2,7-二苯芴酮伴随巨大红移的聚集诱导发光：真实还是假象？

先前报道的2,7-二苯芴酮具有不寻常的,伴随150 nm荧光红移的聚集诱导发光现象. 通过重复实验,发现这种异常行为由合成的2,7-二苯芴酮中少量2,7-二苯芴(DPF)造成. 固态纯2,7-二苯芴酮分子在528 nm处确实有强烈的荧光,是在二氯甲烷稀溶液中的4∽5倍(542 nm),但在固体中是蓝移而不是红移. 合成的2,7-二苯芴酮固体的荧光增强和波长红移现象由少量2,7-二苯芴杂质造成. 在稀溶液中,2,7-二苯芴的荧光远强于2,7-二苯芴酮且波长较短,当2,7-二苯芴酮中含有痕量(约1%)2,7-二苯芴时,主要的荧光峰来自于2,7-二苯芴. 因为2,7-二苯芴的吸收峰与2,7-二苯芴酮重叠,所以2,7-二苯芴的电子能可以转移到2,7-二苯芴酮上. 随着浓度的增加,因为2,7-二苯芴与周围2,7-二苯芴酮分子的距离更近,能量转移会变快. 这造成了2,7-二苯芴的荧光猝灭(356和372 nm)和2,7-二苯芴酮的荧光增强(溶液中542 nm,固体中528 nm). 因此,在高浓度溶液或者固体中,仅有542或528 nm的荧光峰出现,356和372 nm 处荧光峰消失.     

有机紫外滤波材料的紫外光谱性质研究

通过缩合反应合成了一种有机紫外滤波染料--2,7-二甲基-3,6-偶氮环庚-1,6-二烯高氯酸盐,并采用元素分析、红外光谱、紫外光谱等手段对其进行表征,着重讨论了不同浓度的染料溶液和染料掺杂的聚乙烯醇(PVA)薄膜的紫外光谱性质.实验表明,当染料浓度较低时,溶液的最大吸收波长为322 nm,薄膜的最大吸收波长为325 am.随着染料浓度的增加,溶液和PVA膜紫外截止通带宽度加宽,表现为285～345 nm区间为强吸收带,而在日盲紫外波段(240～285 nm)保持较高的透过率.利用染料溶液和染料掺杂的PVA膜的这种光谱特性,制作出日盲紫外滤波器.     

荧光和UV-Vis光谱法研究DL-天冬氨酸-Ag的反应

用UV-Vis、荧光光谱和电泳等方法研究了DL-天冬氨酸(Asp)同银(Ⅰ)离子的相互作用及介质的pH、Asp浓度等条件对天冬氨酸同银(Ⅰ)离子作用的影响.天冬氨酸-银体系在235.2nm和493nm左右有最大吸收;在281.7nm激发波长下天冬氨酸产生荧光(发射波长为333.8nm),当Asp同银离子发生反应后,出现了荧光猝灭现象.天冬氨酸-银体系带负电荷,双电层的电动电位为-1.81×10-4V.     

桥基取代2,7’-(乙烯基)-二-8-羟基喹啉类化合物的密度泛函理论研究

在B3LYP/6-31G(d)水平上对2,7′-(乙烯基)-二-8-羟基喹啉(2,7′-Ethq_2)及其6种桥基取代物的几何结构进行了全优化,探讨了取代基对分子的结构、电荷转移、前线分子轨道能级、能隙等方面的影响.采用含时的密度泛函理论(TD-DFT)研究各分子的气相及液相中的电子光谱,分析光谱的变化规律.结果表明,取代基的电子效应和立体效应对取代物的电子结构和电子光谱有重要影响,取代基重新调整了2,7′-Ethq_2的原子电荷布居,改变了前线分子轨道能隙,导致吸收光谱发生变化.氨基和氰基对2,7′-Ethq_2影响较为显著,吸收波长红移较大.此外溶剂的极性对其电子光谱也有影响,随溶剂极性的增大,硝基取代物的最大吸收波长发生明显的红移,其它取代物的最大吸收波长均发生较小的蓝移.     

