基于荧光猝灭的磷酸盐光化学溶胶-凝胶传感膜

利用溶胶 -凝胶技术对荧光物质铝 -桑色素进行包埋 ,根据荧光猝灭原理制取了对水体中磷酸根离子有较好响应的光纤光化学传感膜 ;研究了温度、pH值对传感膜荧光强度的影响以及膜的响应时间、泄漏性、光稳定性及干扰情况等性能指标 ;该传感膜的响应时间t95 % =6min ,磷酸根离子的线性范围在0.1～7.0mg/L,检出限为0.02mg/L。

有机染料聚集在光化学传感中的应用

有机染料在可见-近红外光区具有较高的摩尔消光系数和良好的荧光发光性能,因而常被用于光谱化学传感中。通常有机染料分子含有较大的π体系,在溶液中易于通过分子间弱相互作用(氢键、卤键、亲疏水作用、π-π堆积作用、范德华力等)聚集形成具有特定结构的组装体,聚集过程往往伴有明显的颜色或光谱变化。若向染料分子中引入特定的官能团,与分析物结合诱导染料聚集/解聚产生明显的光谱变化,可用于对分析物的识别。聚集体可同时提供多个结合位点,并具有组装单元之间可调控的空间取向、较高的传感结合基团局部浓度。因此基于聚集过程的光化学传感表现出优越的传感灵敏度和选择性。本文结合本课题组近年来的研究工作综述了有机染料聚集在光化学传感中的应用,分别从诱导聚集、诱导解聚以及聚集重组三个方面展开讨论,并展望了此类荧光传感体系未来的研究与发展方向。

基于多指示剂的智能光化学pH传感技术

提出了一种宽范围的ｐＨ传感技术。含有单一指示剂的ｐＨ识别器的检测范围一般都比较窄，而把二种有着不同检测区域的ｐＨ指示剂结合在一起形成的ｐＨ识别器可扩大其检测范围。人工神经网络能够识别非常复杂的模式，使用它可充分地利用ｐＨ识别器对光信号的调制信息。

汞离子化学传感检测的研究与应用

汞是一种典型的剧毒重金属,痕量的汞能产生很强的毒性,在生物体具有累积性,严重影响人类的身体健康。因此低浓度水平汞的测量以及寻找能够快速准确检测汞离子的方法对包括人类在内的生命活动具有十分重要的意义。该文总结了近些年来对汞离子检测的常见仪器分析方法,重点综述了近年来关于汞离子的光化学传感和电化学传感检测方法研究及应用。

阴离子探针性质及应用的最新研究进展

由于阴离子在化学和生命过程中的重要作用,设计和合成生物学、医学和环境中重要阴离子的受体分子是当前超分子化学中迅速发展的研究领域之一,如酰胺、脲、胺基、酚羟基等氢键供体作为识别点,已被广泛应用于阴离子受体的设计和合成中.将荧光基团键联于这类受体的超分子识别体系,既具有选择性的识别阴离子性能,又具有在识别过程中灵敏的荧光响应和传感特性,对开发以阴离子识别为基础的在环境阴离子污染物监控、有害阴离子的医疗诊断和微量分析等方面的灵敏的荧光传感器具有重要意义和广阔的应用前景.本文对不同结构的阴离子受体脲、硫脲、胺基、酰胺等及它们对阴离子选择性识别和光化学传感的研究进展做了较详细的综述.

Study of a high-temperature and high-pressure FBG sensor with Al_2O_3 thin-wall tube substrate

A fiber Bragg grating(FBG) high-temperature and high pressure sensor has been designed and fabricated by using the Al2O3 thin-wall tube as a substrate.The test results show that the sensor can withstand a pressure range of 0-45 MPa and a temperature range of -10-300 ℃,and has a pressure sensitivity of 0.0426 nm/MPa and a temperature sensitivity of 0.0112 nm /

A selective optical chemical sensor for the determination of iodine based on fluorescence quenching of LiTOE

