Deposition of Layer－by－layer Inorganic－organic Nano－hybrid Ultrathin Films onto SBA－15

Deposition of inorganic-organic nano-hybrid ultrathin films onto mesoporous silicate materials has been proven possible by using layer-by-layer assembly method. In combination with sol-gel method, titania, subsequently dye molecules (or polymer) were successfully fabricated onto the inner wall of SBA-15. Their structures were preliminarily characterized by FTIR and solid-state UV-Vis spectroscopy, thermal analysis, and BET surface area measurements,respectively.     

Functional Polyoxometalate Thin Films via Electrostatic Layer-by-Layer Self-Assembly

Polyoxometalates (POMs) comprise a structurally diverse class of inorganic transition metal oxygen clusters which—owing to their unique electronic properties—hold promise for a host of technological applications such as electrochromic windows, sensors, or heterogeneous catalysts, prototypic examples of which will be briefly exemplified. The integration of POMs into functional architectures and devices, however, necessitates the development of general methods that allow positioning these clusters in well-defined supramolecular architectures, thin films, or mesophases. This short review highlights recent advances in the preparation of composite multilayers fabricated by electrostatic layer-by-layer self-assembly (ELSA) of POMs and a variety of water-soluble cationic species, including transition metal complexes, cationic surfactants, polycations and bipolar pyridine.     

含金属纳米粒子的层层自组装及单壁碳纳米管的催化生长

利用层间的静电吸附作用，重氮树脂和不同种类的含金属纳米粒子被依次吸附到硅片表面形成层层自组装膜。通过改变自组装膜的层数可以控制纳米粒子在表面吸附的量，同时利用重氮树脂的光敏特性可以实现纳米粒子在表面的图案化排布。以这些纳米粒子为催化剂，研究了单壁碳纳米管在硅片表面的化学气相沉积生长。     

微孔分子筛纳米晶的控制合成及其催化应用

纳米分子筛因具有高的外表面积和短的孔道结构而显示了独特的催化活性和选择性, 近年来已成为催化界的研究热点.本文就分子筛纳米晶的控制合成、催化基础研究,特别是当前分子筛纳米晶在自组装分级多孔材料和分子筛基纳米复合材料方面的新方向进行了系统的综述,分析了纳米分子筛研究中的机会和应用前景.     

Electrogenerated Chemiluminescence (ECL) Determination of Ephedrine with a Self-Assembly Multilayer Ni(II)-Polyluminol Modified Electrode

By combining the layer-by-layer (LBL) self-assembly technique with the electrochemical polymerization method, multilayer Ni(II)-polyluminol films were modified on the surface of a vaseline-impregnated graphite electrode. It was found that, compared with an electrode modified by direct electrochemical polymerization, this modified electrode offered a suitable ECL reaction micro-environment created by the special multilayer films, which was beneficial to the ephedrine hydrochloride enhancing effect for luminol ECL intensity. The ECL enhancing effect of ephedrine hydrochloride on the electro-oxidation luminol was improved on this modified electrode. Based on this finding, a new sensitive ECL method was developed for ephedrine hydrochloride determination under the optimal conditions. At the same time, a new idea is proposed for improving the analytical performance of the luminol ECL system by modifying the ECL reaction micro-environment with the layer-by-layer self- assembly method. Under the optimum experimental conditions, the ephedrine hydrochloride concentration in the range of 2.0 × 10⁻⁸–7.0 × 10⁻⁶ mol L⁻¹ was proportional to the enhanced ECL signal, and it offered an 8.0 × 10⁻⁹ mol L⁻¹ detection limit for ephedrine hydrochloride.     

层层自组装制备基于多壁碳纳米管的胆碱生物传感器

以经混酸处理的多壁碳纳米管(MWCNTs)修饰铂(Pt)电极,在此基础上固定(PAA/PVS)3复合膜,采用层层自组装技术将高分子聚电解质PDDA与胆碱氧化酶交替组装在已修饰的电极上,构建了电流型胆碱生物传感器。实验结果表明,MWCNTs的引入使电极对H2O2的催化电流明显增大,制成的酶电极可以有效控制酶量的使用,酶膜组装层数为8时最优,对胆碱的线性响应范围为5×10-7～1×10-4mol/L;灵敏度为12.53μA/mmol;响应时间为7.60s;检出限为2×10-7mol/L(S/N=3)。传感器的抗干扰能力强,稳定性好,30d时的响应电流值仍保持最初的89.5%。3次平行实验的RSD为3.64%。     