2',7'-二氯荧光素荧光法测定环境样品中微量As(Ⅲ)的研究

本文报道了以2',7'-二氯荧光素为指示剂,荧光法间接测定微量As3+的新方法.在pH=5.5～7.5中性缓冲介质中,I2与2',7'-二氯荧光素反应,使2'7'-二氯荧光素的荧光猝灭,当加入As3+与I2反应使体系荧光增强,体系激发波长和发射波长分别为λex＝508 nm,λem＝524 nm.As3+含量在1.0～80 μg·L-1范围内呈良好线性关系,检测限为1.0 μg·L-1.该方法灵敏度高,选择性好,用于工业废水和河水样品微量As3+的测定,结果满意.     

激光光源-在线荧光光谱检测中的光强度比较研究

基于激光光源和氙灯光源在线荧光光谱法测定罗丹明B、维生素B₂、荧光素和异硫氰酸荧光素含量比较研究激光光源产生的荧光强度和氙灯光源产生的荧光强度。罗丹明B、维生素B₂、荧光素和异硫氰酸荧光素浓度均为10 μg·mL-1,积分时间100 ms,测定3次得其平均值。在线荧光光谱法最大吸收波长分别为580,450,488和510 nm;最大发射波长依次为594,530,525和524 nm。紫外-可见分光光度法测得其最大吸收波长为557,441,481和490 nm;荧光分光光度法测得其最大发射波长为586,520,519和520 nm。通过测定药物,发现激光光源产生的荧光光强度较强于氙灯光源产生的荧光光强度,原因不仅跟光源有关,而且与药物分子的共轭体系大小、共轭大π键的共平面性及其刚性程度、分子母体上取代基的种类有关,分子所处的外界环境如温度、溶剂、溶液酸碱度、激发光的照射等因素也会影响荧光效率。激光光源和氙灯光源产生的荧光光强度大小顺序为罗丹明B>荧光素>异硫氰酸荧光素>维生素B₂。激光光源在线荧光光谱法在一定程度上填补了在线荧光光谱仪在食品、药品痕量检测方面应用的空白。     

溴化5-［4-(2-吡啶-乙氧基)苯基］-10，15，20-三苯基卟啉对铜离子的显色反应研究

本文研究了溴化 5- [4 - ( 2 -吡啶 -乙氧基 )苯基 ]- 10 ,15,2 0 -三苯基卟啉与 Cu2 +的显色反应条件 ,在 p H=4 .0时 ,其络合物最大吸收波长为 4 13nm,试剂最大吸收波长为 4 4 3.5nm。对比度大约为 30 nm。试剂与铜络合比为 1∶ 1,其络合物表观摩尔吸光系数为 3.4× 10 5L·mol-1· cm-1,铜含量在 0— 0 .5μg/ 10 m L范围内符合比耳定律 ,本研究可用于痕量铜的测定     

1-（4-硝基苯基）-3-（4,6-二甲基-2-嘧啶）-三氮烯的合成及其与锌（Ⅱ）的显色反应

合成了一种新显色剂1-(4-硝基苯基)-3-(4,6-二甲基-2-嘧啶)-三氮烯(简称NPDMPMT),并研究了在非离子型表面活性剂Triton X-100存在下,于pH为11.0的Na2B4O7-NaOH缓冲溶液中与锌(Ⅱ)的显色反应.结果表明.Zn与试剂NPDMPMT形成1:2的橙黄色配合物,在456nm处有一最大正吸收,在530nm处有一最大负吸收,建立以530nm为参比波长,456nm为测量波长的双峰双波长测定法,其表观摩尔吸光系数为3.16×105L·mol-1·cm-1,锌(Ⅱ)浓度在0-8.0μg/25mL范围内符合比耳定律.方法用于人发中微量锌的测定,结果令人满意.     

