Fabrication of PLGA coated silica nanorattle for controlling the drug release behavior

Silica nanorattle with hollow and mesoporous structure has been proven to be an excellent drug carrier.However,how to control the drug release from silica nanorattle is still a challenge.In this study,we designed two methods,in-situ polymerization method and water in oil in water(W/O/W) double emulsion method,to coat a nanosized poly(lactic-co-glycolic acid)(PLGA) layer onto the surface of silica nanorattle for controlling the drug release behavior.Hydrophobic antitumor drug docetaxel was loaded into the PLGA coated silica nanorattle(PLGA@SN).The drug release profile,cellular uptake and cytotoxicity on human liver cancer HepG2 cells were evaluated to prove that the PLGA layer plays an effective role in tuning the drug delivery.     

Preparation,characterization and antibacterial property of naringin loaded PLGA nanospheres

Naringin is a predominant flavanone in grapefruit and shows a variety of biological effects such as antioxidative, anticancer, anti-inflammatory and antibacterial activity. However, its application in pharmaceutical field is limited by low water solubility, poor bioavailability and instability. To overcome the problem, naringin has been encapsulated in poly(lactic-co-glycolic acid) (PLGA) polymer by emulsion-diffusion-evaporation method in this work. Moreover, naringin loaded PLGA nanospheres were characterized by scanning electron microscope (SEM), dynamic light scatter method (DLS), fourier transform infrared (FTIR) spectra, UV–vis spectra and fluorescence spectra of DNA-EB competition displacement. The mean diameter of PLGA nanospheres and NRG/PLGA nanospheres was 123 ?± ?25 ?nm and 137 ?± ?30 ?nm, respectively. The drug encapsulation efficiency was 86.4% while the drug loading rate was 22.3%. The fluorescence spectra of the competitive DNA-binding experiments revealed that the functional activity of naringin was retained after loaded in PLGA. It is revealed that the initial burst effect happened in the initial 24 ?h and followed by sustained release lasting for 10 days. Moreover, the nanospheres exhibited strong antibacterial activity, and 99.9% of E. coli and S. aureus were killed when treated with naringin loaded PLGA nanospheres at the concentration of 0.2 ?mg ?mL^?1 within 24 ?h. Furthermore, the viable cells remained only 48% when the concentration of NRG/PLGA nanospheres was 32 ?μg ?mL^?1 and NRG/PLGA nanospheres was important for inhibition of cancer cells. It is concluded that the stable naringin loaded PLGA nanospheres could have potential application in food industry and nanomedicine field.     

Preparation and cellular uptake of PLGA particles loaded with lamivudine

Poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles loaded with lamivudine and coated with bovine serum albumin (BSA) were prepared via a double emulsion method. The influences of experiments parameters such as volume of inner aqueous phase, concentration of organic phase and ultrasonication time on the particle size and drug entrapment efficiency were investigated, obtaining PLGA particles with a diameter of ~260 nm and drug entrapment efficiency of ~35%. The particles were observed by scanning electron microscopy and transmittance electron microscopy, showing a core-shell structure. BCA assay found that 58 mg BSA was present on/in 1 g LPB particles. The loaded lamivudine showed a burst release at beginning and sustained release until 24 h in physiological conditions. Low pH could accelerate the release of lamivudine from PLGA particles, making the PLGA particles potential intelligent intracellular drug carriers. The PLGA particles were readily internalized into the human liver cells within a short time and increased gradually with the prolongation of incubation time regardless of the loading of lamivudine. The particles either resided within lysosomes or transferred to cytoplasm, but could not enter into the cell nucleus. The cell viability was not significantly influenced in the presence of the particles regardless of lamivudine encapsulation, suggesting that this kind of particles may be a good candidate for the intracellular anti-hepatitis B drug delivery.     

