双锥形塑料光纤溶解氧浓度的测定

本文利用荧光标记物的荧光猝灭效应测量水中溶解氧浓度.以塑料光纤作为传感和传光元件,为了提高溶解氧传感的灵敏度,传感头制成双锥形.以邻菲咯啉钌作为荧光标记物,用溶胶-凝胶法制备含有荧光标记物的敏感材料.根据Stem-Volmer方程,通过测量荧光标记物的荧光强度来测定溶解氧的浓度.文中提出了一个模型来解释荧光强度与溶解氧浓度之间的亚线性关系.通过对所测得的曲线进行拟合,可以得出敏感膜约有85%的厚度不受氧漂白的作用.     

侧链含芘丁酸酯结构单元的聚氧硅烷合成与氧猝灭特性

采用氢化硅烷化反应，合成了侧链含芘丁酸结构单元的聚氧硅烷荧光高分子。用FTIR和^1HNMR表征了它们的分子结构，采用荧光分光光度计测定了它们在溶液中的激发光谱、发射光谱和氧猝灭系数。结果表明，在聚氧硅烷侧链上引入长链烷烃芘衍生物后，由于侧基上芘环的相互作用，在高波长的受激态发射区（Excimer Emssion）具有强的发射峰，而低波长的分子态发射区（Monomer Emission）的强度较弱。聚氧硅烷荧光高分子对氧气敏感，具有较高的氧猝灭系数，在ME区和EE区的氧猝灭系数分别为59％和54％。随着溶液浓度的降低，在ME区的强度增加，氧猝灭系数增大，而在EE区的强度减弱，氧猝灭系数增加不大。     

苯基喹啉/丙烯酸酯共聚物的合成及荧光性能研究

合成了一种新型的喹啉衍生物单体-2-苯基喹啉-4-羧酸-丙烯酸-乙二醇二酯(PQFAED),并通过乳液聚合的方法制备了PQFAED和丙烯酸酯单体(MMA/MAA/BA)的共聚物-P(PQFAED/MMA/MAA/BA)。用IR、UV、GPC、TGA、PGC-MS及荧光光谱表征了单体及共聚物的结构,分析了硝基爆炸物(TNT、RDX及PETN)对该共聚物膜的荧光猝灭作用。结果表明,共聚物薄膜的最大发射波长为436nm,相对于单体的最大发射峰发生了36nm的红移;荧光"结构自猝灭效应",使PQFAED在相同生色团浓度下的荧光强度远低于其相应共聚物的荧光强度;共聚物薄膜对多硝基爆炸物有较好的荧光响应,可作为爆炸物检测的传感材料。     

表面分子印迹共轭聚合物传感薄膜对2,4-DNT的选择性响应

将侧链含氨基的强电子离域性共轭聚合物(PDD)化学键合到纤维素纳米微纤(TOCN)薄膜上,利用表面分子印迹技术,制备了以2,4-二硝基甲苯(2,4-DNT)为模板的表面印迹共轭聚合物传感薄膜(MI-PDD/TOCN薄膜);并深入研究了该MI-PDD/TOCN薄膜对2,4-DNT检测的应用。研究结果显示,TNT溶液(或蒸气)对MI-PDD/TOCN薄膜的荧光猝灭常数(或荧光猝灭效率)仅为1.6×104M-1(或暴露300 s,18.2%),而2,4-DNT溶液(或蒸气)对其的荧光猝灭常数(或荧光猝灭效率)高达2.78×104M-1(或暴露300 s,88.4%),表明了MI-PDD/TOCN薄膜对2,4-DNT分子具有优良的响应灵敏度与特异的选择性。     

微波绿色合成N,S共掺杂碳点及其在Fe3+检测和温度传感方面的应用

以韭菜为前驱体,采用微波法一步绿色合成N,S共掺杂的粒径均匀、分散性好的碳点。所合成的碳点近似球状,粒径2.0-5.0 nm。在365 nm的紫外灯照射下发明亮的蓝色荧光,发射峰具有激发波长依赖性。Fe³⁺对所制备的碳点有明显选择性荧光猝灭现象。在5-300μmol/L的范围内,荧光猝灭程度(F/F₀)与Fe³⁺浓度呈现良好的线性关系(R=0.9930),检测限为4.0μmol/L。同时探测温度对制备碳点的影响,在20-55℃范围内,碳点荧光强度与温度具有较好的线性响应。由于生理温度范围在此温度范围内,所制备的碳点可用于细胞温度传感。     

