新型香豆素类荧光化合物的合成及荧光性质研究

合成了两种香豆素类荧光化合物6,8-二氯-7-羟基香豆素-3-羧酸（DClC）和6-氯-7-羟基香豆素-3-羧酸（MClC）,其中DClC未见文献报道,并通过红外光谱、核磁共振、质谱等手段对产物的结构进行了表征。同时首次研究了这两种香豆素衍生物的紫外、荧光性质,以及不同极性溶剂、pH值、表面活性剂等的影响。结果表明,pH对性质测定影响较大,当pH=10时,DClC和MClC的荧光强度明显增强。     

三维荧光光谱技术在溶解有机质-吸附态砷相互作用中的应用进展

溶解有机质使含砷矿物还原溶解是地下水中砷富集的因素之一,三维荧光光谱技术可以进一步研究溶解有机质在砷迁移过程中的多重作用。本文从溶解有机质的组分、荧光特征指数以及荧光猝灭三个方面综述了三维荧光光谱技术在溶解有机质-砷相互作用中的应用。溶解有机质中的腐殖质组分会与砷形成络合物促进砷向地下水中迁移,还原性醌类充当电子穿梭体,增强了砷在水中的迁移性能。通过荧光指数、腐殖化指数和氧化还原指数可以判断溶解有机质的来源、腐殖化程度以及氧化还原态组分。地表水中砷浓度低,荧光指数高,腐殖化指数较低且以腐殖质物质为主;地下水中砷浓度和腐殖化指数较高,荧光指数低,且腐殖质的醌类部分较少,表明随着水中砷浓度升高,荧光指数成下降趋势,地表水中的腐殖质醌类充当电子穿梭加强了氧化铁的还原和砷迁移作用,促进地表水中的砷向地下水中迁移。砷和溶解有机质会形成砷-溶解有机质络合物,使溶解有机质发生荧光猝灭。pH值和金属离子会影响溶解有机质和砷的络合,但pH值主要影响溶解有机质自身的荧光强度,对砷-溶解有机质络合物的荧光强度影响不大,Ca²⁺能够明显增强溶解有机质-砷的类蛋白荧光。     

基于稀土铕离子配合物的时间分辨荧光pH探针的合成及应用

以4,7-二苯基-1,10-菲哆啉(母体)和2-噻吩甲酰三氟丙酮为协同剂和β-二酮配体,合成了一种稀土三元铕离子配合物,其荧光寿命为0.544 0 ms,并以其为荧光探针对水环境的pH进行时间分辨荧光测定。荧光探针的时间分辨荧光强度在pH 7.00~8.95时达到最大值并保持较好的稳定性;在pH小于7.00和pH大于8.95时,荧光探针的时间分辨荧光强度随着pH变化而变化;在pH 2.50~7.00和pH 9.91~14.00时,荧光探针的时间分辨荧光猝灭率与pH呈线性关系。溶解氧浓度和离子强度变化对pH测定结果无影响。采用荧光探针测定实际水样的pH,结果与玻璃电极的测定结果相符,测定值的相对标准偏差(n=8)在4.3%~8.1%之间。     

不同pH环境中离子化水溶性染料分子的荧光性质

本文以3,4,9,10-苝四羧酸酐为原料合成了3,4,9,10-苝四羧酸和N,N′-二((3-二甲氨基)丙基)-3,4,9,10-苝二酰亚胺,这两个苝系衍生物在水溶液中的溶解度和荧光效率并不高,但是在不同的pH值条件下,两个衍生物形成了水溶性较强的PTCA阴离子和PMI阳离子,并且具有不同的荧光性质。实验结果显示:PTCA在pH 10.0的碱性环境中显示出较强的蓝色荧光,PMI在pH 5.0的弱酸性环境中显示出较强的黄色荧光,并且根据测试的荧光光谱推测了两种具有相同发色团、相似结构的衍生物在不同pH环境中可能存在分子或离子的堆积模式及发光模式。本文还探讨了PTCA阳离子在pH 6.0缓冲溶液中,作为离子型荧光探针对部分金属离子的识别。     

