生物素化普鲁兰多糖纳米颗粒制备与表征

合成生物素化普鲁兰多糖衍生物(BP),采用纳米沉淀法制备纳米颗粒(BPNs),考察制备条件对纳米颗粒性质影响,为进一步将其作为药物载体的研究提供基础.通过酯化反应将生物素羧基与普鲁兰多糖连接,生成的衍生物BP通过FI-IR和1H-NMR表征,取代度采用电感耦合等离子体光谱仪(ICP)确定;BPNs进行透射电镜、动态光散射仪和ζ电位仪表征与检测,颗粒表面生物素采用Quant*TagTM Biotin Kit生物素测定试剂盒测定.获得取代度21(BP1),46(BP2),81(BP3)3种衍生物,其中BP2和BP3能够制备纳米颗粒(LBPNs,HBPNs).纳米颗粒呈球形,表面光滑规整,平均粒径100～300nm,水中ζ电位在一17mV左右.制备过程中,粒径随BP浓度(10～50mg/ml)增加而增加((136.2±46.8)nm,(190.8±89.6)nm和(254.5±140.0)nm).调整水相组成为水:元水乙醇(v/v)1:1和1:2时粒径分别为(170.7±30.4)nm和(158.8±21.0)nm.HBPNs和LBPNs表面的生物素量为衍生物的(1.9±0.03)%和(2.0±0.04)%.生物素化普鲁兰多糖衍生物通过纳米沉淀法能制备出纳米颗粒,颗粒表面存在有生物素,颗粒性质受制备条件影响.     

可德兰衍生物——脱氧胆酸偶联物自聚集纳米微粒的制备及表征

对可德兰衍生物--羧甲基可德兰进行疏水改性并考察羧甲基可德兰--脱氧胆酸偶联物(DCMC)的自聚集行为,为进一步将其作为药物载体的研究提供依据.将可德兰羧甲基化以后和脱氧胆酸(DOCA)用酯键相连接,DOCA的取代度用紫外分光光度计测定;DCMC自聚集纳米微粒的形态以透射电镜观察、粒径及粒径分布用动态光散射仪测定、表面电位用ζ电位仪测定;芘荧光法测定DCMC临界聚集浓度.获得DOCA的取代度为2.1%、3.2%、4.1%、6.3%(摩尔分数)的DCMC;自聚集纳米微粒呈球形;在蒸馏水中粒径呈单峰分布,平均粒径为192～347nm,随DOCA的取代度增高而降低,在PBS中平均粒径随pH值的降低而增高;在蒸馏水中ζ电位接近-60mV,然而在PBS中ζ电位绝对值降低,为-26～36mV,且随pH值的降低而降低;在蒸馏水中的临界聚集浓度为0.014～0.052mg/ml,随DOCA的取代度增高而降低,在PBS中的临界聚集浓度比蒸馏水中稍低.用DOCA疏水改性的可德兰衍射物能形成球形的自聚集纳米微粒,该纳米微粒的理化性质受DOCA的取代度、溶剂性质、溶剂pH值的影响.     

H_2O_2处理碳包覆铁纳米颗粒的表面特性及分散行为

采用体积分数30%的H2O2处理碳包覆铁纳米粒子外层的非晶态类石墨碳层,并将其超声分散于水介质中,通过改变pH值分析测定碳包覆铁纳米粒子表面zeta电位和粒径。结果表明:碳包覆铁纳米粒子非晶碳层的特殊结构可通过双氧水化学处理使其表面产生羧基和羟基;在强碱性介质下,羟基和羧基可强化颗粒间的静电斥力,提高碳包覆铁纳米粒子在水介质中的分散性能。当pH值约为11.5时,碳包覆铁纳米粒子表面zeta电位为48 mV,水合粒子粒径可达到110 nm。     

载银氧化锌复合纳米粒子的制备与表征

采用沉淀法制备了纳米氧化锌,并以它为前驱物,采用高温分解法对纳米氧化锌进行了裁银改性处理,制备了栽银氧化锌复合纳米粒子,考察了载银前后纳米粒子的粒径与结构。研究发现,采用沉淀法制备的纳米氧化锌尺寸较为均匀,粒径约为170nm,分散性也较好;载银后的复合纳米粒子粒径略有增加,这来源于银在纳米氧化锌粒子外的成功包覆。     

