Recent Applications of Carbon Nanomaterials for microRNA Electrochemical Sensing

MicroRNA (miRNA) is an important tumor marker in the human body, and its early detection has a great influence on the survival rate of patients. Although there are many detection methods for miRNA at present such as northern blotting, real-time quantitative polymerase chain reaction, microarrays, and others, electrochemical biosensors have the advantages of low detection cost, small instrument size, simple operation, non-invasive detection and low consumption of reagents and solvents, and thus they play an important role in the early detection of cancer. In addition, with the development of nanotechnology, nano-biosensors show great potential. The application of various nanomaterials in the development of electrochemical biosensor has greatly improved the detection sensitivity of electrochemical biosensor. Among them, carbon nanomaterials which have unique electrical, optical, physical and chemical properties have attracted increasing attention. In particular, they have a large surface area, good biocompatibility and conductivity. Therefore, carbon nanomaterials combined with electrochemical methods can be used to detect miRNA quickly, easily and sensitively. In this review, we systematically review recent applications of different carbon nanomaterials (carbon nanotubes, graphene and its derivatives, graphitic carbon nitride, carbon dots, graphene quantum dots and other carbon nanomaterials) for miRNA electrochemical detection. In addition, we demonstrate the future prospects of electrochemical biosensors modified by carbon nanomaterials for the detection of miRNAs, and some suggestions for their development in the near future.     

纳米材料在电化学生物传感器及生物电分析领域中的应用

纳米尺度上的生物分析化学是当今国际生物分析领域研究的前沿和热点.该文阐述了纳米粒子在电化学免疫传感器及电化学DNA传感器领域的应用,着重介绍了以纳米材料为载体设计新型的具有生物分子识别和电信号增强作用的纳米标记粒子在构建高灵敏电化学生物传感器以及多组分同时检测中的应用.     

Ferrocene-Labelled Electroactive Aptamer-Based Sensors (Aptasensors) for Glycated Haemoglobin

Glycated haemoglobin (HbA_1c) is a diagnostic biomarker for type 2 diabetes. Traditional analytical methods for haemoglobin (Hb) detection rely on chromatography, which requires significant instrumentation and is labour-intensive; consequently, miniaturized devices that can rapidly sense HbA_1c are urgently required. With this research, we report on an aptamer-based sensor (aptasensor) for the rapid and selective electrochemical detection of HbA_1c. Aptamers that specifically bind HbA_1c and Hb were modified with a sulfhydryl and ferrocene group at the 3′ and 5′-end, respectively. The modified aptamers were coated through sulfhydryl-gold self-assembly onto screen printed electrodes, producing aptasensors with built in electroactivity. When haemoglobin was added to the electrodes, the current intensity of the ferrocene in the sensor system was reduced in a concentration-dependent manner as determined by differential pulse voltammetry. In addition, electrochemical impedance spectroscopy confirmed selective binding of the analytes to the aptamer-coated electrode. This research offers new insight into the development of portable electrochemical sensors for the detection of HbA_1c     

Thin Films and Composites Based on Graphene for Electrochemical Detection of Biologically‐relevant Molecules

Graphene is one of the most studied materials ever, owing to its exceptional electronic, mechanical and thermal properties, which allow for many different types of application. In this review, we shall concentrate on the use of graphene and derivatives for electrochemical sensors and biosensors, where emphasis is placed on the importance of surface functionalization as this permits synergistic combinations with other nanomaterials and biomolecules. In addition to describing recent advances in graphene‐based electroanalytical applications, we discuss a few examples of their use in detecting small biomolecules and in immunosensing for a few diseases using films and composites. Also discussed are the possible methods for mass production of graphene, which is key to low‐cost biosensors for implantable devices and portable systems in point‐of‐care diagnosis.     

An Electrochemical Aptamer Biosensor for Bisphenol A on a Carbon Nanofibre-silver Nanoparticle Immobilisation Platform

A nanocomposite platform of silver nanoparticles and carbon nanofibres (AgCNFs) was used to immobilise a bisphenol A specific 63-mer ssDNA aptamer to form a biosensor. The fabrication process of the biosensor was studied with electrochemical impedance spectroscopy and cyclic voltammetry in the presence of [Fe(CN)₆]^3−/4− as redox probe. The biosensor detected bisphenol A in a linear range of 0.1–10 nM, with a limit of detection of 0.39 nM using square wave voltammetry (SWV). The biosensor exhibited good selectivity in the presence of interfering species at 100-fold concentrations and was used to detect BPA in real water sample.     

