氧化石墨烯修饰倾斜光纤光栅10–12级重金属离子传感

设计了一种氧化石墨烯(GO)功能化的倾斜光纤光栅(TFBG)传感器,用于检测水溶液中的重金属离子.通过氧等离子体活化光纤表面,以及采用GO的无水乙醇分散液,避免了咖啡环效应引起的GO的团聚和堆叠,充分了暴露GO的表面和羧基.吸附重金属离子后, GO-TFBG传感器的透射光谱中的谐振峰发生红移,这是由GO向重金属离子的电子转移导致的有效折射率变化造成的.对Pb²⁺和Cd²⁺离子最低检测限可达到10^–10 mol/L (ng/L量级),相应灵敏度分别为0.426 d B/(nmol·L^–1)和0.385 d B/(nmol·L^–1)(2.06和3.43 d B/(μg·L^–1)).此外, GO-TFBG传感器具有出色的器件一致性, 5组传感器的传感性能稳定.本研究实现了GO纳米片在光纤表面的无团聚和均匀成膜,获得了具有超大表面积的GO并充分暴露表面羧基实现对重金属离子的吸附,利用了TFBG不同模式谐振对环境的高度敏感性,完成了对低浓度重金属离子的高灵敏度、可重...     

Rhodamine B-Coated Gold Nanoparticles as Effective “Turn-on” Fluorescent Sensors for Detection of Zinc II Ions in Water

We designed a fluorescence resonance energy transfer system consisting of fluorophore Rhodamine B and gold nanoparticles for sensing of zinc ions in aqueous solution. The electrostatic attraction between positively charged N-atoms in Rhodamine molecules and negatively charged citrate corona of gold nanoparticles led to substantial fluorescence quenching. However, the quenching is switched off in the presence of zinc ions and therefore the system can be used as an effective “turn-on” fluorescence sensor. UV-Vis absorption, fluorescence spectroscopy, and transmission electron microscopy were used for sensor evaluation. The approach of “turn-on” fluorescence has real potential for sensing metallic ions in water.     

Evaluation of cerium doped tin oxide nanoparticles as a sensitive sensor for selective detection and extraction of cobalt

Chemo-sensor technology demands to design a single, preconcentrator based sensing system having higher sensitivity, sufficient selectivity and efficient removal of metal ions with simple operating and recognition methodology. Here we effectively deliberated Ce doped SnO₂ nanoparticles based sensing system which can be exploited for the recognition and extraction of Co(II) ions in a single step by strong interaction between Ce doped SnO₂ nanoparticles and Co(II). The sensing ability of Ce doped SnO₂ nanoparticles were deliberated for a selective removal of cobalt using inductively coupled plasma-optical emission spectrometry. The sensing ability of Ce doped SnO₂ is studied for various metal ions, such as Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ni(II) and Zn(II) but the designed sensor was most selective toward Co(II) which was 5000 time more sensitive to Co(II) rather than different interfering metal ions. In addition, the desorption study for regeneration of Ce doped SnO₂ nanoparticles was carried out. This novel approach provides a new route for simultaneous detection and removal of Co(II) in a single step and can be a time and cost alternative tool for environmental safety.     

基于石墨相氮化碳量子点直接荧光猝灭法检测碘离子的研究

石墨相氮化碳(g-C₃N₄)荧光纳米材料具有原料便宜、制备容易、荧光量子产率高、光学稳定性好、毒性低等优点,并且避免有机荧光染料复杂的合成步骤或者金属半导体量子点对环境潜在的危害,这些优点使得g-C₃N₄纳米材料成为新兴的荧光探针用于检测金属离子。最近,已有文献报道重金属汞离子能够高灵敏高选择性地猝灭g-C₃N₄量子点的荧光,加入碘离子能够提取被键合的汞离子形成碘化汞(HgI₂)进而恢复g-C₃N₄量子点的荧光,从而建立一种高灵敏检测碘离子的荧光传感器。然而,该方法依然需要重金属汞离子的参与,限制了该方法的推广应用。通过硝酸氧化块体g-C₃N₄并结合水热法处理制备了一种水溶性好、荧光强度高的g-C₃N₄量子点。该量子点的荧光发射波长位于368 nm,且其荧光发射波长不随激发波长的改变而改变,表明该量子点的尺寸比较均一。笔者发现碘离子在220 nm处有一个较强的吸收峰,与该量子点的激发光谱(中心波长245 nm)具有较大的重叠,从而产生内滤效应引起该量子点的荧光发生猝灭。利用这一性质,构建了一种选择性检测碘离子的新型荧光传感器。在最优检测条件下,g-C₃N₄量子点的荧光猝灭强度(ΔF)与碘离子浓度(X,μmol·L-1)在10～400 μmol·L-1之间具有良好的线性关系,线性方程为ΔF=0.325 79X+6.039 05(R2=0.999 5),检出限为5.0 μmol·L-1。通过“混合即检测”并且不需要借助与重金属离子的配位作用就能够检测碘离子,因此该方法具有快速、环保以及操作简便等优点。     