氧化铝-水纳米流体的制备及其分散性研究

通过在水介质中添加纳米氧化铝粒子,研制了一种新型传热冷却工质Al2O3-H2O纳米流体,给出的纳米流体沉降照片和粒径分布显示了加入分散剂的悬浮液具有较高的分散性、稳定性.同时还测定了纳米Al2O3-H2O悬浮液的zeta电位和吸光度,探讨了不同pH值和SDBS分散剂加入量对纳米氧化铝粉体在水相体系分散稳定性的影响.结果表明:zeta电位的绝对值与吸光度有良好的对应关系,zeta电位绝对值越高,吸光度越大,粉体体系的分散性能越好;pH值约在8.0时,溶液的zeta电位绝对值较高,吸光度较大,说明此时有较好的分散效果;SDBS能显著提高水溶液中Al2O3表面zeta电位绝对值,增大了颗粒问静电排斥力,改善了悬浮液稳定性.在0.1%纳米Al2O3-H2O悬浮液中,SDBS分散剂最佳加入量(质量分数)为0.10%时,能得到分散稳定的悬浮液体系.     

不同形貌CuO纳米粒子的制备与性能

采用CuSO4.5H2O、Cu(NO3)2、(CH2)6N4和NaOH为原料,采用沉淀法分别制备纤维状CuO纳米粒子和纺锤状CuO纳米粒子,用透射电镜和X射线衍射仪对产物的大小﹑形貌和组成进行表征;按质量比为9∶1的比例将黑索金分别与纤维状CuO纳米粒子和纺锤状CuO纳米粒子混合,对样品进行热失重测试分析,根据黑索金热分解温度的变化来衡量催化剂的活性。结果表明,采用沉淀法制备CuO纳米粒子时,反应温度、终点pH值对产物形貌有显著影响;不同形貌的CuO纳米粒子对黑索金的分解催化作用效果不同。     

氧化铝-水纳米流体的分散性研究

通过在水介质中添加纳米氧化铝粒子，研制了一种新型传热冷却工质-氧化铝-水纳米流体，给出的纳米流体沉降照片和粒径分布显示了加入分散剂的悬浮液具有较高的分散性、稳定性．同时还测定了纳米Al2O3-水悬浮液的zeta电位和吸光度，探讨了不同pH值和SDBS分散剂加入量对纳米氧化铝粉体在水相体系分散稳定性的影响。结果表明：zeta电位的绝对值与吸光度有良好的对应关系，zeta电位绝对值越高，吸光度越大，粉体体系的分散性能越好；pH值约在8.0时，溶液的zeta电位绝对值较高，吸光度较大，说明此时有较好的分散效果．SDBS能显著提高水溶液中舢203表面zeta电位绝对值，增大了颗粒间静电排斥力，改善了悬浮液稳定性。在0．1％纳米Al2O3-水悬浮液中，SDBS分散剂最佳加入量（质量分数）为0．10％时，能得到分散稳定的悬浮液体系。     

壳聚糖-脱氧胆酸及其叶酸偶联体的表征及自组装特性研究

以1-乙基-(3-二甲基氨基丙基)碳酰二亚胺(EDC)为催化剂,将脱氧胆酸接枝到壳聚糖主链的氨基上,得到疏水改性的双亲性壳聚糖;再将叶酸连接于壳聚糖氨基,可得到具有肿瘤靶向潜力的双亲性共聚物.利用红外光谱、1H核磁、X射线晶体衍射图谱对其结构进行表征.脱氧胆酸-壳聚糖、叶酸-壳聚糖-脱氧胆酸在水相中通过透析处理均能形成自聚集体,利用荧光探针技术研究其自聚集行为.制得的两种自聚集体均具有较低的临界胶束浓度(10-2mg/ml),透射电镜和粒径分析测试显示制得的自聚集体为纳米级颗粒.随着脱氧胆酸取代度的增加,粒径降低,临界胶束浓度下降,但叶酸直接偶联壳聚糖导致自组装阻力增加.     

