CdTe量子点与蛋白质相互作用的荧光猝灭效应

本文在水热法合成水溶性CdTe及核壳结构CdTe/CdS量子点的基础上,分别研究了细胞色素c对CdTe量子点及CdTe/CdS核壳量子点荧光的猝灭效应和CdTe量子点对牛血清白蛋白荧光的猝灭效应,并阐述了猝灭机理。结果显示,细胞色素c对CdTe量子点的荧光猝灭效应具有一定的粒径依赖性,粒径越小,猝灭效应越强;细胞色素c对CdTe/CdS核壳量子点的猝灭效应比对CdTe量子点的更强,揭示了受激电子的表面传递机理。CdTe量子点通过松散牛血清白蛋白的螺旋结构而猝灭其荧光。     

配体对CdTe量子点与BSA的选择性相互作用的影响

以巯基乙酸(TGA)、巯基丙酸(MPA)、巯基甘油(TG)、L-半胱氨酸(L-cys)和谷胱甘肽(GSH)等5种巯基分子为稳定剂, 水相合成了5种CdTe量子点. 以牛血清白蛋白(BSA)作为靶分子, 通过吸收光谱、荧光光谱和时间分辨荧光动力学等手段研究了各种配体分子稳定的CdTe量子点与BSA的直接相互作用. 结果表明, 5种量子点均能有效猝灭BSA的荧光, 其猝灭程度按配体次序为GSH>L-cys>TGA>TG>MPA; 而BSA对不同配体稳定的CdTe量子点的荧光光谱的影响则具有明显的选择性. BSA对TGA-CdTe和MPA-CdTe量子点的荧光先敏化增强而后猝灭下降; L-cys分子由于同时具有氨基和羧基而与BSA的相互作用较强, 因此BSA能显著猝灭L-cys-CdTe量子点的荧光; 而BSA对TG-CdTe量子点的荧光猝灭程度较小; GSH分子的空间效应使GSH-CdTe量子点的荧光被BSA猝灭的程度最小. 吸收光谱和时间分辨荧光动力学研究表明, 5种量子点与BSA之间的相互作用均为静态过程. 探讨了量子点的配体分子结构与蛋白质的相互作用机理.     

CdTe/CdS量子点荧光探针测定司帕沙星含量

在水溶液中合成了巯基乙酸修饰的CdTe/CdS量子点(QDs), 基于喹诺酮类抗生素司帕沙星与CdTe/CdS量子点的荧光猝灭作用, 建立了用CdTe/CdS量子点作为荧光探针检测微量司帕沙星的新方法. 用荧光光谱、紫外光谱研究了CdTe/CdS QDs与司帕沙星的相互作用. 研究表明: 该荧光猝灭的机理属于静态猝灭, 反应的作用机理可能是司帕沙星促使QDs表面键合的有机分子发生变化, 在Cd的电子空穴上形成了碲氧复合物, 致使荧光猝灭. 实验发现, pH为6.50的磷酸缓冲溶液中, 量子点的浓度为3.75×10^－4 mol/L时, 司帕沙星的浓度在0.1～50 μg/mL范围与CdTe/CdS量子点荧光猝灭强度呈良好的线性关系, 相关系数0.9992, 检出限0.01399 μg/mL. 该方法简便、快捷、灵敏、线性范围宽, 应用于司帕沙星片剂司帕沙星含量的测定, 分析结果与标示量一致; 用于牛奶中司帕沙星残留量的检测, 回收率在93.1%～102.4%, 结果满意.     

