色氨酸-亚硝酸体系荧光性质的研究及应用

本文首次提出了利用亚硝酸氧化色氨酸的荧光反应测定色氨酸的方法。亚硝酸氧化色氨酸,继而在氢氧化钠介质中生成荧光物质,其激发波长和发射波长分别是:λ~e~x=320nm,λ~e~m=392nm。当色氨酸浓度为0.2～1.6μg/mL时,工作曲线呈良好的线性。本方法用于测定蛋白质样品中的色氨酸,结果令人满意。本文还对反应产物的特性进行了研究。     

荧光素-酚藏花红荧光能量转移用于测定Cu2+

重金属离子能引起水体的严重污染,由于它的积累性和不可降解性,目前重金属污染已成为人们广泛关注的热门话题,在食品、环境污染监督检验中被列为重点检测项目。目前测定重金属离子的主要仪器分析方法有：原子吸收光谱法、原子发射光谱法、ICP-质谱法、X-射线荧光光谱法、离子选择性电极、伏安法及库仑法等。这些方法的研究多有报导,但这些方法存在耗时、分析步骤复杂、分析仪器昂贵、采样频率低等缺点。     

四环素-Ca2+-CTMAB三元配合物体系荧光光谱的研究与应用

研究了Ca2+和阳离子表面活性剂CTMAB对四环素(TC)的荧光增敏作用,提出了一种利用Ca2+-TC-CTMAB三元配合物协同增敏体系来测定TC含量的新方法.在Ca2+-CTMAB及TC共存体系中,由于三元配合物的生成使TC的荧光强度急剧增加,其荧光强度与TC浓度在8.0×109-9～1.0×10-5 mol/L范围内具有良好的线性关系,方法检出限为5.97×10-9 mol/L.该法用于TC片剂、尿液及牛奶中残留TC的测定,加标回收率为82.4%～98.3%.同时对TC在不同介质中的荧光增敏作用机理进行了初步探讨.     

稳态荧光探针法研究Ca2+与十二烷基苯磺酸钠的相互作用

用稳态荧光探针法研究了Ca2+与十二烷基苯磺酸钠(SDBS)的相互作用.研究发现,Ca2+与SDBS在一定条件下产生沉淀.将芘探针溶在有沉淀体系中所测得的第一峰荧光强度I1与第三峰荧光强度I3之比(I1/I3)的大小随表面活性剂浓度变化的突变点与用透光率法测得的沉淀点相对应;将沉淀体系离心,把芘溶在离心后所得的上清液中,此时所测得的I1/I3值随表面活性剂浓度变化的突变点则与透光率法测得的沉淀开始溶解的点相对应.且随着盐的加入及盐浓度的增加,芘的I1/I3值减小.在相同盐浓度下,二价金属盐比一价金属盐对芘的I1/I3值影响大.     

Fluorescence properties of amido-substituted 2,3-naphthalimides: Excited-state intramolecular proton transfer (ESIPT) fluorescence and responses to Ca2+ ions

2,3-Naphthalimide derivatives incorporating trifluoroacetamido (3a) and methansulfonamido (3b) functionalities at the 1-position were prepared and their intramolecular excited state proton transfer (ESIPT) fluorescence and responses to metal ions were investigated. Compound 3a displayed normal fluorescence in the amide form in toluene and MeCN and no response to metal cations in the corresponding amidate ion form. In contrast, compound 3b gave off dual emission assignable to normal and ESIPT fluorescence. Additionally, the amidate form of compound 3b displayed off-on fluorescence response to Ca²⁺.     

N-邻羧基苯基-N-(2-氨己基)草酰胺荧光特性的研究及应用

研究了酸度、温度对不对称草酰胺：N-邻羧基苯基-N-（2-氨己基)草酰胺(OBZE)荧光特性的影响。测定了该试剂的荧光量子产率。在pH8．0～9．5的H3BO3-NaOH缓冲介质中，NO3^-能使OBZE荧光强度定量猝灭，据此建立了荧光猝灭法测定NO3^-的新体系。OBZE的激发波长为210nm，发射波长为395nm。荧光猝灭值与NO3^-在0．004～0．68mg／L呈范围内线性关系，方法的检出限为0．004mg／L。实验了多种干扰离子的影响，已用于水中硝酸根离子的测定。     

新型钙荧光探针在H2O2对HL-60胞浆钙影响研究中的应用

采用H2O2、黄嘌呤和黄嘌呤氧化酶、H2O2/抗坏血酸/Fe^2＋（或H2O2/Fe^＋）、H2O2和辣根过氧化酶（HRP）等不同活性氧产生体系,对自行合成的胞浆特异性钙荧光探针STDIn的活性氧耐受性进行了考察.以STDIn-AM为探针标记HL-60细胞,激光共聚焦技术检测单细胞内Ca^2＋-STDIn荧光强度的变化;探讨了不同浓度的H2O2对胞内Ca^2＋浓度变化的影响,从膜结构和生物信号传导的角度研究了氧自由基对培养细胞的生物效应.     