一种基于PET机理pH荧光探针的合成及其性能研究

本文利用光致诱导电子转移(PET)类探针的设计策略,合成了一种以吡喃腈类衍生物为母体、哌嗪为探测基团的新型pH荧光探针DCM-PA。结果表明:DCM-PA的最大吸收波长(λ_(abs))和最大荧光发射波长(λ_(em))分别为421nm和590nm,斯托克斯位移近170nm。在pH=2~12范围内,DCM-PA的荧光强度随pH的升高而降低,pH=2时的荧光强度是pH=12时荧光强度的12倍;DCM=PA的pKa值为7.2,在pH=6~9范围,荧光强度与pH呈良好的线性关系。对比试验证实DCM-PA实现了pH检测的机理:酸性条件下,哌嗪基团与质子结合削弱了其供电子能力,使DCM-PA荧光增强;碱性条件下,哌嗪通过PET作用使探针荧光猝灭。抗干扰试验表明,DCM-PA在中性酸碱度下对多种阴、阳离子均具有良好的抗干扰能力。     

新型苯并噻唑类探针的合成及其对S2-的荧光和比色检测

本文设计合成了一种基于激发态分子内质子转移(ESIPT)机理的苯并噻唑类荧光探针TZ-1,并对其结构进行了表征。实验结果表明,在体积比1∶1的DMSO/PBS(10mmol/L,pH=7.4)溶液中,探针TZ-1具有高选择性并可在3s内实现荧光"off-on"(在365nm紫外灯照射下,由无荧光变成橙色荧光)识别S~(2-),检测限为81μmol/L,pH适用范围为6～12;此外,加入S~(2-)后探针TZ-1的DMSO/PBS溶液由无色变为浅黄色,通过裸眼即可识别S~(2-)。     

稀水溶液中聚乙烯吡咯烷酮构象行为的荧光研究

以苊烯(ACE)为荧光标记物,8-苯胺基-萘磺酸(ANS)为荧光探针,利用荧光各向异性、荧光猝灭以及非辐射能量转移等静态荧光技术研究了聚乙烯吡咯烷酮(PVP)在稀水溶液中的构象行为.结果表明,PVP在稀水溶液中呈松散自由线团构象,这种构象不随溶液pH的变化而显著变化.不同于其它水溶性高分子,PVP有很强的氢键形成能力,易与具有活泼氢的其它高分子或小分子相结合,并易被金属氧化物类吸附剂吸附.因此PVP可被用来修饰某些具有疏水结构的水溶性高分子.PVP水溶液在pH=7以上相当稳定,放置1周性质没有显著变化.     

10-苯基-吖啶酮测定核酸的荧光分析新体系研究

10-苯基-吖啶酮（PACR）是吖啶类强荧光物质,在pH6．5的Tds-HCl的缓冲介质中,在258nm的紫外光激发下,于420nm处有很强的荧光发射。核酸的加入,可以使得体系荧光在峰位基本不变的情况下,发生荧光猝灭。其荧光猝灭程度与小牛胸腺DNA在0．1～3．0mg／L范围内呈良好的线性关系,检出限可达0．044mg／L。本文还用光谱法探讨了10-苯基-吖啶酮与DNA之间的作用机理,认为二者之间可能存在嵌插作用。     

一种pH荧光探针的合成及光谱研究

设计合成了一种pH荧光分子探针2,5-双(4-羟基-苯亚甲基)环戊酮,并对其光谱性能进行了研究.pH滴定实验表明:探针的紫外吸收和荧光光谱对溶液的pH值有很强的依赖性.当体系溶液由酸性变为碱性时,探针紫外吸收光谱发生明显的红移,并伴有溶液颜色的显著变化.荧光光谱强度在酸性条件下随pH的变化不大,而在碱性条件下荧光强度则...     

