具有"开-关"特性的pH荧光探针DPVF的合成与表征

合成并表征了{4-[2-(4-氟苯基)-乙烯基]-苯基}-二甲基胺(DPVF).结果表明,DPVF(10.0 μmol·L-1)的水∶乙醇=1∶1(体积比)溶液的紫外可见吸收强度对pH值(7.02～2.22)变化灵敏,荧光强度对pH值(7.02～1.66)变化灵敏.荧光增强阶段是氟原子质子化,荧光减弱阶段是氟原子与氮原子同时质子化,氮原子与氟原子都是pH功能基.该化合物显示了"开-关"荧光发射性能,可应用于荧光分子开关;同时又是一个很好的pH荧光探针,检测pH值范围为7.02～1.66,pH值检测最高灵敏度为ΔpH=0.04.     

一种新型1,8-萘酰亚胺衍生物的合成及光谱性能研究

在温和的条件下合成了一种新型的化合物N-正丁基-4-(2-(2-羟乙基氨基)乙氨基)-1,8-萘酰亚胺(ABN)。利用红外光谱、核磁和质谱表征了ABN的结构。在甲醇中,ABN的最大吸收波长为436nm(摩尔消光系数为1.20×104 L/mol·cm),最大荧光波长为522nm(荧光量子效率为0.509)。随着溶剂极性的增加,ABN溶液的吸收和荧光发射光谱发生红移。在二甲基甲酰胺(DMF)/Britton-Robinson缓冲溶液[V(DMF)∶V(Britton-Robinson缓冲溶液)=1∶99]中,ABN的荧光强度随pH值减小而增强,并且在pH=6.73~9.61与pH值呈良好的线性关系。     

4-硫辛酸酯基-4'-二甲氨基查尔酮的合成及其发光性能研究

通过4-羟基-4＇-二甲氨基查尔酮与硫辛酸在缩合剂DCC和催进剂DMAP作用下,合成了具有二硫键的4-硫辛酸酯基-4＇-二甲氨基查尔酮,并通过熔点和核磁共振氢谱对其结构进行了表征。研究了溶剂极性和溶液浓度对4＇-二甲氨基查尔酮衍生物的发光性能的影响。结果表明,随着发光分子浓度的减小,荧光强度先增大后减小;另外,随着溶剂极性的增加,其紫外最大吸收波长红移,荧光发射波长也红移,荧光发射强度先下降后升高再下降,具有溶剂极性敏感的荧光特性,可用作荧光探针。     

4′-二甲氨基查尔酮衍生物的发光性能研究

研究了溶剂极性对4′-二甲氨基查尔酮衍生物的紫外-可见光吸收及荧光性能的影响。结果表明,随着溶剂极性的增加,其紫外-可见光最大吸收波长红移,荧光发射波长也红移,荧光发射强度先下降后升高再下降,具有溶剂极性敏感的荧光特性,可用作荧光探针。     

7-羟基-4-甲基香豆素的合成及其荧光性质研究

很多香豆素具有多种生物活性,同时也具有优良的荧光性能。本论文以间苯二酚和乙酰乙酸乙酯为原料,在微波辅助下合成了一种简单香豆素——7-羟基-4-甲基香豆素(C1)。荧光性质研究结果显示,C1的荧光性质受溶剂的极性及pH等因素影响较大。在极性较大溶剂中,C1荧光的最大激发波长及发射波长均发生红移,在pH值较大的碱性条件下,其荧光强度明显增大。     

1,8-萘酰亚胺类化合物的荧光光谱性能研究

研究了11种新型1，8-萘二甲酰亚胺类荧光化合物的荧光光谱性能。利用紫外光谱仪和荧光光谱仪测定了这两类化合物的紫外光谱和荧光光谱，分别得到最大吸收波长、最大激发波长、最大荧光发射波长，并以硫酸奎宁的0.5mol／l硫酸水溶液为参比标准，测定了各化合物的荧光量子产率在此基础上，研究了浓度、溶荆对荧光性能的影响、以及化合物结构与荧光性能的关系。结果表明，1，8-萘酰亚胺粪化合物随着浓度的增大，荧光光谱发生红移，且斯托克斯位移增大。随着溶剂极性的增大，最大荧光发射波长发生红移，斯托克斯位移增大，荧光量子产率增大在1，8-萘酰亚胺类化合物的4-位引入笨并呋喃取代基后，最大荧光发射波长红移70nm～100nm，斯托克斯位移增大20nm～50nm，荧光量子产率明显增大。     

