稀土离子对钙调蛋白与蜂毒素作用的影响

分别用钙调蛋白和蜂毒素的内源荧光光谱以及铽离子的敏化荧光光谱考察了铽离子对钙调蛋白构象变化以及对钙调蛋白与蜂毒素相互作用的影响 .结果表明 ,铽离子首先结合在钙调蛋白的第Ⅰ和第Ⅱ位点 ,铽离子不影响钙调蛋白与蜂毒素的相互作用 ,蜂毒素与钙调蛋白作用后不影响铽离子在钙调蛋白上的键合顺序 .傅里叶变换红外光谱结果表明三价的镧离子与钙调蛋白作用使钙调蛋白的α螺旋结构增加 ,β折叠结构减少 ,与钙离子对它的二级结构影响相类似 .稀土离子在钙调蛋白 -蜂毒素复合体系中主要与钙调蛋白作用 .     

Production and Separation of Carrier-Free Lutetium, Ytterbium and Thulium Radionuclides from 75 MeV 12C6+ Irradiated Terbium Foil Target

Heavy ion activation of natural terbium foil with 75 MeV ¹²C⁶⁺ results in the formation of carrier-free lutetium isotopes, ^165–167Lu, and their corresponding decay products, ^165–167Yb and ^165–167Tm, in the matrix. Carrier-free lutetium and ytterbium isotopes have been separated quantitatively from terbium bulk target matrix using HDEHP liquid cation exchanger. Radiochemically pure thulium radionuclides have been obtained after the decay of ytterbium radionuclides.     

Determination of orotic acid in aqueous solutions by micellar electrokinetic capillary chromatography using sensitized lanthanide-ion luminescence detection

Summary A sensitive and selective laser-induced luminescence detection scheme for orotic acid in urine, separated by micellar electrokinetic capillary chromatography (MEKC) has been developed. The 325 nm line from a helium cadmium laser is used to excite orotic acid, which transfers its energy to terbium. Resultant luminescence of terbium is linear with orotic acid concentration over more than 2.5 orders of magnitude. This novel and practical system enables the detection of 50 nm orotic acid in urine in less than 1.5 minutes while using only nanoliters of sample. The significant decrease in analysis time over traditional methods (spectrophotometric and chromatographic) comes from the high efficiency of MEKC. A dramatic improvement in sensitivity and selectivity over UV detection in capillary electrophoresis is achieved through the use of laser-induced lanthanide ion energy transfer luminescence detection. Finally, no sample pretreatment is needed and the method is free from any known interferences in urine.     

酒石酸脱除单铽转铁蛋白中铽（III）的荧光动力学研究

0.01 mol/L Hepes, pH7.4,室温条件下,以酒石酸为脱除剂,监测铽（III） 与脱铁蛋白结合的两种配合物C端单铽转铁蛋白和N端单铽转铁蛋白随酒石酸浓度变 化的脱除动力学,根据其动力学行为,我们推测存在两种平行的脱除途径：一次途 径和饱和途径,其中C端单铽转铁蛋白的铽（III）脱除呈现饱和与一次相结合途径 ,N端单铽转铁蛋白为简单的一次途径。NaCl的加入可促进两种单铽（III）的脱除 ,且C端铽转铁蛋白较N端单铽转铁蛋白更易受NaCl的影响。     

Uranyl sensitization of samarium(III) luminescence in a two-dimensional coordination polymer

Heterometallic carboxyphosphonates UO(2)(2+)/Ln(3+) have been prepared from the hydrothermal reaction of uranyl nitrate, lanthanide nitrate (Ln = Sm, Tb, Er, Yb), and phosphonoacetic acid (H(3)PPA). Compound 1, (UO(2))(2)(PPA)(HPPA)(2)Sm(H(2)O)·2H(2)O (1) adopts a two-dimensional structure in which the UO(2)(2+) metal ions bind exclusively to the phosphonate moiety, whereas the Ln(3+) ions are coordinated by both phosphonate and carboxylate functionalities. Luminescence studies of 1 show very bright visible and near-IR samarium(III)-centered emission upon direct excitation of the uranyl moiety. The Sm(3+) emissive state exhibits a double-exponential decay with lifetimes of 67.2 ± 6.5 and 9.0 ± 1.3 μs as measured at 594 nm, after excitation at both 365 and 420 nm. No emission is observed in the region typical of the uranyl cation, indicating that all energy is either transferred to the Sm(3+) center or lost to nonradiative processes. Herein we report the synthesis, crystal structure, and luminescent behavior of 1, as well as those of the isostructural terbium, erbium, and ytterbium analogues.     

