电化学DNA生物传感器*

对特异DNA序列的检测在基因相关疾病的诊断、军事反恐和环境监测等方面均具有非常重要的意义,DNA传感器的研究就是为了满足对特异DNA序列的快速、便捷、高灵敏度和高选择性检测的需要。近年来涌现出了多种传感策略,根据检测方法的不同可以大致分为光学传感器、电化学传感器、声学传感器等。由于电化学检测方法本身所具有的灵敏、快速、低成本和低能耗等特点,电化学DNA传感器已成为一个非常活跃的研究领域并在近几年中得到了快速发展。本文概括了近年来在DNA传感器的重要分支——电化学DNA传感器领域内的一些重要进展,主要包括DNA探针在传感界面上的固定方法和各种电化学DNA杂交信号的检测方法。     

Graphene Oxide-Sensitized Surface Plasmon Resonance Biosensor of Porcine Reproductive and Respiratory Syndrome Virus

Biosensor analysis based on the surface plasmon resonance (SPR) phenomenon enables label-free, highly sensitive analyte detection without prior sample purification or processing. However, potential applications of SPR biosensors in virus detection in biological samples remain to be explored. Owing to its excellent biocompatibility and abundance of hydroxyl and carboxyl functional groups, graphene oxide (GO) has been widely used as a biosensor of proteins and metal ions in living cells. The present work explored the effect of GO modification on the sensitivity of an SPR biosensor and used a GO-modified sensor to detect porcine reproductive and respiratory syndrome virus in cell culture, as shown. The GO modification markedly enhanced the sensitivity of the Fourier transform SPR sensor and enabled linear detection of porcine reproductive and respiratory syndrome virus (PRRSV) with a multiplicity of infection in the range 0.2–1.7 (R² = 0.998). Such a GO-modified sensor provides a promising alternative for virus detection.     

Catalytic DNA Origami-based Chiral Plasmonic Biosensor

Plasmonic circular dichroism(CD) has been emerged as a pro-mising signal for building biosensors due to its high sensitivity and specificity. In the past years, DNA nanotechnology enabled diverse chiral plasmonic devices, which can response biomolecules and then generate dynamic plasmonic CD signals at the visible range. Although some of them have been successfully employed as biosensors, the detection sensitivity is still relatively low. Herein we report a chiral plasmonic sensor with an improved detection sensitivity by integrating catalytic hairpin assembly circuits into DNA origami structures. We tested two kinds of tumor marker RNA sequences as detection targets and it turns out that the detection limit is below 10 pmol/L, improving one order of magnitude compared to previous work. The chiral plasmonic sensor with internal signal amplification circuits can stimulate a variety of smart nano-sensors for biological detection and offer a promising strategy for pathogenic RNA detection with plasmonic CD output.     

Partially Oxidized Graphene/Metallic Single‐Walled Carbon Nanotubes Film‐Coated Electrode for Nanomolar Detection of Dopamine

Enriched metallic single‐walled carbon nanotubes (mSWCNTs) were dispersed in aqueous solution of partially oxidized graphene (po‐Gr). As‐prepared po‐Gr/mSWCNTs suspension was used to modify glassy carbon electrode (GCE) surface, which showed high electrocatalytic activity for dopamine (DA) oxidation in pH 7.0 phosphate buffered saline (PBS) solution. Using po‐Gr/mSWCNTs/GCE we could detect DA from 350 to 3600 nM, with a detection limit down to 25 nM in physiological condition (in pH 7.0 PBS); whereas, po‐Gr/GCE (without mSWCNTs) and bare GCE produced measurable signals only at or above 200 nM DA. Thus, the po‐Gr/mSWCNTs film we fabricated is a promising nanomaterial for fabrication of biosensors for nanomolar detection of DA.     

基于仿生聚多巴胺膜和纳米金的酶固定化平台的构建

首次以仿生聚多巴胺膜为功能基底膜并结合使用纳米金, 构建了一种高导电性、稳健的酶生物分子固定化平台. 以固定辣根过氧化物酶(HRP)为例, 发展了一种新的电化学酶传感器用于H2O2的测定. 结果表明, 酶传感器借助聚多巴胺膜对基底电极的高结合力及其高生物亲和性与电活性, 并协同纳米金的“电子通道”作用, 不仅可以实现酶分子在电极表面的大量而高活性的固定化, 而且能促进电子在酶活性中心和电极表面间的快速传递. 与采用其它常见聚合物材料(例如壳聚糖)的酶传感器比较, 以聚多巴胺/纳米金固定化平台发展的酶传感器具有更优良的检测H2O2的性能. 其对H2O2的检测线性范围为4.0×10－7～4.5×10－4 mol•L－1, 检测限为3.7×10－7 mol•L－1, 灵敏度为100.2 μA•L•mmol－1. 此外, 该酶传感器还具有优良的检测重现性和存贮稳定性, 以及较好的抗干扰能力.     

