载银多聚赖氨酸-海藻酸钠静电自组装多层膜修饰钛表面及其抗菌研究

目的 利用层层自组装技术在钛表面构建聚L赖氨酸（PLL）-海藻酸钠（ALG）多层膜,并在膜层中导入纳米银颗粒,以评价其杀菌效果。方法 利用层层自组装的方法将带正电荷的PLL与带负电荷的ALG在钛片上交替吸附沉积形成聚电解质多层膜,再用盐诱导相分离技术在多层膜中形成一定尺寸的微孔并在其中包裹纳米银粒子。扫描电子显微镜（SEM）、傅立叶红外光谱（FTIR）和能谱分析（EDX）对表面进行表征。并与变形链球菌共培养,观察对细菌的粘附和杀灭的作用。结果 SEM、FTIR和EDX分析证实：多层膜成功沉积在钛片表面,并且纳米银粒子被包裹于其中。荧光显微镜显示纯钛表面有大量的活细菌,沉积聚电解质多层膜后细菌数量减少,导入纳米银离子之后附着于钛片上的细菌数量更少,并且随着膜层数的增多,银离子含量增加,抗菌效果也增强。SEM结果与荧光结果一致。结论 通过层层自组装的方法在钛金属表面沉积载银PLL-ALG聚电解质多层膜,能抑制细菌的粘附。同时,随着膜层数的增加,银粒子含量增加,抗菌效果增强。     

钛表面自组装聚L-赖氨酸和海藻酸钠多层膜对成骨细胞增殖和分化的影响

目的在钛表面沉积聚L-赖氨酸(PLL)和海藻酸钠(ALG)聚电解质多层膜,以评价其对成骨细胞增殖和分化的影响。方法用层层自组装的方法在钛表面沉积PLL和ALG,形成Ti-(PLL-ALG)10-PLL涂层,用傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)对涂层进行表征。以纯钛作为对照组,Ti-(PLL-ALG)10-PLL作为实验组,分别在其表面进行MC3T3细胞培养,1d、3d、5d和7d后用CCK-8检测细胞增殖率,用ALP检测碱性磷酸酶的活性。结果 FTIR和SEM显示PLL和ALG已沉积到钛表面。MC3T3细胞在Ti-(PLL-ALG)10-PLL表面的增殖率在第1天和3天时明显高于对照组,P值分别为0.04和0.028;第5天和7天则无显著性差异(P>0.05)。第7天和14天Ti-(PLL-ALG)10-PLL组碱性磷酸酶值明显高于对照组,P值分别为0.08和0.02。结论通过层层自组装的方法在钛种植体表面沉积Ti-(PLL-ALG)10-PLL聚电解质多层膜能促进MC3T3细胞在其表面的增殖和分化。     

绿茶多酚导致口腔收敛性感觉的吸附动力学研究

目的:利用吸附动力学原理和模型,探索绿茶多酚的典型化合物表没食子儿茶素没食子酸酯(EGCG)引起口腔收敛性感觉的分子机制.方法:通过消散因子石英晶体微天平测量EGCG吸附于全唾液(WS)和腮腺唾液(PS)表面的质量、厚度、弹性和黏度,考察EGCG单层膜的特性;计算Langmuir 和Fruendlich 模型的吸附常数...     

Analysis of the mechanism for electrodeposition of the ZnSe phase on Cu substrate

Electrodeposition mechanism of selenium, zinc and ZnSe phase was studied with the electrochemical techniques. The chronoamperometry and voltammetry were combined with quartz crystal microbalance technique to analyse the deposition processes. It was found that they strongly depend on the applied potentials. The deposition of pure Se starts at 0 V vs. saturated calomel electrode (SCE) and the efficiency of this process decreases due to H₂Se formation and hydrogen evolution when the more negative potentials are reached. The voltammetric and microgravimetric measurements suggest that the deposition of Zn from the bath containing both ions, follows selenium deposition and synthesis of ZnSe is initiated at −0.6 V vs. SCE. The chronoamperometric transients combined with microgravimetry confirmed the range of potentials in which Se and ZnSe are deposited. Below −0.84 V vs. SCE the formation of H₂Se was observed. Then H₂Se may react with Zn²⁺ ions and another mechanism of ZnSe synthesis is possible.     

Direct electrochemistry and enzymatic activity of bacterial polyhemic cytochrome c3 incorporated in clay films

Quartz crystal microbalance and voltammetric measurements are used to study the electroenzymatic activity of incorporated bacterial polyhemic cytochrome c₃ in clay minerals. Two different natural clays have been chosen, i.e., kaolinite and montmorillonite, which differ in structure, swelling property and cation exchange capacity. Comparative voltammetric studies of various electroactive species at clay-modified pyrolytic graphite electrodes are first undertaken, which allow the complete characterization of the clay deposit. Then, the incorporation process of bacterial polyhemic cytochrome c₃ in the two clays is studied coupling quartz crystal microbalance and voltammetric measurements. Based on their respective characteristics, each clay yields a different behavior of the incorporated cytochrome c₃, with significantly different electroactive fractions of the immobilized protein. The consequences of the interactions between the protein and the clays on the enzymatic activity of cytochrome c₃ is then further examined. Firstly, the influence of the incorporation of cytochromes in clays on the metal reductase activity developed by bacterial polyheme c-type cytochromes is discussed. Secondly, hydrogenase enzymatic reactions are studied inside the clay films. An electrode is constructed by immobilizing hydrogenase in the clay and progressively incorporating either artificial (methyl viologen) or physiological (cytochrome c₃) hydrogenase partner. It is shown that this modified electrode yields an efficient and stable response for either H₂ consumption or evolution over a large range of pH.     

