基于多孔金结构的三相界面酶电极的制备及高效电化学酶传感性能

界面微环境是影响酶催化反应及酶传感性能的关键因素. 本研究基于三维微纳米结构多孔金基底, 通过调控电极表面的亲水和疏水浸润性, 制备了具有固-液-气三相界面微环境的氧化酶电极, 并研究了界面微环境对酶催化反应动力学的影响规律. 基于所制备的三相界面多孔金结构酶电极, 反应物氧气能够从气相直接快速地传输到酶催化反应界面, 极大地提升了界面氧气浓度及其稳定性, 从而大幅度提高了氧化酶活性及酶电极响应的稳定性. 以葡萄糖为模型待测物, 基于该三相界面酶电极的电化学酶生物传感器拥有宽的线性范围、 高的灵敏度、 低的检出限以及良好的稳定性. 这类独特的三相反应界面设计为高效酶生物传感器的建构以及生物分子的精准检测提供了新思路.     

Fiber-Optic Biosensor for the Detection of Atrazine: Characterization and Continuous Measurements

An optical fiber enzymatic biosensor was formed by immobilizing cells containing atrazine chlorohydrolase to the surface of a pH-sensitive optode. This enzyme catalyzes the dechlorination of atrazine, releasing hydrochloric acid and creating a signal response from the optode that was proportional to the atrazine concentration. Biosensors capable of quantitative and sensitive atrazine concentration measurements were developed using the atrazine chlorohydrolase of both Pseudomonas sp. ADP and Clavibacter michiganese sp. ATZ1. The biosensors based on both bacteria had a limit of detection of less than 1 ppb (validated using gas chromatography) and a linear range from 1 ppb to 100 ppb atrazine. Response times were a function of concentration and the source of enzyme, with a response time of 10 or 20 min for a 25 ppb atrazine solution. The performance of these sensors at various temperatures, pH values, and buffer capacities was also studied. The use of poly-L-lysine to increase the physical stability of biosensors containing Pseudomonas sp. ADP provided higher durability with no performance drawbacks. The atrazine biosensor was also used to measure atrazine concentrations in a soil column that was continuously fed a solution in which the atrazine concentration was increased or decreased. The atrazine biosensor provided continuous, in-situ measurements in the soil column, the first time that continuous biosensor measurements have been demonstrated in a soil system.     

High Sensitive Electrochemiluminescence Biosensor Based on Ru(phen)32+-loaded Double Strand DNA as Signal Tags use to Detect DNA Methyltransferase Activity

DNA methyltransferase (DNA MTase) can act as biomarker for many diseases and it is important to develop some new methods for sensitive detection of DNA MTase. In this work, a highly efficient electrochemiluminescence (ECL) sensor had been designed for detection of DNA MTase based on Ru(phen)₃²⁺ loaded double strand DNA (dsDNA- Ru(phen)₃²⁺) as signal tags. Ru(phen)₃²⁺ had been efficiently embed in the dsDNA produced through a simple hybridization chain reaction. First, a hairpin probe was designed, which can be specifically recognized by Dam MTase and modified with -SH at one end. It was modified on the surface of gold electrode by -SH as an immobilization probe (IP). This IP will be methylated in the present of Dam MTase and digested by DpnI following. Results in the release of capture probe (CP) which remains on the surface of gold electrode. The CP can hybridize with the single stand part of the dsDNA- Ru(phen)₃²⁺ and make the immobilization of ECL tags on the electrode surface, which results in a strong ECL signals detected. However, without the effect of Dam MTase, the hairpin structure of IP remains stable and cannot capture signal tags, and can only detecte weak ECL signals. The biosensor can detect the activity of Dam MTase in the concentration range of 0.01 U/mL to 20 U/mL with the ECL intensity and the logarithm of the concentration have a linear relationship, and the detection limit is calculated to be 7.6 mU/mL. The developed sensor has the ability to specifically detect Dam MTase, which can be differentiated from other types of DNA MTase. In addition, the designed method has good applicability to detect Dam MTase activity in serum samples and been applied to detect its inhibitor with high efficiency.     

Poly(cytosine)‐templated Silver Nanoclusters as Fluorescent Biosensor for Highly Sensitive Detection of Uric Acid

Uric acid (UA) is an important biomarker in urine and serum samples for early diagnosis. This study re‐ ports a fluorescent biosensor based on Poly(cytosine)‐templated silver nanoclusters (C‐Ag NCs) and uricase for the highly sensitive and fast detection of UA. The strong fluorescence of the C‐Ag NCs prepared from poly (cytosine) nucleotides templates could be sensitively quenched by trace amount of H₂O₂, which produced from oxidation reaction of UA catalyzed by uricase. This biosensor exhibits two linear ranges as 50 nM～50 μM and 50 μM～400 μM, with a detection limit of 50 nM. The sensitivity of the biosensor is considerably improved compared with the methods reported in the literature. Furthermore, the detection ability of uric acid in serum samples is confirmed and this C‐Ag NCs‐based uric acid biosensor shows good promise of practical application.     