溴化5-[4-(3-吡啶丙氧基苯基)]-10，15，20-三苯基卟啉对铜离子显色反应的研究

本文研究了溴化 5- [4 - (3-吡啶丙氧基苯基 ) ]- 10 ,15,2 0 -三苯基卟啉 ,在 p H=4 .0时与 Cu2 + 的显色反应条件 ,其络合物最大吸收波长为 4 13nm。在相同条件下 ,试剂最大吸收波长为 4 4 4nm,对比度大约30 nm。试剂与铜络合比为 1∶ 1,表观摩尔吸光系数为 2 .9× 10 5L· mol-1·cm-1,铜含量在 0— 6 0 μg/ L范围内符合比耳定律 ,可用于痕量铜的测定。     

一种新型有机染料HEASPS在不同波长时的双光子吸收和频率上转换性质研究

报道了一种新型双光子吸收染料 ,即反式 - 4- [4′- (N-羟乙基 - N-乙基胺基 )苯乙烯基 ]- N-甲基吡啶对甲苯磺酸盐的非线性光学性质 ;测试了染料在 72 0～ 110 0 nm波段的非线性透过率曲线。结果发现 :双光子吸收最强波长相对线性吸收峰波长的两倍处有明显蓝移 ;计算出的相应波长的双光子吸收截面在 930 nm处染料有最大双光子吸收截面(2 .0 6× 10 - 4 7cm4·s/ photon) ;测量了染料在 90 0～ 110 0 nm波段的上转换效率 ,在 10 2 0 nm处有最高效率 (5 .1% ) ,最高激射效率的波长相对最强双光子吸收的波长有明显红移     

荧光光谱法研究瑞香黄烷类化合物与牛血清白蛋白的相互作用

在模拟人体生理条件下（pH 7.4）,采用荧光光谱法研究了瑞香黄烷A（DPA）和瑞香黄烷B（DPB）与牛血清白蛋白（BSA）的相互作用。DPA和DPB通过静态猝灭过程使得BSA荧光强度减弱;在25℃下,DPA和DPB与BSA结合常数分别为3.35×106L.mol-1和7.36×106L.mol-1,结合位点数分别为1.073和1.196;通过计算反应热力学参数值,可推断DPA和DPB与BSA作用力主要为氢键或范德华力;根据Foerster非辐射能量转移理论计算DPA和DPB与BSA的结合距离分别为3.11nm和3.04nm;同步荧光光谱法研究表明,DPA和DPB与BSA的结合对蛋白质的构象未产生影响,其结合位点更接近于色氨酸;同时还考察了部分共存金属离子对DPA和DPB与BSA结合作用的影响。     

烟碱与牛血清白蛋白相互作用的光谱研究

在0.1 mol·L-1的磷酸氢二钠-柠檬酸体系中,采用荧光光谱、紫外吸收光谱研究了牛血清白蛋白(BSA)与烟碱的相互作用。荧光滴定表明这种相互作用使BSA的内源荧光猝灭,尼古丁和BSA形成1∶1稳定复合物。不同温度和酸度下的猝灭作用证实其静态猝灭行为和疏水作用机制。紫外吸收光谱和同步荧光光谱表明,相互作用引起BSA构象变化,而同步荧光光谱提示结合位点更接近于色氨酸。     

Interaction of aconitine with bovine serum albumin and effect of atropine sulphate and glycyrrhizic acid on the binding

The interaction of aconitine with bovine serum albumin (BSA) and effect of atropine sulphate and glycyrrhizic acid on binding constant, binding sites, and conformation were studied in an aqueous buffer solution (pH 7.40) by ultraviolet absorption and fluorescence spectroscopy. The study results show that aconitine quenched the endogenous fluorescence of BSA via a dynamic quenching procedure. Predominant intermolecular forces between aconitine and BSA were hydrophobic interactions, which stabilized the complex of aconitine–BSA. The distance between the donor and acceptor was 2.62 nm. The conformation of BSA was investigated by synchronous fluorescence techniques, indicating that the microenvironment around tryptophan (Trp) residues was changed. Furthermore, with the addition of atropine sulphate or glycyrrhizic acid, binding constant and the number of binding sites of aconitine to BSA were decreased, and the conformation had no change, which provide an important theoretical support for aconitine detoxification by atropine sulphate and glycyrrhizic acid.     

