸盐缓冲溶液、室温25℃条件下,差分脉冲伏安法响应电流与被测葡萄糖浓度在0.05~10.55 mmol/L范围内呈线性关系,线性方程为I(108A)=0.2629 C(mmol/L)+1.4149,线性相关系数 r=0.9955,检出限1 μmol/L (3σ). G/AuNPs/GOD柔性电极的制备可为特定环境和可穿戴设备的葡萄糖检测提供了新的途径和方法,拓展了葡萄糖检测的应用范围.     

基于计算谱学的纳米材料结构表征及其在石墨烯氧化物中的应用

从理论上对材料结构进行表征一般是基于第一性原理电子结构计算对可能的结构模型进行能量分析, 从而得到材料的基态构型. 而经过复杂路径合成的纳米材料并不总是处于基态能量构型. 因此, 对可能的结构模型进行计算谱学模拟, 然后直接与实验谱图对比, 可以提供更为可靠的结构信息. 本文简单介绍了谱学模拟的理论背景, 以石墨烯氧化物为例展示了计算谱学在复杂纳米材料结构表征中的关键作用.     

Enhanced Electrocatalytic Detection of Choline Based on CNTs and Metal Oxide Nanomaterials

Choline is an officially established essential nutrient and precursor of the neurotransmitter acetylcholine. It is employed as a cholinergic activity marker in the early diagnosis of brain disorders such as Alzheimer’s and Parkinson’s disease. Low levels of choline in diets and biological fluids, such as blood plasma, urine, cerebrospinal and amniotic fluid, could be an indication of neurological disorder, fatty liver disease, neural tube defects and hemorrhagic kidney necrosis. Meanwhile, it is known that choline metabolism involves oxidation, which frees its methyl groups for entrance into single-C metabolism occurring in three phases: choline oxidase, betaine synthesis and transfer of methyl groups to homocysteine. Electrocatalytic detection of choline is of physiological and pathological significance because choline is involved in the physiological processes in the mammalian central and peripheral nervous systems and thus requires a more reliable assay for its determination in biological, food and pharmaceutical samples. Despite the use of several methods for choline determination, the superior sensitivity, high selectivity and fast analysis response time of bioanalytical-based sensors invariably have a comparative advantage over conventional analytical techniques. This review focuses on the electrocatalytic activity of nanomaterials, specifically carbon nanotubes (CNTs), CNT nanocomposites and metal/metal oxide-modified electrodes, towards choline detection using electrochemical sensors (enzyme and non-enzyme based), and various electrochemical techniques. From the survey, the electrochemical performance of the choline sensors investigated, in terms of sensitivity, selectivity and stability, is ascribed to the presence of these nanomaterials.     

Impedance Based Nanotoxicity Assessment of Graphene Nanomaterials at the Cellular and Tissue Level

The interest in graphene for biomedical applications has grown substantially in the past few years creating a need for biocompatibility testing. Biomedical engineering applications using graphene such as biosensing devices, microbial detection, disease diagnosis, and drug delivery systems are progressing rapidly, perhaps overlooking any possible hazards as graphene nanomaterials may interact with biological materials differently than other graphitic materials such as carbon nanotubes and fullerenes. As a potential application for graphene is drug delivery, the toxicity of graphene was tested against an in vitro model of the blood brain barrier (BBB) by measuring trans-endothelial-electrical resistance (TEER). A new approach in terms of electrical impedance sensing was also utilized to kinetically analyze the cytotoxicity of graphene nanomaterials towards the BBB model's individual components, rat astrocytes (CRL-2006) and mouse endothelial cells (CRL-2583), in real time by measuring the impedimetric response. Graphene showed little or no toxicity toward both individual cell types as the resistance measurements were similar to those of the control and further, graphene did not interrupt the integrity of the BBB model as a whole showing the biocompatibility of graphene and the broad potential of using these new nanomaterials for biomedical applications.     

A ultrasensitive nonenzymatic glucose sensor based on Cu2O polyhedrons modified Cu electrode

A novel nonenzymatic glucose sensor was successfully fabricated based on the Cu2O polyhedrons covered Cu foil.The Cu2O polyhedrons covered Cu foil was constructed via a facile,low-cost and larger scale producible method.The Cu2O polyhedrons covered Cu foil can be directly used as the working electrode of nonenzymatic glucose sensor,which present good stability and flexibility.The results indicated that the Cu2O polyhedrons modified Cu electrode(Cu2O/Cu electrode) showed high electrocatalytic activity for the oxidation of glucose in alkaline solution.There are two linear regions of glucose concentration for the glucose sensor based on Cu2O/Cu electrode,respectively in 10 mmol/L to 0.53 mmol/L(sensitivity:3029.33 mA(mmol/L) à1 cm à2) and in 0.53-7.53 mmol/L(sensitivity:728.67 mA(mmol/L) à1 cm à2).