基于XRD与SEM研究风淬渣微粉用于重金属污染土壤的修复机理

钢渣是冶金工业中产生的主要固体废弃物,其产量约为每年粗钢产量的15%~20%。由于技术的局限,导致我国钢渣利用率较低,仅为年钢渣产量的10%,同时加之管理制度的不健全,导致钢渣大量露天堆放,对土地资源、地下水源,以及空气质量形成严重影响。面对上述问题,利用钢渣开发一种价格低廉的固化药剂用于重金属污染土壤的修复,既是冶金固体废弃物可持续发展的重要途径之一,也是大幅降低重金属污染土壤修复成本的重要途径之一。该研究创新性是用风淬渣微粉作为固化药剂对含有Cd,Cu,Pb,Ni和Zn的重金属污染土壤进行修复。研究了风淬渣粉磨时间、风淬渣微粉掺量和养护时间对修复重金属污染土壤效果的影响。利用激光粒度分析仪测试风淬渣微粉的粒度分布、比表面积与孔隙度吸附仪测试风淬渣微粉的孔结构、扫描电子显微镜测试风淬渣微粉-重金属污染土壤混合物的微观形貌、X-射线衍射仪测试风淬渣微粉的矿物成分,分析风淬渣微粉修复重金属污染土壤的机理。结果表明,风淬渣的性质安全,对生态环境不存在污染,可以用于修复重金属污染土壤的固化技术。当风淬渣粉磨时间为100 min、风淬渣微粉掺量为20%、养护时间为14 d时,风淬渣微粉对重金属污染土壤中Cu,Cd,Ni,Zn和Pb的固化效果均达到91%以上。随着风淬渣粉磨时间的延长,风淬渣微粉的粒径尺寸减小、粒度分布趋向均匀。风淬渣的多孔结构破坏、比表面积提高,有利于提高风淬渣微粉对重金属污染土壤的修复效果。随着风淬渣微粉掺量的增加,风淬渣微粉形成的水化凝胶（C-S-H）数量增加,有利于提高风淬渣微粉包裹重金属污染土壤的效果,以达到固化重金属污染土壤中Cd,Cu,Pb,Ni和Zn的目的。风淬渣微粉对固化重金属污染土壤中Cu,Cd,Ni,Zn和Pb具有选择性,在不同养护时间下,重金属分别以Cd₂SiO₄,Cu(OH)₂·2H₂O,PbCO₃,3Ni(OH)₂·2H₂O,Ni₂SiO₄,Zn(OH)₂和Zn₂SiO₄形式存在。     

Surface enhanced Raman spectroscopic readout on heavy metal ions based on surface self assembly

A new method is reported for detecting heavy metal ions by using the self assembled monolayer (SAM) technique and surface enhanced Raman spectroscopy (SERS). The p‐mercaptobenzoic acid (MBA) served as the SERS readout molecule and the modified tag to attach on the smooth gold substrate as well as the tag of nanoparticles by the SAM method. Two carboxyl groups from MBA molecules which were attached respectively to gold substrate and gold nanoparticles were linked through the heavy metal ions (Cu²⁺, Pb²⁺ and Zn²⁺) as bridge, and thus sandwich structure of ‘MBA modified gold substrate/heavy metal ions/MBA modified gold nanoparticles’ was built for detection. The observation of the oxidation peak of metal nanoparticles from cyclic voltammetry (CV) curve, gold nanoparticles from scanning electron microscopy (SEM) images and SERS signal of MBA from the sandwich structure indicated the existence of heavy metal ions. The difference in the wavenumbers of vibrational modes from MBA in the sandwich structure constructed by different could be used to identify different heavy metal ions. The assembled structure was rinsed by strong chelator of EDTA solution to remove the heavy metal ions from the sandwich structure and thus to obtain a fresh gold substrate modified with MBA for the cyclic detection. Copyright © 2007 John Wiley & Sons, Ltd.     