CdTe/CdS量子点-蛋白质与头孢曲松钠的相互作用

以3-巯基丙酸为稳定剂,采用水热法合成了具有优异光学性质的CdTe/CdS核壳型量子点,量子产率为13.8%。量子点与牛血清白蛋白(BSA)偶联后荧光强度明显增大。通过测定荧光强度确定了偶联的最佳反应条件:pH7.4,反应温度37℃,反应时间40min。研究了溶液pH值和NaCl浓度对量子点及量子点-BSA溶液荧光强度的影响。对牛血清白蛋白测定的线性范围为1.1~19.5mg/L;检出限为0.47mg/L。头孢曲松钠对量子点-BSA的荧光有明显猝灭作用,荧光猝灭程度与其浓度有良好的线性关系。实验结果表明为静态猝灭,头孢曲松钠与BSA按1∶1结合,结合常数为6.31×103L/mol。用圆二色光谱技术探讨了其对BSA构象的影响。     

CdTe/CdS半导体量子点作为农药百草枯的高灵敏传感器

用硫普罗宁(Tiopronin, TP)作为稳定剂合成了水溶性的高荧光CdTe/CdS量子点. 研究了该量子点与10种农药的相互作用. 实验发现, 当农药浓度为4.76×10^-6 mol/L时, 农药百草枯(Paraquat)能显著猝灭CdTe/CdS量子点的荧光, 使其荧光强度下降87.3%, 而分别加入乙酰甲胺磷及辛硫磷等其它9种农药, 仅能使CdTe/CdS量子点的荧光强度下降0.1%～5.1%, 显示了该CdTe/CdS量子点对百草枯的特异性传感作用. 采用吸收光谱和时间分辨荧光动力学研究了百草枯对CdTe/CdS量子点的荧光猝灭机理. 计算得出荧光强度猝灭的Stern-Volmer常数K为2.03×10⁶, 而寿命猝灭的Stern-Volmer常数K为4.25×10⁵. 结果表明, 百草枯对CdTe/CdS量子点的荧光猝灭主要为静态过程, 而动态过程的贡献较小. 利用二者的猝灭作用建立了对农药百草枯的高灵敏检测新方法, 校正曲线的线性范围为9.90×10^-9～1.50×10^-6 mol/L, 检出限为6.35×10^-9 mol/L, R=0.999. 用该方法对3种食品和3种水样中残留农药进行了检测, 加标回收率均在82.2%～98.5%之间, 其相对标准偏差为2.62%~8.35%.     

水溶性CdSe/CdS量子点的合成及其与牛血清蛋白的共轭作用

用巯基乙酸(TGA)作为稳定剂，合成了水溶性的CdSe和核壳结构的CdSe/CdS半导体量子点。吸收光谱和荧光光谱研究表明，核壳结构的CdSe/CdS半导体量子点比单一的CdSe量子点具有更优异的发光特性。用TEM、电子衍射(ED)和XPS分别表征了CdSe和CdSe/CdS纳米微粒的结构、形貌及分散性。红外光谱和核磁共振谱证实了巯基乙酸分子中的硫原子和氧原子与纳米微粒表面的金属离子发生了配位作用。在pH值为7.4的条件下，将合成的CdSe和CdSe/CdS量子点直接与牛血清白蛋白(BSA)相互作用。实验发现，两种量子点均对BSA的荧光产生较强的静态猝灭作用；而BSA对两种量子点的荧光则具有显著的荧光增敏作用，存在BSA时CdSe/CdS量子点的荧光增强是不存在BSA时体系荧光强度的3倍。     

表面富S2-的CdS量子点的合成及其与甲硝唑的作用

在冰水浴条件下,用柠檬酸三钠和六偏磷酸钠为稳定剂,通过控制较低浓度的氯化镉溶液和硫化钠溶液缓慢反应,合成了荧光稳定性好、表面富硫的水溶性CdS量子点。利用荧光光谱、紫外-可见吸收光谱和共振光散射光谱研究了CdS量子点与甲硝唑相互作用的光谱行为,发现甲硝唑与CdS富硫表面的过量S2-的结合引起量子点的荧光猝灭效应,甲硝唑对CdS荧光量子点的荧光猝灭为静态猝灭,它们主要以静电引力结合。     