纯钛钛片表面胶原/透明质酸聚电解质复合膜涂层的构建

目的尝试在纯钛钛片表面构建胶原/透明质酸聚电解质复合膜涂层,并评价其生物相容性。方法纯钛钛片表面经打磨抛光及氧化性混酸溶液处理,得到表面富含钛羟基的基底面(设为对照组),在此基础上接着通过层层自组装技术将I型胶原和透明质酸引入到钛片表面(设为实验组)。采用扫描电镜(SEM)、X射线光电子能谱(XPS)和接触角实验对两组钛片的表面进行表征。最后,在两组钛片表面培养成骨前体细胞,检测其早期粘附、增殖及分化的能力。结果 SEM结果显示,对照组钛片的表面非常平整,高倍镜下发现其表面有很多直径为数十纳米的颗粒状结构。而实验组钛片的表面也很光滑,高倍镜下也可见很多纳米颗粒,但其直径较对照组为小。XPS分析发现实验组钛片表面元素成分氮的含量随着组装层数的增加而不断升高。接触角实验显示实验组钛片表面的可湿性随着钛片表面聚电解质组装层数的变化而不断变化,实验组钛片表面的接触角较对照组小。实验组钛片明显促进了成骨细胞的早期粘附(P<0.05),而且培养在实验组钛片表面的细胞增殖得更快(P<0.05)。同时,在实验组钛片表面生长的成骨细胞分化能力更强。结论 I型胶原和透明质酸能够被成功的组装到纯钛钛片表面,该涂层结构有利于成骨前体细胞的生长,显示了良好的生物相容性。     

Electrochemical and mass measurements during small voltage amplitude perturbations of conducting polyaniline films

The electrochemistry of conducting polyaniline (PANI) films has been studied in sulfuric acid solutions using a.c. impedance and cyclic voltammetry (CV), coupled with the quartz crystal microbalance (QCMB) technique. In normal full potential range slow sweep CV experiments, the fact that the mass-to-charge ratio increases markedly with potential in the positive scan, but is essentially constant during the negative scan, may be related to slow water penetration into the film during its oxidation. When only small potential amplitudes of ca. 25 mV or less are employed, the CV and QCMB measurements reveal that additional film sites can be initially oxidized, but not reduced, unless the potential is made more negative. This leads to an apparent loss in film capacitance when only narrow potential ranges are cycled. These results, together with increased hysteresis in the mass response with increasing sweep rate as well as the known asymmetries of the PANI CV response, suggest that given enough time, water can penetrate the film, hydrating some of the reduced PANI sites and facilitating their oxidation but not their reduction. The subsequent steady-state but lowered film capacitance must reflect the reversible oxidation/reduction of film sites which are not susceptible to delayed water transport and/or the stabilizing effects due to site hydration.     

Electropolymerization and doping/dedoping properties of polyaniline thin films as studied by electrochemical-surface plasmon spectroscopy and by the quartz crystal microbalance

The electropolymerization and doping/dedoping properties of polyaniline ultrathin films on Au electrode surfaces were investigated by a combination of in situ electrochemical techniques, i.e., electrochemical surface plasmon spectroscopy (ESPR) and the electrochemical quartz crystal microbalance (EQCM). In the ESPR measurements, we employed two wavelengths, i.e., 632.8 and 1152 nm in order to distinguish independently the electrochromic behavior. In addition, we used spectroelectrochemical transmittance measurements in order to probe further the optical properties of the polymer films as a function of the applied potential. The real and imaginary parts of the dielectric constant of the polyaniline thin film at several doping levels was determined quantitatively by taking into consideration the thickness values obtained from the EQCM measurement. The combination of these two techniques provides a powerful method for probing the electrical, optical, and dielectric properties of conjugated ultrathin polymer films.     

Investigation of the cathodic electropolymerization of acrylonitrile,ethylacrylate and methylmethacrylate by coupled quartz crystal microbalance analysis and cyclic voltammetry

The cathodic electropolymerization of acrylonitrile (AN), ethylacrylate (EA) and methylmethacrylate (MMA), has been monitored for the first time by coupled electrochemical quartz crystal microbalance (QCM) and cyclic voltammetry analyses. These data have been compared to the previously published analyses for methacrylonitrile (MAN). At the potential E_p1 of the less cathodic of the two voltammetric peaks observed (peak I), the polymer formed is anchored firmly to the cathode even in a good solvent for it, and it remains adsorbed when the voltammetric scan is repeated up to E_p1. In parallel, a linear relationship is observed between the frequency change recorded in situ by the QCM up to E_p1 and the PAN film thickness measured ex-situ by ellipsometry. However, when potentials more negative than peak I are scanned, the polymer desorption (degrafting) occurs as assessed by solubilization in a good solvent. Polymerization is also resumed but in solution and no longer as grafted chains. The major difference between the acrylic monomers (AN and EA) and the methacrylic ones (MMA and MAN) is that part of the methacrylic chains are not grafted at E_p1. This coexistence of adsorbed and desorbed chains is not observed for the polyacrylic chains in that potential range. The mass of PAN deposited onto the cathode has been approximated from the film thickness and the Sauerbrey equation, so allowing the M_n of the grafted chains to be estimated.