Mechanochemical Sensing: A Biomimetic Sensing Strategy

Existing biosensors employ two major components: analyte recognition and signal transduction. Although specificity is achieved through analyte recognition, sensitivity is usually enhanced through a chemical amplification stage that couples the two main units in a sensor. Although highly sensitive, the extra chemical amplification stage complicates the sensing protocol. In addition, it separates the two elements spatiotemporally, reducing the real‐time response of the biosensor. In this review, we discuss the new mechanochemical biosensors that employ mechanochemical coupling strategies to overcome these issues. By monitoring changes in the mechanical properties of a single‐molecule template upon analyte binding, single‐molecule sensitivity is reached. As chemical amplification becomes unnecessary in this single‐molecule mechanochemical sensing (SMMS) strategy, real‐time sensing is achieved.     

Electrochemical Sensing of Explosives

This article reviews recent advances in electrochemical sensing and detection of explosive substances. Escalating threats of terrorist activities and growing environmental concerns have generated major demands for innovative field‐deployable tools for detecting explosives in a fast, sensitive, reliable and simple manner. Field detection of explosive substances requires that a powerful analytical performance be coupled to miniaturized low‐cost instrumentation. Electrochemical devices offer attractive opportunities for addressing the growing explosive sensing needs. The advantages of electrochemical systems include high sensitivity and selectivity, speed, a wide linear range, compatibility with modern microfabrication techniques, minimal space and power requirements, and low‐cost instrumentation. The inherent electroactivity of nitroaromatic, nitramine and nitroester compounds makes them ideal candidates for electrochemical detection. Recent activity in various laboratories has led to the development of disposable sensor strips, novel electrode materials, submersible remote sensors, and electrochemical detectors for microchip (‘Lab‐on‐Chip’) devices for on‐site electrochemical detection of explosive substances. The attractive behavior of these electrochemical monitoring systems makes them very promising for addressing major security and environmental problems.     

Stabilization of Sensing Assay within Polyelectrolyte-Coated Alginate Microspheres for Optical Urea Sensing

Abstract

A new absorbance-based enzymatic biosensor for determination of urea (in the range 0.01 to 6.7 mM) is described. Quantification using cresol red dye, immobilized in the nanofilm coatings assembled on alginate microspheres to immobilize the urease enzyme, has been accomplished using ratiometric absorbance measurements. The effect of salt concentration in polyelectrolyte nanofilms (on the stability of dye molecules) and buffer pH (on the enzyme stability) are reported. The results demonstrate excellent stability of sensing assay within alginate microspheres. Urea-sensing experiments demonstrate the potential to develop an optical urea sensor that is stable over a month.     

薄膜荧光传感

<正>不同于其它探测技术,荧光以激发态实现传感。因此,荧光传感具有灵敏度高、可设计性好、仪器结构相对简单、能耗低、不涉及放射性源、易于实现便携等优点,受到了人们的特别关注^1,2。薄膜荧光传感是荧光传感的一种重要形式,是继离子迁移谱技术之后最具发展潜力的可实现便携的气相微痕量物质探测技术。敏感薄膜创制是薄膜荧光技术的核心,薄膜性能主要取决于决定传感发生机制的传感单元,以及影响传感对象分子吸附、解析和扩散的活性层(adlayer)结构。一般而言,     

金属氧化物室温气敏材料的结构调控及传感机理

室温气敏材料能耗低、稳定性好、安全性高,并且有助于简化传感器的器件结构,具有很好的实际应用前景。开发具有优异室温传感性能的气敏材料成为近年来传感领域的研究热点。金属氧化物半导体材料来源广泛、环境友好、结构调控灵活,在室温气体传感性能方面取得一定的进展。本文介绍了金属氧化物气敏材料的发展历程及气体传感机理,详述了各种具有室温气敏性能的金属氧化物纳米结构,重点讨论构建金属氧化物室温传感性能的有效策略和传感机制,并对室温传感材料的未来发展进行了展望。     

Recognition and Sensing of Creatinine

Current methods for creatinine quantification suffer from significant drawbacks when aiming to combine accuracy, simplicity, and affordability. Here, an unprecedented synthetic receptor, an aryl‐substituted calix[4]pyrrole with a monophosphonate bridge, is reported that displays remarkable affinity for creatinine and the creatininium cation. The receptor works by including the guest in its deep and polar aromatic cavity and establishing directional interactions in three dimensions. When incorporated into a suitable polymeric membrane, this molecule acts as an ionophore. A highly sensitive and selective potentiometric sensor suitable for the determination of creatinine levels in biological fluids, such as urine or plasma, in an accurate, fast, simple, and cost‐effective way has thus been developed.     