Fura-2荧光探针研究Ca2+对大肠杆菌细胞的跨膜作用

以Fura-2／AM作为荧光探针,研究了Ca^2 对大肠杆菌HB101细胞的跨膜作用．考察了不同浓度外源钙离子处理不同生长时期细胞的跨膜行为,并采用停流技术测定了荧光动力学．结果表明大肠杆菌在用CaCl2溶液处理后,胞外Ca^2 可大量进入胞内,且进入细胞的钙离子量与胞外钙离子浓度相关;处于对数生长前期的细胞与对数生长后期和稳定期的细胞相比,胞内自身Ca^2 浓度低,但其摄取外源Ca^2 的能力最强,这应该与其生理代谢活性是相关的,而且这一时期是大肠杆菌细胞最易建立人工诱导感受态的时期．该研究对于测定革兰氏阴性菌细胞内Ca^2 浓度及胞外离子的跨膜传导行为,以及探索钙离子诱导的大肠杆菌人工感受态建立的生理机制都具有重要意义．     

Ca2+ selectivity of the sarcoplasmic reticulum Ca2+-ATPase at the enzyme-water interface and in the Ca2+ entrance channel

The sarcoplasmic reticulum (SR) Ca(2+)-ATPase, a P-type transmembrane protein, can transport Ca(2+) from the cytoplasmic to the luminal side over other cations specifically. The proposed Ca(2+) entrance channel, composed of the main-chain carbonyl oxygen and side-chain carboxyl oxygen atoms of the amino acids, opens on the enzyme surface, just above the biphospholipid layer membrane-water interface, where Trp residues are frequently found. In this work, the physicochemical nature of Ca(2+) selectivity over Mg(2+) on the surface of the SR Ca(2+)-ATPase has been investigated using the density functional theory (DFT) method. The selection process can be regarded as the first step of the specificity of the enzyme to transport Ca(2+). Subsequently, the specificity of the entrance channel to conduct Ca(2+) over other cations has also been explored. As revealed by thermodynamic analyses, either the aromatic or the aliphatic amino acid residues distributed on the surface of Ca(2+)-ATPase have a bigger affinity to Mg(2+) than to Ca(2+), resulting in a concentration decrease of free Mg(2+) in the local region. Thus, Ca(2+) can transport into the Ca(2+)-entrance channel more easily. Whereafter, for a small quantity of Mg(2+) entering this channel accompanying the Ca(2+) current, the strong electrostatic interactions between Mg(2+) and the ligands will limit the activity of this metal ion, which facilitates the weakly bonded Ca(2+) passing through the channel at a relatively high rate, as suggested by the "sticky-pore" hypothesis. Furthermore, the corresponding theoretical investigations have demonstrated that the increase of the ligand electronegativity can enhance their discrimination between these two cations effectively.     

Bioluminescent properties of obelin and aequorin with novel coelenterazine analogues

The main analytical use of Ca²⁺-regulated photoproteins from luminous coelenterates is for real-time non-invasive visualization of intracellular calcium concentration ([Ca²⁺]_i) dynamics in cells and whole organisms. A limitation of this approach for in vivo deep tissue imaging is the fact that blue light emitted by the photoprotein is highly absorbed by tissue. Seven novel coelenterazine analogues were synthesized and their effects on the bioluminescent properties of recombinant obelin from Obelia longissima and aequorin from Aequorea victoria were evaluated. Only analogues having electron-donating groups (m-OCH₃ and m-OH) on the C6 phenol moiety or an extended resonance system at the C8 position (1-naphthyl and α-styryl analogues) showed a significant red shift of light emission. Of these, only the α-styryl analogue displayed a sufficiently high light intensity to allow eventual tissue penetration. The possible suitability of this compound for in vivo assays was corroborated by studies with aequorin which allowed the monitoring of [Ca²⁺]_i dynamics in cultured CHO cells and in hippocampal brain slices. Thus, the α-styryl coelenterazine analogue might be potentially useful for non-invasive, in vivo bioluminescence imaging in deep tissues of small animals.     