ATR-FTIR光谱技术在聚合物膜研究中的应用

红外光谱是聚合物研究中常用的一种表征手段,而衰减全反射红外光谱（ATR-FTIR）更是由于在研究聚合物薄膜方面具有显著的优势而被广泛使用。逐层组装（layer-by-layer Assembly）技术是一种常用的组装聚合物超薄膜的方法,ATR-FTIR光谱技术的引入可以在获取膜组装过程中相应信息的同时有效地避免表征过程中对样品的损害。另一方面,ATR-FTIR方法与二维相关光谱技术（two-dimensional correlation spectroscopy, 2D correlation spectroscopy）相结合也是研究小分子（主要是水分子）在聚合物薄膜中的渗透行为的有效手段。本文对ATR-FTIR的基本原理和显著特点作了介绍,并以实例阐述该方法在逐层组装技术和水分子在薄膜内渗透行为研究两方面的应用。     

Fabrication of chitosan microcapsules via layer-by-layer assembly for loading and in vitro release of heparin

The heparin-loaded microcapsules were successfully prepared by layer-by-layer deposition of chitosan (CHI) and heparin (Hep). Film growth was confirmed by the reversal of ζ-potentials during polysaccharide deposition. Both scanning electron microscopy and transmission electron microscope evidenced the integrity of (CHI/Hep)₅ capsules after the removal of cores. By assembling the carriers with chitosan that are inherently degradable, the capsules were engineered to degrade specifically in the presence of lysozyme. It was demonstrated that the loaded heparin was released from the capsules over a long period of time when being incubated in lysozyme solution. With these results, such CHI/Hep capsules may have a great potential as controlled release carrier for heparin.     

Metallosupramolecular Chemistry in Two Dimensions

Ultrathin films of metallosupramolecular coordination polyelectrolytes (MEPEs) on planar solid substrates assembled by electrostatic layer-by-layer self-assembly (ELSA) are characterized with UV-vis spectroscopy, optical ellipsometry, and X-ray reflectometry. MEPEs based on different ditopic ligands and transition metal ions are employed and shown to form regular ELSA multilayers. A quantitative analysis is in agreement with a surface coverage of approximately two MEPE monolayers per deposition step. In addition, we demonstrate that multilayers of MEPEs with different transition metal ions can be assembled. Even with kinetically labile metal ions, there is no metal ion exchange in these multilayers. Absorption spectra of multilayers on silicon show a band inversion of the MLCT band, which is rationalized in terms of optical effects.     

Enhanced Sunscreen Effects via Layer-By-Layer Self-Assembly of Chitosan/Sodium Alginate/Calcium Chloride/EHA

The sunscreen nanocapsules were successfully synthesized by the way of layer-by-layer self-assembly using charged droplets (prepared by emulsification of LAD-30, Tween-80 and EHA (2-Ethylhexyl-4-dimethylaminobenzoate)) as templates. Chitosan/sodium alginate/calcium chloride were selected as wall materials to wrap EHA. The emulsions with the ratio of Tween-80 to EHA (1:1) were stable. A stable NEI negative emulsion can be obtained when the ratio of Tween-80 and LAD-30 was 9:1. Chitosan solutions (50 kDa, 0.25 mg/mL) and sodium alginate solutions (0.5 mg/mL) were selected to prepare nanocapsules. The nanocapsules were characterized via some physico-chemical methods. Based on the synergistic effects of the electrostatic interaction between wall materials and emulsifiers, EHA was effectively encapsulated. DLS and TEM showed that the sunscreen nanocapsules were dispersed in a spherical shape with nano-size, with the increasing number of assembly layers, the size increased from 155 nm (NEI) to 189 nm (NEII) to 201 nm (NEIII) and 205 nm after solidification. The release studies in vitro showed sustained release behavior of the nanocapsules were observed with the increase of the number of deposition layers, implying a good coating effect. The sunscreen nanocapsules could control less than 50% the release of EHA after crosslinking of calcium chloride and sodium alginate, which also could effectively avoid the stimulation of the sun protection agent on the skin.