4-[2-(二甲氨基)乙氧基]-N-十八烷基-1,8-萘酰亚胺荧光染料的合成及其性能研究

以4-溴-1,8-萘酐为原料,合成脂溶性4-[2-(二甲氨基)乙氧基]-N-十八烷基-1,8-萘酰亚胺。对其进行了1H NMR和IR表征。考察了荧光染料在DMF、乙腈、丙酮、乙酸乙酯和乙醚5种溶剂中的荧光光谱和吸收光谱,发现由于溶剂效应,随溶剂极性由小到大,荧光光谱和吸收光谱的最大峰值波长逐渐红移。考察了不同金属离子和pH对荧光染料荧光光谱的影响,结果表明荧光强度随Fe3+、Zn2+、Co2+浓度增大而逐渐增强,Fe3+的影响最为显著;当pH<7时,荧光强度随着pH的降低逐渐增强;进一步考察了Fe3+、Zn2+、Co2+对吸收光谱的影响,结果发现吸收光谱均蓝移。分析认为荧光染料的光致电子转移被阻碍,实验结果表明,合成的新型荧光染料可用于溶液中金属离子和pH的检测。     

Colorimetric and Fluorescent Bimodal Ratiometric Probes for pH Sensing of Living Cells

pH measurement is widely used in many fields. Ratiometric pH sensing is an important way to improve the detection accuracy. Herein, five water‐soluble cationic porphyrin derivatives were synthesized and their optical property changes with pH value were investigated. Their pH‐dependent assembly/disassembly behaviors caused significant changes in both absorption and fluorescence spectra, thus making them promising bimodal ratiometric probes for both colorimetric and fluorescent pH sensing. Different substituent identity and position confer these probes with different sensitive pH‐sensing ranges, and the substituent position gives a larger effect. By selecting different porphyrins, different signal intensity ratios and different fluorescence excitation wavelengths, sensitive pH sensing can be achieved in the range of 2.1–8.0. Having demonstrated the excellent reversibility, good accuracy and low cytotoxicity of the probes, they were successfully applied in pH sensing inside living cells.     

Development of FRET-based dual-excitation ratiometric fluorescent pH probes and their photocaged derivatives

Dual-excitation ratiometric fluorescent probes allow the measurement of fluorescence intensities at two excitation wavelengths, which should provide a built-in correction for environmental effects. However, most of the small-molecule dual-excitation ratiometric probes that have been reported thus far have shown rather limited separation between the excitation wavelengths (20-70 nm) and/or a very small molar absorption coefficient at one of the excitation wavelengths. These shortcomings can lead to cross-excitation and thus to errors in the measurement of fluorescence intensities and ratios. Herein, we report a FRET-based molecular strategy for the construction of small-molecule dual-excitation ratiometric probes in which the donor and acceptor excitation bands exhibit large separations between the excitation wavelengths and comparable excitation intensities, which is highly desirable for determining the fluorescence intensities and signal ratios with high accuracy. Based on this strategy, we created a coumarin-rhodamine FRET platform that was then employed to develop the first class of FRET-based dual-excitation ratiometric pH probes that have two well-resolved excitation bands (excitation separations>160 nm) and comparable excitation intensities. In addition, these pH probes may be considered as in a kind of "secured ratioing mode". As a further application of these pH probes, the dual-excitation ratiometric pH probes were transformed into the first examples of photocaged dual-excitation ratiometric pH probes to improve the spatiotemporal resolution. It is expected that the modular nature of our FRET-based molecular strategy should render it applicable to other small-molecule dual-dye energy-transfer systems based on diverse fluorescent dyes for the development of a wide range of dual-excitation ratiometric probes with outstanding spectral features, including large separations between the excitation wavelengths and comparable excitation intensities.     