Rhodamine-Based Cu2+ -Selective Fluorosensor: Synthesis, Mechanism, and Application in Living Cells

A rhodamine B-based fluorescence probe (1) for the sensitive and selective detection of Cu²⁺ ion has been designed and synthesized using pyridine moiety. The optical properties of this compound have been investigated in acetonitrile-water binary solution (7:3 v/v). Compound 1 is found to be an excellent sensor for a biologically/physiologically very important transition metal ion (Cu²⁺) using only the two very different modes of measurements (absorption and emission); one case displayed intensity enhancement whereas in other case showed intensity depletion (quenching). A mechanistic investigation has been performed to explore the static nature of quenching process. The sensor has been found to be very effective in sensing Cu²⁺ ion inside living cells also.     

InGaAs单光子探测器传感检测与淬灭方式

针对InGaAs单光子雪崩光电二极管(SPAD)的光电感应特性,研究了基于门控主动式淬灭的SPAD动态偏置控制和电路实现的策略.采用门控主动淬灭控制可降低淬灭时间,有效抑制暗计数和后脉冲效应.接口感应检测电路采用标准互补金属氧化物半导体(CMOS)工艺进行制造,而SPAD则采用非标准CMOS工艺.利用铟柱互连混合封装工艺实现SPAD与感应接口电路的协同工作.在低温-30?C的条件下,实现了SPAD光触发雪崩电流信号的提取和快速淬灭.研究了感应电阻和临界检测电压对传感检测电性能的影响,并采用简单电路结构实现状态检测,实测得到的SPAD恢复时间、传输延时分别为575,563 ps,淬灭时间为1.88 ns,满足纳秒级精度传感检测应用的需要.     

Off-on Fluorescent Sensor from On-off Sensor: Exploiting Silver Nanoparticles Influence on the Organic Fluorophore Fluorescence

Turn-off fluorescence of organic fluorophore, 2-{[4-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-phenyl]carboxylic acid (NTPC), with metal ions (Fe³⁺, Cu²⁺, Pb²⁺) was converted into turn-on fluorescent sensor for biologically important Zn²⁺, Cu²⁺ and Fe³⁺ metal ions in aqueous solution at ppb level by exploiting strong fluorescence quenching phenomena of metal nanoparticles when organic fluorophores assembled in the vicinity of metallic surface. Amino acid attached phenolic ligands (L) were used as reducing as well as functional capping agents in the synthesis of silver nanoparticles (AgNPs). The hydrogen bonding functionality of L facilitated the assembling of NTPC in the vicinity of metallic surfaces that leads to complete quenching of NTPC fluorescence. The strong and selective coordination of L with metal ions (Zn²⁺, Cu²⁺ and Fe³⁺) separates the NTPC from the AgNPs surface that turn-on the NTPC fluorescence. HR-TEM and absorption studies confirm the metal coordination with L and separation of NTPC from the AgNPs surface. Mn²⁺ showed selective red shifting of NTPC fluorescence after 12 h with all sample. Effects of different amino acid attached phenolic ligands were explored in the metal ion sensitivity and selectivity. This approach demonstrates the multifunctional utility of metal NPs in the development of turn-on fluorescence sensor for paramagnetic heavy metal ions in aqueous solution.

Fluorescence sensor for Cu(II) based on R6G derivatives modified silicon nanowires

A fluorescence sensor for selective detection of Cu(II) is realized by covalently immobilizing derivatives of rhodamine6G (R6G) on the surface of silicon nanowires (SiNWs). It features the release of R6G from the SiNWs in the presence of Cu(II), which causes a significant enhancement of the fluorescence over other metal ions. The present Cu(II) sensor has good selectivity and sensitivity, and exhibits a linear response in the range of 0.0-7.0 μM Cu(II). Different from conventional Cu(II) sensor with fluorescence quenching, the present sensor based on fluorescence enhancement facilitates the practical application. Especially, the release of the R6G from SiNWs could be utilized as fluorescent labeling for Cu(II) in microenvironment.     

