N-乙酰基L-半胱氨酸单层保护的金纳米粒子和重金属离子作用的研究

以N-乙酰基-L-半胱氨酸(NAC)为配体,用NaBH4还原HAuCl4制备了Au/NAC物质的量比为1∶3的NAC修饰的金纳米粒子(NAC-AuNPs)。用透射电镜、红外光谱和紫外-可见吸收光谱对其进行了表征,利用荧光光谱法和紫外-可见吸收光谱法系统研究了Cu2+、Ag+、Hg2+及Pb2+与NAC-AuNPs的作用。研究结果表明:Ag+和NAC-AuNPs的作用方式是Ag+较牢固地附着在金纳米表面,荧光猝灭以静态猝灭为主;Cu2+和NAC-AuNPs表面的配体发生了作用,荧光猝灭主要为动态猝灭;Hg2+则是部分附着到金纳米表面,荧光猝灭表现为静态猝灭和动态猝灭都存在;Pb2+与金纳米几乎没有作用。并就重金属离子结构与其同金纳米粒子相互作用的关系进行了分析。     

Cu2＋和Fe3＋与明胶的相互作用

利用荧光猝灭法, 研究了不同温度、酸度下, Cu2＋和Fe3＋与明胶的相互作用.计算了猝灭常数和结合常数.紫外光谱和显微红外光谱的测定结果表明, Cu2＋、Fe3＋与明胶分子中的酰胺键发生了作用.探讨了猝灭机理.计算出的热力学函数表明,在Cu2＋、Fe3＋与明胶的相互作用过程中熵变起主要的作用.     

含萘直链多胺化合物的荧光pH效应及核苷磷酸盐的分子识别

合成了三种含萘但链长不同的多胺类化合物.研究了它们在不同pH条件下的荧光光谱，发现所研究化合物的荧光强度与pH值间有着强烈的依赖关系，因此这类化合物可用作测定溶液pH值的荧光探针.在上述化合物溶液中分别引入不同的核苷磷酸盐（ATP、ADP、AMP），发现所研究的化合物如N-(2-氨乙基)-N’-（2-[(1-萘甲基)氨乙基]）乙二胺(化合物3)，其荧光可被不同的核苷磷酸盐所猝灭.以Stern-Volmer常数（KSV）或猝灭常数（Kq）作为评估猝灭能力大小的标准表明,不同核苷磷酸盐的猝灭能力是各不相同的.其中ATP有着对化合物3荧光最大的猝灭功能.实验结果表明,分子尺寸的匹配和化合物中基团的空间合理排布是化合物和核苷磷酸盐间能发生相互作用的重要根据,而猝灭则强烈地依赖于这类物种间的相互作用,因此可利用化合物荧光强度的改变来识别各种不同的核苷磷酸盐.     

几种金属离子对胭脂红与牛血清白蛋白相互作用的影响——荧光光谱研究

利用荧光光谱法研究了不同温度(15、27、39℃)下食用合成色素胭脂红对牛血清白蛋白(BSA)的内源荧光猝灭特性,考察了Cu2+、Ni 2+、Pb2+等金属离子对二者相互作用的影响,并测定了不同温度下的猝灭常数KSV、结合常数KA和结合位点数n.结果表明,3种金属离子基本不影响胭脂红对BSA荧光猝灭机理,但Cu2+、Ni 2+、Pb2+离子都与BSA有一定的结合能力,可在不同程度上增强胭脂红与BSA的结合作用及其对BSA内源荧光的猝灭.     