Two near-infrared highly sensitive cyanine fluorescent probes for pH monitoring

Two near-infrared(NIR) p H-activated heptamethine indocyanine probes with quaternary ammonium unit were designed and synthesized. The absorption and emission titrations indicate that cationic structure improves the cyanine dye's aqueous solubility and these two probes exhibit highly sensitive response to p H in acid condition. Their fluorescence intensities both gradually increase about 25-fold from p H 7.60 to 3.00 with p Ka values of 4.72 and 4.45 respectively, which are suitable for studying acidic organelles in living cells. Moreover, their fluorescence intensities are linearly proportional to p H values in the range of 5.50–4.00. These results are probably attributed to the protonation of the indole nitrogen atoms, which are verified by 1H NMR spectra. Furthermore, these two probes can achieve real-time imaging of cellular p H and detection of p H in situ in living He La cells due to their excellent properties,including good reversibility, desirable photostability, high selectivity, low cytotoxicity and remarkable membrane permeability.     

Selective and sensitive fluorescence "turn-on" Zn~(2+) probes based on combination of anthracene,diphenylamine and dipyrrin

Two fluorescence "turn-on" Zn~(2+) probes were developed by introducing an anthracenyl fluorophore through the linkage of a diphenylamino moiety at the 5-position of a dipyrrin moiety.Thus,two compounds with weak fluorescence were designed,synthesized,and employed as CHEF(chelation enhanced fluorescence) type fluorescence "turn-on" Zn~(2+) probes,which exhibit dramatic fluorescence enhancement upon addition of Zn~(2+),showing high sensitivities and impressive detection limits of 13 and12 nM,respectively,better than their analogues containing simple aryl substituents at the 5 positions of a di-or tripyrrin moiety.In addition,both of the probes exhibit good selectivity,short response time of less than 10 s and wide applicable pH ranges.Furthermore,the weak fluorescence nature of the probes was rationalized based on viscosity dependence measurements and theoretical calculations.These results provide further insight into the development of selective and sensitive zinc probes.     

In vivo fluorescence imaging of bone-resorbing osteoclasts

Osteoclasts are giant polykaryons responsible for bone resorption. Because an enhancement or loss of osteoclast function leads to bone diseases such as osteoporosis and osteopetrosis, real-time imaging of osteoclast activity in vivo can be of great help for the evaluation of drugs. Herein, pH-activatable chemical probes BAp-M and BAp-E have been developed for the detection of bone-resorbing osteoclasts in vivo. Their acid dissociation constants (pK(a)) were determined as 4.5 and 6.2 by fluorometry in various pH solutions. These pK(a) values should be appropriate to perform selective imaging of bone-resorbing osteoclasts, because synthesized probes cannot fluoresce intrinsically at physiological pH and the pH in the resorption pit is lowered to about 4.5. Furthermore, BAp-M and BAp-E have a bisphosphonate moiety that enabled the probes to localize on bone tissues. The hydroxyapatite (HA) binding assay in vitro was, therefore, performed to confirm the tight binding of the probes to the bone tissues. Our probes showed intense fluorescence at low pH values but no fluorescence signal under physiological pH conditions on HA. Finally, we applied the probes to in vivo imaging of osteoclasts by using intravital two-photon microscopy. As expected, the fluorescence signals of the probes were locally observed between the osteoclasts and bone tissues, that is, in resorption pits. These results indicate that our pH-activatable probes will prove to be a powerful tool for the selective detection of bone-resorbing osteoclasts in vivo, because this is the first instance where in vivo imaging has been conducted in a low-pH region created by bone-resorbing osteoclasts.     

Fluorescent pH probes for alkaline pH range based on perylene tetra-(alkoxycarbonyl) derivatives

The pH detection in the alkaline range is particularly important in many fields such as leather processing, waste water treatment, paper industry, and metal mining and finishing. Compared with traditional analysis methods such as colorimetric sensors and electrochemical sensors, the fluorescence and colorimetric probes for pH measurements have attracted much more attention due to their advantages of high sensitivity, excellent selectivity, noninvasiveness, low cost, fast response time, the possibility of continuously measurement, etc. However, there are few fluorescent probes fiting for alkaline pH monitoring. Acturally, the design and synthesis of them were more significant for new probes producing. In this study, the design, synthesis, and practical application of two novel fluorescent pH probes for alkaline pH assay were discussed. Both of the two probes were derived from perylene tetra-(alkoxycarbonyl). The red or blue shift of the absorption/fluorescence spectrum was caused by the introduction of electron donor amino or oxygen ring in the bay region. Due to electronic separation of the OH group from the electron-withdrawing core, the probes have high pKa values and cover the pH range from 8 to 12. They exist in either fluorescent acid form or non-fluorescent basic form. It was investigated that the amino substituent at bay region had a higher pKa value than O-heterocyclic annulated perylene, which showed that the adjustable pKa value could be achieved by the modification of electron withdrawing groups. The probes would have a wide use for testing strips measurements and monitoring pH changes in concrete.     

