Water Sorption Properties and Antimicrobial Action of Zinc Oxide Nanoparticles-Loaded Cellulose Acetate Films

In this work, ZnO nanoparticles loaded cellulose acetate (ZOLCA) films have been prepared and characterized by XRD, SPR and SEM analysis. The moisture permeation properties of the films have been investigated. The GAB isotherm model has been found to fit well on the moisture uptake data obtained at different temperatures. The monolayer sorption capacity χ_m was found to decrease from 0.059 to 0.0079 g water/g dry film with increase in temperature from 20 to 37°C. The isosteric heat of sorption, when studied in the lower water activity range of 0.04 to 0.10, was evaluated to be 46.55 to 87.29 kJ/mol. The water vapor permeability across the ZOLCA films was found to increase with temperature and activation energy of moisture sorption process was found to be 48.57 kJ/mol. These films have shown excellent antibacterial action against model bacteria E-Coli when investigated by qualitative and quantitative methods. Films exhibit great potential to be used as edible films to protect food stuff against microbial infections.     

细菌视紫红质／聚乙烯醇复合膜的制备及相关功能研究

细菌视紫红质（bR)是一种独特的光敏蛋白，具有光致变色和光驱质子泵功能 。将bR蛋白包埋于聚乙烯醇（PVA）基质中，制备了bR/PVA复合膜。利用紫外－可 见分光光度计和自制的毫秒级动力学光谱仪，检测了样品的吸收光谱和光循环M中 间体在脉冲光激发下随时间的变化；同时，利用凝胶扫描成像仪及相关分析软件考 察了样品成膜后的均匀程度。实验表明：bR/PVA复合膜具有良好的均匀性、透明性 和力学性能，而且bR蛋白保持了原有的生物活性和光学性质，bR与M中间体之间能 达到一种光可控制的双稳态，M中间体的寿命也得到了显著的延长，证实了bR可以 提供一个用于信息存储的模型材料。     

Preparation,Characterization and Drug Release Studies from Poly(D,L-lactic acid)/organoclay Nanocomposite Films

Biocompatible/biodegradable poly(D,L-lactic acid)/layered silicate nanocomposites were prepared by the solution-intercalation film casting technique. The obtained nanocomposites present a shift of glass transition temperature (T_g) to higher values. An increase in the onset temperature of thermal degradation (T_onset) was also observed by TGA. Hydrolytic degradation of PLA nanocomposites becomes apparent after the first 3 months of immersion of specimens into deionized water. Drug release studies from PLA/organoclay nanocomposite membranes showed slightly faster release behavior in comparison with unreinforced specimens containing 5 phr guaifenesin (GFN), whereas the different organic clay modifications studied in this work, did not seem to have any effect in the release profile of GFN.     

Biocompatible Crosslinked Nanofibers of Poly(Vinyl Alcohol)/Carboxymethyl‐Kappa‐Carrageenan Produced by a Green Process

This study presents a new type of biocompatible nanofiber based on poly(vinyl alcohol) (PVA) and carboxymethyl‐kappa‐carrageenan (CMKC) blends, produced with no generation of hazardous waste. The nanofibers are produced by electrospinning using PVA:CMKC blends with ratios of 1:0, 1:0.25, 1:0.4, 1:0.5, and 1:0.75 (w/w PVA:CMKC) in aqueous solution, followed by thermal crosslinking. The diameter of the fibers is in the nanometer scale and below 300 nm. Fourier transform infrared spectroscopy shows the presence of the carboxyl and sulfate groups in all the fibers with CMKC. The nanofibers from water‐soluble polymers are stabilized by thermal crosslinking. The incorporation of CMKC improves cytocompatibility, biodegradability, cell growth, and cell adhesion, compared to PVA nanofibers. Furthermore, the incorporation of CMKC modulates phenotype of human adipose‐derived stem cells (ADSCs). PVA/CMKC nanofibers enhance ADSC response to osteogenic differentiation signals and are therefore good candidates for application in tissue engineering to support stem cells.     

壳聚糖-g-聚甲基丙烯酸凝胶粒的制备及其药物释放行为

以壳聚糖和甲基丙烯酸为原料,硝酸铈铵为引发剂,合成了不同接枝率的壳聚糖-g-聚甲基丙烯酸(CS-g-PMAA),用FTIR、1H NMR和元素分析表征了产物的结构,以柠檬酸三钠和戊二醛为交联剂制备了具有核壳结构的CS-g-PMAA载药体系。 用UV/Vis检测了CS-g-PMAA粒子对模型药物的释放行为。 结果表明,CS-g-PMAA接枝率为12.21%时药物释放速率最慢,其在pH=1.8介质中药物累积释放量(11 h)为44.18%,而壳聚糖粒子的累积释放量高达65.24%,即接枝改性壳聚糖粒子对药物的缓慢控制释放性能较好; CS-g-PMAA粒子的释药行为还依赖于介质的pH值和盐浓度,在低pH值和低盐浓度下,药物释放速率较快;酶环境下由于载体材料的降解使药物释放速率加快。 分析了不同条件下CS-g-PMAA载药粒子中药物的释放机理。     