CdS纳米粒子的表面修饰及其对光学性质的影响

用反胶束法合成了用表面活性剂分子磺基焉珀酸双－２－乙基已酯钠盐（ＡＯＴ）进行表面修饰的ＣｄＳ纳米粒子（记为ＣｄＳ／ＡＯＴ－ＳＯ３＾－）,研究了这种纳米粒子在正庚烷（ｈｅｐｔａｅ）和吡啶（Ｐｙ）溶剂中的荧肖及光解行为,发现其在正庚烷中荧光很强,而Ｐｙ却强烈地猝灭ＣｄＳ纳一子的荧光,用电荷转移猝灭机制进行了解释,这种解释为ＣｄＳ纳米粒子在Ｐｙ中光解实验进一步证实。     

两种臂式荧光氮杂冠醚化学传感器

合成了萘基臂式苯并氮杂15-冠-5 (3)和5-氯喹啉基臂式苯并氮杂15-冠-5 (4)两种荧光化学传感器, 由元素分析、NMR等进行了结构表征|在乙醇溶剂中采用紫外光谱和荧光光谱法分别研究了冠醚3和4对金属离子K^＋, Ca^2＋, Mg^2＋, Pb^2＋, Co^2＋, Ni^2＋, Mn^2＋, Cu^2＋, Zn^2＋, Cd^2＋和Hg^2＋的选择性传感性能. 结果表明, 冠醚3仅对Cu^2＋离子有显著的传感作用, 是一种典型的辐射能量转移过程. 冠醚4对Ni^2＋, Co^2＋, Cu^2＋和Mn^2＋离子有特殊的敏感性, 金属离子浓度逐渐增大使冠醚4产生先增强后猝灭的荧光现象, 荧光增强归因于阻断了从冠环氮原子到喹啉荧光体的弱光诱导电子转移(PET)过程, 而选择性猝灭源于冠醚环与喹啉基团对金属离子协同螯合的机制. 冠醚3和4的构性关系表明, 发光体基团对传感器的选择性能够产生重要的影响.     

荧光猝灭法研究氧氟沙星与Cu2+的络合

采用荧光猝灭法研究Cu2+与氧氟沙星(OFL)的相互作用特征,考察Cu2+浓度和环境温度对荧光猝灭的影响。结果表明,Cu2+对OFL有明显的荧光猝灭效应,并随Cu2+浓度的增大而增大;环境温度的升高抑制了Cu2+对OFL的荧光猝灭效应,说明两者的表观猝灭可能是以静态猝灭为主。     

基于脱氧核酶的新型铅离子荧光探针

将荧光猝灭基团修饰的17E脱氧核酶(17E DNAzyme)与荧光基团修饰的底物链通过6个脱氧核苷酸相连, 得到了一种新型的对Pb2+敏感的荧光探针. 由于DNAzyme与底物链发生分子内杂交, 荧光基团与猝灭基团相互靠近, 导致荧光猝灭. 当Pb2+存在时, DNAzyme被激活, 底物链被切断后释放出荧光基团标记的DNA片段, 从而产生明显的荧光信号. 据此可在常温下快速检测Pb2+, 检测下限为10 nmol/L. 在Zn2+, Mn2+, Co2+, Cd2+, Cu2+, Mg2+和Ni2+等多种二价金属离子中, 除Zn2+, Mn2+和Cd2+略有干扰外, 其它几种金属离子均无响应, 表明该荧光探针对Pb2+具有良好的选择性.     

新型水溶性咪唑基硅量子点制备及用于果蔬中痕量铜的荧光检测

硅量子点因其极佳的亲生物性和光学性能成为纳米材料新宠,但传统硅量子点水溶性差限制了它的广泛应用。本实验以三甲基硅咪唑为硅前驱体采用水热法制备水溶性咪唑基硅量子点。相对于硼氢化钠、抗坏血酸、牛血清蛋白、半胱氨酸和柠檬酸,柠檬酸钠作为还原剂和稳定剂制得的硅量子点荧光发射最强。合成反应于220℃下可在2 h内完成,所制备的硅量子点水溶性好,平均粒径为2.6 nm,红外分析证实其表面存在游离的咪唑基。研究表明,硅量子点能与铜离子相互作用导致荧光强度的明显下降。考察不同温度下Cu2+对硅量子点荧光的猝灭行为,发现荧光猝灭程度随温度升高而增大。这说明荧光下降属于静态猝灭,即Cu2+与硅量子点上的咪唑基作用形成稳定配合物。此外,共振光散射分析还揭示荧光猝灭过程伴随着粒子团聚。基于硅量子点的荧光猝灭行为,建立了痕量铜的荧光检测方法。当Cu2+浓度在0.04~2400μmol/L之间,硅量子点的荧光强度随Cu2+浓度的增加而线性下降,检出限(S/N=3)达1.29×10-8 mol/L。本方法具有高的灵敏度、选择性和重现性,已应用于果蔬中痕量铜的荧光检测。     