含三联吡啶聚苯乙烯荧光微球的制备与性能EI北大核心CSCD

将三联吡啶基团引入交联的聚苯乙烯树脂(Merrifield树脂)表面后在甲醇中与硝酸铕进行配位反应,制备了新型荧光微球。利用红外光谱、元素分析、光电子能谱和荧光光谱等分析手段对聚合物和铕配合物进行了表征,研究了其对有机磷酸酯的荧光传感性能。结果表明,该微球及其在非水溶剂的悬浮液在手持式紫外灯照射下均发射出铕离子的特征红色荧光,氯磷酸二乙酯可以迅速、有效地猝灭其荧光。其在617 nm处的荧光猝灭常数为0.308×103 L/mol,这种微球有望在有机磷农药检测用的荧光传感器中得到应用。     

含芘的超支化介孔聚合物的合成及对硝基芳烃的荧光传感性能

合成了以金刚烷为核心,以二苯乙炔基芘为连接臂的超支化聚合物P。金刚烷的三维立体结构及分子骨架的刚性结构特点,赋予了聚合物多孔的结构特点。研究结果表明,聚合物P具有均匀的狭缝孔道结构,其孔径多分布在10 nm左右,属于介孔材料。此外还合成了共聚单体二苯乙炔基芘(M)用于对比研究其光学性质及对硝基芳烃的荧光猝灭性能。聚合物P与单体M相比具有更大的Stokes位移,二者在含有三硝基甲苯(TNT)的溶液中,其平衡时的猝灭率几乎相同。然而二者在相同条件下制备的旋涂膜在二硝基甲苯(DNT)饱和蒸汽中,当达到猝灭平衡时,聚合物P的猝灭率为82%,而化合物M的猝灭率仅为22%。说明聚合物P多孔的特点使其透气性大大提高。以不同浓度的聚合物溶液制备出一系列厚度不同的薄膜,发现随着薄膜厚度的增加,荧光峰发生红移,但在DNT饱和蒸汽中的猝灭率变化不大。这种介孔的结构特点在一定程度上克服了旋涂膜传感器的猝灭率对厚度的依赖性。     

含长链烷基芘类衍生物的合成与氧猝灭特性

采用酯化反应,合成了系列芘丁酸烷基酯和烷基酸芘丁酯,用IR和1HNMR表征分子结构,采用荧光分光光度计测定了它们在溶液中的荧光特性.结果表明,芘类衍生物的取代基、键桥对激发波长、发射波长和氧猝灭系数的影响较大,以OOC键结方式的烷基酸芘丁酯具有更高的氧猝灭性能,烷基链长短对荧光强度和氧猝灭系数影响不大.     

基于相移检测的有机改性溶胶-凝胶光学氧敏感膜研究

以四乙氧基硅烷(TEOS)和二甲基二乙氧基硅烷(DDS)为共聚前驱体,Ru(phen)3Cl2为荧光指示剂,采用溶胶凝胶技术,通过改变DDS/TEOS比值,制备了基于荧光猝灭原理的有机改性氧敏感膜.探讨了成膜条件,研究了DDS的掺杂量对敏感膜结构和性能的影响.结果表明,掺入适量的有机硅醇盐DDS,敏感膜均匀无龟裂,有较好的机械性和柔韧性.将敏感膜组装到基于相移检测的光纤氧传感器并对气态氧进行检测,检测下限达2×10-6,响应时间＜30 s;对溶解氧进行检测,检测下限达0.5 mg/L,响应时间＜50 s.与纯TEOS敏感膜相比,有机改性敏感膜具有更好的重复性和稳定性,更有利于溶解氧的测量.     