Solid Supramolecular Architecture of a Perylene Diimide Derivative for Fluorescent Enhancement

A new p‐phenylenevinylene‐linked perylene diimide has been synthesized and self‐assembled for the formation of zero‐dimensional molecular aggregate structures of nanospheres and vesicles through solvent tuning. The solid‐state optical properties induced by a special wavelength laser were studied and the results indicated excellent fluorescent enhancement properties. The emission intensity of these aggregates increased with elongation of the laser irradiation time. Based on the analysis of variable‐temperature ¹H NMR spectra, DFT calculations, and the single‐crystal structure of the linkage group, a conformation‐dependent fluorescent enhancement mechanism could be demonstrated. The mechanism is different from the fluorescent bleaching of normal solid‐state fluorescent materials and offers potential applications in optical devices.     

Synthesis of Pd‐Pt Ultrathin Assembled Nanosheets as Highly Efficient Electrocatalysts for Ethanol Oxidation

Control over composition and morphology of nanocrystals (NCs) is significant to develop advanced catalysts applicable to polymer electrolyte membrane fuel cells and further overcome the performance limitations. Here, we present a facile synthesis of Pd?Pt alloy ultrathin assembled nanosheets (UANs) by regulating the growth behavior of Pd?Pt nanostructures. Iodide ions supplied from KI play as capping agents for the {111} plane to promote 2‐dimensional (2D) growth of Pd and Pt, and the optimal concentrations of cetyltrimethylammonium chloride and ascorbic acid result in the generation of Pd?Pt alloy UANs in high yield. The prepared Pd?Pt alloy UANs exhibited the remarkable enhancement of the catalytic activity and stability toward ethanol oxidation reaction compared to irregular‐shaped Pd?Pt alloy NCs, commercial Pd/C, and commercial Pt/C. Our results confirm that the Pd?Pt alloy composition and ultrathin 2D morphology offer high accessible active sites and favorable electronic structure for enhancing electrocatalytic activity.     

巯基乙酸自组装膜DNA电化学传感器对转基因NOS的定量检测

以转基因植物中常用的根癌农杆菌终止子(NOS)为检测对象, 将巯基乙酸自组装于金电极表面形成巯基乙酸自组装单分子膜, 再利用乙基-(3-二甲基氨丙基)碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)的活化作用将NOS探针ssDNA序列固定于金电极表面形成NOS电化学生物传感器, 以亚甲基蓝(MB)为杂交指示剂, 对NOS靶基因相关序列进行了定量检测.     

A Fluorescent Biosensor for Detection of Zearalenone

ABSTRACT

A fluorescent biosensor was developed on a KinExA^TM flow spectrofluorimeter for the near real-time detection of soluble zeaalenone.

Briefly, solutions of zearalenone and a monoclonal antibody directed against a protein conjugate of zearalenone, were incubated for thirty minutes to permit equilibrium binding to occur. The reaction mixture was then passed over a packed column of small beads (98 μm) whose surfaces were coated with a covalent conjugate of zearalenone and bovine serum albumin (BSA). Following a short wash with buffer to remove excess unbound primary reagents, the packed beads were subjected to a brief contact with fluorescein isothiocyanate-labeled polyclonal secondary antibody directed against the primary monoclonal, once again followed by a short wash. As this assay depends on the ability of soluble antigen to compete with immobilized antigen, increasing concentrations of zearalenone result in decreasing fluorescence observed on the bead pack. This assay is rapid (? 60 minutes) and can be adapted to various other analytes of interest.     

A Simple and Highly Sensitive Electrochemical Biosensor for microRNA Detection Using Target‐Assisted Isothermal Exponential Amplification Reaction

A simple and highly sensitive electrochemical biosensor for microRNA (miRNA) detection was successfully developed by integrating a target‐assisted isothermal exponential amplification reaction (EXPAR) with enzyme‐amplified electrochemical readout. The binding of target miRNA with the immobilized linear DNA template generated a part duplex and triggered primer extension reaction to form a double‐stranded DNA. Then one of the DNA strands was cleaved by nicking endonuclease and extended again. The short fragments with the same sequence as the target miRNA except for the replacement of uridines and ribonucleotides with thymines and deoxyribonucleotides could be displaced and released. Hybridization of these released DNA fragments with other amplification templates and their extension on the templates led to target exponential amplification. Integrating with enzyme‐amplified electrochemical readout, the electrochemical signal decreases with the increasing target microRNA concentration. The method could detect miRNA down to 98.9 fM with a linear range from 100 fM to 10 nM. The fabrication and binding processes were characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The specificity of the method allowed single‐nucleotide difference between miRNA family members to be discriminated. The established biosensor displayed excellent analytical performance toward miRNA detection and might present a powerful and convenient tool for biomedical research and clinic diagnostic application.     

