喜树碱/氧化石墨烯/类水滑石纳米杂化物的制备及表征

采用共组装法成功制备了电中性疏水抗癌药物喜树碱（CPT）/氧化石墨烯（GO）/Mg-Al类水滑石（HTlc）纳米杂化物. 先将CPT负载于荷负电的GO纳米片表面上制备成CPT/GO复合物,再与荷正电的HTlc纳米片（HNS）共组装,形成CPT/GO/HTlc纳米杂化物,其中GO纳米片和HNS相间叠加,CPT负载于层间. 采用X-射线衍射、透射电子显微镜、原子力显微镜、扫描电子显微镜-能量色谱仪、傅里叶变换红外光谱、紫外-可见分光光度计和热重/差示扫描量热分析等技术对纳米杂化物进行了表征. 37 ℃下分别在pH 7.4和4.0的磷酸缓冲液中,考察了CPT/GO/HTlc纳米杂化物的药物释放行为. 结果表明,CPT/GO/HTlc纳米杂化物的药物释放过程符合准二级动力学方程,且具pH响应性,在酸性（pH 4.0）介质中的释放速率和释放率明显高于中性（pH 7.4）介质. 共组装法是构筑药物/ GO/HTlc纳米杂化物的简便方法,该纳米杂化物在药物输送领域具有良好的应用前景.     

(羟基喜树碱@胆酸钠)-层状双金属氢氧化物纳米杂化物的组装及表征

采用“药物修饰-共组装”法制备了(羟基喜树碱@胆酸钠)-层状双金属氢氧化物纳米杂化物. 先用胆酸钠(SCL)包裹羟基喜树碱(HCPT)形成胶束, 再与微反应器制备的层状双氢氧化物(LDH)纳米片共组装形成纳米杂化物, 其载药量可达12.9%, 杂化物中HCPT以高生物活性的内酯形式存在. 采用聚乙二醇(PEG)和羧甲基纤维素(CMC)分别对所制备的(HCPT@SCL)-LDH纳米杂化物进行了表面修饰, 结果表明, 纳米杂化物的分散性得到明显改善; PEG的修饰效果优于CMC, 所获得的PEG-(HCPT@SCL)-LDH杂化物的平均粒径可小至约70 nm, 具有良好的分散性和药物缓释效果. 其药物释放过程可用准二级动力学方程描述, 颗粒内部扩散是药物释放过程的控制步骤.     

羟基喜树碱-类水滑石纳米杂化的共组装制备及表征

采用共组装法在水溶液中制备羟基喜树碱(HCPT)-层状双金属氢氧化物(LDH)纳米杂化物.先利用微通道反应器通过共沉淀法制备了Zn₂Al-NO₃ LDH纳米片,然后与羧酸盐型HCPT在水介质中共组装,制备了HCPT插层LDH的纳米杂化物.利用酸处理,可将层间HCPT由非生物活性的羧酸盐型转化为生物活性的内酯型,这对高生物活性HCPT-LDH纳米杂化物的绿色制备具有重要意义.共组装法制备HCPT-LDH纳米杂化物,耗时短、载药量高、分散性好,且利用原料配比可方便地调控载药量. HCPT分子在LDH层间以其长轴倾斜于层板呈双层排列.所制备的HCPT-LDH纳米杂化物具有良好的药物缓释性能,颗粒内部扩散是药物释放过程的控速步骤.药物释放过程可用准二级动力学模型描述.可以用于构筑LDH基药物输送-控释体系.     

10-羟基喜树碱-癸二酸-LDH杂化物的制备及性能

采用二次插层法成功制备了10-羟基喜树碱(HCPT)-癸二酸(SC)插层的层状双金属氢氧化物(LDH). 先采用共沉淀法制备SC柱撑LDH杂化物(SC-LDH), 再在乙醇介质中将HCPT插入LDH层间形成HCPT-SC-LDH纳米杂化物. 依据SC和HCPT的分子尺寸和纳米杂化物的通道高度, 推测SC分子在层间可能为双层排列, SC分子两端的羧基同时键合在同一个LDH层片表面上; HCPT分子插入(或溶入)SC分子碳氢链形成的疏水区中. 所制备的纳米杂化物既可稳定HCPT的内酯环, 又可明显提高HCPT的溶解度, 还具有明显的药物缓释效果, 其释放动力学过程符合准二级动力学方程.     