基于水凝胶的细菌传感检测

水凝胶具有含水量高、柔韧性好、黏弹性高、生物相容性高以及独特的刺激响应特性,这使得水凝胶材料在细菌传感检测方面备受关注。基于水凝胶的细菌传感器及传感芯片的研究,对细菌的基础科学研究具有重要意义,更对细菌的快速高效检测、特定环境中的细菌污染防控和疾病传播控制等具有重要应用价值。本文针对近年来水凝胶在细菌传感检测方面的研究工作进行综述。简要介绍了水凝胶的种类,水凝胶与细菌之间相互作用的影响因素。重点综述了基于温敏型水凝胶、pH敏感型水凝胶、酶敏感型水凝胶以及特异性标识物功能化修饰的水凝胶构建的传感器和传感检测方法,并综述了基于水凝胶的新型柔性传感器和微流控传感芯片的研究进展。基于水凝胶的细菌传感器在检测效率、信号采集和稳定性等方面仍需进一步提升和拓展。随着新型水凝胶材料的出现,智能细菌传感器、柔性细菌传感器和集成微流控细菌传感芯片是目前发展的方向,在细菌检测方面显示出良好的发掘潜力和应用前景。     

Sensing through signal amplification

The naked eye detection of single molecules in a complex mixture is the ultimate detection limit. Since a single molecule is unable to generate a strong enough signal, sensing methodologies able to reach that limit by necessity need to rely on signal amplification. This tutorial review describes various molecular approaches towards signal amplification in which a single analyte molecule affects the properties of a multitude of reporter molecules. Sensing by advanced instrumentation or changes in the physical properties of materials are excluded. The review is divided into four parts (catalysts, macromolecules, metal surfaces and supramolecular aggregates) depending on the species responsible for generating reporter molecules. Although on first sight apparently very diverse in nature, the majority of approaches rely on two key concepts: catalysis and multivalency. The ability of a catalyst to convert a multitude of substrate molecules into product (defined by the turn over number) makes a catalyst an intrinsic signal amplifier in case the chemical conversion of the substrate is accompanied by a measurable change in physical properties. For sensing purposes, catalytic activity must depend on the interaction between the analyte and the catalyst. Sensing using multivalent structures such as polymers and functionalized nanoparticles relies on the ability of a single analyte molecule to affect the properties of a multitude of reporter molecules collected in the multivalent structure. Chemical sensing systems will be discussed with detection limits that indeed go down to a few molecules and can rival the best biological assays. It will be shown that the most sensitive methods rely on a cascade of amplification mechanisms.     

Sensing nanomaterials of wearable glucose sensors

The metabolic disorder of glucose in human body will cause diseases such as diabetes and hyperglycemia.Hence the determination of glucose content is very important in clinic diagnosing.In recent years,researchers have proposed various non-invasive wearable sensors for rapid and real-time glucose monitoring from human body fluids.Unlike those reviews which discussed performances,detection environments or substrates of the wearable glucose sensor,this review focuses on the sensing nanomaterials since they are the key elements of most wearable glucose sensors.The sensing nanomaterials such as carbon,metals,and conductive polymers are summarized in detail.And also the structural characteristics of different sensing nanomaterials and the corresponding wearable glucose sensors are highlighted.Finally,we prospect the future development requirements of sensing nanomaterials for wearable glucose sensors.This review would give some insights to the further development of wearable glucose sensors and the modern medical treatment.     

Electrochemical Sensing in Contact Lenses

Electrochemical sensors embedded in hydrogel-based contact lenses provide valuable health-related information, enabling non-invasive and real-time continuous monitoring. Recently, considerable progress has been made in tear based electrochemical sensors. The scope of reported analytes is continuously expanding. This review identifies key chemical biomarkers (including metabolites, ions, proteins) that can be electrochemically detected in tears. The working principles of i) amperometric enzymatic biosensors, ii) ion-selective sensors for pH and ions, iii) voltammetric sensors and iv) affinity sensors are summarized. This review provides guidelines for the future development of contact lens based electrochemical sensors.     

纳米等离子体生物传感及成像

贵金属纳米材料具有显著的局域表面等离子体共振（LSPR）效应,可有效地将共振光子限域在金属表面.随着多种形貌贵金属纳米材料的可控合成及其功能化表面化学技术的日臻成熟,贵金属纳米材料已被广泛应用于生物标记、传感成像、分析分离及生物医学领域.从贵金属纳米等离子体材料的性质出发,综述局域表面等离子体共振材料在传感及细胞成像中的最新进展,并对基于局域表面等离子体共振材料的纳米光子学传感器未来发展前景做出展望.     

Sensing Acetylcholine and Anticholinesterase Compounds

Acetylcholine is a key neurotransmitter, and anticholinesterase agents are essential compounds used as medical drugs, pesticides, and chemical warfare agents. A semisynthetic fluorescence‐based probe for the direct, real‐time detection of acetylcholine and anticholinesterase compounds is introduced. The probe possesses good sensitivity, tunable detection range, and can be selectively targeted to cell surfaces, thereby making it an attractive tool for applications in analytical chemistry and quantitative biology.     