吖啶橙受溶液pH和浓度变化的光谱研究

利用荧光光谱分析仪研究吖啶橙受溶液pH和浓度变化的吸收光谱和荧光光谱的变化。实验表明,当改变吖啶橙溶液pH和浓度时,它的吸收光谱和荧光光谱发生位移。吖啶橙为1×10-6mol/L时,不同pH的吖啶橙溶液均在(490±3)nm出现一个强吸收峰,pH=6.5,吸收光谱的λm ax=430 nm,发生蓝移;而荧光光谱的λm ax随pH增大发生红移,荧光强度减弱。在浓吖啶橙溶液中,不同pH的吖啶橙溶液的吸收光谱的形状基本相同,出现两个吸收峰,λm ax1分别为(455±3)nm和(430±3)nm,λm ax2分别为(505±4)nm和(510±2)nm,吸收光谱红移;荧光光谱的λm ax均为(535±2)nm,荧光强度荧光很弱。pH相同或相近时,吖啶橙溶液的吸收光谱蓝移和荧光光谱红移,浓度越大,荧光强度越弱。还探讨了吖啶橙在水溶液中的赋存状态,结果表明,在稀溶液中,吖啶橙主要以单体的形式存在;在高浓度吖啶橙溶液中则以吖啶橙单体、二聚体,甚至多聚体形式存在。这说明溶液pH主要影响到吖啶橙分子基态的质子化和氢键的形成能力,使得分子的基态与激发态之间的能量间隔发生了变化,吖啶橙被质子化,则引起发光光谱向短波方向移动,而离解作用,则引起发光光谱向长波方向移动;吖啶橙浓度变化影响吖啶橙在水溶液赋存状态,引起吸收光谱向短波方向移动或向长波方向移动。     

1，4－双（4’－N，N－二甲基氨基苯乙烯基）萘的合成及荧光性质

利用Wittig反应合成了一个以萘为π-Center的对称型“D-π-D”有机绿色发光化合物1，4-双(4'-N，N-二甲基氨基苯乙烯基)萘(BDASN)，并测试了其在不同环境中的光谱性质．在378nm激发波长的激发下，BDASN显示出很强的荧光发射峰，峰位在521nm(CH2Cl2)．随着溶剂极性增大，最大发射波长红移且荧光强度降低，与“D-π-A”分子具有相似的分子内电荷转移(TICT)行为．在β-环糊精(β-CD)中BDASN的绿色发光带被猝灭，同时在450nm附近蓝发光带的荧光强度骤增．     

新试剂(2，6-二溴-4-硝基苯)-3-(4-硝基苯)-三氮烯的合成及其与镉显色反应研究

合成了新试剂(2,6-二溴-4-硝基苯)-3-(4-硝基苯)-三氮烯(DBNPNPT)。测定了其亚氨基质子离解常数pKa＝9.5。研究了试剂与镉的显色反应,结果表明,在Triton X-100存在下,pH10.6～11.4时,试剂与镉发生灵敏显色反应。用双波长法测定,其表观摩尔吸光系数达2.08×105L·mol-1·cm-1。镉含量在0～10μg/25mL符合比耳定律。     