CdTe/CdS荧光探针测定痕量铜(Ⅱ)

以巯基乙酸为稳定剂,在水溶液中合成CdTe/CdS量子点,基于量子点与Cu2+混合后发生荧光猝灭作用,建立CdTe/CdS量子点作为荧光探针检测微量铜的新方法。在pH 4.60的HAc-NaAc缓冲溶液中,反应时间为10 min时,Cu2+质量浓度在0.01～1.00μg/mL范围与CdTe/CdS量子点的荧光猝灭程度呈良好的线性关系,相关系数为0.9978,检出限为9.90×10-3μg/mL。方法可以用于雨水、自来水和延河水中Cu2+的分析。     

碲化镉量子点的制备及与岩白菜素相互作用的研究

以巯基丙酸为稳定剂,采用一步水合法制备水溶性功能化CdTe量子点。并通过高分辨透射电子显微镜(HRTEM)、X射线衍射仪(XRD)、傅里叶红外变换光谱(FT-IR)、荧光分光光度计(MF)对量子点的光学性能和结构进行表征。应用荧光猝灭法,研究溶液状态下岩白菜素和CdTe量子点的相互作用及时间、温度等诸多因素对相互作用的影响,并在此基础上对二者相互作用的机理进行了研究分析。在溶液状态下,岩白菜素对CdTe量子点有明显的猝灭作用,Stern-Volumer猝灭常数K_(SV)值在10~5L/mol数量级,其二者的猝灭机理为静态猝灭,热力学结果显示其二者的猝灭过程是自发进行的。     

芥子碱与牛血清白蛋白的相互作用

利用荧光光谱法研究了新芥子碱与牛血清白蛋白(BSA)的相互作用,结果表明,新芥子碱对牛血清白蛋白的荧光有猝灭作用,且荧光光谱有较大的红移,其猝灭类型属于静态猝灭;根据Stern-Volmer荧光猝灭方程计算得到不同温度下的新芥子碱和BSA的结合常数和结合位点数;由实验计算得到该猝灭反应的热力学参数,表明新芥子碱与BSA之间相互作用以氢键和范德华力为主;根据能量转移理论求得新芥子碱与BSA的结合距离及能量转移率。     

Multi-spectroscopic Study on the Interaction between CdTe Quantum Dots and Bovine Serum Albumin

The interaction between CdTe quantum dots (QDs) and bovine serum albumin (BSA) was systematically investigated by fluorescence, UV‐vis absorption and circular dichroism (CD) spectroscopy under physiological conditions. The experimental results showed that the fluorescence of BSA could be quenched by CdTe QDs with a static quenching mechanism, indicating that CdTe QDs could react with BSA. The quenching constants according to the modified Stern‐Volmer equation were obtained as 1.710×10⁶, 1.291×10⁶ and 1.010×10⁶ L·mol^?1 at 298, 304, and 310 K, respectively. ΔH, ΔS and ΔG for CdTe QDs‐BSA system were calculated to be ?33.68 kJ·mol^?1, 6.254 J·mol^?1·K^?1 and ?35.54 kJ·mol^?1 (298 K), respectively, showing that electrostatic interaction in the system played a major role. According to F?rster theory, the distance between Trp‐214 in BSA and CdTe QDs was given as 2.18 nm. The UV‐vis, synchronous fluorescence and CD spectra confirmed further that the conformations of BSA after addition of CdTe QDs have been changed.     

大黄酸铜(Ⅱ)配合物与血清白蛋白的相互作用

采用荧光光谱法和紫外光谱法研究了大黄酸铜配合物与牛血清白蛋白之间的相互作用.大黄酸铜配合物能显著猝灭牛血清白蛋白的内源荧光并以静态猝灭为主;计算了298 K和309 K温度下结合常数、结合位点,根据热力学参数判断大黄酸铜配合物与牛血清白蛋白之间具有较强的疏水作用力;依据F?rster的偶极-偶极非辐射能量转移理论,计算出大黄酸铜在蛋白质中结合位置与色氨酸残基间的距离为3.21 nm, 表明大黄酸铜的部分片段能够插入蛋白质分子内部;用同步荧光光谱和圆二色光谱技术探讨了大黄酸铜对牛血清白蛋白构象的影响.     