Capillary electrophoresis with post-column addition of terbium and sensitized lanthanide-ion luminescence detection for the determination of diflunisal and salicylic acid

A detection scheme based on the Post-column addition of terbium followed by sensitized luminescence detection has been developed. Two model Compounds- saliculic acid and diflunisa- were separated by capillary electophoresis in an alkaline phosphate buffer. A Solution containing terbium and CTAB was added post-column via a “home-built” reactor resulting in the rapid fromation of the strongly luminescent terbium-salicylic acid and terbium-diflunisal complexes in a reaction capillary. Following complexationn in the reaction capillarty, the 325 nm line from a HeCd laser was used to excite the analytes which efficiently transfer their energy to terebium. Resuulant luminescence of terebium was liner of 2 orders of magnitude. This novel and practical system enables the detection of micromolar concentrations of diflunisal and salicylic acid- a 10 fold improvement over UV absorbance detection in the same system. Post-column addition of terbium also eliminates the problems associated with strong adsorption of the lanthanide ion to the silica walls of the separation capillary and the formation of metal-ligand complexes with different coordination numbers.     

Enantioselective regulation of a metal complex in reversible binding to serum albumin: dynamic helicity inversion signalled by circularly polarised luminescence

The helicity of the (SSS)-Delta enantiomer of a terbium and europium(iii) complex is inverted on reversible binding to 'drug site II' of serum albumin, signalled by a switch in its circularly polarised emission; no such behaviour occurs with the (RRR)-Lambda complexes, thereby defining a unique chiroptical probe of albumin binding.     

A novel terbium complex using oxadiazole derivative as a neutral ligand： Synthesis and properties

A novel terbium complex using 1,3,4-oxadiazole derivative as a neutral ligand was synthesized and characterized. Its thermal stability and photoluminescent properties were studied. The strong emission peaked at 546 nm with a full width at half maximum of 5 nm was observed in the pure terbium complex film under excitation of 328 nm light, which is attributed to the characteristic emission of terbium ion. The good thermal stability and intense sharp emission of this terbium complex display its potential application in electroluminescence devices.     

微量铽的萤光光度测定——铽与吡啶-2,6-二羧酸螯合物的萤光

铽与吡啶-2,6-二羧酸(以下简称DPA)形成螯合物的萤光有人从生物化学角度作过一些研究^[1],但对测定稀土氧化物中微量铽的研究未见报导。本文系统地研究了Tb³⁺-DPA螯合物萤光产生的条件,拟订了测定稀土氧化物中微量铽的萤光光度法,探讨了螯合物萤光强度与其组成的关系。     

基于核酸脱碱基位点的铽离子荧光增强型单核苷酸多态性识别研究

基于核酸脱碱基(AP)位点构建了无机配体稀土铽离子(Tb^3＋)荧光增强型单核苷酸多态性(SNP)识别方法. 在目标链靶标碱基对应的探针链上相应位置引入AP位点, 发现Tb^3＋可以选择性地结合在AP位点, 光激发时发生从DNA碱基到结合的Tb^3＋的能量转移, 使Tb^3＋特征荧光显著增强. 这种荧光增强作用与靶标碱基及AP位点侧翼碱基类型密切相关. 当靶标碱基和侧翼碱基为G时, 荧光最强. 该方法可用于区分肿瘤抑制基因p53密码子177位的C/G碱基变异.     

Application of time-resolved luminescence to dry reagent chemical technology

A time-resolved luminescence method describing the use of terbium(III) in the dry reagent format is presented for the first time. Paper strips previously treated with sucrose are used as solid substrates where terbium(III) is immobilised by adsorption. The strips are stable for at least 6 months and they can be easily stored under a desiccant medium. Only the addition of the buffered sample is required for the analysis. This methodology has been applied to the determination of two local anaesthetics, namely benzocaine and procaine. These compounds release p-aminobenzoic acid after a hydrolysis step in alkaline medium, which reacts to terbium(III) giving a luminescent chelate. The luminescence intensity measurements are obtained at λ_ex 286 and λ_em 545 nm by using the time-resolved mode of the instrument. The method presents a linear range from 1.1 to 21.9 μM and the calculated LOD is 0.4 μM. It has been satisfactorily applied to the analysis of pharmaceutical samples and the recoveries obtained are in the range 88-108%.     