太赫兹时域光谱技术的重金属离子吸附检测方法研究

随着工业化进程的不断推进,水体重金属污染问题日益严重。秸秆具有来源广泛、价格低廉、易再生等优点,故成为水体重金属污染处理的理想吸附剂。为研究太赫兹波技术在水体重金属污染检测的应用前景,实验选取原始秸秆和碱化秸秆分别对重金属离子进行吸附,利用太赫兹时域光谱技术(THz-TDS)在室温氮气环境下对原始秸秆样品、碱化秸秆样品、原始秸秆吸附重金属离子样品、碱化秸秆吸附重金属离子样品和碱化秸秆吸附重金属离子解吸后的样品进行光谱测量,秸秆经碱化处理后处于1.75～1.85 THz的杂合吸收峰带吸收系数有明显下降,并伴有肩峰式吸收带后移的现象,在吸附重金属离子后,原始秸秆样品中原有的1.75～1.85 THz杂合吸收带消失,却在1.8～2.05 THz形成了杂合吸收带。碱化秸秆在1.7～2.05 THz呈现复杂的多个肩峰式吸收,而碱化秸秆吸附重金属样品在1.7～2.05 THz呈现平滑的强吸收带,碱化秸秆吸附重金属离子水解吸后吸收谱线近乎平行。结合秸秆及碱化吸附重金属的化学反应过程对吸收谱进行分析,可得到不同组分样品的分子振动及官能团信息,并得到碱化秸秆吸附重金属应为络合吸附和静电吸附两种吸附方式。证明了太赫兹时域光谱技术在水体重金属污染检测中的可靠性和良好的应用前景。     

用于检测水环境中银离子浓度的荧光适体传感器研究

银凭借其独特的性能,在医疗材料、摄影、电子、成像等行业中应用广泛。然而,银离子被列为最具毒性的重金属离子之一,会对环境以及人类的生命健康造成严重威胁。为了灵敏、特异性的检测水环境中的银离子浓度,利用纳米金的优良光学猝灭性以及双链核酸适体捕获银离子能力更强的优点,结合荧光能量共振转移原理,提出一种用于检测水环境中银离子浓度的荧光适体传感器。将修饰SH键的核酸适体与纳米金混合形成稳定的纳米结构,并加入标记有FAM的核酸适体,形成检测银离子浓度的工作溶液。当不存在银离子时由于不匹配碱基C-C之间的排斥力导致两条核酸适体不结合,反应体系中具有较强的荧光;当存在银离子时,双链核酸适体中不匹配的C-C能与银离子通过金属离子-碱基的相互作用形成稳定的C-Ag+-C碱基对,这种复合结构的产生会拉近纳米金和荧光基团之间的距离,使得荧光信号随着银离子浓度的增加而逐渐减弱。根据加入银离子前后荧光强度的变化可实现银离子浓度的检测。同时,为了提高传感器的灵敏性和稳定性,实验优化了工作溶液中纳米金与核酸适体的浓度比、氯化钠浓度、缓冲液的pH以及培养温度等参数。结果表明,当浓度为0.012 5 g·L-1的纳米金与5 μmol·L-1核酸适体的体积比为5∶1,NaCl浓度为260 mmol·L-1,缓冲液pH 7,培养温度为30 ℃时,工作溶液初始荧光强度最强,银离子检出限为10 nmol·L-1,相关系数为R2=0.99。此外,该传感器对银离子的浓度检测表现出较好的特异性,且具有操作简单、灵敏和不引入有毒溶剂等优点,在水环境中的银离子浓度检测领域有较好的应用前景。     

Influence of Fe(III) on the Fluorescence of Lysozyme: a Facile and Direct Method for Sensitive and Selective Sensing of Fe(III)

Lysozyme is widely used for the synthesis of nanomaterials (e.g., gold nanoparticle) to fluorescently sense metal ions. However, the effect of metal ions on the fluorescence of lysozyme is not studied yet. Herein, we have explored the interactions of lysozyme with different metal ions to develop a direct sensing platform for Fe(III). It has been observed that the fluorescence of lysozyme was slightly decreased in the presence of Cu(II), Hg(II), As(V), Co(II), Cd(II), Cr(II), Fe(II), Mn(II), Pb(II), and Zn(II), while a significant decrease in the lysozyme fluorescence was observed for Fe(III). The effect of thermal stability on the fluorescence quenching was also studied from 25 to 60 °C. In the present study, the lysozyme sensing probe was able to selectively and accurately detect 0.5–50 ppm of Fe(III) with a LOD of 0.1 ppm (1.8 µM) at 25 °C.

