硫化氢气体传感器研究

随着科学技术的发展,在科研与生产中,使用气体做原料、燃料情况增多,这些气体比如硫化氢是有毒的,危害性很大,它们在使用与运输中易造成大气和环境污染,危害人类,因此对于各种气体的检测和控制就更重要。近年来,传感器在朝着灵敏、精确、适应性强、小巧和智能化的方向发展。在这一过程中,人们开始综合分析光学气体检测基础上,利用硫化氢气体对光谱的吸收特性,采用光谱吸收法检测硫化氢气体浓度。采用宽带光源波长调制技术设计检测硫化氢气体浓度传感器,利用光源光波对气体吸收选择性,增大了气体吸收灵敏度。降低了交叉灵敏度,解决了传感器中毒等关键技术问题。所以．研究硫化氢气体的检测方法与气体传感器就成为重要课题了。     

碳基导电材料在传感检测分析中的应用研究进展

碳基导电材料是指以碳原子为骨架的材料体系,具有结构多样、可调控性强和化学稳定性高等优异性能。将碳基导电材料引入传感检测分析可以改善传感器的信号强度,提高传感检测分析的稳定性。与传统材料制成的传感器相比,使用碳基导电材料制备的传感器检测分析物质具有更高的灵敏度、更低的检测限及更宽的线性范围。因此,基于碳基导电材料的检测分析技术已显现出巨大的潜力,在医学诊疗、环境监测和食品检测等领域均具有广阔的应用前景。本文介绍了以维度划分的碳基导电材料的类别及其所制备的传感器在传感检测分析中的应用,提出了碳基导电材料及其所制备的传感器在检测分析物质中存在的问题及挑战,并对未来研究的趋势进行了展望。     

硫化氢气体的危害性及其检测方法

由于硫化氢是一种剧毒和强腐蚀性气体，对它进行适时的检测和监测尤为必要。本文对硫化氢的各种检测技术，特别是电化学技术及新兴的传感器技术作了较为全面的论述。     

石墨烯/卟啉复合气凝胶的制备与性能研究

石墨烯气凝胶既有石墨烯材料固有的柔性及优异的电学、力学性能，同时又具有高比表面积、低密度、大孔隙率等特点，其独特的三维结构有利于引入其他功能材料，从而赋予复合材料更为优异的性能。原卟啉分子具有高度共轭结构，并且与金属离子配位结合后可发挥催化功能。鉴于此，本工作利用原卟啉分子与石墨烯片层的π-π相互作用，在石墨烯气凝胶上组装一定浓度的原卟啉分子，从而制备了石墨烯/卟啉复合气凝胶材料。该方法工艺简单，容易操作。本工作分析了复合气凝胶材料的微观形貌和成分组成，研究了原卟啉分子的组装对石墨烯气凝胶导电性能的影响，以及石墨烯/卟啉复合气凝胶对硝酸根离子(NO₃^-)的检测作用。研究结果表明所制备的复合材料具有均匀的三维多孔结构，原卟啉分子的引入可以显著降低石墨烯气凝胶的电阻，而三维气凝胶结构可以有效地实现原卟啉与石墨烯的复合并实现对NO₃^-的灵敏检测。     

硫化氢气体的危险性及其检测方法

由于硫化氢是一种剧和强腐蚀性气体、对进行地的检测和监测九为必要。本文地硫化氢的各种检测技术，特别是电化学技术及新兴的伟传感器技术作了较为全面的论述。‘化     

三维过渡金属材料在非酶葡萄糖电化学传感器中的研究进展

非酶电化学传感器因其灵敏度高、稳定性强、价格低廉等优点受到广泛关注,将非酶电化学传感器应用于葡萄糖浓度的检测对于医疗健康具有重要的意义.三维过渡金属电极材料具有独特的网络结构,能够提供足够的催化活性位点和扩散通道,确保了电极的灵敏度和稳定性.综述了常见三维过渡金属电极的类型、特点及其在非酶葡萄糖电化学传感器中的应用.最...     

电极结构对高分子电阻型湿度传感器性能的影响

本文以聚苯乙烯磺酸钠为湿敏材料,制备了以金叉指电极为基底的高分子电阻型湿度传感器。研究了电极基片材料和叉指电极构型对传感器湿敏响应特性的影响。研究表明,采用多孔结构的基片材料可降低传感器电阻,增强湿敏膜与基片的结合能力从而提高传感器的稳定性;叉指电极构型对传感器的电阻大小有一定影响,增加电极中心线间距离使传感器的稳定性提高。     

