Photoelectrochemical Cytosensors

Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living-cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions.     

低电流密度下恒电流法制备的聚苯胺修饰电极

研究了低电流密度下恒电流法制备的聚苯（ＰＡ）修饰电极的性质及其影响因素，探讨了低电流密度聚合的ＰＡ膜的优点。发现此种条件下聚合的ＰＡ膜具有较好的电荷传输能力，它不仅对Ｂｒ＾－，Ｔｌ＾＋／Ｔｌ等电对的氧化还原反应有更好的电催化活性，而且对Ｈ＾＋的Ｎｅｒｎａｓｔ响应也更接近理论值。     

In-channel indirect amperometric detection of nonelectroactive anions for electrophoresis on a poly(dimethylsiloxane) microchip

In the present paper, we describe a microfluidics-based sensing system for nonelectroactive anions under negative separation electric field by mounting a single carbon fiber disk working electrode (WE) in the end part of a poly(dimethylsiloxane) microchannel. In contrast to work in a positive separation electric field described in our previous paper (Anal. Chem. 2004, 76, 6902-6907), here the electrochemical reduction reaction at the WE is not coupled with the separation high-voltage (HV) system, whereas the electrochemical oxidation reaction at the WE is coupled with the separation HV system. The electroactive indicator is the carbon fiber WE itself but not dissolved oxygen. This provides a convenient and sensitive means for the determination of nonelectroactive anions by amperometry. The influences of separation voltage, detection potential, and the distance between the WE and the separation channel outlet on the response of the detector have been investigated. The present detection mode is successfully used to electrochemically detect F-, Cl-, SO4(2-), CH3COO-, H2PO4-. Based on the preliminary results, a detection limit of 2 microM and a dynamic range up to three orders of magnitude for Cl- could be achieved.     

Cu(phen)2+2和Cu(bpy)2+2与6-巯基嘌呤、腺嘌呤相互作用的研究

在ｐＨ为７．０的磷酸盐缓冲溶液中，用荧光光谱、紫外光谱、电化学及紫外光谱电化学等方法研究了铜配合物与６－巯基嘌呤、腺嘌呤的相互作用．结果表明，Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤发生了相互作用，但作用程度不同．根据荧光光谱实验数据计算出Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤的配位比均为１∶１；它们与６－巯基嘌呤作用的配位常数分别为２．２３×１０４Ｌ／ｍｏｌ和６．１１×１０４Ｌ／ｍｏｌ；与腺嘌呤作用的配位常数分别为１．９５×１０４Ｌ／ｍｏｌ和５．１２×１０４Ｌ／ｍｏｌ．电化学实验也获得了相近的结果．这为解释Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与ＤＮＡ的作用机理及作用部位提供了有益的信息     

Synthesis of porphyrin-appended terpyridine as a chemosensor for cadmium based on fluorescent enhancement

The design and synthesis of a porphyrin-appended terpyridine, 5-(4-([2,2′:6′,2″]-terpyridin-4-yl-carboxyamidyl)phenyl)-10,15,20-triphenylporphyrin (H₂TPPTPy) and its application as potential fluoroionophore for recognition of metal ions are reported. For preparation of the fluoroionophore, a novel simple strategy with improved total yield has been applied for the synthesis of 2,2′:6′,2″-terpyridine-4′-carboxylic acid as a ligand. H₂TPPTPy shows chelation-enhanced fluorescence effect with cadmium ion via the interruption of photoinduced electron transfer (PET) process, which has been utilized as the basis of the fabrication of the Cd(II)-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd(II)-sensitive chemosensor were investigated. It shows a linear response toward Cd(II) in the concentration range of 3.2 × 10⁻⁶ to 3.2 × 10⁻⁴ M with a limit of detection of 1.2 × 10⁻⁶ M. The chemosensor shows good selectivity for Cd(II) over a large number of cations, such as alkali, alkali earth and transitional metal ions except Cu(II) and Zn(II). The sensor has been used for determination of Cd(II) in water samples with satisfactory recoveries.     