C60和苯乙炔共聚物荧光性能研究

合成表征了Ｃ６０和苯乙炔共聚物。详细地测试了聚合物溶液的荧光性能。研究结果表明溶液浓度为０．５ｇ／Ｌ时,聚合物呈出现了荧光浓度自猝灭效应。对于Ｃ６０含量为５％的聚合物在３５０ｎｍ被激发时,荧光光谱除在４４０ｎｍ有一个聚苯乙炔的荧光发射峰之外,在４０４ｎｍ呈现出了一个新的弱荧光峰,聚合物中Ｃ６０对这个荧光具有猝灭效应,聚合物发光机制被分析。     

Tailoring of sol-gel films for optical sensing of oxygen in gas and aqueous phase

Sol-gel-based optical sensors for both gas-phase and dissolved oxygen have been developed. Both sensors operate on the principle of fluorescence quenching of a ruthenium complex which has been entrapped in a porous sol-gel silica film. A comprehensive investigation was carried out in order to establish optimal film-processing parameters for the two sensing environments. Both tetraethoxysilane and organically modified sol-gel precursors such as methyltriethoxysilane and ethyltriethoxysilane were used. Film hydrophobicity increases as a function of modified precursor content, and this was correlated with enhanced dissolved oxygen (DO) sensor performance. Extending the aliphatic group of the modified precursor further improved DO sensitivity. The influence of water/precursor molar ratio, R, on the sol-gel film microstructure was investigated. R value tailoring of the microstructure and film surface hydrophobicity tailoring were correlated with oxygen diffusion behavior in the films via the Stern-Volmer constants for both gas phase and DO sensing. Excellent performance characteristics were measured for both gas-phase and DO oxygen sensors. The long-term quenching stability of DO sensing films was established over a period of 6 months.     

Lifetime-based sensing: influence of the microenvironment

The influence of the microenvironment on the fluorescence behavior of indicator molecules is investigated. A model is developed to describe the fluorescence decay of indicator molecules in a nonuniform medium. Its consequences for fluorescence lifetime-based chemical sensors are discussed and verified in two examples, namely, a pH sensor using a pyrene compound in a hydrogel and a ruthenium complex for oxygen sensing embedded in a polystyrene membrane.     

Optical determination of low-level water concentrations in organic solvents using fluorescent acridinyl dyes and dye-immobilized polymer membranes.

The fluorescent acridinyl indicators 4-(9-acridinyl)-N-(5-hexenyl)-N-methylaniline (KD-F0011), 6-(9-acridinyl)-1,2,2,3-tetramethyl-2,3-dihydro- 1H-perimidine (KD-F0021), and 6-(9-acridinyl)-2-(3-butenyl)-1,2,3-trimethyl-2,3-dihydro-1H-perimidine (KD-F0022) were designed, synthesized, and applied for highly sensitive optical determination of low-level water in organic solvents. All these dyes were found useful as fluorescence indicators for the detection of water below 1% (v/v) in different solvent media with a low detection limit of 0.002% (v/v) or 20 mg/L (22 ppm by weight) for KD-F0021 in THF solution. Sensing membranes made from poly(ethylene glycol) dimethacrylate by photocopolymerization with the indicator KD-F0011 were also prepared. Using the membrane sensor, the lowest detection limit of 0.001% (v/v) or 14 mg/L (20 ppm) water was achieved in diethyl ether samples. This system enables the continuous monitoring of the water content in a flow-through arrangement, where single-wavelength excitation (404 nm) and single-wavelength detection (532 mm) can be used for the fluorescence determination, allowing a simple measurement setup. In a continuous-flow experiment using THF samples, fully reversible and fast signal changes with t95% = 1-2 min for water concentrations up to 0.50% (v/v) were observed. A detection limit of 0.004% (v/v) or 40 mg/L (45 ppm) water in THF was achieved. These characteristics make this type of sensor a useful tool for the online continuous monitoring of water present as an impurity in organic media, which is difficult to achieve using a Karl Fischer instrument.     