可降解聚合物溶胀性能对给药系统释药效果的影响

针对以乳酸-羟基乙酸共聚物(PLGA)作为药物载体的新型贮库式微孔结构缓控释给药系统,为量化PLGA溶胀特性对释药效果的影响,在模拟体液环境下,以具有不同单体质量比的PL-GA膜片上的微孔为研究对象,对PLGA在降解过程中的溶胀现象进行了实验研究,得到单体质量比为50∶50的PLGA的微孔径向溶胀速率约为2.7×10-10 m/s,质量比为65∶35的PLGA的微孔径向溶胀速率约为6.6×10-11 m/s.以单体质量比为50∶50的PLGA为例,将实验得到的微孔溶胀速率作为边界条件,对考虑PLGA溶胀作用前、后的微孔给药系统释药过程进行了有限元模拟,结果表明:聚合物溶胀使给药系统释药时间从无溶胀时的16d延长到33d;不考虑溶胀时,PL-GA基体仅起承载药物的作用,而考虑溶胀后,微孔和PLGA基体共同承担药物释放功能,其中近40%的药物通过微孔释放,近60%的药物通过聚合物载体释放;给药系统在整个释药过程中累积释药比率线性度较好.     

PLGA基载药复合微球的制备及其释放性能

以聚乳酸-羟基乙酸(PLGA)为载体材料,牛血清蛋白(BSA)为蛋白模型药物,采用复相乳化溶剂法制备PLGA载药微球,探索载药微球制备过程中囊芯比、初乳水油比、分散剂浓度、超声乳化时间对微球粒径大小、载药率、包封率的影响。结果表明,最优载药微球的制备条件为:囊芯比1:1,初乳水油比3:5,分散剂质量分数0.5%,超声乳化时间2 min。在此条件下,所得PLGA微球的粒径为268.7 nm,载药率30.88%,包封率46.95%; 电镜照片表明微球表面连续光滑,粒径分布较均匀。采用静电吸附法用阳离子聚电解质壳聚糖对最佳条件下的PLGA载药微球进行表面修饰,扫描电镜表明复合后微球粒径变大,能谱分析表明复合后微球中有N元素存在,即复合微球中存在壳聚糖,电荷测试表明微球表面带正电; 体外释放实验表明PLGA-CS复合载药微球的缓释时间延长,释药初期的突释性明显改善。     

壳聚糖修饰的Lysozyme-PLGA阳离子纳米药物的制备与表征

通过二环己基碳二亚胺将聚乳酸-羟基乙酸共聚物(PLGA)活化,又与溶菌酶进行化学键合,再采用单乳化-溶剂挥发技术制备表面带正电荷的壳聚糖(CHS)PLGA纳米微球。对纳米微球制备条件进行了优化。结果表明在ρ(CHS)=3 mg/mL,ρ(PLGA)=5 mg/mL,溶菌酶与PLGA的质量比为0.2的条件下,得到的纳米微球包封率为87.8%,载药量为14.7%。微球粒径φ可控制在(450±50)nm之间,在pH=4时,纳米微球表面ζ电位为42.5mV。SEM图像显示经CHS修饰的Lysozyme-PLGA的纳米微球形状规整。药物释放试验显示纳米微球在20 d后释放达到70%,且释放曲线规整。     

Synthesis of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/SiO<Subscript>2</Subscript>/Au magnetic composites for immobilization of bovine serum albumin

A method for the two-step synthesis of magnetic composites with a γ-Fe₂O₃ core, silica inner layer and numerous gold nanoparticles supported on the surface of the silica (γ-Fe₂O₃/SiO₂/Au) is described. First, thiol-functionalized γ-Fe₂O₃/SiO₂ composites and gold colloids are prepared by modifying γ-Fe₂O₃/SiO₂ composites with mercaptosilane and reduction of Au³⁺ to Au⁰ with citrate, respectively. Gold nanoparticles are then assembled on the surface of the thiol-functionalized γ-Fe₂O₃/SiO₂ composites to form γFe₂O₃/SiO₂/Au composites. The structure of the composite particles is confirmed by transmission electronic microscopy and powder X-ray diffraction. Immobilization studies with bovine serum albumin (BSA) demonstrate that the γ-Fe₂O₃/SiO₂/Au composites can be used to immobilize BSA, making them useful for biomedical and biological applications.     