Nanomaterials in Electrochemical Sensing Area: Applications and Challenges in Food Analysis

Recently, nanomaterials have received increasing attention due to their unique physical and chemical properties, which make them of considerable interest for applications in many fields, such as biotechnology, optics, electronics, and catalysis. The development of nanomaterials has proven fundamental for the development of smart electrochemical sensors to be used in different application fields such, as biomedical, environmental, and food analysis. In fact, they showed high performances in terms of sensitivity and selectivity. In this report, we present a survey of the application of different nanomaterials and nanocomposites with tailored morphological properties as sensing platforms for food analysis. Particular attention has been devoted to the sensors developed with nanomaterials such as carbon-based nanomaterials, metallic nanomaterials, and related nanocomposites. Finally, several examples of sensors for the detection of some analytes present in food and beverages, such as some hydroxycinnamic acids (caffeic acid, chlorogenic acid, and rosmarinic acid), caffeine (CAF), ascorbic acid (AA), and nitrite are reported and evidenced.     

介孔碳纳米材料的制备与改性

介孔碳纳米材料因具有快速传输通道、优异的导电性、极高的比表面积和出色的化学稳定性在众多领域受到广泛关注.实现介孔碳纳米材料的可控制备和精准改性是当前的研究热点和重点.基于此,本文分析总结了这类材料的制备和改性方法,并讨论了存在的问题和未来研究方向.     

新型碳纳米材料在低温燃料电池催化剂中的应用

 碳纳米管及其衍生纳米碳材料是一种介于富勒烯与石墨之间的碳的存在形式,具有独特的电子性质. 碳纳米材料可与其表面负载的金属活性相产生一种特殊的载体-金属相互作用; 纳米管中电子转移的动力学行为极佳,并且其特殊的纳米级孔道结构有利于反应物及产物的传质,因此作为低温燃料电池催化剂载体备受关注. 综述了多种新型碳纳米材料如碳纳米管、碳纳米纤维、碳纳米盘、碳纳米角和碳纳米分子筛等在低温燃料电池催化剂中的应用,并对其存在的问题和可能的发展方向进行了讨论.     

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins,Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.     

Hyaluronic Acid-Conjugated Carbon Nanomaterials for Enhanced Tumour Targeting Ability

Hyaluronic acid (HA) has been implemented for chemo and photothermal therapy to target tumour cells overexpressing the CD44⁺ receptor. HA-targeting hybrid systems allows carbon nanomaterial (CNM) carriers to efficiently deliver anticancer drugs, such as doxorubicin and gemcitabine, to the tumour sites. Carbon nanotubes (CNTs), graphene, graphene oxide (GO), and graphene quantum dots (GQDs) are grouped for a detailed review of the novel nanocomposites for cancer therapy. Some CNMs proved to be more successful than others in terms of stability and effectiveness at removing relative tumour volume. While the literature has been focused primarily on the CNTs and GO, other CNMs such as carbon nano-onions (CNOs) proved quite promising for targeted drug delivery using HA. Near-infrared laser photoablation is also reviewed as a primary method of cancer therapy—it can be used alone or in conjunction with chemotherapy to achieve promising chemo-photothermal therapy protocols. This review aims to give a background into HA and why it is a successful cancer-targeting component of current CNM-based drug delivery systems.     