一种水杨醛席夫碱荧光探针的合成及其对Cr~(3+)荧光识别

二氯甲烷为溶剂,(S)-(-)-1,1'-联-2-萘胺和2-羟基苯甲醛进行缩合得到席夫碱荧光探针S-2。其结构经1H NMR,13C NMR和LC-MS表征。并研究了S-2的荧光性能。结果表明:溶剂极性减小,S-2的荧光强度增强,最大发射波长蓝移;在甲醇和水的混合溶液中,随着甲醇含量的降低,S-2的荧光强度降低,最大发射波长红移。在DCM溶液中,荧光探针S-2对Cr~(3+)具有高选择性和高灵敏度的识别作用,对其它金属离子具有良好的抗干扰能力。通过Job’s曲线和荧光滴定曲线研究发现S-2与Cr~(3+)的配位比为1︰1。     

FITC and Ru(phen)32+ co-doped silica particles as visualized ratiometric pH indicator

The performance of fluorescein isothiocyanate (FITC) and tris(1, 10-phenanathroline) ruthenium ion (Ru(phen)32+) co-doped silica particles as pH indicator was evaluated. The emission intensity ratios of the pH sensitive dye (FITC) and the reference dye (Ru(phen)32+) in the particles were dependent on pH of the environment. The changes in emission intensity ratios of the two dyes under different pH could be measured under single excitation wavelength and readily visualized by naked eye under a 365-nm UV lamp. In particular, such FITC and Ru(phen)32+ co-doped silica particles were identified to show high sensitivity to pH around the pKa of FITC (6.4), making them be potential useful as visualized pH indicator for detection of intracellular pH micro-circumstance.     

燃烧环境对铝酸锶铕镝激发发射光谱的影响

采用燃烧-发泡反应,于不同燃烧环境下,合成了不球磨的铝酸锶铕镝超细长余辉粉体材料。考察了点燃温度、燃烧体系、燃烧液与坩埚体积比、锶与尿素摩尔比以及盖子等因素对产物激发与发射光谱的影响。确定了最佳燃烧条件为:点燃温度600℃,硝酸盐-尿素体系,V(液体)/V(坩埚)=1/10,n(Sr)/n(尿素)=1/12,坩埚加盖。光谱分析表明,燃烧环境不同,产物的激发与发射峰强度不同;温度效应会使发射峰蓝移,压力效应会使发射峰红移,最大频移分别为16 nm和8 nm。     

Fluorescence of Cascade Blue™ inside nano-sized porous shells of silicate

Cascade Blue™ (CB) dye at a concentration as high as 0.227 M was encapsulated within nano-sized porous silicate shells, and its relative fluorescence yield determined over the pH range of 1.8–12.3, using 380 nm as the excitation wavelength. The results were compared with those obtained in aqueous solution using similar pH and total dye concentration. Near neutral pH, the relative fluorescence yields of CB inside the shells exhibited little fluorescence quenching, even though a high concentration of the dye was trapped inside the particles, while the peak wavelength of fluorescence was shifted from 420 nm in solution to 430 nm in shells. Both in shells and solution, the relative fluorescence intensity decreased as the solution pH was raised from 2 to 4, and in shells it nearly disappeared at about pH 3–4. As the pH was further increased, the red shift of fluorescence peak in the shell-trapped dyes was evident at pH 5 and its fluorescence intensity regained equal to that in acid. In the neutral pH range, the fluorescence intensity of CB in the shells was similar to that of the equivalent total concentration of the CB in solution. In solution, a similar red shift of the fluorescence maximum of CB to 430 nm was observed only above pH 9. These observations suggest that the fluorescence intensities of dyes trapped inside nano-sized porous silicate shells can be equal to or higher than that observed in solution under comparable conditions, leading to several hundreds times more fluorescent intensity when it is measured per single shell rather than per unit fluorophore.     