仿细胞外层膜结构壳聚糖纳米颗粒的制备及其控释性能研究

采用模板聚合法以甲基丙烯酸(MA)、甲基丙烯酰氧乙基磷酰胆碱(MPC)为单体,以过硫酸钾为引发剂和壳聚糖进行聚合,制备具有仿细胞外层膜结构壳聚糖纳米颗粒。用动态光散射仪(DLS)、透射电镜(TEM)和zeta电位对纳米颗粒的粒径、zeta电位进行表征,并通过体外阿霉素控释实验对该纳米颗粒的控释性能进行研究。该仿细胞外层膜结构壳聚糖纳米颗粒将在基因治疗、药物控释等领域具有巨大的应用前景。该研究对于探索仿细胞外层膜结构纳米颗粒的控释性能具有重要的学术意义。     

SiO2/CaCO3纳米复合粒子填充改性聚丙烯

通过简单的工艺条件和步骤制备S iO2包覆C aCO3的核壳结构纳米复合粒子,采用硅烷偶联剂对其和纳米S iO2实心粒子进行表面改性处理,并用处理后的两种粒子分别对聚丙烯进行填充改性,然后比较其对复合材料力学性能的影响。结果表明,利用纳米S iO2/C aCO3复合粒子填充改性聚丙烯,可同时达到增强、增韧的目的,而且对材料力学性能的改性效果与纳米S iO2实心粒子的改性效果相近。     

Modified nanoprecipitation method to fabricate DNA-loaded PLGA nanoparticles

Objective: The objective of this study was to formulate DNA-loaded poly(d,l-lactide-co-glycotide) (PLGA) nanoparticles by a modified nanoprecipitation method. Methods: DNA-loaded PLGA nanoparticles were prepared by the modified nanoprecipitation method and the double emulsion/solvent evaporation method. The characterizations of DNA-loaded nanoparticles such as entrapment efficiency, morphology, particle size, zeta potential, structural integrity of the loaded DNA, and stability of the loaded DNA in PLGA nanoparticles against DNase I, in vitro release, cell viability and in vitro transfection capability were investigated. Results: The resulted PLGA nanoparticles by the modified nanoprecipitation method had uniform spherical shape, narrow size distribution with average particles size near 200 nm, negative zeta potential of ?12.6 mV at pH 7.4, and a sustained-release property in vitro. Plasmid DNA could be efficiently encapsulated into PLGA nanoparticles (>95%) without affecting its intact conformation using this modified nanoprecipitation method, which was superior to the double emulsion/solvent evaporation method. The PLGA nanoparticles were much safer to A549 cell compared to commercial Lipofectamine 2000 and could successfully transfer plasmid-enhanced green fluorescent protein into A549 cells. Conclusion: In conclusion, the modified nanoprecipitation method could be applied as an efficient way to fabricate DNA-loaded PLGA nanoparticles instead of the conventional double emulsion/solvent evaporation method.     

Preparation and characterization of novel CdSe quantum dots modified with poly (d,l-lactide) nanoparticles

In this paper, novel CdSe quantum dots (QDs) modified with poly (d, l-lactide) (PLA) nanoparticles by nanoprecipitation method was reported. CdSe QDs modified with PLA nanoparticles were characterized by Photon correlation spectroscope (PCS), transmission electron microscope (TEM), flluorescence spectrophotometer and fluorescence microscope. The modified CdSe QDs were spherical and relatively uniform. The modified CdSe QDs were water soluble and their strong yellow fluorescence emission was observed both in vitro and in vivo. The fluorescence of the modified CdSe QDs was stable in aqueous solution for more than 30 d. These modified CdSe QDs are expected to have much potential for biological labeling and diagnostics based on above properties.     

Nanoparticles obtained by confined impinging jet mixer: poly(lactide-co-glycolide) vs. Poly-ε-caprolactone

This paper is focused on the production and characterization of polymeric nanoparticles obtained by nanoprecipitation. The method consisted of using a confined impinging jet mixer (CIJM), circumventing high-energy equipment. Differences between the use of poly-ε-caprolactone (PCL) and poly(lactide-co-glycolide) (PLGA) as concerns particle mean size, zeta potential, and broad-spectrum antibiotic florfenicol entrapment were investigated. Other analyzed variables were polymer concentration, solvent, and anti-solvent flow rates, and antibiotic initial concentration. To our knowledge, no data were found related to PLGA and PCL nanoparticles comparison using CIJM. Also, florfenicol encapsulation within PCL or PLGA nanoparticles by nanoprecipitation has not been reported yet. The complexity of the nanoprecipitation phenomena has been confirmed, with many relevant variables involved in particles formation. PLGA resulted in smaller and more stable nanoparticles with higher entrapping of florfenicol than PCL.     