外围萘修饰PAMAM树枝形聚合物的合成及其质子化过程研究

合成了外围修饰有萘基团的0～3代聚酰胺-胺树枝形聚合物GnN (n＝0～3), 化合物通过了IR, 1H NMR, 13C NMR和MALDI TOF的表征. 稳态光物理研究表明, 甲醇溶液中GnN外围萘基团与骨架胺之间发生电子转移过程, 形成最大发射峰在450 nm的激基复合物, 萘的荧光被明显猝灭; 当GnN骨架被质子化, 分子内光致电子转移过程和萘与骨架胺基间激基复合物的形成被抑制, 萘单体荧光发射大大增强; 由于质子化后树枝形聚合物骨架趋于伸展构象, 外围萘基团间相互作用增强, 部分形成最大发射峰在400 nm的激基缔合物.     

Laws and mechanism of adsorption of cations by different ion-exchange forms of silica gel

Using radioactive tracer method, the regularities of adsorption of over 30 mono-, di- and trivalent cations including transition metal and lanthanide ions on the H, Ca- and Al-forms of silica gel are established. It has been shown that the affinity of cations of the same charge to the silica gel surface depends both on the nature of the adsorbing ion and the nature of exchangeable cation on the surface. Adsorption of alkali earth metal ions on the Ca-form of silica gel increases with a decrease of their radius i.e. an inversion of the sequence of adsorption compared to H- or Al-form of this adsorbent or polymeric cation-exchange resins takes place. For lanthanide ions the sequence of adsorption is the same for all ion-exchange forms of the silica gel studied, namely, an increase of adsorption with a decrease of their crystallographic radius, i.e. from La ³⁺ to Lu ³⁺ takes place. The laws observed are explained by taking into account the fact that adsorption of cations by silica gel is determined by both electrostatic interactions and additional covalent/donor–acceptor interactions between the surface and cations. The latter is due to formation of π-bonds between the electron pair in surface oxygen and vacant p-, d- or f-orbital of adsorbing cations.     

阳离子荧光敏感器的器件化问题研究

通过对石英玻片表面修饰 ,制作了联有多氨基链萘基的超薄膜荧光敏感器件 ,研究了它在镍、铜等金属离子水溶液及有机溶剂中的荧光猝灭现象 .发现其荧光光谱无论在水或其他有机溶剂中都存在着单体和激基缔合物 (ex cimer)的发射峰 ,当处于镍离子水溶液中时 ,其单体峰随离子浓度的增大出现了先增强后减弱的现象 ,而激基缔合物的发光峰则仅略有减弱但变化不大 .在铜离子水溶液中其荧光的变化情况和镍离子有所不同 ,对单体荧光只能观察到强度减弱的趋势 ,而激基缔合物则变化不大 .比较了未联结的敏感器化合物分子在有机溶剂中荧光被铜离子猝灭的行为 ,发现与其在器件表面时有很大的差别 ,表明其分子结构和构象也有很大的不同     

Preparation and characterization of CuO/SiO2 and NiO/SiO2 with bimodal pore structure by sol-gel method