利用有机改性的类水滑石缓释阿维菌素

采用蒸发溶剂促进插层(evaporating solvent enhanced intercalation)的方法把农药阿维菌素(Avermectin, AVM)插层到十二烷基硫酸钠(SDS)改性的类水滑石(Hydrotalcite-like compound, HTlc)层间，合成了AVM-SDS-HTlc纳米杂化物。研究发现其能够很好的控制阿维菌素的释放，表明AVM-SDS-HTlc纳米杂化物是一种很有潜力的农药控释剂型。AVM-SDS-HTlc纳米杂化物的释放受pH、温度和电解质的影响，酸性介质、较高温度以及有电解质存在会提高其缓释速率。释放过程符合准一级释放动力学，释放的活化能为279 kJ/mol。     

氟尿苷-层状双金属氢氧化物纳米杂化物制备及表征

采用共沉淀法将抗癌药物氟尿苷插入Mg-Al层状双金属氢氧化物(LDHs)的层间,合成了氟尿苷-LDHs纳米杂化物。依据氟尿苷分子大小和杂化物通道高度推测,氟尿苷分子是以长轴垂直或略倾斜于LDHs层片在LDHs层间呈双层排列。分别在pH=4.8和7.2的介质中研究了药物释放动力学,表明符合准二级动力学方程;释放速率随载药量增大而降低;氟尿苷-LDHs纳米杂化物具有良好的缓释效果。     

Triton X-100六角液晶相中制备镁铝层状双金属氢氧化物纳米片及其药物载体应用

以Triton X-100 六角相溶致液晶作微反应器, 采用共沉淀法制备了镁铝层状双金属氢氧化物(LDHs)纳米薄片(L-LDHs). 以双氯芬酸钠(DS)为药物模型分子, 采用离子交换法制备了DS插层LDHs (DS/L-LDHs)纳米杂化物, 在37.0 ℃、pH=7.2的缓冲溶液中, 考察了纳米杂化物的药物释放性能, 并与传统溶液共沉淀法制备的镁铝LDHs (S-LDHs)纳米片状颗粒进行了对比. 采用粉末X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、场发射扫描电镜(FE-SEM)、透射电镜(TEM)和N₂吸附-脱附等技术对所制备的LDHs和DS/LDHs 样品的晶体结构、比表面积、形貌特征等进行了表征. 结果表明, L-LDHs比S-LDHs具有更低的片厚度, 更高的比表面积和药物负载量, 所形成的DS/L-LDHs纳米杂化物药物释放速率也明显低于DS/S-LSHs, 即L-LDHs更适于作药物载体. DS/L-LDHs纳米杂化物的药物释放过程符合准二级动力学方程, 受颗粒内部扩散过程控制. 溶致液晶模板法可实现LDHs的形貌可控制备, 为LDHs基功能材料的研发提供了新途径.     

喜树碱插层的镁铝型层状双金属氢氧化物的合成及表征

采用共沉淀法把抗癌药物喜树碱（Camptothecin, CPT）插入层状双金属氢氧化物(layered double hydroxide, LDH)层间, 合成了CPT-LDH纳米杂化物。结果表明,在CPT-LDH纳米杂化物中,CPT在层间的排布方式有两种,即平行于层板的单层排列和垂直于层板的双层排列;缓释研究表明,CPT-LDH在pH 7.5的磷酸缓冲液中具有明显的缓释效果,其释放速率较相同pH值时CPT和LDH物理混合物的释放速率明显降低;考察了CPT-LDH的药物释放机理,在 pH 7.5的缓冲溶液中,释放过程受粒内扩散过程控制;CPT-LDH纳米杂化物的释放动力学符合准一级动力学过程。     