Study on the interaction between methyl violet and bovine serum albumin by spectral analyses

In this article the interaction between methyl violet (MV) and bovine serum albumin (BSA) was studied with spectroscopy. The results indicated that the fluorescence intensity of BSA was quenched strongly by MV through a static quenching procedure. The association constants, the number of binding sites and basic thermodynamic parameters were obtained based on fluorescence quenching data. The effect of MV on the conformation of BSA had been investigated with synchronous fluorescence spectroscopy and circular dichroism (CD) spectrum.     

咪唑型离子液体与牛血清蛋白的缔合特性

通过紫外-可见光谱、荧光光谱、同步荧光光谱、圆二色谱、衰减全反射红外光谱、负染-透射电镜、等温滴定微量热等实验方法系统地探讨了咪唑型离子液体与牛血清蛋白(BSA)的缔合特性.结果发现,离子液体[Bmim]Cl的加入使得BSA的紫外吸收强度增加,同时也会导致其荧光猝灭,并且这种猝灭是静态猝灭.同步荧光的研究结果表明,[Bmim]Cl分子可与蛋白质中接近色氨酸残基的区域发生相互作用,使蛋白质的构象和内部的疏水结构发生改变;负染色法透射电镜直观地显示了加入离子液体后形成的蛋白质-离子液体复合物结构逐渐变大;圆二色谱和衰减全反射红外光谱表明:在离子液体与BSA缔合过程中,离子液体的加入使得BSA二级结构中的α-螺旋和β-折叠的含量降低,从而引起蛋白质二级结构的变化;表面张力法和等温滴定微量热法进一步证实上述缔合作用为静电作用和疏水作用共同作用的结果,但离子液体的烷基链与BSA疏水内腔之间的疏水作用是离子液体与BSA缔合的主要驱动力.     

吡蚜酮与牛血清白蛋白的相互作用

利用紫外吸收、荧光、同步荧光光谱及圆二色谱研究了吡蚜酮与牛血清白蛋白(BSA)的相互作用. 结果发现, 吡蚜酮使BSA的紫外吸收峰强度降低, 峰位红移; BSA的特征荧光峰猝灭, 荧光猝灭常数KSV随着温度的升高而降低, 表明吡蚜酮与BSA发生了较强的相互作用, 且吡蚜酮对BSA的荧光猝灭机制属于静态猝灭. 计算了不同温度下的结合常数和结合位点数; 由van′t Hoff方程计算出体系的ΔH和ΔS值, 得出二者之间的作用力主要为氢键和范德华力; 根据非辐射能量转移理论确定了给体-受体间的结合距离r=2.4 nm. 采用同步荧光光谱和圆二色谱考察了吡蚜酮对牛血清白蛋白构象的影响.     

Thermodynamic and conformational investigation of the influence of CdTe QDs size on the toxic interaction with BSA

Water-soluble fluorescent colloidal quantum dots (QDs) have been widely used in some biological and biomedical fields, so the interaction of QDs with biomolecules recently attracts increasing attention. In this study, the fluorescence (FL) quenching method, circular dichroism (CD) technique, attenuated total reflection-Fourier transform infrared (ATR-FTIR) and UV-vis absorption spectra were used to investigate systematically the influence of CdTe QDs size on the toxic interaction with bovine serum albumin (BSA). Three size CdTe QDs with maximum emission of 543 nm (green-emitting QDs, GQDs), 579 nm (yellow-emitting QDs, YQDs) and 647 nm (red-emitting QDs, RQDs) were tested. The Stern-Volmer quenching constant (K_sv) at different temperatures, corresponding thermodynamic parameters (ΔH, ΔG and ΔS), and information of the structural features of BSA were gained. The FL results indicated that QDs can effectively quench the FL of BSA in a size-dependent manner, electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs-BSA complexes. The CD and ATR-FTIR spectra showed that the secondary structure of BSA was changed by QDs, indicating the toxic on protein.     