A new luminescence method for determining dysprosium in the presence of terbium

The new luminescence method for determining dysprosium in the presence of terbium is developed based on the difference in the lifetimes of dysprosium and terbium in complexes with 3-(6-benzodioxanyl)pyrazole-5-carboxylic acid (τ = 6 and 910 μs, respectively). The possibility of determining the short-lived and weakly luminescent dysprosium(III) ion in the presence of long-living and intensively luminescent terbium(III) was demonstrated for the first time using time-resolved luminescence. The developed method was used to determine dysprosium in luminescent materials doped with both lanthanides.     

Terbium(III) as fluorescence probe in the study of the interaction of rare earth and transition metal ions with concanavalin A

The binding site for calcium (II) on concanavalin A (con-A) can be occupied by rare earth ions. When terbium (III) ion binds to con-A, its fluorescence intensity is tremendously enhanced because of an energy transfer from one or more tryptophan residues in close proximity to the bound terbium (III). The dissociation constant of the con-A-Tb (III) complex is 8.90 × 10^?6M, obtained from terbium (III) fluorescence titration with con-A. The dissociation constant of the complexes of con-A with other rare earth and transition metal ions was obtained through their competition with terbium (III) in the reaction with con-A, i. e. the quenching of con-A enhanced fluorescence. The results indicate that the binding of rare earth ions with con-A is dependent not only on their ionic radius but also on the hard-soft acid-base strength of the metal ions.     

Novel stoichiometrically erbium-ytterbium cocrystalline complex exhibiting enhanced near-infrared luminescence

Three beta-diketonate complexes of erbium and ytterbium, Er(HFA)3(TPPO)3, Yb(HFA)3(TPPO)3, and Er(1/2)Yb(1/)(2)(HFA)3(TPPO)2 (HFA = hexafluoroacetylacetonate, TPPO = triphenylphosphine oxide) are synthesized and structurally characterized, and their luminescent properties are examined in detail. Compared with monometallic complexes Er(HFA)3(TPPO)3 and Er(HFA)3(TPPO)3, the stoichiometrically Er-Yb cocrystalline complex Er(1/2)Yb(1/2)(HFA)3(TPPO)2 exhibits special indirect near-infrared (NIR) luminescence with the acceptor and sensitizer (donor) coexisting in a single crystal. Of interest is that the NIR luminescence of the erbium ion in Er(1/2)Yb(1/2)(HFA)3(TPPO)2 is significantly enhanced because of the coexistence of the ytterbium ion through the energy-transfer between the ytterbium and erbium ions. The estimated donor-acceptor energy-transfer critical radii R(C,DA), obtained from the F?rster model, are in good agreement with those determined from the single X-ray crystal structure, confirming the dipole-dipole character for such a Yb-Er energy-transfer process.     

The application of trimesic acid to the determination of terbium by spectrofluorimetry

A sensitive, direct spectrofluorimetric method for the trace determination of terbium with use of trimesic acid (TMA) has been developed. The reaction conditions for the fluorescence system of terbium with TMA were studied. The terbium ion can form a stable binary chelate with TMA, having a ratio of 1:1 in the pH range 3.5-6.5. The maximum excitation and emission wavelengths are 260 nm and 545 nm for the terbium chelate, respectively. The reaction is instantaneous and the fluorescence intensity of the terbium chelate remains stable from 0.25 to 4 h. Under the optimal experimental conditions the fluorescence intensity is a linear function of concentration in the range 0.0248-6.35 mug ml(-1) of terbium. The relative standard deviation is still within +/-4% in the presence of one-thousandfold amounts of the other lanthanide ions, and common foreign ions hardly interfere in the determination. The method can be employed for the determination of trace amounts of terbium in rare earth ores or oxides because of its high sensitivity and selectivity with good reproducibility and accuracy.     