自组装辅助聚合法制备纤维素基温度/pH双敏感性荧光纳米凝胶

通过自组装辅助的一步法制备了具有温度和pH双重响应性的荧光纳米凝胶(FNG). 首先设计制备了一种水溶性含双键的荧光单体5-丙烯酰胺荧光素(5-AAF), 在水溶性纤维素醚——羟丙基纤维素(HPC)主链上引发5-AAF的接枝共聚, 同时由于5-AAF的疏水作用力诱导共聚物发生自组装, 并通过双官能团交联剂亚甲基二丙烯酰胺(MBA)的加入使自组装纳米聚集体交联, 从而一步制得具有环境响应性的FNG, 该过程在水相中进行, 具有高效、 “绿色”的优点. 研究结果表明, 改变合成过程中HPC的分子量可调控所得FNG的环境响应性. 对FNG环境响应性的研究表明, FNG链段上的亲疏水基团及与水分子间的氢键作用是影响凝胶温度响应性的主要因素. 此外, FNG的荧光在中性及碱性溶液中显著加强, 在酸性溶液中迅速猝灭. 由于FNG的荧光信号对温度和pH的显著敏感性, 且具有较低的细胞毒性, 因此在荧光标记生物检测及生物微环境的温度/pH检测等领域具有广泛的应用前景.     

Fe3 O4@(TF-LDHs)纳米复合体的制备及药物缓释性能

采用共沉淀法, 以替加氟(Tegafur, TF)插层层状双金属氢氧化物(LDHs)纳米杂化物(TF-LDHs)包覆磁性基质Fe3O4, 得到了具有核/壳结构的纳米复合体[Fe3O4@(TF-LDHs)], 采用XRD, FTIR, TEM, VSM和元素分析等技术对样品的化学组成、 晶体结构\, 形貌及磁性等进行了表征, 探讨了药物分子在LDHs层间的存在状态, 考察了其药物释放行为. 结果表明, Fe3O4@(TF-LDHs)纳米复合体具有顺磁性, 其比饱和磁化强度随磁性基质含量的增大而增强; TF分子在LDHs层间以长轴略倾斜于LDHs层板的方式呈双层排布; Fe3O4@(TF-LDHs)纳米复合体具有明显的药物缓释性能, 其释放动力学过程符合准二级动力学方程, 颗粒内部扩散为释放过程的速率控制步骤.     

Porous film fabricated by a thermoresponsive polymer poly(N-isopropylacrylamide-co-butylmethacrylate) with enhanced hydrophobicity

In this paper, two charge-neutral and poorly water-soluble bactericides (BC), hexaconazole and triadimenol, were first encapsulated in micelles derived from anionic surfactant, calcium dodecylbenzenesulfonate (DBS), and then were successfully intercalated into the gallery of Mg–Al layered double hydroxides (LDHs) by using ion exchange, coprecipitation and reconstruction methods, respectively, to obtain BC–LDHs nanohybrids. The loading amounts of hexaconazole-LDHs nanohybrids are obviously higher than those of triadimenol-LDHs nanohybrids. The release kinetics of bactericides from the nanohybrids was investigated. It was found that the bactericide release kinetic processes of the nanohybrids can be described with pseudo-second-order model. The initial release rates and equilibrium percent releases of the nanohybrids are obviously dependent of synthesis methods. The nanohybrids can well control the release of bactericides, showing they are a potential pesticide controlled-release formulation.     

Fabrication,controlled release,and kinetic studies of indomethacin—layered zinc hydroxide nanohybrid and its effect on the viability of HFFF2

The intercalation of indomethacin into the interlayer gallery of layered zinc hydroxide (LZH) has been successfully executed using the simple ion exchange approaches. The synthesized intercalation compound, indomethacin-LZH nanohybrid, was characterized using PXRD, FTIR, SEM, BET, and STA. From the PXRD results, the intercalation of indomethacin anions into the interlayer gallery of LZH was successful; showing the formation of a new peak at lower 2θ with a basal spacing of 21.96?Å. FTIR analysis of the nanohybrid further supported the presence of indomethacin in the interlayer of the indomethacin-LZH nanohybrid. STA analysis confirms that the nanohybrid has higher thermal stability than pure indomethacin. The in vitro release mechanism of the indomethacin anions from the indomethacin-LZH nanohybrid showed slow release, with 95% and 78% release in phosphate buffer saline (PBS) solution at pH 4.8 and 7.4, respectively. The release behavior of indomethacin from its intercalation compounds in PBS solution at pH 4.8 and 7.4 follows the Higuchi model. In addition, the nanohybrid treated with normal fibroblast cell line shows that it reduces cell viability in a dose and time-dependent manner. This study shows that the high potential of the nanohybrid as an encapsulated material for the controlled release formulation of nonsteroidal anti-inflammatory (NASID) anions.     