An optical chemical sensor has been developed for the determination of iodine based on the reversible fluorescence quenching of 2, 2, 7, 7, 12, 12, 17, 17-octamethyl-21, 22, 23, 24-tetraoxaquaterene-Li （LiTOE） immobilized in a plasticized poly（vinyl chloride） （PVC） membrane. The optimum membrane of the sensor consists of 100 mg of PVC, 200 mg of bis （2-ethytbexyl） sebacate （BOS） and 3.0 mg of LiTOE. The maximum response of the optode membrane for iodine is obtained in Tris-HCl buffer solutlon （pH 8.0）. With the optimum conditions described, the proposed sensor responds linearly in the measuring range of 3.90×10^-2 to 3.90×10^-4 mol/L, and has a detection limit of 6.0×10^-8 mol/L. The response time of the sensor is less than I rain. In addition to high reproducibility and reversibility of the fluorescence signal, the sensor also exhibits good selectivity. It is not interfered by some common anions and cations. It is applied for the determination of iodine in table salt samples. The results agree with those obtained by another method.

Fiber optic biosensor of immobilized firefly luciferase

Luciferase from firefly lantern extract was immobilized on CNBr activated Sepharose 4B. The kinetic properties of immobilized luciferase were extensively studied. The K m′ for D luciferin is 11.9 μmol/L, the optimum pH and temperature for Sepharose bound enzyme were 7.8 and 25℃ respectively. A luminescence fiber optic biosensor, making use of immobilized crude luciferase, was developed for assay of ATP. The peak light intensity was linear with respect to ATP concentration in range of 10 -9 -10 -5 mol/L. A biological application was also demonstrated with the determination of serum ATP from rats bred in low versus normal oxygen environments.

Facile synthesis of poly(aroxycarbonyltriazole)s with aggregation-induced emission characteristics by metal-free click polymerization

Regioseletive 1,3-dipolar polycycloadditions of 4,4'-isopropylidenediphenyl dipropiolate (1) and tetraphenylethene (TPE)-containing diazides (2) are carried out in polar solvents such as DMF/toluene at a moderate temperature of 100℃ for 6 h,producing poly(aroxycarbonyltriazole)s (PACTs) P3 with high molecular weights (Mw up to 23900) and regioregularities (F1,4 up to ～90%) in high yields (up to ～99%).These metal-free click polymerizations can propagate smoothly in an open atmosphere without protection from oxygen and moisture.The obtained polymers are soluble in common organic solvents and thermally stable at temperatures up to 375℃.Thanks to their contained TPE moieties,the PACTs show aggregation-induced emission and can serve as fluorescent chemosensors for superamplified detection of explosives.

New rhodamine derivative as OFF-ON fluorescent chemosensor for detection of Cu^(2+)

A novel fluorescence probe for the detection of Cu2+ has been designed and synthesized, which is based on a ring-opening reaction of spirolactam triggered by Cu2+ . This probe exhibits excellent Cu2+ ion selectivity as well as significant color changes visible to the naked eye at the concentration of 0.03 mM (ca. 2.0 mg/L), the WHO (World Health Organization) recommended level (2.0 mg/L) of Cu2+ ions in drinking water. This novel rhodamine-based fluorescence probe can be directly used to detect Cu2+ with satisfactory sensitivity and selectivity in aqueous solution.

Multifunctional two-dimensional glassy graphene devices for vis-NIR photodetection and volatile organic compound sensing

Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chemical sensing device is developed based on two-dimensional(2D) glassygraphene that meets similar property requirements for the two functionalities. An appropriate bandgap arising from the distorted lattice structure enables glassy graphene to exhibit comparable or even improved photodetection and chemical sensing capability, compared with pristine graphene. Due to strong interactions between glassy graphene and the ambient atmosphere, the devices are less sensitive to photoinduced desorption than the ones based on graphene. Consequently,the few-layer glassy graphene device delivers positive photoresponse, with a responsivity of 0.22 A W^(-1) and specific detectivity reaching ~10^(10) Jones under 405 nm illumination.Moreover, the intrinsic defects and strain in glassy graphene can enhance the adsorption of analytes, leading to high chemical sensing performance. Specifically, the extracted signalto-noise-ratio of the glassy graphene device for detecting acetone is 48, representing more than 50% improvement over the device based on graphene. Additionally, bias-voltage-and thickness-dependent volatile organic compound(VOC) sensing features are identified, indicating the few-layer glassy graphene is more sensitive. This study successfully demonstrates the potential of glassy graphene for integrated photodetection and chemical sensing, providing a promising solution for multifunctional applications further beyond.