The Nitrite Oxidizing Activity of Nitrobacter Strains as a Base of Microbial Biosensor for Nitrite Detection

ABSTRACT

Parameters of three Nitrobacter based sensor models have been studied for the purpose of creation of a nitrite analyzer that could be used for assay of nitroaromatics. It was shown that the sensor based on N. vulgaris strain was most suitable for development of such a device. The sensor possessed high     

Gold Nanoclusters Templated by Poly-cytosine DNA as Fluorescent Probes for Selective and Sensitive Detection of Thiocyanate

Gold nanoclusters(AuNCs) were prepared in the presence of the nucleobases of poly-cytosine DNAs in this paper. We have demonstrated tliat the fluorescence of the AuNCs is quenched by thiocyanate(SCN^-) through the interaction between SCN^- and gold atoms. AuNCs can receive energy from nucleobases to boost their emission intensity, while in the presence of SCN^-, they coordinate with Au atoms and influence the energy transfer between the nucleobases and AuNCs, leading to the fluorescence quenching. The decreased fluorescence intensity was in proportion to the concentration of SCN^- in the range of 8.0×10^-7-1.5×10^-5 mol/L with a limit of detection of 4.2×10^-7 mol/L(3σ). We further validated the practice of this probe througli the detection of SCbT in natural water samples.     

Excimer-based Activatable Fluorescent Sensor for Sensitive Detection of Alkaline Phosphatase

The accurate detection of related biomarkers at early stage is crucial in diagnosis and therapy of cancer. Small molecule fluorescence probes stand out acting as efficient tools to detect biomolecules, especially biomacromolecules. Herein, a new probe that features excimer formation has been designed to detect cancer-related biomarker alkaline phosphatase(ALP). The probe shows high sensitivity to ALP with a low limit detection of 0.13 U/L and high selectivity with resistance to the interference in the complex physiological system. Furthermore, this probe presents good biocompatibility with negligible cytotoxicity and displays remarkable cell imaging functions, which allows for its application in biosystems.Theoretical simulation validates the high affinity of the probe with ALP and depicts the details of the interaction modes, which provides the possible mechanisms underlying the efficient detection of the probe in atomic level. The study of synthesis, properties and applications of the activatable emissive excimers not only enriches the tools to detect ALP, but also provides a new strategy to comprehend the pathogenic mechanism of enzyme-related diseases.     

诺贝尔化学奖类大学生创新实验——Suzuki偶联反应制备DPP类荧光染料

Fluorescent diketopyrrolopyrrole (DPP) derivative was synthesized by coupling reaction, nucleophilic substitution reaction and Suzuki reaction, which was fully characterized by NMR spectroscopy and HRMS. Furthermore, the DPP derivative showed high fluorescence quantum yields of 88.4% and 78.9% in solvent and solid states.     

A Novel Fluorescent Probe Based on Perylene Derivative for Hg2+ Ions and Biological Thiols and its Application in Live Cell Imaging and Theoretical Calculations

The selective and sensitive detection of biothiols; cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) in aqueous solutions is of considerable importance because of their pivotal roles in maintaining the reducing environment in the cells. This study describes a strategy for the determination of biothiols based on the PDI/Met‐Hg²⁺complex platform. We designed and fabricated methionine modified perylene diimide molecule as a selective sensing probe for Hg²⁺ ions in aqueous solutions ( PDI/Met‐Hg ²⁺). The complex between perylene bisimide derivative ( PDI/Met) and Hg²⁺ was investigated and it demonstrated turn‐on fluorescence response for the detection of the biological thiols. Besides, PDI/Met displayed fluorescence quenching response in the presence of mercury ions and the emission intensity of PDI/Met‐Hg²⁺ was recovered after transferring biothiols (Cys, Hcy, and GSH). Thus, PDI/Met could be utilized as a fluorescent chemosensor for the sequential recognition of mercury ions and biological thiols.     