新型碳纳米材料在电化学中的应用

由于碳纳米材料具有良好的力学、电学及化学性能而被人们广泛研究,特别是对于具有大比表面积、高的电导率和良好生物相容性的碳纳米管、碳纳米纤维和石墨烯更是研究的热点。这些新型碳材料具有许多优异的物理和化学特性,被广泛地应用于诸多领域,特别是在电化学领域中显示出其独特的优势。本文主要阐述了碳纳米材料在电化学领域包括生物传感器、超级电容器和燃料电池中的应用。碳纳米材料由于高的比表面积和其较好的生物相容性,在生物电催化反应中起着重要作用,能够提高酶的直接电子传递速率,因而基于碳纳米材料构建的生物传感器灵敏度高、线性范围宽、重复性和稳定性能好。碳纳米材料是超级电容器研究最早和最成熟的一种,由其制备的超级电容器循环稳定性好,再通过和一些赝电容型电极材料复合,可使其比电容得到提高。另外,碳纳米材料作为燃料电池中的催化剂,能够提高燃料电池的能量密度、燃料利用率和抗中毒能力。     

Research of Nanomaterials as Electrodes for Electrochemical Energy Storage

This paper has experimentally proved that hydrogen accumulates in large quantities in metal-ceramic and pocket electrodes of alkaline batteries during their operation. Hydrogen accumulates in the electrodes in an atomic form. After the release of hydrogen from the electrodes, a powerful exothermic reaction of atomic hydrogen recombination with a large energy release occurs. This exothermic reaction is the cause of thermal runaway in alkaline batteries. For the KSL-15 battery, the gravimetric capacity of sintered nickel matrix of the oxide-nickel electrode, as hydrogen storage, is 20.2 wt%, and cadmium electrode is 11.5 wt%. The stored energy density in the metal-ceramic matrix of the oxide-nickel electrode of the battery KSL-15 is 44 kJ/g, and in the cadmium electrode it is 25 kJ/g. The similar values for the KPL-14 battery are as follows. The gravimetric capacity of the active substance of the pocket oxide-nickel electrode, as a hydrogen storage, is 22 wt%, and the cadmium electrode is 16.9 wt%. The density of the stored energy in the active substance oxide-nickel electrode is 48 kJ/g, and in the active substance of the cadmium electrode it is 36.8 kJ/g. The obtained results of the accumulation of hydrogen energy in the electrodes by the electrochemical method are three times higher than any previously obtained results using the traditional thermochemical method.     

Development of an Aluminium Doped TiO2 Nanoparticles‐modified Screen Printed Carbon Electrode for Electrochemical Sensing of Vanillin in Food Samples

A new chemically modified electrode based on titanium dioxide nanoparticles (TiO₂‐NPs) has been developed. Aluminium was incorporated into the TiO₂‐NPs to prepare aluminium doped TiO₂ nanoparticles (Al‐TiO₂‐NPs). Aluminium doped TiO₂ nanoparticles‐modified screen printed carbon electrode (Al‐TiO₂‐NPs/SPCE) was employed as easy, efficient and rapid sensor for electrochemical detection of vanillin in various types of food samples. Al‐TiO₂‐NPs were characterized by energy‐dispersive X‐ray (EDX), transmission electron microscopy (TEM), and X‐ray diffraction (XRD) and analyses showing that the average particle sizes varied for the Al‐NPs (7.63 nm) and Al‐TiO₂‐NPs (7.47 nm) with spherical crystal. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were used to optimize the analytical procedure. A detection limit of vanillin was 0.02 μM, and the relative standard deviation (RSD) was 3.50 %, obtained for a 5.0 μM concentration of vanillin. The electrochemical behaviour of several compounds, such as vanillic acid, vanillic alcohol, p‐hydroxybenzaldehyde and p‐hydroxybenzoic, etc., generally present in natural vanilla samples, were also studied to check the interferences with respect to vanillin voltammetric signal. The applicability was demonstrated by analysing food samples. The obtained results were compared with those provided by a previous method based on liquid chromatography for determination of vanillin.     