Flow characteristics and reaction properties of carbon dioxide in microtubules and porous media

Carbon dioxide reacts with porous media while flowing through them enhancing their permeability. Its flow behavior as well as the permeability enhancement effects were studied in synthetic cores, natural cores and microtubes with an inner diameter of 5 μm. The results show that the permeability of H2O-saturated cores （containing carbonate ingredients） was enhanced by increasing the injection volume of a CO2-H2O solution. This enhancement is attributable to carbon dioxide＇s corrosion, which is justified by SEM scanning. The same phenomenon occurs with a CO2-H2O solution in microtubes, but for a different reason. The gas flow velocity of carbon dioxide in microtubes was approximately 100% faster than that of nitrogen because of the scale and the squeezing effects. Carbon dioxide molecules dissolved in water accelerate the diffusion rate of water molecules within the boundary layer, which in turn diminishes the thickness of the water film and enlarges the effective pore size. This flow behavior facilitates the injection of carbon dioxide into low-permeability reservoirs for oil-displacement and formation energy buildup purposes. This behavior also increases the potential for carbon dioxide channeling or release from the formation.     

Synthesis and photo-responsive behaviors of hollow polyazobenzene micro-spheres

By means of distillation precipitation polymerization, the silica-hybrid particles with polyazobenzene shell (PAzo@SiO₂) micro-spheres were prepared with 6-(4-methoxy-4′-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer, divinylbenzene (DVB) as cross-linker, and ~250 nm vinylated sol-gel silica particles as template. Hollow polyazobenzene microspheres were further developed after selective removal of the silica cores with HF solution. When the content of DVB related to Azo-M is 20 wt%, the acetonitrile is 200 mL, and the polymerization time is 4.5 h, the hollow PAzo microspheres with about 20 nm shell are successfully fabricated. These hollow PAzo microspheres have excellent reversible photoisomerization, and their first-order rate constant of trans-cis isomerization only decreases 11.8% compared with homopolymer of azobenzene (Homo-PAzo).     

Rod-shaped Au@PtCu nanostructures with enhanced peroxidase-like activity and their ELISA application

Pt and its based alloy nanoparticles （NPs） have been reported to demonstrate novel enzyme-like activities. Varying composition is very important to realize the opti- mization of their functions through the tuning of electronic structure. In this paper, our effort is focused in this direction by tailoring the electronic structure of Pt NPs via alloying with copper. Using gold nanorod （Au NR） as core, a simple method to prepare PtCu alloy shell is developed （termed as Au@PtCu NR）. The introduction of copper could result in endcap-preferred growth mode owing to the lattice mismatch between alloy shell and the Au core. The variation in the electronic structure changes the substrate affinity, and enhanced affinity was found for H202. Besides, the designed Au@PtCu nanostructures have realized spatial separation of catalytic and recognition sites. Binding of recognition antibodies had negligible effect on their catalytic activity. Based on their peroxidase- like activity, a highly sensitive detection of human immunoglobulin G （IgG） was demonstrated in a direct enzyme-linked immunosorbent assay （ELISA） mode. The detection limit can be as low as 90 pg/mL.     

Promising psyllium-based composite containing TiO2 nanoparticles as aspirin-carrier matrix

Composite nanomaterials represent a new trend in the biomedical field. Coupling inorganic/organic constituents with non-toxicity/biocompatibility properties leads to develop the new systems having special characteristics that can be used in various bio-applications. This paper describes the preparation and characterization of psyllium-based composites containing TiO2 nanoparticles in order to develop new therapeutic strategies for aspirin drug delivery. The structural characteristics of obtained materials were investigated by FTIR spectroscopy. The UV–vis spectrophotometric analysis was performed to evaluate the aspirin release behavior under different pH conditions at 37 1C. Combining psyllium(as an excellent source of fiber) with TiO2 inorganic unit(as vehicle of aspirin) it was found that polymeric-TiO2networks have promising potential for controlled aspirin release as therapeutic agent.     