CuO/SiO₂ and NiO/SiO₂ with bimodal pore structure were prepared by sol-gel reactions of Tetra-methoxysilane (TMOS) and the respective metal nitrate in the presence of poly (ethylene oxide) (PEO) with an average molecular weight of 10 000 and the catalyst of acetic acid. In this process, the interconnected macroporous morphology was formed when transitional structures of spinodal decomposition were frozen by the sol-gel transition of silica. The addition of copper and nickel into the silica-PEO system had a negligible effect on the morphology formation. In gel formation, it was found that NiO crystalline sizes in the samples increased with decreasing Si/Ni molar ratio. It was considered that PEO interacted with both silica and nickel cations. In the CuO/SiO₂ with the presence of PEO_, CuO crystalline sizes were larger than those of NiO/SiO_2. It was considered that there was no obvious interaction between the Cu cation and PEO, most of the copper ions in wet silica gel were present in the outer solution. They easily aggregated as copper salts in the drying process of wet gel and decomposed into CuO particles in heating. While in the CuO/SiO₂ with the absence of PEO, the Cu was selectively entrapped as small particles in the gel skeleton due to the interaction between Cu aqua complex and silica gel network.     

Adsorption, separation, and thermochemical data on the herbicide picloram anchored on silica gel and its cation interaction behavior

The herbicide 4-amino-3,5,6-trichloropicolinic acid (picloram), chemically anchored on silica gel surface (SiPi), has been used for divalent cation M(2+) (Cu, Ni, Zn, and Cd) adsorption from aqueous solutions at room temperature. The series of adsorption isotherms were adjusted to a modified Langmuir equation from data obtained by suspending the solid with MCl(2) solutions, which gave the maximum number of moles adsorbed as 9.27, 7.54, 5.12, and 1.54 x 10(-4) molg(-1) for Cu, Ni, Zn, and Cd, respectively. The minimum cation retention capacity from aqueous solution was observed at pH 1, increasing up to pH 4, and was maintained constant at pH 5 for all cations. The maximum retention capacity followed the sequence Cu>Ni>Zn>Cd. SiPi-M (Cu, Ni) interactions presented endothermic enthalpic values, which contrasted with exothermic values for SiPi-M (Zn, Cd) interactions. The anchored herbicide was also used to separate the cations when loaded in a column. Their resolutions were determined as the ability of this surface to separate cations, to give Rs(Cd-Zn)=2.33, Rs(Cd-Ni)=3.16, Rs(Cd-Cu)=7.21, Rs(Zn-Ni)=1.31, Rs(Zn-Cu)=2.55, and Rs(Ni-Cu)=0.72.     

Conjugated polyelectrolyte-grafted silica microspheres

A direct method for preparation of conjugated polymer-grafted silica particles is reported. Silica particles (0.3 and 5 mum diameter) are treated with a 3-(trimethoxysilyl)propylamine derivative that is functionalized with an aryl iodide unit. A solution step-growth polymerization reaction is performed in solution that contains a dispersion of the aryl iodide-functionalized particles. The reaction is a Pd(0)-catalyzed (Sonogashira) A-B-type polymerization of an oligo(ethylene glycol)-fuctionalized diiodobenzene and a bis(propyloxy)sulfonate-substituted diethynylbenzene. The overall process affords silica particles that feature a surface graft layer of an anionic poly(phenylene ethynylene)-type conjugated polyelectrolyte. The particle surface modification process was monitored by infrared (FTIR) spectroscopy, and the polymer-grafted silica particles were characterized by thermogravimetric analysis, scanning and transmission electron microscopy, confocal fluorescence microscopy, and absorption and fluorescence spectroscopy. The conjugated polyelectrolyte-grafted silica particles are highly fluorescent, and a Stern-Volmer quenching study of the particles' fluorescence with electron-transfer- and energy-transfer-type quenchers shows that the quenching response depends on the type of quenching mechanism.     