磁性纳米粒子在生物传感器中的应用研究进展

磁性纳米粒子是一种新型纳米材料,可应用于各种生物活性物质如蛋白质、DNA等的富集和分离,药物的磁靶向,以及疾病的诊断和治疗等许多领域。由于磁性纳米粒子有着独特的化学和物理性能,已经成功应用到磁控生物传感器、DNA传感器、蛋白质传感器、酶传感器以及其它类型的生物传感器中,并显著提高了生物传感器检测的灵敏度、缩短了生化反应的时间和提高检测的通量,为生物传感器领域开辟了广阔的应用前景。本文概述了磁性纳米粒子在生物传感器中的应用研究进展。     

Hemin Functionalized Multiwalled Carbon Nanotubes as a Matrix for Sensitive Electrogenerated Chemiluminescence Cholesterol Biosensor

Based on hemin‐MWCNTs nanocomposite and hemin‐catalyzed luminol‐H₂O₂ reaction, a sensitive electrogenerated chemiluminescence (ECL) cholesterol biosensor was proposed in this paper. Firstly, hemin‐MWCNTs was prepared via π–π stacking and modified on the surface of GCE. Subsequently, cholesterol oxidase (ChOx) was adsorbed on the modified electrode to achieve a cholesterol biosensor. Hemin‐MWCNTs nanocomposite provided the electrode with a large surface area to load ChOx, and endowed the nanostructured interface on the electrode surface to enhance the performance of biosensor. The biosensor responded to cholesterol in the linear range from 0.3 µM to 1.2 mM with a detection limit of 0.1 µM (S/N=3).     

Amperometric Tyrosinase Biosensor Based on Carbon Black Paste Electrode for Sensitive Detection of Catechol in Environmental Samples

In this work, a renewable tyrosinase-based biosensor was developed for the detection of catechol, using a carbon black paste electrode, without any mediator. The effect of pH, type of electrolyte, and amount of tyrosinase enzyme were explored for optimum analytical performance. The best-performing biosensor in amperometric experiments at potential −0.2 V vs. Ag/AgCl (3 mol L⁻¹ KCl) was obtained using a 0.1 mol L⁻¹ phosphate buffer solution (pH 7.0) as electrolyte. Under optimized conditions, the proposed biosensor had two concentration linear ranges from 5.0×10⁻⁹ to 4.8×10⁻⁸ and from 4.8×10⁻⁸ to 8.5×10⁻⁶ mol L⁻¹ and a limit of detection of 1.5×10⁻⁹ mol L⁻¹. The apparent Michaelis-Menten constant ( ) was calculated by the amperometric method, and the obtained value was 1.2×10⁻⁵ mol L⁻¹ whose result was similar when compared with other studies previously. The biosensor was applied in river water samples, and the results were very satisfactory, with recoveries near 100 %. In addition, the response of this biosensor for different compounds, taking into account their molecular structures was investigated and the results obtained showed no interference with the response potential of catechol. The electrochemical biosensor developed in this work can be considered highly advantageous because it does not require the use of a mediator (direct detection) for electrochemical response, and also because it is based on a low-cost materials that can be used with success to immobilise other enzymes and/or biomolecules.     

A Modulated Tyrosinase Enzyme‐Based Biosensor for Application to the Detection of Dichlorvos and Atrazine Pesticides

A study was been made of tyrosinase amperometric biosensors for the determination of organophosphorus (dichlorvos) and triazine (atrazine) pesticides. The biosensors are based on the competitive inhibition of tyrosinase (Tyr) by the pesticides. Tyr becomes active when the reduced form of the charge‐transfer mediator (1,2‐naphthoquinone‐4‐sulfonic acid (NQS), 1,2‐naphthoquinone (NQ) and 3,5‐di‐tert‐butyl‐1,2‐benzoquinone (t‐BQ) were tested) are electrochemically generated onto the working electrode surface, which permits modulation of the enzymatic activity. The inhibition is reversible as there is a complete recovery of the current due to enzyme activity without the studied pesticides. The charge‐transfer mediators (the quinonic molecules) and the enzyme were co‐immobilized on the working electrode to obtain reagentless biosensors. Kinetic studies in solution were carried out to compare the efficiency of the measurement mechanism.     

鱼鳔膜为基质的生物传感器测定葡萄糖的研究

以鱼鳔膜为基质同定葡萄糖氧化酶,偶联氧电极,构建了葡萄糖生物传感器,通过测定溶解氧浓度的变化定量测定葡萄糖.考察了酶浓度、pH值、缓冲液浓度对传感器的影响,优化了实验条件:即酶浓度为1 mg,pH 7.0,缓冲液浓度为100 mmol/L.此传感器具有较宽的线性范围(0.016～1.2 mmol/L),较短的响应时间(...     

基于可见吸收信号的乳酸脱氢酶光纤传感器

报道一种测定乳酸脱氢酶活力的基于可见吸收信号的光纤生物传感器，在该传感体系中，通过辅酶Ｉ的氧化还原对（ＮＡＤ＾＋／ＮＡＤＨ）将乳酸脱氢酶和心肌黄酶催化的两个脱氢过阳以耦合，第一个脱氢过程对分析对象进行了化学识别，第二个脱氢过程引起可见吸收信号的变化，该传感器对０～４００Ｕ／Ｌ的乳酸脱氢酶有线性响应关系，检测下限为４８ＵＬ，该传感器已用于人体血清中乳酸脱氢酶活力的测定。