Synthesis of Hybrid Organic-Inorganic Hydrotalcite-Like Materials Intercalated with Duplex Herbicides: The Characterization and Simultaneous Release Properties

In this study, a controlled-release formulation of duplex herbicides, namely, 2,4,5-trichlorophenoxybutyric acid (TBA) and 3,4-dichlorophenoxy-acetic acid (3,4D), was simultaneously embedded into Zn-Al-layered double hydroxides (LDHs). The resulting nanohybrid Zinc-Aluminium-3,4D-TBA (ZADTX) was composed of a well-ordered crystalline layered structure with increasing basal spacing from 8.9 Å to 20.0 Å in the Powder X-ray Diffraction (PXRD) with 3,4D and TBA anions located in the gallery of LDHs with bilayer arrangement. The release of 3,4D and TBA fit the pseudo-second-order model. This duplex nanohybrid possessed a well-controlled release property (53.4% release from TBA and 27.8% release from 3,4D), which was highly effective, requiring the use of a small quantity and, hence, environmentally safer.     

Synthesis and release behavior of composites of camptothecin and layered double hydroxide

A simple method, reconstruction of calcinated layered double hydroxides (CLDH) in an organic (ethanol)-water mixed solvent medium containing drug, was developed to intercalate partially a non-ionic and poorly water-soluble drug (camptothecin) into the gallery of layered double hydroxides (LDHs) to form the drug-LDH composites. The purpose of choosing organic-water mixed solvent is to increase remarkably the solubility of camptothecin (CPT) in the reconstruction medium. A probable morphology of CPT molecules in the gallery of LDHs is that CPT molecules arrange as monolayer with the long axis parallel to the LDH layers. The in vitro drug release from the composites was remarkably lower than that from the corresponding physical mixture, which shows these drug-inorganic composites can be used as a potential drug delivery system.     

Novel Methods of Enhanced Retention in and Rapid, Targeted Release from Liposomes

Liposomes are single bilayer capsules with distinct interior compartments in which hydrophilic drugs, imaging agents, diagnostics, etc. can be sequestered from the exterior environment. The polar parts of the individual lipids face the water compartments, while the hydrophobic parts of the lipid provide a barrier in which hydrophilic or charged molecules are poorly soluble. Hydrophobic molecules can be dissolved within the bilayer. The bilayers are typically from 3 - 6 nm thick and the liposome can range from about 50 nm - 50 microns in diameter. The question asked in this review is if any one bilayer, regardless of its composition, can provide the extended drug retention, long lifetime in the circulation, active targeting to specific tissues and rapid and controllable drug release at the site of interest. As an alternative, we review methods of self-assembling multicompartment lipid structures that provide enhanced drug retention in physiological environments. We also review methods of externally targeting and triggering drug release via the near infrared heating of gold nanoshells attached to or encapsulated within bilayer vesicles.     

Vesicle formation induced by layered double hydroxides in the catanionic surfactant solution composed of sodium dodecyl sulfate and dodecyltrimethylammonium bromide

In this paper, it is reported that positively charged Mg₃Al layered double hydroxide (LDH) nanoparticles can induce the spontaneous formation of vesicles in micelle solution of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) with a mass ratio of 8:2. The formation of vesicles was demonstrated by negative-staining transmission electron microscopy observations. The size of the vesicles increased with the increase in the concentration of Mg₃Al-LDH nanoparticles. A composite of LDH nanoparticles encapsulated in vesicles was formed. A possible mechanism of LDH-induced vesicle formation was suggested. The positively charged LDH surface attracts negatively charged micelles or free amphiphilic molecules, which facilitates their aggregation into bilayer patches. These bilayer patches connect to each other and finally close to form vesicles. It was also found that an adsorbed compound layer of SDS and DTAB micelles or molecules on the LDHs surface played a key role in vesicle formation.