In vitro study of poly(ethylene carbonate) as a drug-eluting stent coating

An in vitro feasibility study of the use of poly(ethylene carbonate) (PEC) as a biodegradable coating material for drug-eluting stents is reported, and the performance of PEC is compared with that of poly(lactic-co-glycolic acid) (PLGA). Scanning electron microscopy (SEM) images of PEC and PLGA discs after treatment with an alkaline KO2 solution as a superoxide source showed that the PEC maintained its integrity whereas holes and small particles appeared during the treatment of PLGA. Sirolimus and paclitaxel were loaded into PEC and PLGA in order to study drug release performance. Attenuated total reflectance–infrared (ATR– FTIR) spectroscopy of sirolimus, PEC and the sirolimus-loaded PEC coating showed that no chemical reaction occurred between sirolimus and PEC. The results of atomic force microscopy (AFM) revealed that the mean roughness (Ra) values of the bare metal stent (BMS) and the drugeluting stent (DES) were 2.3 nm and 1.0 nm, respectively. After balloon expansion experiments, no delamination or destruction of the PEC coating was observed. The drug release profile of sirolimus was different from that of paclitaxel when PEC was employed as the drug carrier, and the release curves of sirolimus were different when PEC and PLGA were used as drug carriers. All the experimental results demonstrated that PEC was one of the best potential stent-coating materials.     

Significance of native arsenic in the Baogutu gold deposit, western Junggar, Xinjiang, NW China

Native arsenic together with comb quartz and stibnite is found in the Baogutu gold deposit, western Junggar (Xinjiang), NW China. It is anhedral with various grain size (<0.001 to 2 mm), and contains 98 wt% to 98.7 wt% As. Micro-granular electrum, the main auriferous mineral in the Baogutu gold deposit, is commonly enclosed in or closely accompanied by native arsenic. Three ore-forming paragenetic stages could be identified. Native arsenic mainly formed at stage II which is also the major stage for gold deposition. Mineral assemblage formed at this stage is native arsenic-stibnite-electrum-arseno- pyrite-miargyrite-freibergite-pyrrhotite-pyrite. Based on native arsenic and its coexisting minerals, the temperature (230 to 170℃), oxygen fugacity (logfO₂ = −42―−56.5) and sulfur fugacity (logf S₂ = −13.3― −16.6) of stage II are estimated. From stage I to stage II, the temperature, sulfur fugacity and S²⁻ con-centration of hydrothermal fluid decrease obviously, whereas the As concentration increases. Coexis-tence with native arsenic of electrum and its contents of 0.5 wt%―1.3 wt% As suggest that As is im-portant to transport Au when S²⁻ concentration decrease in hydrothermal fluid. Crystallization of native arsenic induced the deposition of electrum and consequently the formation of the Baogutu gold deposit.     

Synthesis of nanoporous silica with interior composite cells with synthetic block copolypeptide as template

IN NATURE,PROTEIN AND POLYSACCHARIDE ARE INVOLVED IN THE FORMATION OF A REMARKABLE DIVERSITY OF EXQUISITE NANOSTRUCTURED SILICATES IN BIOLOGICAL SYSTEMS SUCH AS DIATOMS AND SPONGES.THE SILAFFIN[1]AND SILICATEIN[2]ISOLATED FROM MARINE DIATOMS AND SPONGES C…     

Pickering乳液法原位制备载药磁性SiO_2空心球及缓释性能

采用共沉淀法制备纳米Fe3O4颗粒,然后通过Pickering乳液模板法原位将布洛芬和纳米Fe3O4颗粒包覆在SiO2空心球中,制备出载药磁性SiO2空心球,对其组成、结构及药物释放性能进行了表征。研究结果表明:载药磁性SiO2空心球粒径大小平均为2μm,壁厚约为240 nm,内含布洛芬;原位载药可使空心球的壁厚增加;该材料适合用作药物的载体,具有缓释效果。     