Physicochemical characterization of psychosine by 1H nuclear magnetic resonance and electron microscopy

Krabbe's disease is an autosomal recessive disease that affects the lysosomal enzyme galactosylceramidase. The storage of one of its substrates, psychosine (β-galactosylsphingosine), is thought to be responsible for the induction of pathological changes. Psychosine has a free amine group which is necessary for the mediation of its toxic effects. In the present study, the physicochemical properties of psychosine were investigated. Nuclear magnetic resonance (NMR) detected pH titration was used to determine that the amine group had a pKa of 7.18±0.05. Pulsed-field gradient NMR spectroscopy was used to determine that the diffusion coefficient of 2.8 mM psychosine in D₂O at pD 4.46 or 7.04 is 1.16±0.02×10⁻¹⁰ m²/s or 0.77±0.02×10⁻¹⁰ m²/s, respectively. Negative staining electron microscopy (EM) studies of acidic and neutral solutions of psychosine also were performed. At pH 4.5, spherical structures were formed, which were relatively stable between 3, 120, and 216 h following preparation; the diameter ranged from ∼14 nm at the earliest time point to ∼18 nm at the last time point. The critical micelle concentration (CMC) was 1.26 mM at pH 4.0. At pH 7.1, the structures changed from spherical structures with a diameter of 15–23 nm, at the earliest time point, to a heterogeneous population of structures ranging from spherical structures, with a diameter of only a few nm, to irregularly shaped oblong structures that had one or more dimensions exceeding 100 nm. The NMR and EM data indicate that the deprotonation of the amine group causes psychosine to form aggregates that are unstable, which prevents a determination of the CMC at a neutral pH. These data indicate that molecular interactions of psychosine at the acidic pH of the lysosome, where it is normally digested, are more orderly than those at the pH of the cytoplasm or extracellular space where psychosine goes during disease.     

Preparation of waterborne polyurethane with outstanding fluorescence properties and programmable emission intensity

The hard segment content and hydrophilic group content of a fluorescent waterborne polyurethane (FWPU) were used to optimize the polymer structure which can influence the fluorescence properties. The synthesis of FWPU was based on 2,2′‐((4‐([3,3′:6′,2″‐terpyridine]‐4′‐yl)phenyl)azanediyl)diethanol (TPPDA) as fluorophore. The structure of FWPU was characterized using Fourier transform infrared and ¹H NMR spectroscopies, and the polymer molecular weight and polydispersity were measured using gel permeation chromatography. The relationship between fluorescence properties and FWPU structure was studied using luminescence spectrometry. Compared to TPPDA, the maximum emission wavelength of FWPU showed a hypsochromic shift, and the fluorescence emission intensity and quantum yield of FWPU were increased obviously. Moreover, increasing the hard segment content led to an enhancement of the fluorescence lifetime of FWPU, and to the fluorescence intensity increasing at first and then decreasing. The fluorescence emission intensity and quantum yield of FWPU were increased nearly 11 and 7 times, respectively, compared to TPPDA when the hard segment content was 65%. With an increase of hydrophilic group content, the fluorescence emission intensity of FWPU increased. The fluorescence emission intensity of FWPU exhibited a response to pH, which facilitated its employment as a fluorescence probe. FWPU with excellent solid fluorescence is very suitable for processing into optical devices, with increasing hard segment content and hydrophilic group content both enhancing the solid fluorescence emission intensity of FWPU. © 2016 Society of Chemical Industry     

A multifunctional ribonuclease A-conjugated carbon dot cluster nanosystem for synchronous cancer imaging and therapy