可降解光交联聚酸酐与聚酰胺-甲基丙烯酰胺凝胶的合成及药物控释

合成聚酰胺-胺型树状分子（PAMAM）并进行端基甲基丙烯酰基修饰,将最外层接枝光化学活性双键,修饰产物与甲基丙烯酸酐化癸二酸(MSA)用DMSO溶解并在光引发剂存在下,经过紫外光照射得到具有一定生物相容性的凝胶。运用1H NMR和FT-IR对聚酰胺-甲基丙烯酰胺的结构进行表征。凝胶的降解实验表明,聚酸酐含量为50-60wt%的凝胶以表面溶蚀的方式降解,随着甲基丙烯酸酐化癸二酸（MSA）在凝胶中含量不同,降解时间在45~60天之间,pH在6.5-8.06范围内改变。包埋氧氟沙星凝胶的降解实验表明,可以通过改变聚酸酐的含量控制降解时间和药物释放量。     

聚(乳酸-羟基乙酸)共聚物涂层的释药性能

以乙酸乙酯为溶剂,配制聚(乳酸-羟基乙酸)共聚物(PLGA)雷帕霉素溶液,利用滴涂法在316L不锈钢表面制备PLGA载药涂层。于37℃磷酸盐缓冲液(PBS)中进行体外动态药物释放,并用紫外-可见分光光度计测定药物释放量。结果表明:PLGA涂层中PLGA分子量越小,羟基乙酸(GA)含量越高,药物释放越快;药物释放量与滴涂量呈线性关系,药物释放率与滴涂量的倒数呈线性关系;涂层中药物含量增加,其释放量也随之增加,而药物释放率先增加后降低。     

含5-氟尿嘧啶的羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)半互穿网络水凝胶的药物释放性能

以5-氟尿嘧啶(5-FU)为模型药物,对羧甲基纤维素钠/聚(N-异丙基丙烯酰胺)半互穿网络水凝胶(CMC/PNIPA semi-IPN)的药物释放性能进行了研究。结果表明:在37℃、pH=7.4时,药物的释放速率以及释放量都随着凝胶中羧甲基纤维素钠含量的增加而增大。在25℃时,pH对药物释放速率的影响较小;而在37℃时,药物释放速率受pH的影响较大。该凝胶体系用做5-FU的口服释放载体具有较佳的释放性能。     

pH敏感阳离子聚电解质凝胶的溶胀和释药性能

共聚物;pH敏感阳离子聚电解质凝胶的溶胀和释药性能     

魔芋葡甘聚糖/聚乙烯醇纳米纤维膜及其释药行为研究

为了研制药物缓释效果优良的薄膜材料,利用静电纺丝设备研制不同比重的魔芋葡甘露聚糖/聚乙烯醇纳米纤维膜,并通过扫描电镜、傅里叶变换红外光谱和示差扫描量热法表征纳米纤维膜的结构和性能,结合体外实验和数学模型研究其缓释行为.结果显示当魔芋葡甘露聚糖含量占纳米纤维膜总质量约76%时,纳米纤维膜中微纤丝粗细最均匀且结点较少,纳米纤维膜中魔芋葡甘聚糖和聚乙烯醇之间存在明显的相互作用,含有5-氨基水杨酸的纳米纤维膜在pH=7.4 PBS磷酸盐缓冲液中25 h的累积释放量大约为45%,显示出良好的药物缓释效果,其缓释行为与Higuchi模型具有较高的拟合度.研究表明利用静电纺丝设备研制的魔芋葡甘聚糖/聚乙烯醇纳米纤维膜可以为药物缓释载体的开发提供理论依据.     

Structural Characteristics and Permeability of Ethyl Cellulose Films Containing Different Plasticizers

The effect of different type of plasticizers was investigated in ethyl cellulose as coating polymer for manufacturing coated pellets of modified release containing a water soluble model drug. Scanning electron microscopic image analysis (SEM), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopic chemical surface analysis (XPS) were used to study the films, and the dissolution profiles of coated pellets were evaluated. The effect of the different plasticizers and coating levels on the first order dissolution rate constant is determined by statistical experimental design. Correlation was found between the dissolution rate constant and the structural characteristics of the coating layer containing different plasticizers. Partial segregation of the plasticizers was detected especially on the surface of the films, which is in correlation with the differences in the glass transition temperatures. PEG 400 is found to be compatible enough to form continuous, durable EC coating at 5% concentration level, which gave the slowest dissolution.     