纳米材料的结构分析

介绍宏观与微观的纳米粒子具有特殊的结构与性能,采用现代分析测试技术确定纳米材料的结构,并探索其原子或分子组成的规律是目前纳米科学的最微处理的研究内容之一。评述了纳米材料结构分析方法及理论研究的新成果。     

基于碳纳米材料的无酶电化学传感器同时检测抗坏血酸、多巴胺和尿酸

人体中抗坏血酸（AA）、多巴胺（DA）和尿酸（UA）的浓度失调可能导致一系列疾病,如癌症、老年痴呆症、高尿酸血症等,而且这三个物种通常共存于体液中,有接近的氧化还原电位,因此实现三者的同时检测,既具有一定的难度,又具有极其重要的现实意义。近年来用于同时检测AA、DA和UA的电化学传感器取得了令人瞩目的进展,其中碳材料因其成本低廉、导电性好、稳定性好、比表面积大等特点逐渐引起人们的广泛关注。本文综述了基于碳材料构筑的检测AA、DA和UA的无酶电化学传感器的研究进展,对此类电化学传感器的今后发展做了展望。     

Applications of Carbon Nanotubes in Electrochemical DNA Biosensors

The discovery of carbon nanotubes (CNTs) about a decade ago has brought fascinating evolutions in electronics, material industry, as well as bio-techniques for DNA analysis, gene therapy, drug delivery etc. It has also dramatically promoted the development of DNA biosensing techniques, especially electrochemical DNA biosensor. The application of CNTs in electrochemical DNA biosensors includes two main aspects: on one hand, using CNTs as a novel substrate not only enables immobilization of DNA molecules but also serves as a powerful amplifier to amplify signal transduction event of DNA hybridization. On the other hand, CNTs can also be employed as a powerful carrier to pre-concentrate enzymes or electroactive molecules for electrochemical sensing of DNA hybridization as a novel indicator. In this review, we place emphasis on recent studies of CNTs-based electrochemical DNA biosensors based on these two aspects, with advantages and disadvantages of each aspect introduced herein.     

核酸功能化稀土基纳米材料在生物检测中的应用

体内一些生物分子和离子的水平通常与细胞、组织、器官等结构和功能的变化相关,从而直接影响到疾病的预防、诊断和治疗,因此对体内这些物质的生物检测在医疗和健康领域具有重要的意义.基于稀土基纳米材料构建的纳米荧光探针具有灵敏度高、简单高效、抗干扰能力强等优点,在生物检测方面具有巨大的潜力.对稀土基纳米材料的核酸功能化能够进一步为纳米荧光探针提供更好的特异性识别能力和生物相容性,从而增强其在复杂样品中的生物检测能力.本综述总结了核酸功能化的稀土基纳米材料作为纳米荧光探针在生物检测领域的研究进展,简要介绍了其主要种类和性能、检测机理及检测物质,最后对该领域面临的挑战及未来的发展方向进行了展望.     

Electrochemical Immunosensors for Food Analysis: A Review of Recent Developments

Electrochemical immunosensors have the potential to transform analytical procedures within the food industry by providing highly specific, rapid, and inexpensive determination of pathogens. In this paper, recent advances in this area are outlined. In particular, attention is paid to new methods that have been developed for the modification of working electrode surfaces. Many advances have been related to the use of novel nanomaterials such as carbon nanotubes, graphene, and metallic nanoparticles, often used in conjunction with each other or polymers. The use of these materials has generally provided superior sensor sensitivity. The application of immunosensors to the detection of a range of pathogens in real samples is then investigated to establish whether they provide solutions in practical applications.     

电化学双电层电容器用新型炭材料及其应用前景

活性炭是目前使用最为广泛的一种电化学双电层电容器（EDLC）的电极材料,但其固有的缺点制约了EDLC性能的进一步提高。用新型高性能炭电极材料可使EDLC比能量和比功率性能进一步提高。这些新型炭材料包括基于石墨层状结构的纳米门炭,基于碳纳米管阵列结构的毛皮炭,通过高温置换反应制备的骨架炭以及电极可整体成型的纳米孔玻态炭。本文介绍了这些炭材料的电化学特性及其在电化学双电层电容器中的应用,指出用这4种新型炭材料制备EDLC的比能量或比功率性能远高于目前活性炭基EDLC,具有良好的应用前景。     

纳米材料修饰电极在电化学分析中的应用研究进展

综述了纳米材料修饰电极在电化学分析中的应用研究.主要总结了国内外纳米金属材料、纳米金属氧化物材料、碳纳米管与碳纳米管复合物以及其他纳米材料在电化学分析中的应用研究,并指出了纳米材料修饰电极在电化学分析应用中存在的问题.