Measurement of cation binding to immobilized vanillin by isothermal calorimetry

Isothermal calorimetry was used to determine enthalpy changes for interaction of divalent cobalt, nickel, copper, and zinc chlorides with silica gel functionalized with vanillin, Sil-Van. The thermal effect, Q(int), and the corresponding amount of cation that interacts, n(int), were obtained in the same experiment. Langmuir expressions for adsorption isotherms were applied to determine the maximum adsorption capacity to form a monolayer, N(mon), and the energy of interaction for a saturated monolayer per gram of Sil-Van, Q(mon). From knowledge of N(mon) and Q(mon), the molar enthalpy of interaction for formation of a monolayer of anchored cations per gram of Sil-Van, Delta(mon)H(m), was determined. Interactions between the Lewis-acidic cations and the donor atom attached to silica are reflected by Delta(mon)Hm values in the order Ni2+ > Cu2+ > Zn2+ congruent with Co2+.     

Spectral investigation of coordination of cuprum cations and protons at PAMAM dendrimer peripherally modified with 1,8-naphthalimide units

The investigations aim at revealing the ability of a 1,8-napthalimide-modified poly(amidoamine) dendrimer from second generation to respond to the presence of cuprum cations and protons in the environment. It has been established that a single Cu(2+) cation present in the dendrimer molecule is capable of quenching more than 78% of its fluorescence what is an indication of high sensitiveness. An enhancement of the fluorescence emission of the dendrimer has been observed in acidic medium. It has been established that the processes of coordinating the ions in different sites of the dendrimer are reversible.     

Sorption of transition metals by silica gel with fixed amide of maleic acid and polyhexamethyleneguanidine on the surface

The possibility was determined for covalent binding of amide of maleic acid and polyhexamethyleneguanidine to a silica gel surface previously activated with cyanur chloride. Adsorption of Zn(II), Cd(II), Pb(II), Cu(II), Mn(II), Ni(II), Fe(III), and Co(II) cations from aqueous solution with a modified silica obtained was studied. The possibility of subsequent formation on the surface of mixed ligand complexes     

A new continuous fluorometric assay for acetylcholinesterase activity and inhibitor screening with emissive core-shell silica particles containing tetraphenylethylene fluorophore

Emissive core-shell silica particles with tetraphenylethylene moieties were prepared and characterized. Fluorescence quenching was observed for the silica particles upon addition of compound 2 (Dabcyl-ACh). This was attributed to the electrostatic interaction between the silica particles and 2 and the resulting photoinduced energy transfer between them. After incubation with AChE, the fluorescence intensity started to increase. The fluorescence enhancement became more significant when the concentration of AChE was higher. The reaction kinetic parameters for AChE were successfully estimated with the silica particles and 2. These results reveal that the ensemble of the silica particles and 2 can be utilized for AChE assay. Moreover, the fluorescence spectra of the ensemble of the silica particles and 2 containing AChE were also measured after further addition of either neostigmine or tacrine which are typical inhibitors of AChE. The results manifest that the ensemble of the emissive silica particles and 2 is also useful for screening the inhibitors of AChE.     

Synthesis of bispyrenyl sugar-aza-crown ethers as new fluorescent molecular sensors for Cu(II)

Two N-pyrenylacetamide-substituted sugar-aza-crown ethers have been synthesized as new fluorescent chemosensors. The designed ligands 1 and 2 exhibit fluorescence characteristics of a pyrene monomer and a dynamic excimer emission when compared to N-pyrenylacetamide as a model compound. Both ligands displayed a Cu2+-sensitive fluorescence quenching with a 1:1 stoichiometry and high stability constants (log K = 6.7 for 1 and 7.8 for 2). The quenching effect was rationalized on the basis of photoinduced electron transfer from the excited pyrene to the complexed Cu2+ cation, while the changes in excimer-to-monomer ratio were explained by a conformational analysis through DFT calculations. The predicted structure suggests that the Cu2+ cation is coordinated with the two carbonyl groups and the sugar-aza-crown ethers which rigidified the complex structure and placed the two pyrene moieties far apart.