聚-γ-谷氨酸包覆介孔分子筛MCM-41控释体系研究

用硅酸酯水解法制备了孔径为3 nm的MCM-41作为烯效唑载体,采用负压浸渍法载药.用XRD、BET、TEM、SEM、TG等仪器对包覆体系进行了表征分析.用低平均分子量γ-PGA(M.W.≈9180 Da)包覆负载药物的纳米粒子,形成控释体系.在不同乙醇-PBSaq溶液中,对不同控释体系的控释效应进行了探究.通过零级释放、一级释放、Higuchi和Rigter-Peppas释放动力学模型的拟合探究控释体系的药物控释机理.分析结果表明：烯效唑在MCM-41外表面及孔道内均有吸附,负压浸渍法能有效促使烯效唑分子进入3 nm孔道内部,以单分子层的吸附为主;在聚乙烯亚胺作用下,制得包覆壳层厚度均一、分散性较好的MCM-41@γ-PGA纳米控释体系;未包覆的载药体系的药物释放不满足零级释放、一级释放和Higuchi模型,但满足Rigter-Peppas释放动力学模型,遵循Fick扩散机理.     

乙交酯丙交酯共聚物电纺丝超细纤维对利福平的控制释放

载药电纺丝超细纤维体系是药物控制释放领域中一个全新的剂型,近年来已引起广泛的关注.研究了乙交酯丙交酯共聚物(PLGA,LA/GA=80/20)电纺丝超细纤维在磷酸盐缓冲液(pH=7.4)中对利福平的控制释放行为.结果显示利福平的释放过程可分为2个阶段:在第一阶段为释放慢速期,药物的释放速率取决于纤维中利福平分子的扩散速...     

A novel fluorescent label based on biological fluorescent nanoparticles and its application in cell recognition

Uniform-sized fluorescent nanoparticles have been prepared by employing silica as the shell and a highly luminescent dye complex of ruthenium ion and bipyridyl, tris(2,2’-bipyridyl) dichlororuthenium(II) hexahydrate as the core of the nanoparticles. A novel fluorescent label method is proposed, which is based on the biological fluorescent nanoparticles on the foundation of nanotechnology, biotechnology and fluorescent label technology. In comparison with the conventional fluorophores as fluorescent labels such as fluorescein isothiocyanate (FITC) label, this new label shows more superiority in photochemical stability, detection sensitivity and application scope for the biomedicine research. SmIgG⁺ B lymphocytes isolated from the circulating blood of human beings can be easily recognized by using this new fluorescent label.     

叶酸修饰聚酰胺-胺负载5-氟尿嘧啶纳米给药体系的制备及其体外性能研究

使用化学键键合的方式分别将叶酸(FA)和5-氟尿嘧啶-1-基乙酸(FUA)偶联于树状大分子聚酰胺-胺(PAMAM)制备纳米载药体系FA-PAMAM-FUA,并结合单因素分析法筛选出最佳制备条件为FA∶PAMAM∶FUA的物质的量的比为10∶1∶450,p H值为6.用紫外可见光谱、红外光谱和纳米粒度仪对FA-PAMAM-FUA的光学特性、粒径大小和体外释药性能进行了表征.结果表明:优化条件下制备的FAPAMAM-FUA粒径呈正态分布,平均粒径为90.28±20.00 nm,分散度为0.258±0.002(n=3),体系载药量达28.45%,FA-PAMAM-FUA给药体系对药物具有一定的p H敏感特性以及缓释功能.采用MTT法考察了5-Fu、FA-PAMAM-FUA对乳腺癌细胞MCF-7的增殖抑制作用,结果表明两者对MCF-7细胞的增殖具有明显地抑制作用,剂量依赖性强,随浓度的增高,FA-PAMAM-FUA对癌细胞增殖抑制作用较5-Fu明显增强.     

盐酸环丙沙星/二氧化硅复合粒子的原位制备及其缓释性能

利用硅酸钠在盐酸环丙沙星的酸溶液中的原位水解成功制备了盐酸环丙沙星/二氧化硅复合粒子。对所得产品进行的SEM、TEM、粒度分布、XRD和FTIR等分析表明,盐酸环丙沙星/二氧化硅复合粒子为粒径0.3～0.7μm的球形粒子,呈无定形态,且盐酸环丙沙星与二氧化硅以物理方式结合。热重分析结果表明,所得复合粒子药物负载量约为28.8％(质量分数)。体外溶出实验证明,产品具有良好的缓释性能,药物释放主要受扩散控制,具有均匀的释放速率和持久的缓释时间。