Na+-Ca2+ exchanger modulates Ca2+ content in intracellular Ca2+ stores in rat osteoblasts

Na+-Ca2+ exchanger (NCX) transports Ca2+ coupled with Na+ across the plasma membrane in a bi-directional mode. Ca2+ flux via NCX mediates osteogenic processes, such as formation of extracellular matrix proteins and bone nodules. However, it is not clearly understood how the NCX regulates cellular Ca2+ movements in osteogenic processes. In this study, the role of NCX in modulating Ca2+ content of intracellular stores ([Ca2+]ER) was investigated by measuring intracellular Ca2+ activity in isolated rat osteoblasts. Removal of extracellular Na+ elicited a transient increase of intracellular Ca2+ concentration ([Ca2+]i). Pretreatment of antisense oligodeoxynucleotide (AS) against NCX depressed this transient Ca2+ rise and raised the basal level of [Ca2+]i. In AS-pretreated cells, the expression and activity of alkaline phosphatase (ALP), an osteogenic marker, were decreased. However, the cell viability was not affected by AS-pretreatment. Suppression of NCX activity by the AS-pretreatment decreased ATP-activated Ca2+ release from intracellular stores and significantly enhanced Ca2+ influx via store operated calcium influx (SOCI), compared to those of S-pretreated or control cells. These results strongly suggest that NCX has a regulatory role in cellular Ca2+ pathways in osteoblasts by modulating intracellular Ca2+ content.     

Photoluminescence properties and application of yellow Ca0.65Si10Al2O0.7N15.3:xEu2+ phosphors for white LEDs

A series of yellow-emitting oxynitride Ca_0.65Si₁₀Al₂O_0.7N_15.3:xEu²⁺ phosphors with α-sialon structure were synthesized. The phase composition and crystal structure were identified by X-ray diffraction and the Rietveld refinement. The excitation and emission spectra, reflectance spectra and thermal stability were investigated in detail, respectively. Results show that Ca_0.65Si₁₀Al₂O_0.7N_15.3:0.12Eu²⁺ phosphors can be efficiently excited by UV-Vis light in the broad range of 290–450 nm and exhibit broad emission spectra peaking at 550–575 nm. The concentration quenching mechanism are discussed in detail and determined to be the dipole-dipole interaction. When the temperature increased to 150 °C, the emission intensity of Ca_0.65Si₁₀Al₂O_0.7N_15.3:0.12Eu²⁺ phosphor is 88.46% of the initial value at room temperature. White LED was fabricated with N-UV LED chip combined with blue Ca₃Si₂O₄N₂:Ce³⁺ and yellow Ca_0.65Si₁₀Al₂O_0.7N_15.3:Eu²⁺ phosphors. The color rendering index and correlated color temperature of this white LED were measured to 78.94 and 6728.12 K, respectively. All above results demonstrate that the as-prepared Ca_0.65Si₁₀Al₂O_0.7N_15.3:xEu²⁺ may serve as a potential yellow phosphor for N-UV w-LEDs.     

天然水中钙镁离子的测定

对Ｃａ２＋、Ｍｇ２＋在含２×１０３ｍｏｌ／ＬＥＤＴＡ和１５×１０２ｍｏｌ／Ｌ硼砂载体溶液中的毛细管电泳行为进行了讨论,并在２００ｎｍ、３５℃、２０ｋＶ的优化条件下,５ｍｉｎ内对天然水中的Ｃａ２＋、Ｍｇ２＋离子进行了同时定量,为分析水质硬度提供了一种高效、快速的测定方法。     

The Different Fluorescent Response of Quin 2 to the Binding of Ca^2＋ and La^3＋ and its Application

The fluorescence spectra of Quin 2, (2-[(2-bis-[carboxymethyl] amino-5-methylphenoxy)methyl]-6-methoxy-8-bis [carboxymethyl] aminoquiniline), a Ca^2 probe, were investigated upon incubation with Ca^2 or La^3 . The results showed that binding of La^3 to Quin 2 resulted in different fluorescent spectrum from that of Ca^2 . Based on this observation, a fluorescent method was developed for simultaneously determination of the dissociation rates of Ca^2 and La^3 from a Ca-La- calmodulin complex (Ca2La2CaM).     