基于复合金属氧化物的三乙胺气体传感器研究进展

随着市场对有机挥发性气体检测需求的提高,半导体气体传感器因其工作温度低、循环稳定性良好、响应恢复时间短等特性受到了广泛关注。三乙胺是一种重要的化工原料,然而,其挥发性特性及刺激性气味和低毒性对人类的生命安全造成了威胁。近年来国内外有不少三乙胺气体检测的研究论文和产品介绍,但全面性的综述文章极少。本文以前期学者对三乙胺气体检测的工作为抓手,首先讲述了三乙胺传感器的响应机理和提高气敏响应的内在因素,总结了以不同金属氧化物为基质的复合型半导体传感器对三乙胺气体的检测情况,并详细介绍了不同材料形貌与气敏性能之间的关系。另外,对部分材料的气敏增强机理作了简要概述。最终,对三乙胺气体传感领域做出展望,并为后续开展相关领域工作提供了理论基础。     

GMI磁传感器的灵敏度和噪声研究现状

基于软磁非晶材料巨磁阻抗(giant magneto impedance,GMI)效应的传感器是近年来磁传感器领域的研究热点之一。GMI磁传感器具有微型化、高灵敏度、快速响应、高温度稳定性和低功耗等特点,在微弱磁场检测方面,具有广阔的应用前景。而高灵敏度与低噪音对GMI传感器尤为重要。然而,由于GMI效应及应用是近十几年刚刚发展起来的新领域,人们更多的关注GMI效应的基础理论研究,而GMI传感器相关理论研究相对较少。基于此,一方面介绍了GMI磁传感器灵敏度和噪声的国内外研究现状,同时介绍了GMI传感器的应用情况。     

卟啉衍生物功能化石墨烯材料的光电性能新进展

石墨烯是一种新型二维近似平面结构的碳纳米材料,具有非常卓越的光电性能,为更好地发挥其优异性能,对其表面功能化改性颇受人们关注。重点阐述了卟啉类衍生物对石墨烯的共价和非共价功能化修饰及通过共价和非共价方式构筑其纳米复合材料和此纳米材料在非线性光学和电化学传感器制备等应用中的最新研究进展,并展望了石墨烯卟啉杂化材料在相关领域里的应用。     

Porphyrin colorimetric indicators in molecular and nano-architectures

One of the most important outcomes of organic nanotechnologies could be development of well-integrated systems for sensing of particular chemical species. Use of color indicators is an attractive approach to guest reporting. Of the known chromophores, porphyrin and its derivatives are the most widely studied functional chromophores in a diverse range of research fields. In this review, recent developments in colorimetric indicator functions of porphyrin derivatives and related compounds in their molecular and nano-architectures are reviewed according to the classification: (i) rather simple porphyrin derivatives, (ii) porphyrin conjugates, (iii) porphyrins embedded in bulk materials, and (iv) porphyrins in organized films. Porphyrin derivatives with unusual structures, such as expanded and N-confused ones have been used for color indicators in specific cases. Electron and energy transfers in porphyrins conjugated with other functional moieties resulted in dynamic sensing systems including switch-on and switch-off actions. Immobilization of porphyrin color indicators in appropriate matrices is important for practical applications. Use of supramolecular films such as self-assembled monolayers, Langmuir-Blodgett films, and layer-by-layer assemblies as porphyrin nanoarchitectures often offers opportunities for colorimetric outputs based on control of their aggregate structures.     

Laser fluorometric detection of porphyrin methyl esters for high-performance thin-layer chromatography

A new detection method is presented for the determination of porphyrins present in biological materials. Separation is accomplished by high-performance thin-layer chromatography after esterification of individual carboxylic acid porphyrins. Detection is achieved by utilizing one of the visible lines of an argon-ion laser for fluorometric excitation. Good selectivity and detectability are demonstrated for the determination of porphyrin profiles in human urine. The detection limits for uro-, heptacarboxy-, hexacarboxy-, pentacarboxy-, copro-, and mesoporphyrin methyl esters are in the 18-35 pg range.     

On-line LC-MS analysis of urinary porphyrins

A reversed-phase high-performance liquid chromatography-mass spectrometry (LC-MS) method is described for the separation and simultaneous analysis of porphyrins related to disorders of heme biosynthesis (uro-, heptacarboxylic, hexacarboxylic, pentacarboxylic, and coproporphyrins). The method involves initial porphyrin esterification and extraction from urine. Detection and quantification is performed from the extracts by separation with a Hypersil BDS column and on-line detection by MS through coupling with an atmospheric pressure chemical ionization interface. The porphyrin esters are detected as protonated molecules [M + H]+. Their mass spectra also exhibit an [M + Na]+ fragment of lower intensity. The analytical performance of this method is compared with those of LC with UV and fluorescence detection. LC-MS used in selective [M + H]+ ion monitoring provides the lowest detection and quantitation limits. In scan mode, this LC-MS method affords, without further isolation or concentration steps, the measurement of mass spectra of unknown compounds present in the urine of patients with altered porphyrin excretion.     