Polypyrrole-functionalized porous silicon for gas sensing applications

Electrodeposition of polypyrrole film on porous silicon surface was used to improve its photoluminescence properties for sensing of chemical species in gas phase. Photoluminescence quenching sensor response was measured for water and a homological set of linear alcohols in gas phase. We observed modified photoluminescence quenching response from polypyrrole-modified porous silicon as compared with as-prepared porous silicon. For as-prepared porous silicon samples, the dependence of photoluminescence quenching on analyte concentration revealed Stern–Volmer behavior. Concentration dependence of photoluminescence quenching response of polypyrrole-modified samples for water and methanol exhibited Stern–Volmer behavior as well, for C₂–C₆ linear alcohols a period of photoluminescence enhancement on the concentration dependence onset followed by photoluminescence quenching at higher concentrations was observed. The interval of photoluminescence enhancement response from polypyrrole-modified samples was continuously decreasing with the length of alcohol chain. Dramatic reduction of sensor photoluminescence response to lower alcohols was attributed to strong interaction with polypyrrole surface layer and suppressed analyte penetration into porous matrix. Operational stability of polypyrrole-modified porous silicon was improved as compared to as-prepared porous silicon.     

Oxygen optrode for use in a fiber-optic glucose biosensor

An optical fiber oxygen sensor, based on the dynamic quenching of the luminescence of tris(1,10-phenanthroline)-ruthenium(II) cation by molecular oxygen, is presented. The complex is adsorbed onto silica gel, incorporated in a silicone matrix possessing a high oxygen permeability, and placed at the tip of the optical fiber. Oxygen has been monitored continuously in the 0-750 Torr range, with the detection limit being as low as 0.7 Torr. The device has been applied to the development of a fast responding and highly sensitive fiber-optic glucose biosensor based on this highly sensitive oxygen transducer. The sensor relates oxygen consumption (as a result of enzymatic oxidation) to glucose concentration. The enzyme is immobilized on the surface of the oxygen optrode; carbon black is used as an optical isolation in order to prevent ambient light and sample fluorescence to interfere. Measurements have been performed in a flow-through cell in air-equilibrated glucose standard solutions of pH 7.0. The effects of enzyme immobilization procedures (including enzyme immobilization on carbon black) as to response times (around 6 min), analytical ranges (0.06-1 mM glucose), reproducibility in sensor construction, and long-term stability have been studied as well.     

Sensitivity of microstructure fibers to gaseous oxygen

The paper presents new experimental results related to fluorescence quenching of a transducer, the tris(1,10-phenanthroline)ruthenium(II) chloride hydrate, applied into several types of microstructure fibers (MSFs). Different types of MSFs with a diameter ranging from 125 to 1010 μm coated with a jacket of UV-curable acrylate were prepared. Segments of these MSFs with a minimum length of about 5 cm were used in the experiments. The segments were modified by thin xerogel layers containing the transducer. The layers were prepared from input sols mixed of TEOS or MTES, ethanol, hydrochloric acid, water, and the transducer. The sols were applied onto the walls by passing a column of the sol through the holes. The formed gel layers were dried at 75 °C. Single-capillary fibers (SCFs) modified with the same sensing layers were also prepared for reference measurements.

The sensitivity of the sensing MSFs as well as of the SCFs to gaseous mixtures of oxygen and nitrogen was determined in experiments, in which the fibers were excited by a blue LED at about 470 nm and the spectra of the output light were measured in a range of 400–1000 nm for different concentrations of oxygen. Temporal changes of the output power were measured at about 590 nm.

On the basis of experimental results one can arrive at a conclusion that there are two different mechanisms of fluorescence quenching in MSFs. For small values of the hole size and thin walls between the holes the fuorescence quenching does not depend on the concentration of oxygen. In contrast to it, for large air holes and large thicknesses of the walls the fluorescence quenching does depend on the concentration of oxygen.     

复杂水质环境下基于PSO-ELM的BOD快速检测

针对检测生化需氧量(BOD)的传统五日培养法(BOD5)操作复杂、时效性差的不足,以及水质中复杂环境因素干扰检测过程等问题,提出了基于微生物膜法的快速检测系统,进而以粒子群算法(PSO)优化的极限学习机(ELM)算法来实现BOD检测。检测系统以溶解氧传感器和微生物膜反应器为核心,能够在35min内完成检测,其中微生物反应器使用功能化的螺旋玻璃管制成,但微生物膜易受水质复杂环境的影响。为此,运用PSO-ELM算法消除水质中浊度(SS)、pH值、氧化还原电位(ORP)对检测结果的干扰,与BP神经网络和ELM算法相比,运行时间分别缩短0.92s和0.24s,测试误差分别减小5.3%和4.0%。在实际海水水样的测试结果中,该方法与BOD5法相对误差保持在2.69%~3.86%内。     

