芘标记有机硅聚合物的合成和荧光氧猝灭特性

合成了丙烯酸芘甲酯、二甲基乙烯基芘甲氧基硅烷、10-十一碳烯酸芘甲酯三种含芘单体,用硅氢加成方法制备了一系列含芘封端侧链的聚二甲基硅氧烷光-氧敏感高分子,并分别用四乙氧基硅烷和甲基含氢硅油A交联.对基于上述高分子的压力敏感涂料(PSP)的荧光氧猝灭和光物理行为进行了研究.结果表明,芘封端的侧基结构和交联剂对此类PSP的性能,包括激基缔合物荧光强度和氧猝灭灵敏度、Stern-Volmer关系的线性和贮存稳定性等都有明显的影响.含长碳链芘甲酯侧链的聚合物显示较高激基缔合物荧光强度和氧灵敏度;以甲基含氢硅油A作为交联剂,既能提高PSP的储存稳定性,又能提高氧猝灭灵敏度.     

表面活性剂胶束化过程中对芘的荧光猝灭

本文研究了烷基三苯基 盐及N-烷基吡啶盐胶束化过程中对芘的荧光猝灭。讨论了表面活性剂分子在水溶液中的优势构型以及芘在胶束中的增溶位置。简单说明了胶束增敏发光分析的机理。研究表明,胶束形成前后荧光猝灭均符合Stern-Volmer方程。     

水溶液中芘的荧光被核酸碱基猝灭的研究

众所周知,稠环芳烃是一类具有致癌性的物质.虽然对其致癌机理的认识尚未形成一致的看法,但一般都认为同稠环芳烃与DNA,蛋白质等生物活性物质的相互作用有关.因为致癌物后的致癌作用最终都是通过损伤细胞中的DNA而实现的.     

烷基苄基铵对芘的荧光猝灭行为研究

广义的荧光猝灭系指所有能使荧光强度降低的物理和化学过程,但通常涉及的主要有动态猝灭和静态猝灭,二者均遵从Stern-Volmer方程,但由于猝灭作用本质不同,它们在荧光寿命变化、温度效应及吸收光谱等方面表现出差异可资区别.本文通过稳态荧光强度变化和荧光衰减速率的比较研究了具有不同烷基链长的十四烷基苄基二甲基氯化铵(Zeph)和苄基三甲基溴化铵(TMBA)对芘的荧光猝灭,并基于电导实验结果以及猝灭剂全反式构象从理论上计算了Zeph和TMBA的猝灭速率常数,讨论了荧光猝灭的性质和长链分子的构型。     

荧光猝灭法测定次黄嘌呤及机理研究

研究了次黄嘌呤猝灭伊文思蓝的荧光猝灭机理并根据次黄嘌呤对伊文思蓝荧光的猝灭作用建立了测定次黄嘌呤的新方法.线性回归方程为:ρ=6.292×103F-1-26.49,相关系数为0.9990,线性范围为0.20～20.0 μg/mL,检出限为0.14 μg/mL,相对标准偏差(RSD)为2.5%.求算了伊文思蓝与次黄嘌呤的形成常数K=2.63×102L/moL,实验了pH、放置时间、干扰离子等对测定的影响.     

十二烷基磺酸钠增强的吡啶锉 对芘的荧光猝灭

水溶液中三种吡啶 盐(吡啶盐酸盐, HP+;N-苄基吡啶,BP^+; 苄基紫精, BV^2^+)对芘的荧光猝灭因十二烷基磺酸钠(SLS)的引入而增强, 且猝灭常数对SLS浓度的敏感性BV^2^+>BP^+>HP^+, 电导实验表明体系中无簇集体形成。认为SLS与吡啶 的静电作用及表面活性剂分子中烷基链的绕曲是导致猝灭增强的原因。     