Engineering Design,Implementation, and Sensing Mechanisms of Wearable Bioelectronic Sensors in Clinical Settings

Wearable sensing devices have transformed the hourly analysis of events such as body signals and environmental risks into real-time monitoring in minutes or seconds. Wearable sensors have facilitated the ability to obtain useful data by monitoring the physiological parameters and activities of an aided and a healthy individual. Wearable devices employ detectable biomarkers in the human body, such as in tears, saliva, interstitial fluid, sweat, and so on. These can deliver relevant information on human health, online activity monitoring, and therapeutic treatments. This section outlines the significance of sample types and associated biomarkers as indicators in the development and manufacturing of wearable biosensors. We have emphasized the most recent advances of wearables based on skin-like and textile, giving attention to personalized health monitoring to record signals of motion and physiological and body fluid investigation. Furthermore, this review categorizes wearable biosensors based on the sensing mechanism, electrochemical, optical, and mechanical. Additionally, the recent wearables related to the detection of the newly havoc-causing pandemic, COVID-19, and the future perspective for the development of much more advanced and potent wearable biosensors have been highlighted. The final section highlights unmet difficulties and gaps in wearable sensors in personalized therapy.     

ZrO2-Graphene-Chitosan nanocomposite modified carbon paste sensor for sensitive and selective determination of dopamine

A sensitive and stable electrochemical sensor was developed by modification of carbon paste electrode with ZrO₂/graphene/chitosan nanocomposite. The modified sensor served as a potential electrocatalytic platform for dopamine. Electrochemical impedance spectroscopy studies indicated reduction of charge transfer resistance at the modified electrode surface thereby facilitating the electron transfer process which resulted in higher current response to dopamine. The electrochemical behavior of dopamine at the modified electrode was studied using cyclic and square wave voltammetry. The maximum current response for the electro-oxidation of dopamine was observed at pH 7.4 and the process was realized to be diffusion controlled. The modified sensor demonstrated linearity in the range 1000–5000 nM, with high sensitivity (22 nA/nM), detection limit of 11.3 nM and selectivity for dopamine in the presence of ascorbic and uric acid which are found to co-exist with dopamine in physiological media. The method was employed for quantification of dopamine in a pharmaceutical formulation.     

Electrochemical Determination of Dopamine Using a Novel Perylenediimide-Derivative Modified Carbon Paste Electrode

A novel perylenediimide derivative, N,N′-bis(4-{2-[2-(2-methoxyethoxy ethoxy]ethoxy}phenyl)-3,4:9,10-perylene tetracarboxydiimide, was utilized for the modification of a carbon paste electrode to develop a practical and sensitive electrochemical sensor for dopamine detection. The effects of experimental parameters (modifier amount, pH, and scan rate) on the dopamine peak current were examined. The performance of the modified carbon paste electrode was evaluated under optimum conditions and 4.6-fold increase in the peak current was obtained compared to an unmodified carbon paste electrode. The linear range was between 1 and 100?µM dopamine and the limits of detection and quantification were 0.011 and 0.036?µM, respectively. The developed sensor was also applied for the quantitative determination of dopamine in injections and promising results were obtained.     

Application of cell-based biosensors for the detection of bacterial elicitor flagellin

Cell-based biosensors, bioelectronic portable devices containing plant living cells have been used for monitoring some physiological changes induced by pathogen-derived signal molecules called flagellin. The screen-printed electrodes have been adapted for preparation of biosensors. The proton-sensitive thick films have been printed using composite bulk modified with edition of RuO(2). Obtained disposable electrodes were made possible to measure the pH change with well sensitivity and reproducibility. Tobacco cells attached to the electrode surface, cell-based biosensor, can be used for the detection of flagellin, the virulence factor of bacterial pathogen. We culture tobacco cells on the surface of such electrotransducer for several weeks and monitor of potential of cells under flagellin stimulation. The detection of the electrochemical proton gradient across the plasma membrane serves as the analytical signal. The electrode response depended upon H(+) concentration in extracellular solution. It can be conveniently observed on the surfaces of biosensors. Suitable stability and the good response time of constructed biosensors were observed. Future development of these cell-based biosensors could draw advances in selective monitoring of microbial pathogens and other physiologically active components. Moreover, this new method is much faster compared with the traditional microbial testing.     