     

Luminescence-Based Optical Fiber Chemical Sensors

A scheme for the simultaneous determination of temperature and analyte concentration for application in luminescence-based chemical sensors is proposed. This scheme is applied to an optical oxygen sensor, which is based on the quenching of the fluorescence of a ruthenium complex. Temperature measurement is performed using the excitation radiation and an absorption long-pass filter. Preliminary results are presented that show the viability of an oxygen measurement that is independent of temperature and optical power level. The possibility of self-referenced temperature measurements with semiconductor nanoparticles is also investigated. In order to optimize the sensor design, several different optical fiber probe geometries for oxygen sensing are tested and compared, including different methods of coupling radiation into the optical fiber system. Polyvinyl alcohol (PVA) and polyacrylamide membranes are tested as supports for sensor immobilization in fiber-optical pH sensing devices in aqueous solution. Some results are presented that show the feasibility of using fiber-optical pH indicators for remote monitoring.     

Porous silicon-based optical biosensors and biochips

Porous silicon multilayered microstructures have unique optical and morphological properties that can be exploited in chemical and biological sensing. The large specific surface of nanostructured porous silicon can be chemically modified to link different molecular probes (DNA strands, enzymes, proteins and so on), which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. We designed fabricated and characterized several photonic porous silicon-based structures, which were used in sensing some specific molecular interactions. The next step is the integration of the porous silicon-based optical transducer in biochip devices: at this aim, we have tested an innovative anodic bonding process between porous silicon and glass, and its compatibility with the biological probes.     

Incorporation of Siderophore Binding Sites in a Dipodal Fluorescent Sensor for Fe(III)

A new fluorescent probe 3, has been developed for the detection of Fe(III) in water based samples. The design of 3 involved the incorporation of Fe(III) binding sites observed in naturally occurring Siderophores into a synthetic sensing assembly. The probe, containing two Schiff base receptors connected to a mesitylene platform, was prepared in two steps. The dipodal sensor displayed good selectivity for Fe(III) when tested against other physiological and environmentally important metal ions, in HEPES buffered solution at pH 7.0, through a quenching of the fluorescent intensity. Stern-Volmer analysis of this quenching interaction indicated a 1:1 (host : guest) binding stoichiometry between the probe and Fe(III). The association constant, K _a calculated using the Benesi-Hildebrand equation was found to be 3.8 × 10⁴ M⁻¹. Crucially, the sensor was capable of measuring Fe(III) competitively in solutions containing both Fe(III) and Cu(II). Thus, the adoption of Fe(III) binding sites found in nature, into synthetic luminescent assemblies has proven an effective design strategy for the development of new Fe(III) probes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Luminescence-Based Optical Fiber Chemical Sensors

Abstract

A scheme for the simultaneous determination of temperature and analyte concentration for application in luminescence-based chemical sensors is proposed. This scheme is applied to an optical oxygen sensor, which is based on the quenching of the fluorescence of a ruthenium complex. Temperature measurement is performed using the excitation radiation and an absorption long-pass filter. Preliminary results are presented that show the viability of an oxygen measurement that is independent of temperature and optical power level. The possibility of self-referenced temperature measurements with semiconductor nanoparticles is also investigated. In order to optimize the sensor design, several different optical fiber probe geometries for oxygen sensing are tested and compared, including different methods of coupling radiation into the optical fiber system. Polyvinyl alcohol (PVA) and polyacrylamide membranes are tested as supports for sensor immobilization in fiber-optical pH sensing devices in aqueous solution. Some results are presented that show the feasibility of using fiber-optical pH indicators for remote monitoring.     