Structure and Mechanical Properties of Chitosan/Poly(Vinyl Alcohol) Blend Films

Summary: The origins of the thermal and mechanical properties of chitosan and poly(vinyl alcohol) (PVA) with inter- and intra-hydrogen bonds were investigated systematically by using X-ray, DSC, positron annihilation and viscoelastic measurements. Based on their individual properties, the characteristics of the blend films were estimated in relation to their morphology and mechanical properties as a function of chitosan content. The characteristics of the blend films were also analyzed in terms of the deviation from a simple additive rule of chitosan and PVA content. These results suggested that the miscibility of chitosan and PVA could be ensured by entanglement of the amorphous chain segments of chitosan and PVA. Further detailed analysis revealed that the chitosan content on the film surface is higher than that of the admixture content of chitosan after elongation, although the chitosan and PVA chains were crystallized independently. The elongation could be achieved for the blend films whose PVA content was higher than 50% and the drawn blend films were transparent. Thus, it may be expected that sufficiently entangled meshes formed between chitosan and PVA amorphous chains within the film, the PVA content being higher than 50%, were maintained under the elongation process.     

聚甲基丙烯酸甲酯/聚甲基丙烯酸-2-羟乙酯复合微球的合成及药物吸放性能

采用在甲基丙烯酸甲酯（MMA）悬浮聚合过程中滴加甲基丙烯酸-2-羟乙酯（HEMA）乳液聚合组分的悬浮-乳液耦合聚合方法,制备了大粒径聚甲基丙烯酸甲酯／聚甲基丙烯酸-2-羟乙酯（PMMA／PHEMA）复合微球。PMMA／PHEMA复合微球表面以HEMA乳液聚合物为主,且具有微孔结构。PMMA／PHEMA复合微球在水和苄醇中的平衡溶胀率大于PMMA微球。PMMA／PHEMA复合微球48h异丁苯丙酸负载百分比为35．6％,PMMA为27．6％。在磷酸盐缓冲液中释放时间达到360h,释放量占负载总量的82％;而PMMA微球的释放时间为216h,释放量仅占负载总量的60％。     

新型羧甲基壳聚糖水凝胶流变性能,药物释放及细胞相容性研究

羧甲基壳聚糖含有丰富的羧基和氨基, 通过1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)共催化交联羧甲基壳聚糖形成新型水凝胶. 调节EDC/NHS用量, 制备不同交联度的羧甲基壳聚糖水凝胶(CMCS hydrogels). 研究水凝胶的流变行为, 结果表明, 高交联度的水凝胶具有较好的弹性形变能力, 较高的储存模量, 这是因为随着交联度的升高, 羧甲基壳聚糖水凝胶化学交联网络结构趋于完善. 以胸腺五肽(TP-5)为模型药物, 初步评价CMCS水凝胶药物释放行为, 结果表明水凝胶交联度越高, 胸腺五肽释放速度越慢. MTT法初步评价了水凝胶细胞毒性, 细胞形态和细胞相对增值速率, 结果表明水凝胶毒性很低. 由此可见, 水凝胶具有良好的生物相容性, 在药物缓释和组织工程领域具有广阔的应用前景.     

聚N,N-二乙基丙烯酰胺温敏水凝胶的药物释放研究

在合成聚Ｎ,Ｎ－二乙基丙烯酰胺温敏水凝胶的基础上研究了该水凝胶在ＬＣＳＴ附近对药物的释放（以氟哌酸为主）。温度与交联度的变化对药物的释放皆有明显的影响。通过对释放曲线进行计算机模拟得到释放液浓度的经验公式,并从理论上初步解释了公式中各参数的物理意义。作出了理论近似计算得到的表观扩散系数的变化曲线,其在ＬＣＳＴ附近各温度的变化趋势符合预测     

壳聚糖-纤维素硫酸钠聚电解质复合物膜对药物表观渗透系数的测试

药物渗透系数是考察复合物膜的药物释放性能的重要参数. 本文以溶解性不同的两种药物扑热息痛和5-氨基水杨酸(5-ASA)为模型药物研究了其在壳聚糖-纤维素硫酸钠聚电解质复合物膜中的渗透性能. 结果表明：壳聚糖-纤维素硫酸钠聚电解质复合物膜的渗透性能与其溶胀性能密切相关;复合物膜中壳聚糖和纤维素硫酸钠的配比、相对分子量和pH值对膜的渗透性能和溶胀性能影响显著,以扑热息痛作为模型药物研究了壳聚糖-纤维素硫酸钠聚电解质复合物膜在模拟胃肠液中对药物的渗透性能. 通过调整该复合物膜的配方,可以使该膜分别实现胃、小肠和结肠定位释药的目的.     