毛细管区带电泳分离麦芽寡糖的研究

高效毛细管电泳是近年来分离科学中发展最为迅速的方法之一．它具有分离效率高、所需样品量极少、适合于生物大分子的分离测定和自动化程度高等特点．在毛细管电泳中，区带电泳作为主要的分离模式发挥了重要的作用［1］．本文中以麦芽寡糖类物质为对象，研究了离子流体动力学半径在分离中的作用和规律，提出了麦芽寡糖的迁移时间、淌度与其所含糖基数目的线性关系，并在不同的体系与操作电压下得到了验证．同时，也为利用毛细管电泳技术估算麦芽寡糖所含糖基数提供了简易的途径．1实验部分自行组装毛细管电泳电化学检测系统，高压电源0～30k…     

聚碱性品红修饰电极的制备及应用

研究了碱性品红在玻碳电极上聚合的最佳实验条件及其聚合机理，发现该修饰电极的多巴胺具有良好的催化作用，能大大提高多巴胺在的玻碳电极上的响应，在ｐＨ＝７．０的磷酸盐缓冲溶液中，用修饰电极测定巴胺的线性范围为２×１０＾－７～１×１０＾－５ｍｏｌ／Ｌ，检测限为１×１０＾－７ｍｏｌ／Ｌ，并且具有稳定性好，响应快，选择性等特点。     

碳纤维微电极研究(Ⅺ)——利用温度效应测定电极反应的热力学和动力学参数

研究了温度对碳纤维微电极上伏安曲线的影响及温度与电极电位的关系,测定了电极反应的热力学参数.由电流与温度的关系测定了去极剂的扩散活化能E_(al)和D_o,利用微电极具有高速传质的特性,测定了常规电极上为可逆反应的电极反应标准速率常数(?),并通过(?)与温度的关系测定了电极反应的活化能.     

Solid-contact potentiometric sensor for ascorbic acid based on cobalt phthalocyanine nanoparticles as ionophore

A novel solid-contact potentiometric sensor for ascorbic acid based on cobalt phthalocyanine nanoparticles (NanoCoPc) as ionophore was fabricated without any need of auxiliary materials (such as membrane matrix, plasticizer, and other additives). The electrode was prepared by simple drop-coating NanoCoPc colloid on the surface of a glassy carbon electrode. A smooth, bright and blue thin film was strongly attached on the surface of the glassy carbon electrode. The electrode showed high selectivity for ascorbic acid, as compared with many common anions. The influences of the amount of NanoCoPc at the electrode surface and pH on the response characteristics of the electrode were investigated. To overcome the instability of the formal potential of the coated wire electrode, a novel electrochemical pretreatment method was proposed for the potentiometric sensor based on redox mechanism. This resulting sensor demonstrates potentiometric response over a wide linear range of ascorbic acid concentration (5.5 × 10⁻⁷ to 5.5 × 10⁻² M) with a fast response (<15 s), lower detection limit (ca. 1.0 × 10⁻⁷ M), and a long-term stability. Furthermore, microsensors based on different conductors (carbon fiber and Cu wire) were also successfully fabricated for the determination of practical samples.     

The video-rate imaging of sub-10 nm plasmonic nanoparticles in a cellular medium free of background scattering

Plasmonic nanoparticles (e.g., gold, silver) have attracted much attention for biological sensing and imaging as promising nanoprobes. Practical biomedical applications demand small gold nanoparticles (Au NPs) with a comparable size to quantum dots and fluorescent proteins. Very small nanoparticles with a size below the Rayleigh limit (usually <30–40 nm) are hard to see by light scattering using a dark-field microscope, especially within a cellular medium. A photothermal microscope is able to detect very small nanoparticles, down to a few nanometers, but the imaging speed is usually too slow (minutes to hours) to image living cell processes. Here an absorption modulated scattering microscopy (AMSM) method is presented, which allows for the imaging of sub-10 nm Au NPs within a cellular medium. The unique physical mechanism of AMSM offers the remarkable ability to remove the light scattering background of the cellular component. In addition to having a sensitivity comparable to that of photothermal microscopy, AMSM has a much higher imaging speed, close to the video rate (20 fps), which allows for the dynamic tracking of small nanoparticles in living cells. This AMSM method might be a valuable tool for living cell imaging, using sub-10 nm Au NPs as biological probes, and thereby unlocking many new applications, such as single molecule labeling and the dynamic tracking of molecular interactions.

An absorption modulated scattering microscopy technique that allows for the imaging of sub-10 nm gold nanoparticles within a cellular scattering medium is presented.