Highly sensitive optical waveguide sensor for SO2 and H2S detection in the parts-per-trillion regime using tetraaminophenyl porphyrin

ABSTRACT

Optical waveguide (OWG) sensors present great potential for detecting trace levels of harmful gases because of their high sensitivity and anti-electromagnetic interference. However, OWG-based SO2 and H2S-detecting sensors in the parts-per-trillion (ppt) range are still lacking. We fabricated 5,10,15,20-(tetra-4-aminophenyl) porphyrin (TAPP) thin film-based OWG sensor devices (TAPP-OWG) to detect SO2 and H2S gases, in which TAPP thin film was immobilized over the surface of a potassium ion exchange glass OWG. These sensors successfully measure extremely low concentrations of SO2 and H2S (detection limit?=?1 ppt), providing good repeatability for SO2 (10 ppt) and H2S (10 ppt) gases, with relative standard deviations of 1.67% and 3.68%, respectively. With fast response (t1) and recovery (t2) times for SO2 (t1=4 s, t2=157 s) and H2S (t1=2 s, t2=117 s) at room temperature, TAPP thin film enhances the potential of OWGs for use in high-sensitivity trace-level gas detection.     

Optical determination of bacterial exosporium sugars using immobilized porphyrins

Three porphyrins were tested as possible candidates for identification and quantification of the presence of sugars known to be contained in the exosporium of the bacterial endospores of some Clostridium and Bacillus species. The effect of the sugars on both absorbance and fluorescence characteristics of the immobilized porphyrins was investigated for possible application as a wipe test to indicate the presence of these sugars. Changes in porphyrin absorbance spectra were unique for each sugar with limits of detection as low as 2 ppb using immobilized porphyrins and 0.2 ppb using porphyrins in solution. Meso-tetra(4-boronic acid) porphyrin (TPPB) is likely the most useful porphyrin of those tested for detection of the sugars. Detection of methyl a-L-rhamnopyranoside between 13 and 1450 parts per billion (ppb), L-rhamnose between 15 and 150 ppb, L(-)-fucose between 80 and 1300 ppb, and D(+)-galactosamine between 18 and 1700 ppb is demonstrated using TPPB.     

Near unity photon-to-electron conversion efficiency of photoelectrochemical cells built on cationic water-soluble porphyrins electrostatically decorated onto thin-film nanocrystalline SnO₂ surface

Thin transparent SnO(2) films have been surface modified with cationic water-soluble porphyrins for photoelectrochemical investigations. Free-base and zinc(II) derivatives of three types of cationic water-soluble porphyrins, (P)M, viz., tetrakis(N-methylpyridyl)porphyrin chloride, (TMPyP)M, tetrakis(trimethylanilinium)porphyrin chloride, (TAP)M, and tetrakis(4'-N-methylimidazolyl-phenyl)porphyrin iodide, (TMIP)M, (M = 2H or Zn) are employed. The negative surface charge and the porous structure of SnO(2) facilitated binding of positively charged porphyrins via electrostatic interactions, in addition to strong electronic interactions in the case of (TMPyP)M binding to nanocrystalline SnO(2). The SnO(2)-porphyrin binding in solution was probed by absorption spectroscopy which yielded apparent binding constants in the range of 1.5-2.6 × 10(4) M(-1). Both steady-state and time-resolved fluorescence studies revealed quenching of porphyrin emission upon binding to SnO(2) in water suggesting electron injection from singlet excited porphyrin to SnO(2) conduction band. Addition of LiClO(4) weakened the ion-paired porphyrin-SnO(2) binding as revealed by reversible emission changes. Over 80% of the quenched fluorescence was recovered in the case of (TMPyP)M and (TAP)M compounds but not for (TMIP)M suggesting stronger binding of the latter to SnO(2) surface. Photoelectrochemical studies performed on FTO/SnO(2)/(P)M electrodes revealed incident photon-to-current conversion efficiencies (IPCE) up to 91% at the peak maxima for the SnO(2)-dye modified electrodes, with very good on-off switchability. The high IPCE values have been attributed to the strong electrostatic and electronic interactions between the dye, (TMPyP)M and SnO(2) nanoparticles that would facilitate better charge injection from the excited porphyrin to the conduction band of the semiconductor. Electrochemical impedance spectral measurements of electron recombination resistance calculations were supportive of this assignment.     