Biophysical studies of the interaction between a triazole derivative and bovine serum albumin by multi-spectroscopic and molecular modeling methods

The interaction between 3-thiol-4-(2,4-dichlorobenzylideneamino)-5-methyl-4H-1,2,4-triazole (CBTZ) and bovine serum albumin (BSA) under physiological conditions was investigated by fluorescence,UV-vis absorption and circular dichroism (CD) spectroscopy as well as molecular modeling methods. The result of fluorescence experiment indicates the static quenching as a result of the formation of the CBTZ-BSA complex. The binding constants (Ka) at different temperatures were calculated according to the modified St...     

Mechanism and conformational studies of farrerol binding to bovine serum albumin by spectroscopic methods

The mechanism and conformational changes of farrerol binding to bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence quenching technique, UV–vis absorption, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that farrerol could strongly quench the intrinsic fluorescence of BSA through a static quenching procedure. The thermodynamic parameters enthalpy change and entropy change for the binding were calculated to be −29.92 kJ mol⁻¹ and 5.06 J mol⁻¹ K⁻¹ according to the van’t Hoff equation, which suggested that the both hydrophobic interactions and hydrogen bonds play major role in the binding of farrerol to BSA. The binding distance r deduced from the efficiency of energy transfer was 3.11 nm for farrerol–BSA system. The displacement experiments of site markers and the results of fluorescence anisotropy showed that warfarin and farrerol shared a common binding site I corresponding to the subdomain IIA of BSA. Furthermore, the studies of synchronous fluorescence, CD and FT-IR spectroscopy showed that the binding of farrerol to BSA induced conformational changes in BSA.     

聚乙二醇200基硝苯柳胺与钥孔戚血蓝蛋白的相互作用

采用荧光光谱、紫外吸收光谱和圆二色谱(CD)研究了聚乙二醇200基硝苯柳胺与钥孔戚血蓝蛋白(KLH)的相互作用。结果表明,聚乙二醇200基硝苯柳胺对KLH的荧光猝灭机制属于静态猝灭;由Lineweaver-Burk方程计算出不同温度下结合常数K,由Van’t Hoff方程计算出△H和△S平均值,结合力主要为静电作用力;根据F rster非辐射能量转移机制求得给体与受体间的结合距离r=5.76 nm;同步荧光光谱表明,聚乙二醇200基硝苯柳胺能够被KLH存储和转运,但结合时对蛋白的构象有一定的影响;圆二色光谱的数据表明相互作用后KLH的二级结构发生了改变:KLH的α-螺旋的含量从43.1%下降到37.8%。     

Study of the interaction between bovine serum albumin and ZnS quantum dots with spectroscopic techniques

The interaction between bovine serum albumin (BSA) and ZnS quantum dots (QDs) was studied by fluorescence, UV-vis spectroscopic techniques. The results showed that the fluorescence of BSA was strongly quenched by ZnS QDs and the quenching mechanism was discussed to be a static quenching procedure, which was proved by quenching rate constant K(q.) The recorded UV-vis data and the fluorescence data quenching by the QDs demonstrated that the interaction between them leads to the formation of QDs-BSA complex. Furthermore, the temperature effects on the structural and spectroscopic properties of individual QDs and protein and their bioconjugates (QDs-BSA) were also researched. It was found that, compared to the monotonically decrease of the individual QDs fluorescence intensity, the temperature dependence of the QDs-BSA emission had a much more complex behavior, highly sensitive to the conformational changes of the protein.