Pullulan acetate coated magnetite nanoparticles for hyper-thermia: Preparation, characterization and in vitro experiments

Amphipathic polymer pullulan acetate (PA)-coated magnetic nanoparticles were prepared and characterized by various physicochemical means. The cytotoxicity and cellular uptake of the magnetic nanoparticles were examined. The hyperthermic effect of the magnetic nanoparticles on tumor cells was evaluated. Transmission electron microscopy (TEM) showed that the PA coated magnetic nanoparticles (PAMNs) had spherical morphology. Dynamic light scattering (DLS) showed that the size distribution of PAMNs was unimodal,with an average diameter of 25.8 nm ± 6.1 nm. The presence of the adsorbed layer of PA on the magnetite surface was confirmed by Fourier transform infrared (FTIR) spectroscopy. Magnetic measurements revealed that the saturation magnetization of the PAMNs reached 51.9 emu/g and the nanoparticles were superparamagnetic. Thermogravimetric analysis (TGA) showed that the Fe₃O₄ particles constituted 75 wt% of the PAMNs. The PAMNs had good heating properties in an alternating magnetic field. Cytotoxicity assay showed that PAMNs exhibited no significant cytotoxicity against L929 cells. TEM results showed that a large number of PAMNs were internalized into KB cells. PAMNs have good hyperthermia effect on KB cells in vitro by magnetic field induced hyperthermia. These novel magnetic nanoparticles have great potential as magnetic hyperthermia mediators.      

Green preparation and catalytic application of Pd nanoparticles

A green strategy for the facile preparation and effective stabilization of Pd nanoparticles has been developed by using D-glucose as the reducing and stabilizing agents. The UV/vis absorption spectroscopy, transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurements were used to characterize the as-prepared Pd nanoparticles. It was found that the D-glucose concentration and pH value had an important effect on the size distribution and stability of the nanoparticles. Further, the Pd nanoparticles exhibited good catalytic properties in the degradation of azo dyes.     

Complexation as an approach to entrap cationic drugs into cationic nanoparticles administered intranasally for Alzheimer's disease management: preparation and detection in rat brain

Abstract

Objective: Complexation was investigated as an approach to enhance the entrapment of the cationic neurotherapeutic drug, galantamine hydrobromide (GH) into cationic chitosan nanoparticles (CS-NPs) for Alzheimer’s disease management intranasally. Biodegradable CS-NPs were selected due to their low production cost and simple preparation. The effects of complexation on CS-NPs physicochemical properties and uptake in rat brain were examined.

Methods: Placebo CS-NPs were prepared by ionic gelation, and the parameters affecting their physicochemical properties were screened. The complex formed between GH and chitosan was detected by the FT-IR study. GH/chitosan complex nanoparticles (GH-CX-NPs) were prepared by ionic gelation, and characterized in terms of particle size, zeta potential, entrapment efficiency, in vitro release and stability for 4 and 25?°C for 3 months. Both placebo CS-NPs and GH-CX-NPs were visualized by transmission electron microscopy. Rhodamine-labeled GH-CX-NPs were prepared, administered to male Wistar rats intranasally, and their delivery to different brain regions was detected 1?h after administration using fluorescence microscopy and software-aided image processing.

Results: Optimized placebo CS-NPs and GH-CX-NPs had a diameter 182 and 190?nm, and a zeta potential of +40.4 and +31.6?mV, respectively. GH encapsulation efficiency and loading capacity were 23.34 and 9.86%, respectively. GH/chitosan complexation prolonged GH release (58.07%?±?6.67 after 72?h), improved formulation stability at 4?°C in terms of drug leakage and particle size, and showed insignificant effects on the physicochemical properties of the optimized placebo CS-NPs (p?>?0.05). Rhodamine-labeled GH-CX-NPs were detected in the olfactory bulb, hippocampus, orbitofrontal and parietal cortices.