RE-SELEX: restriction enzyme-based evolution of structure-switching aptamer biosensors

Aptamers are widely employed as recognition elements in small molecule biosensors due to their ability to recognize small molecule targets with high affinity and selectivity. Structure-switching aptamers are particularly promising for biosensing applications because target-induced conformational change can be directly linked to a functional output. However, traditional evolution methods do not select for the significant conformational change needed to create structure-switching biosensors. Modified selection methods have been described to select for structure-switching architectures, but these remain limited by the need for immobilization. Herein we describe the first homogenous, structure-switching aptamer selection that directly reports on biosensor capacity for the target. We exploit the activity of restriction enzymes to isolate aptamer candidates that undergo target-induced displacement of a short complementary strand. As an initial demonstration of the utility of this approach, we performed selection against kanamycin A. Four enriched candidate sequences were successfully characterized as structure-switching biosensors for detection of kanamycin A. Optimization of biosensor conditions afforded facile detection of kanamycin A (90 μM to 10 mM) with high selectivity over three other aminoglycosides. This research demonstrates a general method to directly select for structure-switching biosensors and can be applied to a broad range of small-molecule targets.

RE-SELEX is the first homogenous method for in vitro evolution of structure-switching DNA aptamers.     

Fabrication of glutathione photoelectrochemical biosensor using graphene-CdS nanocomposites

A novel glutathione (GSH) photoelectrochemical biosensor was fabricated using the newly synthesized graphene-CdS (GR-CdS) nanocomposites. The GR-CdS nanocomposites were prepared by a fast, one-step, aqueous reaction. The as-prepared GR-CdS structure inherited the excellent electron transport of GR and facilitated the spatial separation of photo-generated charge carrier, therefore resulting in the enhanced photocurrent, and making it a promising candidate for developing photoelectrochemical biosensors. The proposed GSH sensor displays satisfactory analytical performance with an acceptable linear range from 0.01 to 1.5 mmol L(-1) with a detection limit of 0.003 mmol L(-1) at a signal-to-noise ratio of 3, and also shows an excellent specificity against anticancer drugs and can be successfully applied for GSH detection in real samples. The as-synthesized GR-CdS nanocomposites exhibited obviously enhanced photovoltaic properties, which could be extended to the detection of other enzymes and biomolecules, thus providing a promising platform for the development of photoelectrochemical biosensors.     

Electroanalytical biosensors and their potential for food pathogen and toxin detection

The detection and identification of foodborne pathogens continue to rely on conventional culturing techniques. These are very elaborate, time-consuming, and have to be completed in a microbiology laboratory and are therefore not suitable for on-site monitoring. The need for a more rapid, reliable, specific, and sensitive method of detecting a target analyte, at low cost, is the focus of a great deal of research. Biosensor technology has the potential to speed up the detection, increase specificity and sensitivity, enable high-throughput analysis, and to be used for monitoring of critical control points in food production. This article reviews food pathogen detection methods based on electrochemical biosensors, specifically amperometric, potentiometric, and impedimetric biosensors. The underlying principles and application of these biosensors are discussed with special emphasis on new biorecognition elements, nanomaterials, and lab on a chip technology.     

Recent advances in nanoscale metal-organic frameworks biosensors for detection of biomarkers

Early and precise diagnosis are propitious to timely treatment and simultaneously increase the chance of successful treatments. It is of critical importance to develop rapid, sensitive, and reliable sensing techniques of physiological biomarkers for disease diagnosis. Due to the advantages of structural designability and property tunability, nanoscale metal-organic frameworks(nMOFs) have been widely applied in the field of biomedicine in recent years. Particularly, enhanced stability, more modif...     

Recent developments in potentiometric biosensors for biomedical analysis

A large variety of potentiometric biosensors is developed using biocatalytic and bioaffinity-based biosensing schemes. However, only few of them could be applied for the biomedical analysis. The most promising are those for the detection of main products of protein metabolism, namely urea and creatinine. A novel group of potentiometric biosensors is constituted by bioaffinity-based devices that could be used for immunoassays or genoanalysis. This paper reviews the recent trends in these fields as well as discusses advantages, limitations and pitfalls of the developed biosensors. Some potentiometric biosensors useful for real biomedical analysis are reported in detail.     