Carbon dots exhibit great potential in applications such as molecular imaging and in vivo molecular tracking. However, how to enhance fluorescence intensity of carbon dots has become a great challenge. Herein, we report for the first time a new strategy to synthesize fluorescent carbon dots (C-dots) with high quantum yields by using ribonuclease A (RNase A) as a biomolecular templating agent under microwave irradiation. The synthesized RNase A-conjugated carbon dots (RNase A@C-dots) exhibited quantum yields of 24.20%. The fluorescent color of the RNase A@C-dots can easily be adjusted by varying the microwave reaction time and microwave power. Moreover, the emission wavelength and intensity of RNase A@C-dots displayed a marked excitation wavelength-dependent character. As the excitation wavelength alters from 300 to 500 nm, the photoluminescence (PL) peak exhibits gradually redshifts from 450 to 550 nm, and the intensity reaches its maximum at an excitation wavelength of 380 nm. Its Stokes shift is about 80 nm. Notably, the PL intensity is gradually decreasing as the pH increases, almost linearly dependent, and it reaches the maximum at a pH = 2 condition; the emission peaks also show clearly a redshift, which may be caused by the high activity and perfective dispersion of RNase A in a lower pH solution. In high pH solution, RNase A tends to form RNase A warped carbon dot nanoclusters. Cell imaging confirmed that the RNase A@C-dots could enter into the cytoplasm through cell endocytosis. 3D confocal imaging and transmission electron microscopy observation confirmed partial RNase A@C-dots located inside the nucleus. MTT and real-time cell electronic sensing (RT-CES) analysis showed that the RNase A@C-dots could effectively inhibit the growth of MGC-803 cells. Intra-tumor injection test of RNase A@C-dots showed that RNase A@C-dots could be used for imaging in vivo gastric cancer cells. In conclusion, the as-prepared RNase A@C-dots are suitable for simultaneous therapy and in vivo fluorescence imaging of nude mice loaded with gastric cancer or other tumors.     

Quantitative measurement of protein stability from unfolding equilibria monitored with the fluorescence maximum wavelength

The fluorescence of tryptophan is used as a signal to monitor the unfolding of proteins, in particular the intensity of fluorescence and the wavelength of its maximum lambda(max). The law of the signal is linear with respect to the concentrations of the reactants for the intensity but not for lambda(max). Consequently, the stability of a protein and its variation upon mutation cannot be deduced directly from measurements made with lambda(max). Here, we established a rigorous law of the signal for lambda(max). We then compared the stability DeltaG(H(2)O) and coefficient of cooperativity m for a two-state equilibrium of unfolding, monitored with lambda(max), when the rigorous and empirical linear laws of the signal are applied. The corrective terms involve the curvature of the emission spectra at their lambda(max) and can be determined experimentally. The rigorous and empirical values of the cooperativity coefficient m are equal within the experimental error for this parameter. In contrast, the rigorous and empirical values of the stability DeltaG(H(2)O) generally differ. However, they are equal within the experimental error if the curvatures of the spectra for the native and unfolded states are identical. We validated this analysis experimentally using domain 3 of the envelope glycoprotein of the dengue virus and the single-chain variable fragment (scFv) of antibody mAbD1.3, directed against lysozyme.     

稳态荧光光谱法分析超氧化物岐化酶溶液的稳定性

目的考察超氧化物岐化酶(SOD)溶液在不同影响因素下的活性及构象变化。方法通过邻苯三酚自氧化速率法测定SOD溶液的活性,利用稳态荧光光谱法分析在不同影响因素(pH值、超声、变性剂盐酸胍)下SOD三、四级结构的变化与荧光光谱特征变化的关系。结果溶液pH值降低,SOD稳定性增加;在pH2.2～pH7.0的范围内,pH值与SOD比活力呈线性相关;随着pH值的降低,普通荧光最大发射波长由336nm蓝移至325nm。超声次数的增加使同步光谱谱带蓝移,SOD活性下降。随着盐酸胍浓度的升高,SOD活性逐渐下降;在盐酸胍浓度达2.1mol/L时,SOD最大荧光发射峰蓝移至312nm;经盐酸胍变性后,酶的荧光强度比天然态酶有所增加。结论采用稳态荧光光谱法可分析SOD溶液的稳定性。     

铁猝灭荧光分析法测定环丙沙星的研究与应用

在pH=4.5的HAc-NaAc缓冲介质中,Fe3+能与十二烷基硫酸钠(SDS)和环丙沙星作用,使其荧光值显著减小,据此建立了Fe3+-SDS-环丙沙星体系荧光猝灭法测定微量环丙沙星的新方法。该体系的最大激发、发射波长分别为λex=275 nm,λem=441 nm。环丙沙星在4.0×10-7~3.6×10-6mol/L的浓度范围内与荧光值呈良好的线性关系,R=0.995 8,相对标准偏差为0.76%(c=3.0×10-6mol/L)。