Conclusion: Complexation is a promising approach to enhance the entrapment of cationic GH into the CS-NPs. It has insignificant effect on the physicochemical properties of CS-NPs. GH-CX-NPs were successfully delivered to different brain regions shortly after intranasal administration suggesting their potential as a delivery system for Alzheimer’s disease management.     

Study on the stability and microstructural properties of barium sulfate nanoparticles produced by nanomilling

Barium sulfate nanoparticles were produced by nanomilling in stirred media mill using sodium salt of polyacrylic acid (PAA-Na) as a dispersant. The particles sizes of the ground product obtained in the grinding mill were determined by dynamic light scattering (DLS), Brunauer–Emmet–Teller (BET) nitrogen gas adsorption method, and transmission electron microscopy (TEM). The mean particle size calculated with various methods yielded different values due to the different characterization techniques. The stability of BaSO₄ nanoparticles produced was analyzed by zeta potential measurement and Turbiscan. The stability of barium sulfate nanoparticles was high in presence of dispersant PAA-Na and higher pH values. Further, the changes in microstructural properties, caused by wet grinding and adsorption of PAA-Na on BaSO₄ nanoparticles, were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The surface activation and amorphization of BaSO₄ nanoparticles were observed due to increased stresses exerted on the particles during wet grinding.     

Microfluidic platform for controlled synthesis of polymeric nanoparticles

A central challenge in the development of drug-encapsulated polymeric nanoparticles is the inability to control the mixing processes required for their synthesis resulting in variable nanoparticle physicochemical properties. Nanoparticles may be developed by mixing and nanoprecipitation of polymers and drugs dissolved in organic solvents with nonsolvents. We used rapid and tunable mixing through hydrodynamic flow focusing in microfluidic channels to control nanoprecipitation of poly(lactic- co-glycolic acid)- b-poly(ethylene glycol) diblock copolymers as a model polymeric biomaterial for drug delivery. We demonstrate that by varying (1) flow rates, (2) polymer composition, and (3) polymer concentration we can optimize the size, improve polydispersity, and control drug loading and release of the resulting nanoparticles. This work suggests that microfluidics may find applications for the development and optimization of polymeric nanoparticles in the newly emerging field of nanomedicine.     

In Vitro Stability of Poly(D,L-lactide) and Poly(D,L-lactide)/Poloxamer Nanoparticles in Gastrointestinal Fluids

Abstract

Poty(D,L-lactide) (PLA) nanoparticles of various surface and bulk properties were prepared by a nanoprecipitation procedure and evaluated for their physical and chemical in vitro stability in simulated gastrointestinal fluids of 37°C. The influence of polymer characteristics and poloxamer 188 (POL 188) adsorption was studied. Physical stability was followed by visual appearance, particle size, and zeta potential measurements. Molecular weight changes were analyzed by gel permeation chromatography (GPC). Due to a sharp decrease in their negative zeta potential, poloxamer-free nanoparticles flocculated in simulated gastric fluid, irrespective of the polymer properties. Their physical stability in protein-free intestinal fluids increased with an increase in carboxy end group concentration of the PLA and thus, with an increase in their negative zetapotential. Protein effects at pH 7.5 were rather complex indicating a stabilizing effect of negatively charged proteins and a destabilizing effect of positively charged proteins. Poloxamer 188 adsorption sterically stabilized the nanoparticles against flocculation in gastric fluid, irrespective of the PLA characteristics. Physical stability of the PLA/POL 188 nanoparticles in intestinal fluids was affected by the PLA characteristics. Poloxamer 188 increased the physical stability of nanoparticles composed of hydrophobic PLA, irrespective of the proteins present. A gradual particle size increase could, however, be observed for PLA/POL nanoparticles composed of PLA with a high content of carboxy end groups, especially in combination with positively charged proteins. This effect is most likely due to a decrease in PLA/POL interactions resulting from the ionization of the carboxy end groups located on the nanoparticle surface and leading to conformational changes and/or a distinct desorption of POL 188. The chemical stability of PLA and PLA/POL nanoparticles depended on the glass transition temperature (T_gH) of the hydrated polymer matrix. Enzymatic effects could not be detected. Nanoparticles with T_gH > 37°C were chemically stable in both gastric and intestinal fluids at 37°C over a time period of more than 48 hr.