Preparation and Characterization of Poly Vinyl Alcohol/Poly Vinyl Pyrrolidone/Clay Based Nanocomposite by Gamma Irradiation

A series of PVA/PVP/clay nanocomposite were prepared by gamma irradiation with different clay contents of (0.15, 0.3, 1, 1.5, 3 and 5 wt%). The gelation content and swelling behavior were investigated. The morphology and structure of PVA/PVP/clay nanocomposite and dispersion of the clay nanoparticles in the polymeric matrix were examined by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The introduction of clay into polymeric matrix was investigated by X-ray diffraction pattern (XRD) and Transmission electron microscope (TEM). It is observed that, the increase of the clay content causes a decrease in the swelling percent. The thermal stability studies confirmed that the introduction of clay lead to an increase in the thermal stability. The TEM results showed that the clay nanoparticles are interchelated or exfoliated in the polymeric matrix. Some desirable characteristics such as relatively good swelling and excellent barrier capability against microbe penetration suggested that PVA/PVP/clay nanocomposite can be a good candidate as a wound dressing.     

Drug Release and In Vitro Assays of Bioactive Polymer/Glass Mixtures

The bioactive behaviour and drug release of samples composed by sol gel glass with composition 80SiO₂-16CaO₂-4P₂O₅% mol, polymethylmethacrylate (PMMA) and gentamicine or ibuprofen have been studied. The bioactive behaviour of the samples does not depend on the amount (5% and 10% in weight) or on the type of drug used in this study. In all the cases the SEM micrographs show the formation of a layer that covers the surface of the samples after 24 hours soaked in simulated body fluid (SBF). X ray diffraction patterns show two broad peaks after being soaked 3 days. These peaks could be identified with an apatite-like phase, characteristic in this kind of studies.On the contrary, the release kinetics is strongly dependent on the drug employed. In the case of gentamicine, the curve shows a high slope during the first day soaked in SBF and the complete release occurs before 150 hours. For the ibuprofen samples, the drug release is much slower; the samples containing 10% of ibuprofen do not reach the total release after 600 hours. This different behaviour could be related with the solubility of both drugs in aqueous media.     

Thermosensitive Poly(N-isopropylacrylamide)-g -Polyamidoamine Dendrimer Derivatives: Preparation and the Drug Release Behaviors

Summary: A series of thermally responsive dendritic core-shell polymers were prepared based upon dendritic polyamidoamine (PAMAM), modified with carboxyl end-capped linear poly(N-isopropylacrylamide) (PNIPAAm-COOH) in different ratios via an esterification process to obtain PNIPAAm-g-PAMAM. The graft ratio of PNIPAAm could be adjusted by changing the feed ratio of PAMAM-OH to PNIPAAm-COOH and was verified by ¹H NMR and gel penetration chromatography (GPC). The lower critical solution temperature (LCST) of PNIPAAm-g-PAMAM evaluated by UV-vis spectrophotometer was about 32 °C. Indomethacin (IMC) as a model drug was loaded in the thermosensitive polymer-grafted dendrimer derivative and its release behavior was studied below and above its LCST (27 °C vs 37 °C). Results showed that the LCST of PNIPAAm-g-PAMAM was around 32 °C compared with that of the pure PNIPAAm. The release behavior of the indomethacin entrapped in the internal cavities of the PNIPAAm-g-PAMAM showed that almost 77% of the drug was cumulatively released at 27 °C after 10 hours, whereas only 20% was released at 37 °C. The release rate of IMC from the IMC/PNIPAAm-g-PAMAM complex at 37 °C is significantly slower than that at 27 °C, which indicates that the PNIPAAm chains grafted on the surface of PAMAM dendrimer could act as a channel switching on-off button through expending or contracting in response to the temperature variation and could control the drug release by varying the surrounding temperature.     

温度敏感型树枝状大分子衍生物的合成及药物控制释放

通过加入偶联剂活化末端羧基基团进行酰胺化反应, 将得到的带有羧基末端基团的温敏性聚N-异丙基丙烯酰胺接枝到整代的树枝状大分子聚酰胺-胺(PAMAM)上, 制备了树枝状大分子衍生物PAMAM-g-PNIPAm, 通过FTIR和¹H NMR表征其结构, 通过GPC和¹H NMR测定其分子量, 从而验证了接枝产物的形成; 通过紫外-可见分光光度计测定其在不同pH值缓冲液中的低临界溶胀/溶解温度(LCST)值, 发现产物的LCST值受缓冲液pH值的影响很大, 接枝前后的LCST值也发生了变化. 选用难溶性药物吲哚美辛作为模型药物, 考察了树枝状大分子及其温度敏感性衍生物PAMAM-g-PNIPAm作为载体对药物的包载、增溶和不同温度环境下的释放行为. 结果表明, 树枝状大分子衍生物对吲哚美辛具有增溶和控制释放的性能, 在难溶性药物的控制释放领域具有广阔的应用前景.