Electrochemical Biosensors for Detection of Biological Warfare Agents

This review discusses current development in electrochemical biosensors for detection of biological warfare agents. This could include bacteria, viruses and toxins that are aerosoled deliberately in air, food or water to spread terrorism and cause disease or death to humans, animals or plants. The rapid and unequivocal detection and identification of biological warfare agents is a major challenge for any government including military, health and other government agents. Reliable, specific characterization and identification of the microorganism from sampling location, either air, water, soil or others is required. This review will survey different types of electrochemical biosensors has been developed based on the following: i) Immunosensors ii) PCR (DNA base Sensor) iii) Bacteria or whole cell sensor and iv) Enzyme sensor. This article gives an overview of electrochemical biosensor for detection of biological warfare agents. Electrochemical biosensors have the advantages of sensitivity, selectivity, to operate in turbid media, and amenable to miniaturization. Recent developments in immunofiltration, flow injection, and flow‐through electrochemical biosensors for bacteria, viruses, and toxin detection are reviewed. The current research and development in biosensors for biological warfare agents detection is of interest to the public as well as to the defense is also discussed.     

Recent advances in MXenes-based glucose biosensors

It is established that monitoring blood glucose on a daily basis is one of the most effective solutions to prevent and treat diabetes. Consequently, developing a glucose sensing platform with outstanding sensing performance occupies an indispensable position for the early diagnosis and risk assessment of diabetes. Recently, biosensor has been deemed as a promising apparatus to acquire the signals for glucose monitoring based on 2D materials. However, it is unsatisfied to deploy some materials widely as a result of some inherent defects. Carbon nanotubes have comparatively high toxicity. MoS₂ with unfavourable biocompatibility are still arduously implemented on being functionalized. Fortunately, MXene, a brand-new and rapidly developing two-dimensional material, exhibits marvellous application potential in the domain of biosensing. Therefore, it has exerted tremendous attention from diverse scientific fields owning to its remarkable properties, such as excellent hydrophilicity, metal-like conductivity, abundant surface functional groups, unique layered structure, large specific surface area and remarkable biocompatibility. This review mainly focuses on the main synthetic route of MXenes, as well as the recent advancements of biosensors involving MXenes as an electrode modifier for glucose detection. In addition, the promising prospects and challenges of glucose sensing technology based on MXenes are also discussed.     

Nonenzymatic Electrochemical Sensor for Wearable Interstitial Fluid Glucose Monitoring

We report on a nonenzymatic electrochemical sensor for wearable glucose monitoring in interstitial fluid. The sensor exhibited acceptable selectivity and reliability for continuous glucose detection for up to 30 days. The sensor tip is coated with polyurethane, and the biocompatibility of the tip is investigated by tissue staining. A fully integrated wearable glucose monitoring system is developed with a wireless connection with a smartphone. The test results are in agreement with reference methods. So, we believe the sensor is promising for the development of a continuous glucose monitoring system and diabetes management.     

Amperometric Detection of Catecholamine Neurotransmitters Using Electrocatalytic Substrate Recycling at a Laccase Electrode

An enzyme electrode based on the coimmobilization of an osmium redox polymer and laccase on glassy carbon electrodes has been applied to ultra sensitive amperometric detection of the catecholamine neurotransmitters dopamine, epinephrine and norepinephrine, resulting in nanomolar detection limits, as low as 4 nM for dopamine. The sensitivity of the electrode is due to signal amplification via oxidation of the catecholamine by the immobilized laccase, which is regenerated by concomitant reduction of oxygen to water, coupled to the electrocatalytic re‐reduction of the oxidized catecholamine by the osmium redox complex: electrocatalytic substrate recycling. In addition because the sensor can be operated in reductive mode at ?0.2 V (vs. Ag/AgCl), noise and interferences are diminished. Combined with its high sensitivity this enzyme electrode also exhibited excellent selectivity allowing the detection of catecholamines in the presence of ascorbic acid. However, differentiation between the current responses achieved for the three catecholamines is not possible. The effective mode of constant recycling, resulting in amplification of the current response, of the laccase enzyme electrode sensor combined with the inherent advantages of using electrochemical techniques holds great promise for the future of catecholamine detection and monitoring.     

2D MXenes as Perspective Immobilization Platforms for Design of Electrochemical Nanobiosensors

MXenes are a new group of 2D nanomaterials with fascinating properties including high electrical conductivity, hydrophilic nature, easily tunable structure and high surface area. This is why MXene modified interfaces are extremely promising for the preparation of sensitive electrochemical biosensors. While there are numerous reports on MXene‐based enzymatic biosensors for detection of a wide range of analytes, application of MXene for construction of affinity biosensors is in its infancy. The review article summarizes current state‐of the‐art in the field with a focus on MXene modifications needed for construction of robust and high performance MXene electrochemical biosensors.