十二烷基磺酸钠增强的吡啶锉 对芘的荧光猝灭

水溶液中三种吡啶 盐(吡啶盐酸盐, HP+;N-苄基吡啶,BP^+; 苄基紫精, BV^2^+)对芘的荧光猝灭因十二烷基磺酸钠(SLS)的引入而增强, 且猝灭常数对SLS浓度的敏感性BV^2^+>BP^+>HP^+, 电导实验表明体系中无簇集体形成。认为SLS与吡啶 的静电作用及表面活性剂分子中烷基链的绕曲是导致猝灭增强的原因。     

基于芘的荧光熄灭的单质碘荧光敏感膜的研究

单质碘熄灭固定于增塑的ＰＶＣ膜中的芘的荧光，且这种熄灭作用可逆。本据此研制了用于测定单质碘浓度的荧光敏感膜，最佳膜组成为２～４ｍｇ芘、５０ｍｇＰＶＣ粉、１００ｍｇ邻苯二甲酸二异辛酯，测定碘的浓度范围为２．２６×１０＾－５～１．０４×１０＾－３ｍｏｌ／Ｌ。此膜测定单质碘的重现性好，响应时间小于４０ｓ。除Ｆｅ＾３＋、Ｂｉ＾３＋外，其它常见离子均无干扰。将此膜用于食盐中碘的测定，结果令人满意。     

基于氧荧光猝灭速率法的生化需氧量检测

利用氧荧光猝灭速率的方法,结合自行构建的BOD光纤传感装置进行海水中生化需氧量(BOD)含量检测。考察了四种筛选的海洋耗氧菌种在四甲基硅氧烷(TMOS)、二甲基二甲氧基硅烷(Di Me-DMOS)和聚乙烯醇(PVA)包埋固定情况下,对不同浓度的葡萄糖-谷氨酸(GGA)标准溶液的荧光响应情况。BOD敏感膜的荧光响应在0·2~30mg/L浓度范围内呈良好的线性关系,对2mg/L标准溶液测定的相对标准偏差为2·5%(n=6),响应时间(t95%)为4·0min,BOD敏感膜使用寿命大于12个月。实际海水样品检测表明,利用BOD敏感膜检测得到的结果与国标BOD5方法之间存在较好的一致性。     

厚朴酚在乙醇中的荧光自猝灭及猝灭机理

系统研究了厚朴酚的荧光光谱和吸收光谱随浓度的变化, 揭示了厚朴酚具有较强的自猝灭特性. 其猝灭包括静态和动态机制: 随着浓度增加, 厚朴酚发生聚集; 同时, 单体和聚集体对荧光的猝灭表现为动态猝灭, 由单体、二聚体、三聚体造成的荧光猝灭速率常数kqm、k qd、k qt值远大于扩散控制的荧光猝灭速率常数. 说明除扩散控制的短程能量转移引起的猝灭外, 厚朴酚还存在长程能量转移导致的猝灭机制.     

牛血红蛋白催化荧光猝灭法测定痕量甲巯咪唑

在NH3·H2O-NH4Cl缓冲溶液中,牛血红蛋白催化H202氧化L-酪氨酸产生荧光,甲巯咪唑对该荧光体系具有较强的猝灭作用.据此建立了酶催化荧光猝灭法测定痕量甲巯咪唑的方法.结果表明,甲巯咪唑含量在0.986～14.8 μg/L范围内与荧光强度变化值呈线性关系,其线性回归方程为△F405nm=50.923p+191....     

Synthesis of ionic polyurethanes with pyrene rings: Spectral properties and fluorescence quenching study

Hydrophilic ionic polyurethanes with 4‐chloromethylphenylcarbamoyl‐1‐oxymethylpyrene located on the quaternary ammonium structure from a polymer based on poly(ethylene glycol), isophorone diisocyanate, and N‐methyldiethanolamine were prepared by a quaternization reaction, in which the amount of pyrene covalently attached to the polymeric backbone ranged from 1.14 to 19.82 mmol of fluorophore/100 g of polymer. It was interesting to compare the photoluminescence of the pyrene polyurethane carrying a few mole percent of pyrene moieties with that of a third polymer resulting from its subsequent quaternization with benzyl chloride up to a concentration of ionic groups as in the latter (quaternization degree = 14.15%). The process of excimer formation between the pyrene molecules attached to the ionic polyurethane was investigated in tetrahydrofuran (THF), dimethylformamide, film, and THF/H₂O to illustrate the expected differences in the polymer behavior compared with that of the starting pyrene derivative. The formation of aggregates or core–shell micelles was sustained by the fluorescence data, which indicated the existence of pyrene units in the ground state of the molecule, giving rise thus to an explanation for the high excimer‐to‐monomer intensity ratio. The fluorescence decay of pyrene polyurethanes in the presence of various concentrations of nitrobenzene used as a quencher was analyzed too when the fluorescence quenching in the polymer solution normally followed Stern–Volmer kinetics. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3945–3956, 2005     