A highly sensitive chemiluminescence sensor for detecting mercury(Ⅱ) ions: a combination of Exonuclease Ⅲ-aided signal amplification and graphene oxide-assisted background reduction

In this paper, we report a highly sensitive chemiluminescence(CL) sensor for Hg2+ ions based on thymine-Hg2+-thymine(T-Hg2+-T) coordination chemistry. We designed a thymine rich oligonucleotide as a capture probe and a signal probe that includes two functional domains: a horseradish peroxidase-mimicking DNAzyme domain for the generation of CL, and a recognition domain. Graphene oxide(GO) was introduced to adsorb the signal probe via π-π interaction, which brought the DNAzyme domain and GO into close proximity and quenches CL. In the presence of Hg2+ ions, the coordination of Hg2+ with the capture probe yielded a hairpin complex, triggers cascaded strand displacement reactions and Exonuclease III-assisted signal amplifications. As a result, accumulated amounts of DNAzyme were generated and released from GO, leading to an enhanced CL signal. This strategy combines enzyme-based signal amplification and GO as a background reducer, leads to a limit of detection(LOD) of 2 nmol/L. This simple detection system provides a label-free yet sensitive approach for detection of Hg2+ ions.

Fluorescent nanoparticles for chemical and biological sensing

Fluorescent nanoparticles (NPs), including quantum dots (QDs), dye-doped NPs, and rare earth-based NPs, etc., have been a major focus of research and development during the past decade. The impetus behind such endeavors can be attributed to their unique chemical and optical properties, such as bright fluorescence, high photostability, large Stocks shift and flexible processability. The introduction of fluorescent NPs into analytical chemistry has opened up new venues for fluorescent analysis. In this review, we focus on the developments and analytical applications of fluorescent NPs in the chemical and biological sensing of pH, ions, organic compounds, small biological molecules, nucleic acids, proteins, virus and bacteria. The review also points out the in vitro and in vivo imaging application of fluorescent NPs at the cell and body levels. Meanwhile, the ad- vantages of NPs brought field of sensing and signal transductions are also discussed.

One-step synthesis of fluorescent hydroxyls-coated carbon dots with hydrothermal reaction and its application to optical sensing of metal ions

Carbon dots (CDs) with average diameter of 3.1 ± 0.5 nm were facilely synthesized with candle soot through hydrothermal reaction in sodium hydroxide aqueous solution. The as-prepared CDs were covered with a lot of hydroxyls, possessed properties of good water-solubility, anti-photobleaching, salt tolerance, and low cytotoxicity, and had a fluorescence quantum yield (QY) of about 5.5%. The fluorescence of the hydroxyls-coated CDs could be selectively quenched by metal ions such as Cr3+, Al3+ and Fe3+, which is because these metals can easily combine with the hydroxyl groups on the surface of CDs and induce aggregation of hydroxyls-coated CDs. Experiments showed that the quenching of Cr3+ had a Sterm-Volmer constant of 1.03 × 107 M-1 with a liner range of 1.0-25.0 μM and detection limit of 60 nM (3σ).

Bifunctional fluorescent probes for hydrogen peroxide and diols based on a 1,8-naphthalimide fluorophore

This report discloses a series of naphthalimide-based bifunctional fluorescent probes for hydrogen peroxide and diols.As a result,these molecules not only demonstrated high turn-on fluorescent response and good selectivity towards hydrogen peroxide over other relevant reactive oxygen species,but also displayed different responses to diols.Therefore,these fluorescent probes could be served as sensitive,selective and practical chemosensors for both hydrogen peroxide and diols under physiologicallike conditions.