Fluorescence properties of Nd3+-doped tellurite glasses

The compositional and concentration dependence of luminescence of the (4)F(3/2)-->(4)I(J) (J=13/2, 11/2 and 9/2) transitions in four Nd(3+)-doped tellurite based glasses has been studied. The free-ion energy levels obtained for 60TeO(2)+39ZnO(2)+1.0Nd(2)O(3) (TZN10) glass have been analysed using the free-ion Hamiltonian model and compared with similar results obtained for Nd(3+):glass systems. The absorption spectrum of TZN10 glass has been analysed using the Judd-Ofelt theory. Relatively longer decay rates have been obtained for Nd(3+)-doped phosphotellurite glasses. The emission characteristics of the (4)F(3/2)-->(4)I(11/2) transition, of the Nd(3+):TZN10 glass, are found to be comparable to those obtained for Nd(3+):phosphate laser glasses. The non-exponential shape of the emission decay curves for the (4)F(3/2)-->(4)I(11/2) transition is attributed to the presence of energy transfer processes between the Nd(3+) ions.     

A calixarene based fluorescent Sr2+ and Ca2+ probe

A fluorescent probe, PyCalix, which has two pyrene moieties at the lower rim of a calix[4]arene fixed in the cone conformation was synthesized and its complexation behavior with alkali and alkaline earth cations was studied by fluorescence spectrometry. The compound showed intramolecular excimer emission at approximately 480 nm in the fluorescence spectra. Upon complexation with alkaline earth metal cations, a decrease of excimer emission was observed. The decrease of excimer emission was accompanied by an increase of monomer emission of pyrenes at 397 nm. The order of complexation constants of PyCalix with metal ions was Sr(+ approximately Ca2+ > Ba2+ > Mg2+ > K+ > Na+ > Cs+ for all reagents. PyCalix doped polyvinyl chloride (PVC) membrane was fabricated and our results showed that this membrane can be used for selective detection of Sr2+.     

Influence of Ca2+-ion upon viscoelastic properties of gellan gum aqueous solutions

Viscoelastic properties of gellan gum aqueous solutions [San-Eigen F.F. I. (Osaka), Lot No. 62058A] were observed in order to study the influence of Ca²⁺-ions upon the solution properties. The results were (i) the solution of Sample 1 (Ca²⁺ ~ 0.5%) showed narrowing of the oscillating amplitude of the ball after ~10 cycles (this is known as negative thixotropy); (ii) abrupt decreases in viscosity were observed for the solution of Sample 2 (Ca²⁺ ~ 0.1%) in the narrow temperature range of ± 0.5 °C; (iii) unstable behavior of oscillating ball was found for the solution of Sample 3 (Ca²⁺ ~ 0.00%), and this may be attributed to the inhomogeneity in the solution of the order of 10⁻⁴ m, which was removed after stirring for one week.     

氧氟沙星荷移络合物的荧光特性和应用

研究了电子受体氯冉酸(CL)和2,3 二氰5,6 二氯1,4 对苯醌(DDQ)与电子给体氧氟沙星之间的荷移反应。实验发现,氧氟沙星与以上两种电子受体在氯仿中可生成稳定的n π络合物,其荧光强度较之氧氟沙星分别增强了22和54倍。据此建立了两种基于荷移反应简便可靠地测定氧氟沙星的荧光光谱新方法。CL法和DDQ法测定氧氟沙星的质量浓度分别为0 06～2.4μg/mL和0 16～2.0μg/mL时,荧光强度与质量浓度呈良好的线性关系。该方法已用于药物制剂中氧氟沙星的测定,其回收率分别为98.4%～100.9%和98.5%～100.4%。     

Infrared spectroscopic study on Ca2+ binding to Akazara scallop troponin C in comparison with peptide analogues of its Ca2+-binding Site IV

Fourier-transform infrared spectroscopy (FT-IR) was applied to study the coordination structure of Ca²⁺ bound in Akazara scallop troponin C (TnC) and its site-directed mutant possessing inactivated Site IV (E142D mutant) in D₂O solution. The COO⁻ antisymmetric stretching region provides information about the coordination modes of a COO⁻ group to a metal ion. The wild type exhibits a band at 1543 cm⁻¹ in the Ca²⁺-bound state, indicating that the side-chain COO⁻ group of Glu142 (the position 12 of Site IV) serves as the ligand for Ca²⁺ in the bidentate coordination mode [F. Yumoto, M. Nara, H. Kagi, W. Iwasaki, T. Ojima, K. Nishita, K. Nagata, M. Tanokura, Eur. J. Biochem. 268 (2001) 6284–6290]. However, the E142D mutant showed no band around 1543 cm⁻¹ in the Ca²⁺-loaded state, indicating that the side-chain COO⁻ group of Asp142 does not bind to Ca²⁺ in the bidentate coordination mode. This result suggests that the absence of a methylene group is critical for the Ca²⁺ coordination structure of Akazara scallop TnC. The Ca²⁺-ligand interaction at Site IV is discussed in comparison with the results of synthetic peptide analogues of Site IV of Akazara scallop TnC.