Developing a novel ratiometric fluorescent probe based on ESIPT for the detection of pH changes in living cells

As an important parameter of intracellular metabolism, pH plays important roles in maintaining normal physiological processes. The abnormal pH could cause disorder of cell function which may cause neurological diseases. Herein, we present two novel ratiometric fluorescent probes to detect pH changes. The probes employed 2-(2′-hydroxyphenyl)benzothiazole as fluorescent platform, and displayed desirable fluorescence response to pH on the basis of excited state intramolecular proton transfer (ESIPT) process. The probe BtyC-1 showed green fluorescence at 546 nm under acidic conditions, while it displayed strong blue fluorescence at 473 nm and weak green fluorescence at 546 nm under alkaline conditions. Biological experiments demonstrated that the probe BtyC-1 could be successfully applied for the ratiometric imaging of cellular pH and the NH₄Cl-induced pH changes in living cells.     

苯乙烯类菁染料pH探针的合成与活细胞成像

合成了一个以苯乙烯类菁染料为母体的含胺类基团的pH荧光探针, 合成方法简单, 产物收率高, 提纯方便. 在乙醇-水体系中的性能测试结果表明, 随着pH值的降低, 其非质子化形态的吸收峰强度逐渐降低, 而质子化形式的长波长吸收峰强度逐渐升高, 长、短波长相差(Δλ)130 nm, 颜色由黄色变成粉红色, 利于可视观察; 探针在氨基呈非质子化形式时没有荧光, 氨基质子化后探针的荧光强度显著增强. 活细胞实验表明, 探针可以穿透细胞膜, 在细胞质内pH值偏低区域显示红色荧光, 可以用来定性探测酸性细胞器.     

氨基苯基类中氮茚化合物的合成及作为质子探针的研究

设计合成了3个氨基苯基类中氮茚化合物, 研究了其在不同pH值的缓冲溶液中的荧光强度变化. 结果表明, 在pH=2.1～4.2之间, 该类化合物具有荧光敏感性. 化合物3a和3b可以作为良好的质子控制的荧光开关器件信号分子.     

Fiber-optic pH detection in small volumes of biosamples

Determining the pH values of microscopic plant samples may help to explain complex processes in plants, so it is an area of interest to botanists. Fiber-optic probes with small dimensions can be used for this purpose. This paper deals with the fiber-optic detection of the pH values of droplets of plant xylem exudate based on ratiometric fluorescence intensity measurements with an internal reference. For this purpose, novel V-taper sensing probes with a minimum diameter of around 8 μm were prepared that enable the delivery of fluorescence signal from the detection site on the taper tip to the detector. The taper tips were coated with pH-sensitive transducer (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt; HPTS) and a reference [dichlorotris-(1,10-phenanthroline) ruthenium (II) hydrate (Ru-phen dichloride)] immobilized in a xerogel layer of propyltriethoxysilane and (3-glycidoxy)propyl trimethoxysilane. The prepared probes were sensitive to pH values mainly in the range from 6.0 to 9.0. In the pH range 6–9, the results were limited by measurement errors of about 0.2 pH units, and in the pH range 5–6 by measurement errors of about 0.5 pH units. Using the developed V-taper sensing probes, the pH values of in vivo and in vitro samples of small volumes (∼6 μl) of exudate were measured. The results were validated by comparison with conventional electrochemical pH measurements.