Preparation,characterization and release of methyl viologen from a novel nanoparticle delivery system with double shells of silica and PLGA

The use of nanotechnology in drug delivery is a rapidly expanding field. Biodegradable or nontoxic nanomaterials have the most promising application potentials in nanomedicine. Herein, we report a novel core-shell nanoparticle with double shell coatings (silica and poly(D,L-lactide-co-glycolide) (PLGA)) with the total shell thickness of (8.7 ± 1.3) nm. The outer shell of PLGA is biodegradable and used for controlled and sustained release, and the inner shell of silica is mesoporous for the preservation of t...     

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。     

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。     

Preparation and Characterization of Polymeric Micelles from Poly（D, L-lactide） and Methoxypolyethylene Glycol Block Copolymers as Potential Drug Carriers

Amphiphilic diblock copolymers composed of methoxy polyethylene glycol (MePEG) and poly(D,L- lactide) (PDLLA) were prepared for the preparation of polymeric micelles. The use of MePEG-PDLLA as drug carriers has been reported in the open literature, but there are only few data on the application of a se- ries of MePEG-PDLLA copolymers with different lengths in the medical field. The shape of the polymeric mi- celles is also important in drug delivery. Studies on in vitro drug release profiles require a good sink condi- tion. The critical micelle concentration of a series of MePEG-PDLLA has a significant role in drug release. To estimate their feasibility as a drug carrier, polymeric micelles made of MePEG-PDLLA block copolymer were prepared by the oil in water (O/W) emulsion method. From dynamic light scattering (DLS) measurements, the size of the micelle formed was less than 200 nm. The critical micelle concentration of polymeric micelles with various compositions was determined using pyrene as a fluorescence probe. The critical micelle con- centration decreased with increasing number of hydrophobic segments. MePEG-PDLLA micelles have a considerably low critical micelle concentration (0.4-0.5 μg/mL), which is apparently an advantage in utilizing these micelles as drug carriers. The morphology of the polymeric micelles was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The micelles were found to be nearly spherical. The yield of the polymeric micelles obtained from the O/W method is as high as 85%.     

Acute toxicity and oxidative damage induced by silica nanorattle in vivo

Hollow mesoporous nanomaterial is a kind of promising new drug delivery system due to their unique hollow structures.In order to evaluate the toxicity of silica nanorattle (SN) particles in vivo,40 female mice were used in this study to investigate the acute toxicity and oxidative damage.Mice were intravenously injected with SN suspension in sterile 5% glucose at 40,80 and 240 mg/kg,respectively.The control group was administrated with equal-volume 5% glucose.Weight,feed intake,hematology analysis,blood biochemical assay and histopathology diagnosis were examined.The activities of SOD,GSH and CAT were measured as well.The results demonstrated that the levels of ALT and AST in the mice treated with 240 mg/kg SN increased significantly as compared with the control group (P<0.05),whereas the contents of BUN and CREA changed unremarkably.The activity of SOD induced by SN in the liver decreased significantly (P<0.05).In summary,this study revealed that liver was the target organ of the SN.It also can be concluded that activity of SOD played an important role in liver injury caused by SN.     

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.     

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.     

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。     

Pickering乳液聚合法制备pH敏感复合微胶囊及其缓释性能

利用反相Pickering乳液聚合法制备了聚α-甲基丙烯酸/二氧化硅复合微胶囊。以改性纳米二氧化硅为稳定剂,以液体石蜡作为油相,以α-甲基丙烯酸的水溶液作为水相,经超声乳化,可得到水/油型的Pickering乳液。再经过聚合,即可得到复合微胶囊。微胶囊的平均粒径约为10μm,胶囊壁由二氧化硅颗粒层和聚合物层两部分组成,壁厚约为1μm。以罗丹明B为缓释试剂研究了微胶囊的可控缓释性能,研究结果表明复合微胶囊具有良好的pH敏感性,在碱性体系中罗丹明B的释放量为15.0%,在酸性体系中罗丹明B释放量提高至98.4%。     

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.     

小粒径PLGA纳米颗粒的制备

聚乳酸—羟基乙酸共聚物(PLGA)因具有良好的生物相容性,已成为发展最好的可降解聚合物之一,而其粒径是限制其应用的一个重要因素.通过双乳化-溶剂挥发(W/O/W)方法制备小粒径PLGA纳米颗粒.并用纳米粒度及电位分析仪(DLS)对其粒径及Zeta电位进行研究讨论.结果表明,不同的水油比,表面活性剂浓度以及有机相浓度对粒径都有影响.在水油相比大于16∶1,PLGA与表面活性剂质量比大于1∶1,有机相浓度为5 mg/m L时,都出现了小于100 nm的PLGA纳米颗粒,所得PLGA纳米颗粒的粒径范围在49 nm~445 nm.     

微乳液法制备纳米二氧化硅

制备 OP-10/正辛醇/环己烷/氨水微乳液.在该微乳液中,由正硅酸乙酯在碱性条件下受控水解反应制备了 SiO2纳米粒子.通过红外光谱(FT-IR)、X射线衍射(XRD)、透射电镜(TEM)分别对样品结构及形貌尺寸进行了表征.探讨了水与表面活性剂摩尔比(R)、水与正硅酸乙酯摩尔比(H)对SiO2纳米粒子粒径的影响.结果表明制备的SiO2粒子为无定型球形颗粒,粒径为 80～105nm,SiO2纳米粒子粒径随着R和H的增大而增大.     

Silica Microcapsules Prepared by Interfacial Reaction Methods

1 Results Silica spherical particles with hollow structure are directly prepared by interfacial reaction methods using W/O/W emulsion (schematic diagram in Fig.1)[1].Fig.1 Silica microcapsule formationThe mixing of W/O emulsion consisting of sodium silicate solution (inner water phase) and n-hexane solution (oil phase) to outer water phase dissolving NH4HCO3 or other salts affords silica microcapsules.The critical feature of this method is the direct formation of hollow structure.Therefore,the core com...     

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...     

Carmofur/PLA-PEG微球制备及其对包封率的影响

以开环聚合制备的聚乳酸-聚乙二醇（PLA-PEG）共聚物具有优良的生物相容性，广泛应用于药物载体．将其作为壁材用相分离法制备含抗癌药Carmofur的PLA-PEG微球，研究了共聚物质量浓度、油水体积比、油相和水相的温度、共聚物的特性粘数、表面活性剂的用量等因素对药物包封率的影响，并进行了体外药物释放的测试．     

矿泉水面霜的释药性研究

利用水杨酸和水杨酸钠对矿泉水面霜的释药性进行了试验研究,结果证明虽然矿泉水中含有大量离子,但制备的O／W型乳剂面霜不但稳定性比较好,而且对脂溶性和水溶性药物的释放也很理想。     

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。     

共溶剂对超临界流体负载药物的影响

以自制的空心多孔SiO₂纳米球为吸附介质,采用超临界流体技术负载阿维菌素药物,考察了不同的共溶剂及其不同用量对这种纳米载体载药量的影响,并研究了负载后的药物在不同溶出介质中的缓释行为。结果表明：对于这种纳米空心载体,用超临界流体技术负载阿维菌素药物时,加入的共溶剂极性越大,载药量越大,但载药量还受溶剂黏度的影响;对于任何一种共溶剂,加入量过多或过少都不能达到最大的载药量;溶出介质的种类和浓度对负载后药物的释放速率都有明显影响。