Real-time measurements of dissolved oxygen inside live cells by organically modified silicate fluorescent nanosensors

Optical PEBBLE (probes encapsulated by biologically localized embedding) nanosensors have been developed for dissolved oxygen using organically modified silicate (ormosil) nanoparticles as a matrix. The ormosil nanoparticles are prepared via a sol-gel-based process, which includes the formation of core particles with phenyltrimethoxysilane as a precursor followed by the formation of a coating layer with methyltrimethoxysilane as a precursor. The average diameter of the resultant particles is 120 nm. These sensors incorporate the oxygen-sensitive platinum porphyrin dye as an indicator and an oxygen-insensitive dye as a reference for ratiometric intensity measurement. Two pairs of indicator dye and reference dye, respectively, platinum(II) octaethylporphine and 3,3'-dioctadecyloxacarbocyanine perchlorate, and platinum(II) octaethylporphine ketone and octaethylporphine, were used. The sensors have excellent sensitivity with an overall quenching response of 97%, as well as excellent linearity of the Stern-Volmer plot (r(2) = 0.999) over the whole range of dissolved oxygen concentrations (0-43 ppm). In vitro intracellular changes of dissolved oxygen due to cell respiration were monitored, with gene gun injected PEBBLEs, in rat C6 glioma cells. A significant change was observed with a fluorescence ratio increase of up to 500% after 1 h, for nine different sets of cells, which corresponds to a 90% reduction in terms of dissolved oxygen concentration. These results clearly show the validity of the delivery method for intracellular studies of PEBBLE sensors, as well as the high sensitivity, which is needed to achieve real-time measurements of intracellular dissolved oxygen concentration.     

Molecular oxygen-sensitive fluorescent lipobeads for intracellular oxygen measurements in murine macrophages

Intracellular oxygen concentration is of primary importance in determining numerous physiological and pathological processes in biological systems. This paper describes the development and application of micrometer-sized oxygen-sensitive fluorescence lipobeads for intracellular measurements of molecular oxygen in J774 murine macrophages. A ruthenium diimine complex [Ru(bpy-pyr)(bpy)2]C12 (bpy = 2,2'-bipyridine, bpy-pyr = 4-(1"-pyrenyl)-2,2'-bipyridine) is used as the oxygen indicator. The indicator exhibits high chemical and photostability and high sensitivity to oxygen. The indicator molecules are immobilized in a phospholipid membrane that coats polystyrene microparticles. The fluorescence of the lipobeads is effectively quenched by molecular oxygen. The fluorescence intensity of the oxygen-sensitive lipobeads is 3 times higher in a nitrogenated solution than in an oxygenated solution. The lipobeads are internalized by murine macrophages through phagocytosis. They maintain their spectral properties for 24 h in living cells when the cells are stored in phosphate-buffered saline at pH 7.4. The photostability, reversibility, and effect of hypoxia, hyperoxia, and oxidative stress on the intracellular level of oxygen in J774 murine macrophages are described.     

Evaluation of acridine in Nafion as a fluorescence-lifetime-based pH sensor

We report a novel fluorescence-lifetime-based pH sensing method that utilizes acridine incorporated into Nafion (AcNaf) as the fluorescent indicator. The AcNaf sensor is excited using a 380 nm light emitting diode (LED) and the fluorescence lifetimes are measured at 450 and 500 nm. The fluorescence behavior of acridine as a function of pH in aqueous phosphate buffers and incorporated into the Nafion membrane has been investigated. The results show that incorporating acridine into Nafion changes the apparent ground-state pKa from -5.45 to -9, while the apparent excited-state pKa* is only slightly changed (approximately 9.4 in 0.1 M phosphate buffer). The AcNaf film shows a good pH response with a change in average lifetime of approximately 19 ns (at an emission wavelength of 450 nm) over the pH 8 to 10 range. We also show that excited-state protonation does not occur in the AcNaf sensor film and that chloride quenching cannot occur because of the permselective nature of Nafion. We also discuss how the unique structure of Nafion affects the fluorescence behavior of acridine at various pH values and examine the impact of buffer concentration on apparent pKa and pH sensing ability.