Fluorescence Sensor Design for Transition Metal Ions: The Role of the PIET Interaction Efficiency

Multicomponent systems 1, 2, and 3 having fluorophore-spacer-receptor architecture have been prepared with a view to understand the role of the photoinduced intramolecular electron transfer (PIET) interactions in transition metal ion sensing efficiency of these systems. Structurally similar compounds 4-amino-1,8-naphthalimide (4), 4-aminophthalimide (5), and 4-methoxy-1,8-naphthalimide (6) were used as the fluorophore moieties. Dimethylamino group (as in the case of 1a, 2a, and 3a, series A) and an aniline moiety (like in 1b, 2b, and 3b, series B) have been employed as the receptor components. A two-carbon ethylene chain serves as a spacer unit. The absorption and fluorescence spectral features of the systems have been studied in the absence and presence of various transition metal ions. All the multicomponent systems (except 1a) show weak fluorescence intensities compared to that of their constituent fluorophores (4, 5, and 6) in any given solvent. The reason for this low fluorescence quantum yield could be ascribed to the efficient PIET interaction between receptor moiety and the electron deficient fluorophore component of the systems. This has been corroborated with the estimated thermodynamic driving force (delta G*) for the PIET process in the multicomponent systems, calculated using electrochemical and spectral properties of individual components, is more negative for 2 and 3 than for 1 having electron deficient fluorophores 5, and 6, respectively. Especially, as evidenced by their low fluorescence quantum yield values, the PIET interaction is found to be more significant in the systems of series B (1b, 2b, and 3b) than the respective system of series A (1a, 2a, and 3a, respectively). The sensing capability of the systems is directly related to the efficiency of the PIET interaction in the unbound state. Accordingly, all these systems (except 1a) show significant fluorescence enhancement in the presence of transition metal ions, well known for their high fluorescence quenching behavior. The present paper describes, the feasibility of optimizing the PIET interaction in the multicomponent sensor system in unbound state, and thus transition metal ion signaling capability of the system.     

A Novel “Turn On” Glucose-Based Rhodamine B Fluorescent Chemosensor for Mercury Ions Recognition in Aqueous Solution

A novel “turn-on” fluorescent sensor based on glucose and rhodamine B for detection of mercury ions was designed and synthesized. The fluorescent sensor showed an extreme specificity for mercury ions than for other metal ions in aqueous solution. On adding mercury ions to the solution of glucose-based rhodamine B sensor, the absorption and fluorescence signals enhanced remarkably at 567 and 587 nm, respectively. Titration of sensor with mercury ions showed 1:1 stoichiometric reaction. The cyclic voltammetric measurement of an increasing amount of mercury ions in the solution of glucose-based rhodamine B sensor commendably showed the change in the fluorescence characteristics. Furthermore, the successful detection of trace amount of mercury ions in water indicated that glucose-based rhodamine B sensor can be used for the detection of the limited mercury ions in drinking water.     

Methylene blue as a DNA probe for a comparative study of Cd, Pb and Cr ions binding to calf thymus DNA

Methylene blue (MB) was developed as a sensitive DNA probe for a comparative study of Cd²⁺, Pb²⁺ and Cr³⁺ ions binding with calf thymus DNA (ctDNA). The fluorescence intensity of the MB-ctDNA system increased dramatically when heavy metal ions (Cd²⁺, Pb²⁺ and Cr³⁺ ions) were added, which indicated that some of the bound MB molecules were released from the ctDNA base pairs. To compare the binding affinity of these three different heavy metal ions with ctDNA, the relationships between the fluorescence intensity of the MB-ctDNA-M (Metal ions) system and the concentration ratio of [M]/[DNA(p)] were investigated. The results showed that the order of the binding affinity of heavy metal ions with ctDNA had the following sequence: Cr³⁺> Cd²⁺>Pb²⁺. This order was further proved by the effects of heavy metal ions on the number of MB bound to ctDNA, the measurements of binding constants of these heavy metal ions to ctDNA, and the effects of heavy metal ions on the absorption of the MB-ctDNA system. In addition, the interaction mechanisms of Cd²⁺, Pb²⁺ and Cr³⁺ ions with ctDNA were also discussed in detail. These results indicated that their interaction mechanisms are related to the concentration ratios of heavy metal ions to DNA.