Luminescent Sensing with Quantum Dots

Summary This review highlights recent advances in the use of quantum dots (QD’s) as luminescent sensors. The bulk of the study concentrates on systems that possess organic ligands bound to the surface of QD’s. These ligands vary from low molecular weight thiols to larger molecules such as maltose binding protein. All have one thing in common: when a target analyte binds to the ligand/receptor, a perturbation of the system occurs, that registers itself as a change in the luminescence intensity of the QD. Two main mechanisms are prevalent in controlling the luminescent intensity in such systems. The first is Photoinduced Electron Transfer (PET) and the second energy transfer. This review looks at current sensors that operate by using these mechanisms. Two component systems are also investigated where a quencher is first added to a solution of the QD, followed by addition of the target analyte that interacts with the quencher to influence the luminescence intensity.     

Nanostructured Substrates for Optical Sensing

Sensors that change color have the advantages of versatility, ease of use, high sensitivity, and low cost. The recent development of optically based chemical sensing platforms has increasingly employed substrates manufactured with advanced processing or fabrication techniques to provide precise control over shape and morphology of the sensor micro- and nano-structure. New sensors have resulted with improved capabilities for a number of sensing applications, including the detection of biomolecules and environmental monitoring. This perspective focuses on recent optical sensor devices that utilize nanostructured substrates.     

二氧化锡气敏材料的研究进展

采用纳米技术及对纳米级粉体材料的掺杂，可实现对二氧化锡本体材料的改性，很大程度上提高二氧化锡气敏材料的灵敏度和选择性，本文综述二氧化锡气敏材料的制备及应用进展。     

《电化学分析传感》专辑序言

《电化学分析传感》专辑序言 电化学分析传感是一种基于界面电荷相互作用的测量方法,具有高灵敏、响应快、无标记等本征优势. 该方法的核心思路是将待测对象构建成为化学电池的某一部分,通过测量界面电子转移或电荷重排过程中产生的电信号响应,如电池电位、电流、电导、电量变化,对待测目标进行定性定量动态地检测、监测或表征. 　　近年来,伴随着测量仪器性能和数据处理方法的持续提高与优化,电化学分析传感研究前沿热点越来越多地关注到纳米尺度界面上的瞬态电荷相互作用、动态电荷传输机制,特别是发展限域空间内的单体纳米电化学信号放大、传输、记录、解析新模式和新策略. 其中,单体电化学分析,如单颗粒碰撞法等,不仅可以得到常规宏观测量的单一平均结果,同时还能描绘出所有不同颗粒结构与性能的完整分布,揭示少量但关键的电化学活性位点和反应机理;而纳米限域电化学分析,如纳米孔道协同测量等,则能通过限域效应有效延长亚稳态中间体的结构寿命,灵敏识别不同待测单体间的细微理化性质差异及其动态变化过程. 此外,电分析方法也更多地与谱学、成像等技术联用,对界面电化学过程进行原位、实时、在线表征,以期揭示纳米界面的电荷传递和能量转化的化学本质. 进而指导设计构建高灵敏电化学传感器,实现在疾病的早期检测、能源转换的高效率用、水体环境污染的有效治理等国家战略性产业中的广泛应用. 　　本专辑围绕电化学分析传感新方法与新技术,收录了在相关研究领域具有丰富经验积累和影响力的团队所撰写的21篇相关研究进展的综述文章和研究论文（分成两期出版,分别包含10篇和11篇）. 希望借助此专辑的出版,能使广大读者更好地了解当前电化学测量领域的研究现状、研究趋势和存在的问题及挑战,推动我国下一代电化学精准分析技术和高效传感应用的进一步发展. 　　最后,对本专辑的所有作者、审稿人及编辑部工作人员的辛勤工作和付出表示由衷的感谢！     

等离子体金属纳米结构在SERS传感及可穿戴应力传感中的应用

等离子体金属(金、银)纳米结构因其特有的理化性能,被广泛应用于表面增强拉曼散射(Surface-enhanced Raman scattering,SERS)传感及可穿戴应力传感领域.其中,SERS是一种应用贵金属纳米材料增强拉曼散射信号的检测技术,该技术灵敏度高、特异性强,已被广泛用于生物医学、环境监测、食品药品检测...     

Ion and pH Sensing with Colloidal Nanoparticles: Influence of Surface Charge on Sensing and Colloidal Properties

Ion sensors based on colloidal nanoparticles (NPs), either as actively ion‐sensing NPs or as nanoscale carrier systems for organic ion‐sensing fluorescent chelators typically require a charged surface in order to be colloidally stable. We demonstrate that this surface charge significantly impacts the ion binding and affects the read‐out. Sensor read‐out should be thus not determined by the bulk ion concentration, but by the local ion concentration in the nano‐environment of the NP surface. We present a conclusive model corroborated by experimental data that reproduces the strong distance‐dependence of the effect. The experimental data are based on the capability of tuning the distance of a pH‐sensitive fluorophore to the surface of NPs in the nanometer (nm) range. This in turn allows for modification of the effective acid dissociation constant value (its logarithmic form, pK_a) of analyte‐sensitive fluorophores by tuning their distance to the underlying colloidal NPs.     

发光多孔硅的化学传感特征

发光多孔是一种新型的光电器件材料。其荧光的猝灭或增敏，以及其电学特性的变化可作为化学伟感信息用于电化学传感技术。本文评述了自发光多孔硅首次报道以来在化学传感领域的应用研究进展。