A Perspective on the Trends and Challenges Facing Porphyrin‐Based Anti‐Microbial Materials

The emergence of multidrug resistant bacterium threatens to unravel global healthcare systems, built up over centuries of medical research and development. Current antibiotics have little resistance against this onslaught as bacterium strains can quickly evolve effective defense mechanisms. Fortunately, alternative therapies exist and, at the forefront of research lays the photodynamic inhibition approach mediated by porphyrin based photosensitizers. This review will focus on the development of various porphyrins compounds and their incorporation as small molecules, into polymers, fibers and thin films as practical therapeutic agents, utilizing photodynamic therapy to inhibit a wide spectrum of bacterium. The use of photodynamic therapy of these porphyrin molecules are discussed and evaluated according to their electronic and bulk material effect on different bacterium strains. This review also provides an insight into the general direction and challenges facing porphyrins and derivatives as full‐fledged therapeutic agents and what needs to be further done in order to be bestowed their rightful and equal status in modern medicine, similar to the very first antibiotic; penicillin itself. It is hoped that, with this perspective, new paradigms and strategies in the application of porphyrins and derivatives will progressively flourish and lead to advances against disease.     

Speciation of new tri- and tetra-glucoconjugated tetrapyrrolic macrocycles (porphyrins and chlorins): an electronic molecular spectroscopy study

In this work, we study the physicochemical properties of some newly developed glycoconjugated photosensitizers that can be used in photodynamic therapy (PDT) of cancers: meso-tri- and tetra-(meta-O-beta-D-glucosyloxyphenyl)porphyrins and meso-, tri-, and tetra-(meta-O-beta-D-glucosyloxyphenyl)chlorins. Their properties are compared to the non-glycosylated hydroxylated parent compounds meso-tetra-(meta-hydroxyphenyl) porphyrin and meso-tetra-(meta-hydroxyphenyl)chlorin. It was found that at the ground state, all porphyrins present, independent of the substitution, have the same mean ionization constant (pKa = 2.7), corresponding to two indistiguishable steps of protonation of tetrapyrrolic nitrogens. On the other hand, in the case of chlorins, one proton process can be observed and the corresponding nitrogen exhibits a slightly superior basicity (pKa = 3.0) with respect to porphyrins. Hydroxylated compounds present a second transition at high pH corresponding to the ionization of phenol groups (pKa = 10.5). Consequently, all photosensitizers are not charged at physiological pH (approximately 7.4), and so the ionization process does not influence their activity in biological media. Ionization induces very important variations in photosensitizer absorption and emission spectra. For example, absorption in the red region (band V), one of the most important characteristics of a good photosensitizer, is only important for diprotonated porphyrins and neutral chlorins. As far as fluorescence emission is concerned, neutral chlorins are almost six times more fluorescent than the corresponding neutral porphyrins (phi(chlorin)/phi(porphyrin) approximately = 6). It should be emphasized that the spectra modifications induced by pH variations can find interesting applications in the optimization of visible and fluorescence detection in high-performance liquid chromatography (HPLC) as well as in the development of direct, rapid fluorimetric analytical methods.     

New Organic Electrode Materials for Ultrafast Electrochemical Energy Storage

Organic materials are both environmentally and economically attractive as potential electrode candidates. This Research News reports on a new class of stable and electrically conductive organic electrodes based on metal porphyrins with functional groups that are capable of electrochemical polymerization, rendering the materials promising for electrochemical applications. Their structural flexibility and the unique highly conjugated macrocyclic structure allows the produced organic electrodes to act as both cathode and anode materials giving access to fast charging as well as high cycling stability. The extreme thermal and chemical stability of the porphyrin‐based organic electrodes and their chemical versatility suggest an important role for these molecular systems in the further development of novel electrochemical energy storage applications.     

Plasmon Enhanced Fluorescence Based on Porphyrin–Peptoid Hybridized Gold Nanoparticle Platform

A porphyrin–peptoid‐hybridized silica‐coated gold nanoparticle is developed, which is inspired by the protein–chlorophyll ensemble found in photosynthetic antenna. In the natural antenna, chlorophylls are integrated into dense assemblies that are supported by frameworks of proteins, which ensure optimal pigment arrangement for effective light harvesting. In the subject platform, porphyrins are conjugated to the peptoid helix scaffold in a structurally well‐defined alignments and subsequently immobilized on the surface of nanoparticles. This prevents intermolecular aggregation among porphyrins and allows high resolution analysis of the effect of porphyrin configuration on the optical properties of the system. Interestingly, under the influence of plasmon from the gold nanoparticle core, the fluorescence of porphyrin is enhanced up to 24‐fold at the wavelength where the plasmon resonance matches the porphyrin excitation wavelength. In addition, differences in porphyrin configuration result in spectral modification of their fluorescence emissions. Particularly, the peptoid bearing two porphyrins at a distance of 6 Å shows the most significant alteration in fluorescence. The platform can facilitate extensive studies on the relationship between porphyrin arrangement design and their photophysical interaction in antenna complexes.