Antigen detection based on background fluorescence quenching immunochromatographic assay

Gold immunochromatographic assay (GICA) has been around for quite a while, but it is qualitative in the vast majority of applications. A fast, simple and quantitative GICA is in call for better medicine. In the current study, we have established a novel, quantitative GICA based on fluorescence quenching and nitrocellulose membrane background signals, called background fluorescence quenching immunochromatographic assay (bFQICA). Using model analyte alpha-fetoprotein (AFP), the present study assessed the performance of bFQICA in numerous assay aspects. With serial dilutions of the international AFP standard, standard curves for the calculation of AFP concentration were successfully established. At 10 and 100 ng mL⁻¹ of the international AFP standard, the assay variability was defined with a coefficient of variance at 10.4% and 15.2%, respectively. For samples with extended range of AFP levels, bFQICA was able to detect AFP at as low as 1 ng mL⁻¹. Fluorescence in bFQICA strips stayed constant over months. A good correlation between the results from bFQICA and from a well-established Roche electrochemiluminescence immunoassay was observed in 27 serum samples (r = 0.98, p < 0.001). In conclusion, our study has demonstrated distinctive features of bFQICA over conventional GICA, including utilization of a unique fluorescence ratio between nitrocellulose membrane background and specific signals (F1/F2) to ensure accurate measurements, combined qualitative and quantitative capabilities, and exceptionally high sensitivity for detection of very low levels of antigens. All of these features could make bFQICA attractive as a model for antigen-antibody complex based GICA, and could promote bFQICA to a broad range of applications for investigation of a variety of diseases.     

Detection of cations separated by thin-layer chromatography by fluorescence quenching of ethidium bromide

Cations such as Cu²⁺, Cr³⁺ and Hg⁺ can be separated on silica gel thin layer Chromatographic plates. The developing solution contains 0.02M EDTA at pH 2.5. For visualization, the plate was pretreated with ethidium bromide, a strong fluorescer. Quenching of the red fluorescence can be observed visually even down to the 0.1 nmole range per spot.     

A sensitive probe for oxygen sensing in gas mixtures,based on room-temperature phosphorescence quenching

The dye Erythrosine B (which gives room-temperature phosphorescence, RTF) has been covalently bound to a silica-based amino-functionalized exchanger. The resulting material turned out to be extremely useful as a luminescent probe for oxygen. The photochemical properties and the analytical performance of the RTF probe have been studied by use of a gas flow-injection analysis system, which incorporates a convenient exponential dilution chamber for gas sample introduction. The possible origin of the non-linear Stern-Volmer quenching response observed is thoroughly discussed in terms of the quenching and lifetimes. The proposed sensing material is particularly suitable for measuring oxygen in gas mixtures at extremely low concentrations. The detection limit attained was 0.00006% (0.6 ppm) of oxygen in dry argon (making the system one of the more sensitive optosensors for oxygen published so far). A typical precision of ± 0.2%, at the 0.025% oxygen level, was achieved. Response times were less than 2 s for full signal change and no hysteresis effects were noticed. A possible mechanism for the observed oxygen RTF quenching in the new sensing material is proposed.     