High-efficiency room temperature phosphorescence from amorphous metal-free copolymers

Photofunctional materials with room-temperature phosphorescence（RTP）commonly appeared in expensive metal-coordination complexes and rare-earth-based compounds.Recently,the metal-free organic RTP materials have been paid growing attention from scientific community because of the ease of molecular design,low cost as well as potential applications in molecular switches,chemical sensors and biological imaging.To date,efficient RTP materials with high quantum yield are still very limited due to the T_1-S_0 spinforbidden process and weak spin-orbital coupling.Current mechanism based on crystallization-induced or aggregationinduced phosphorescence may serve as an effective way to enhance the RTP[1,2];

Solid-state electrochemiluminescence protein biosensor with aptamer substitution strategy

One solid-state electrochemiluminescence （ECL） protein biosensor based on the competing reaction and substitute reaction between protein-to-DNA aptamer and DNA-to-DNA aptamer was proposed. Additionally, the biosensor was based on ECL photo-quenching effect of ferrocene （Fc） to tris（2,2-bipyridyl）ruthenium（II） （Ru（bpy）2＋）. It was built up by modification of Au nanoparticles （AuNPs） and Ru（bpy）32＋ on one Au electrode firstly, and then self-assembly of one special double-stranded DNA （dsDNA） onto the electrode. This dsDNA was prepared by hybridization of one Fc labeled molecular beacon single-stranded DNA（ssDNA） and one anti-thrombin aptamer ssDNA. Without the target protein, this Fc-dsDNA/Ru（bpy）2＋- AuNPs/Au elec- trode trigged strong ECL signal, so we called it ECL ＂signal on＂ state. When thrombin was present in the sensing solution, the protein reacted with its aptamer from the Fc-dsDNA/Ru（bpy）3^2＋-AuNPs/Au electrode. Then the left molecular beacon ssDNA on the electrode recovered to its normal stem-loop structure and consequently its Fc labeler was close enough to the electrode surface to quench the ECL signal from Ru（bpy）3^2＋. It was in ECL ＂signal off＂ state. We measured the decrease in ECL intensity to sense the target protein. This was one endeavour to sense protein by using un-labeling target or probe strategy, which gave higher sensitivity and selectivity due to the better combination efficiency of protein and the un-labeled aptamer. 6.25 fmo/L thrombin was detected out,

Non-stoichiometry in Ca2Al2SiO7 enabling mixedvalent europium toward ratiometric temperature sensing

Eu^2+/Eu^3+ mixed-valence couple co-doped material holds great potential for ratiometric temperature sensing owing to its different electronic configurations and electron-lattice interaction. Here, the correlation of nonstoichiometry in chemical composition, phase structures and luminescence propertis of Ca2 Al2 Si1-xO7:Eu is discussed, and controlled Eu^2+/Eu^3+ valence and tunable emission appear with decreasing Si content. It is found that the 2 Ca^2++ Si^4+←→ Eu^2++ Eu^3++ Al^3+ cosubstitution accounts for the structural stability and charge balance mechanism. Benefiting from the diverse thermal dependent emission behaviors of Eu^2+ and Eu^3+, Ca2 Al2 Si1-xO7:Eu thermometer exhibits excellent temperature sensing performances with the maximum absolute and relative sensitivity being 0.024 K-1(at 303 K) and 2.46% K-1(at 443 K) and good signal discriminability. We propose that the emission quenching of Eu^2+ is ascribed to 5 d electrons depopulation through Eu^2+/Eu^3+ intervalence charge transfer state, while the quenching of Eu^3+ comes from multiphonon relaxation. Our work demonstrates the potential of Ca2 Al2 Si1-xO7:Eu for noncontact optical thermometry, and also highlights mixed-valence europium-containing compounds toward temperature sensing.

Analyzing excited-state processes and optical signatures of a ratiomeric fluorine anion sensor: a quantum look

Recently, the spectroscopic signatures of a benzoselenadiazole derivative have been investigated in the framework of designing a new ratiometric fluoride sensor （Saravanan et al., Org Lett, 2014, 16： 354-357）. It was suggested that this sensor is un- dergoing excited-state intramolecular proton transfer. In this work, we provide a new look at these experimental data, using a state-of-the-art time-dependent density fimctiona/theory approach to mimic the spectroscopic signatures. New insights about the nature of the excited-state processes are obtained.