MCR-ALS结合分子对接研究隐色孔雀石绿与BSA的作用过程

孔雀石绿(LMG)在治理鱼卵中霉菌和杀灭鱼体寄生虫等方面的效果显著, 广泛应用于水产运输和养殖。孔雀石绿进入动物机体后, 通过生物转化代谢为脂溶性的隐色孔雀石绿(LMG), LMG的毒性超过MG; LMG能快速在组织中蓄积, 具有致癌、致畸、致突变等毒副作用。白蛋白可与多种内源和外源化合物结合, 是血浆中含量最丰富的载体蛋白, 也是药物发挥作用的重要载体和靶标。模拟pH 7.4的生理条件, 通过荧光光谱和圆二色谱法(CD)采集两种不同滴加方式的LMG与牛血清白蛋白(BSA)动态作用过程中的多维数据, 并应用化学计量学多元曲线分辨-交替最小二乘法(MCR-ALS)对多维波谱数据进行解析和描述, 从重叠严重的光谱数据中同时得到作用体系的定量和定性信息。从解析得到的浓度趋势图中, 说明体系在LMG∶BSA=2∶1时达到动态平衡, 并可确认复合物LMG₂-BSA的生成; 解析得到的与所测量的BSA荧光和CD图符合, 印证由MCR-ALS获得的浓度趋势图的可靠性和正确性; 通常由重叠光谱中无法辨别的LMG₂-BSA复合物荧光光谱和CD谱图也可由数学解析获得, 进一步印证了复合物的存在。原子力显微镜(AFM)测量结果表明BSA与LMG结合后, BSA的形貌发生改变, 表面粗糙度(RMS)由(1.24±0.28) nm增至(13.47±0.53) nm; 同时由CD实验结果可知LMG与BSA作用达到平衡时, α-螺旋结构的含量从46.5%降低到42.3%, 推测是BSA所处微环境和构象发生变化所致。荧光探针实验发现经典site Ⅰ标记物华法林加入后, LMG-BSA的猝灭常数由2.65×106 L·mol-1降低为1.88×106 L·mol-1, 但加入site Ⅱ标记物布洛芬后, LMG-BSA的猝灭常数变化不明显, 由此推断LMG可能结合在蛋白质的亚域ⅡA, 即site Ⅰ位。分子对接证实BSA的Ⅰ位有足够的空间容纳LMG, 且LMG与BSA之间的主要作用是疏水作用力。该研究从分子水平了解LMG与生物大分子的作用机制, 并为LMG的毒副作用研究提供重要的信息。     

Spectroscopic study of interaction of styrylcyanine dye Sbt and its derivatives with bovine serum albumin

The spectral-fluorescent characteristics of styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino) styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and homodimers, dyes conjugated with two chromophores in aqueous solutions without and in the presence of bovine serum albumin (BSA), are studied. It is established that in the presence of BSA for dyes Dbt-5 and Dbt-10, an increase of the absorptivity, a slight broadening and the emergence of new band on the short wavelength range with λ_max=410 nm is observed; also hypsochromic shift of the absorption and fluorescence at 30 nm and 7 nm, respectively for the dye D-183 is observed. The intensity of the fluorescence emission fundamental band in all the studied dyes in the presence of BSA increases by 3.5 to 55 times. The binding constant (K) and number of binding sites (N) of studied dyes with BSA are determined. The dependence of the binding constants with BSA from the dipole moment of dye molecules is identified, which shows that in addition to the electrostatic attraction forces between molecules of styrylcyanine dyes with BSA, hydrophobic interactions are essential. It is shown that the aggregation of dye affects the processes of interaction of the dyes with the BSA.     

牛血清白蛋白与酸性铬兰K结合反应的研究

本文对在酸性溶液中牛血清白蛋白与酸性铬兰K结合反应进行了研究。在pH2.87盐酸－乙酸钠缓冲体系中，随着BSA浓度的逐渐增大，酸性铬兰K在523nm的吸光度下降，吸收峰向长波方向移动。研究表明牛血清白蛋白与酸性铬兰K在通过静电引力而结合，结合反应符合相分配模型，并探讨了酸度、试剂浓度、离子强度对结合反应以及表观结合常数Kc、结合数n，Sandell灵敏指数的影响，对反应时间、表面活性剂对体系的影响以及工作曲线进行了研究。     

Interactions between imazethapyr and bovine serum albumin: Spectrofluorimetric study