Studies on the fluorescence quenching of polysilane copolymers by chlorohydrocarbons

The room-temperature solution fluorescence quenching of polysilane copolymers by chlorohydrocarbons such as CCl₄, CHCl₃, C₂Cl₆, and Cl₂CHCHCl₂ was studied. The existence of dynamic quenching was preliminarily demonstrated by the experiment of fluorescence lifetime quenching. The fluorescence quenching data were in conformity with the equation: F₀/F = (1+K_SV[Q])exp(NV[Q]), where F and F₀ are the fluorescence intensity with and without the addition of quencher, K_SV is the Stern-Volmer constant, [Q] is the quencher concentration, N is the Avogadro constant, and V is the volume of the active sphere. The fluorescence quenching by the first three chlorohydrocarbons was attributed to the contemporaneous effect of dynamic quenching and static quenching. There exists, at least mathematically, a critical quencher concentration [Q]_C. When the quencher concentration [Q] < [Q]_C, the fluorescence quenching is dominated by the dynamic quenching part; when [Q] > [Q]_C, it is dominated by the static quenching part. However, the fluorescence quenching by Cl₂CHCHCl₂ was attributed to only static quenching. Furthermore, it was proposed that the dynamic quenching may be related with the electrical positivity of the central carbon nucleus of the quenching molecules while the static quenching may be caused by the “outside heavy atom effect” of the Cl element. © 1996 John Wiley & Sons, Inc.     

Kinetic-catalytic determination of osmium by fluorescence quenching with salicylfluorone and hydrogen peroxide

A highly sensitive and selective fluorescence-quenching kinetic method is proposed for the determination of trace osmium(IV), based on the catalytic effect of osmium(IV) on the salicylfluorone (_ex = 510 nm, _em = 535 nm)-H₂O₂ system at pH 9.3–9.6. Using the fixed time method, osmium(IV) in the range 0.008–0.6 ng/ml can be determined. The detection limit is 0.006 ng/ml. Over thirty anions and cations, including other platinum metal ions, do not interfere, even when present in large excess. The method has been applied successfully for the determination of osmium in a series of synthetic mixtures and refined ore with relative standard deviations of 2–6%.     

A close look at fluorescence quenching of organic dyes by tryptophan.

Understanding fluorescence quenching processes of organic dyes by biomolecular compounds is of fundamental importance for in-vitro and in-vivo fluorescence studies. It has been reported that the excited singlet state of some oxazine and rhodamine derivatives is efficiently and almost exclusively quenched by the amino acid tryptophan (Trp) and the DNA base guanine via photoinduced electron transfer (PET). We present a detailed analysis of the quenching interactions between the oxazine dye MR121 and Trp in aqueous buffer. Steady-state and time-resolved fluorescence spectroscopy, together with fluorescence correlation spectroscopy (FCS), reveal three contributing quenching mechanisms: 1) diffusion-limited dynamic quenching with a bimolecular quenching rate constant k(d) of 4.0 x 10(9) s(-1) M(-1), 2) static quenching with a bimolecular association constant K(s) of 61 M(-1), and 3) a sphere-of-action contribution to static quenching described by an exponential factor with a quenching constant lambda of 22 M(-1). The latter two are characterized as nonfluorescent complexes, formed with approximately 30 % efficiency upon encounter, that are stable for tens of nanoseconds. The measured binding energy of 20-30 kJ mol(-1) is consistent with previous estimates from molecular dynamics simulations that proposed stacked complexes due to hydrophobic forces. We further evaluate the influence of glycerol and denaturant (guanidine hydrochloride) on the formation and stability of quenched complexes. Comparative measurements performed with two other dyes, ATTO 655 and Rhodamine 6G show similar results and thus demonstrate the general applicability of utilizing PET between organic dyes and Trp for the study of conformational dynamics of biopolymers on sub-nanometer length and nanosecond time-scales.     

荧光反猝灭法测定药剂中卡托普利

建立荧光反猝灭法测定卡托普利(CAT)的体系.碘(I-3)与罗丹明B(RhB)缔合作用使罗丹明B荧光信号强度减弱直至荧光猝灭,而卡托普利可将I-3还原为I-,使体系荧光信号再现.在2～20μmol·L-1范围内荧光强度再现值ΔF与卡托普利浓度有线性关系:ΔF=-8.438+10.774c(r=0.9986),检出限为3...