Sensitized near-infrared emission from ytterbium(III) via direct energy transfer from iridium(III) in a heterometallic neutral complex

A tetrametallic iridium-ytterbium complex has been synthesised that shows sensitized near-infrared emission (lambda(max) = 976 nm) upon excitation of the iridium unit in the visible region (400 nm) due to efficient energy transfer from the iridium units to the Yb(III) ion. The iridium phosphorescence is quenched nearly quantitatively while the ytterbium ion emits brightly in the NIR.     

聚N-异丙基丙烯酰胺-丙烯酸共聚微凝胶与Tb(Ⅲ)相互作用的研究

聚N-异丙基丙烯酰胺(PNIPAM)微凝胶是一类具有独特的温度响应性,即具有最低临界溶解温度(LCST)的高分子化合物,由于具有了LCST性能,当PNIPAM微凝胶受热时,在较窄的温度范围内,溶胀于微凝胶内的溶剂被挤出,从而导致微凝胶的粒子尺寸、粒子形态、亲水性、胶体稳定性以及微凝胶分散液的粘度、电泳流动性发生较大改变的现象。     

Structural,luminescence, and NMR studies of the reversible binding of acetate,lactate, citrate,and selected amino acids to chiral diaqua ytterbium,gadolinium, and europium complexes

The nature of the ternary complexes formed in aqueous media at ambient pH on reversible binding of acetate, lactate, citrate, and selected amino acids and peptides to chiral diaqua europium, gadolinium, or ytterbium cationic complexes has been examined. Crystal structures of the chelated ytterbium acetate and lactate complexes have been defined in which the carboxylate oxygen occupies an "equatorial" site in the nine-coordinate adduct. The zwitterionic adduct of the citrate anion with [EuL1] was similar to the chelated lactate structure, with a 5-ring chelate involving the apical 3-hydroxy group and the alpha-carboxylate. Analysis of Eu and Yb emission CD spectra and lifetimes (H2O and D2O) for each ternary complex, in conjunction with 1H NMR analyses of Eu/Yb systems and 17O NMR and relaxometric studies of the Gd analogues, suggests that carbonate, oxalate, and malonate each form a chelated (q = 0) square-antiprismatic complex in which the dipolar NMR paramagnetic shift (Yb, Eu) and the emission circular polarization (gem for Eu) are primarily determined by the polarizability of the axial ligand. The ternary complexes with hydrogen phosphate, with fluoride, and with Phe, His, and Ser at pH 6 are suggested to be monoaqua systems with Eu/Gd with an apical bound water molecule. However, for the ternary complexes of simple amino acids with [YbL1]3+, the enhanced charge demand favors a chelate structure with the amine N in an apical position. Crystal structures of the Gly and Ser adducts confirm this. In peptides and proteins (e.g. albumin) containing Glu or Asp residues, the more basic side chain carboxylate may chelate to the Ln ion, displacing both waters.     

Luminescence behavior of a water soluble calix[4]arene derivative complex with terbium ion(III) in gelation solution

The complexation luminescence behavior of a water soluble calix[4]arene derivative, 5,11,17,23-tetra-sulfonate-25,26,27,28-tetra-carboxymethoxycalix[4]arene (L) with lanthanoid ion (Tb(3+)) has been investigated in gelation solution at 25 degrees C by using UV-vis and fluorescence spectra. The results obtained indicated that the water soluble calix[4]arene derivative can form an efficient energy transfer complex with terbium ion(III). The fluorescence of L x Tb(3+)complex is partially quenched by gelatin in gelation solution. The quenching intensity is related to the concentration and the hydrolysis degree of gelatin. Absorption and fluorescence spectra analysis show that the -COO(-) groups on gelatin have a definite binding ability to Tb(3+), and then, gelatin could compete binding with calix[4]arene derivative upon complexation with Tb(3+), leading to the relative fluorescence quenching of the formation complex of terbium(III) ion with calix[4]arene derivative.     

d-f heterobimetallic association between ytterbium and ruthenium carbon-rich complexes: redox commutation of near-IR luminescence

We describe how the association between an ytterbium ion and a ruthenium carbon-rich complex enables the first switching of the near-IR Yb(III) luminescence by taking advantage of the redox commutation of the carbon-rich antenna.