The interaction between imazethapyr (IMA) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The Stern–Volmer quenching constant (K_SV) at three temperatures was evaluated in order to determine the quenching mechanism. The dependence of fluorescence quenching on viscosity was also evaluated for this purpose. The results showed that IMA quenches the fluorescence intensity of BSA through a static quenching process. The values of the binding constant for the formed BSA–IMA complex and the number of binding sites were found to be 1.51×10⁵ M^?1 and 0.77, respectively, at room temperature. Based on the calculated thermodynamic parameters, the forces that dominate the binding process are hydrogen bonds and van der Waals forces, and the binding process is spontaneous and exothermic. The quenching of protein fluorescence by iodide ion was used to probe the accessibility of tryptophan residues in BSA and the change in accessibility induced by the presence of IMA. According to the obtained results, the BSA–IMA complex is formed in the site where the Trp-134 is located, causing it to become less exposed to the solvent.     

碱性介质中茜素黄R与牛血清白蛋白作用的荧光法研究

在碱性条件下,采用荧光光谱法研究了茜素黄R(alizarin yellow R, AYR)与牛血清白蛋白(BSA)结合反应的光谱特征。研究表明,pH 11.00,激发波长为393 nm时,BSA的发射峰位于641 nm,且AYR对BSA有较强的荧光猝灭作用,AYR在BSA分子上荧光敏感部位有五个结合位点;由温度对AYR-BSA体系荧光猝灭速率的影响和动态猝灭常数K_SV以及静态猝灭结合常数K_LB的计算得出,AYR对BSA内源荧光的猝灭机制属于形成BSA-AYR复合物的静态猝灭,荧光猝灭常数为1.6×104 L·mol-1;由反应前后热力学函数ΔHθ＜0,ΔSθ＜0以及AYR对BSA-CBBG(CBBG-考马斯亮蓝G)体系具有荧光猝灭作用推出,茜素黄R与牛血清白蛋白之间的作用力主要是氢键和范德华力。     

Spectroscopic studies on the interaction of bovine serum albumin with ginkgolic acid: Binding characteristics and structural analysis

The interaction between ginkgolic acid (GA, C15:0) and bovine serum albumin (BSA) is investigated by several spectroscopic methodologies. At first, the binding characteristics of GA and BSA are determined by fluorescence emission spectra. It is showed that GA quenches the fluorescence of BSA and the static quenching constant K_LB is 11.7891×10⁴ L mol^?1 s^?1 at 297 K. GA and BSA form a 1:1 complex with a binding constant of 9.12×10⁵ L mol^?1. GA binds to the Sudlow's drug binding site II in BSA, and the binding distance between them is calculated as 1.63 nm based on the Förster theory. The thermodynamic parameters indicate that the interaction between BSA and GA is driven mainly by hydrophobic forces. On the other hand, structural analysis indicates that GA binding results in an increased hydrophobicity around the tryptophan residues of BSA as revealed by the synchronous fluorescence spectra, and a decrease in α-helix as revealed by the far-UV CD spectra. In addition, ANS, UV–vis and RLS experiments confirmed that GA binding causes a certain structural changes in BSA. These findings provide the binding information between BSA and GA, and may be helpful for pharmacokinetics and the design of dosage forms of GA.     

Effect of temperature and pH on interaction between bovine serum albumin and cetylpyridinium bromide: Fluorescence spectroscopic approach

The fluorescence spectroscopic technique has been efficiently employed to investigate the interaction between bovine serum albumin (BSA) and cetylpyridinium bromide (CPB) under different pH and temperature conditions. The binding constant, number of binding sites, thermodynamic parameters such as ΔG, ΔH, ΔS, and nature of binding forces between BSA and CPB were obtained by measuring the steady state fluorescence quenching of BSA by CPB. The experimental results showed that the fluorescence quenching of BSA by CPB was a result of the formation of CPB-BSA complex. The static quenching was confirmed from the Stern-Volmer quenching constant at different temperatures. The effect of CPB on the conformation of BSA was analyzed using synchronous and three-dimensional fluorescence spectroscopy. pH dependence complex formation between BSA-CPB is due to the interaction between cationic side chain of CPB and the net charge developed on BSA. The distance ‘r’ between BSA and CPB was obtained according to the fluorescence resonance energy transfer.