甘草次酸纳米粒的制备、表征及其抗肿瘤活性研究

目的:制备和表征甘草次酸(GA)纳米粒,并评价其体外抗肿瘤活性。方法:以聚乙烯吡咯烷酮K30为载体,使用反溶剂沉淀-冷冻干燥法制备GA纳米粒。采用X射线衍射分析、红外光谱分析、差示扫描量热分析、粒度分析等方法对所制纳米粒进行表征;采用高效液相色谱法测定纳米粒中GA的溶解度和载药量;采用MTT法考察GA原料药及纳米粒(GA剂量均为12.5、25、50、100、200μmol/L)对人肝癌细胞HepG2的体外抑制活性并计算半数抑制浓度(IC50)。结果:所制纳米粒中GA的X射线衍射特征峰和红外特征吸收峰均消失,吸热峰发生改变。纳米粒的粒径为(194.88±23.52)nm,低于原料药的(2 592.33±207.51)nm;分散指数为0.24±0.04,高于原料药的0.15±0.03;纳米粒的平均载药量为15.99%;溶解度由原料药的(1.05±0.01)μg/mL升至(250.00±0.15)μg/mL。体外抗肿瘤试验结果显示,GA原料药200μmol/L组和纳米粒各剂量组的细胞存活率均较空白对照组显著降低,且GA纳米粒各剂量组(除12.5μmol/L组外)的细胞存活率均显著低于同剂量原...     

Gamma-Irradiation of Non-Frozen,Frozen, and Freeze-Dried Liposomes

Purpose. The aim of this work was to investigate the possibilities and limitations of gamma-irradiation as a sterilisation method for non-frozen, frozen, and freeze-dried liposomes. Methods. Liposomes with an average size of 0.2 µm were irradiated with doses up to about 5 × 10⁴ Gy in a nitrogen atmosphere. Results. Phospholipids in dipalmitoylphosphatidycholine/dipalmitoylphosphatidylglycerol (DPPC/DPPG) 10/1-liposomes and egg phosphatidylcholine/egg phosphatidylglycerol (EPC/EPG) 10/1-liposomes in 10 mM phosphate buffer (pH 7.4) without trehalose degraded considerably upon gamma-irradiation. Irradiation damage was reduced in the presence of 10% trehalose added as a cryoprotectant, but trehalose reacted with species induced by gamma-irradiation as demonstrated by large decreases in pH. Both pH decrease and oxidative damage of EPC/EPG 10/1-liposomes were strongly dependent on the physical state during irradiation (non-frozen, frozen or freeze-dried). No changes in liposomal size were found upon gamma-irradiation, and hardly any change was seen in bilayer rigidity. Differences in the gel-to-liquid phase transition of DPPC/DPPG 10/1-liposome dispersions before and after gamma-irradiation were small in the presence of 10% trehalose, but larger in the absence of trehalose. Conclusions. The degradation of trehalose limits the use of freezing or freeze-drying liposome dispersions as a way to minimise irradiation damage.     

The Effects of Formulation Variables on the Stability of Freeze-Dried Human Growth Hormone

Formulation often has a dramatic effect on degradation of proteins during the freeze-drying process as well as impacting on the shelf-life stability of the freeze-dried product. This research presents the results of a formulation optimization study of the in-process and shelf-life stability of freeze-dried human growth hormone (hGH). Chemical decomposition via methionine oxidation and deamidation of asparagine residues as well as irreversible aggregation were characterized by HPLC assay methodology. In-process degradation and stability of low moisture freeze-dried solids were studied at 25 and 40°C in a nominal nitrogen headspace (0.5% O₂). Formulation variables included pH, level of salts, and the nature of the lyoprotectant. Studies of the effect of shear on aggregation in solutions indicated that shear comparable to that experienced during filtration does not induce aggregation. Irreversible changes in hGH during the freeze-drying process were minimal, but chemical decomposition via methionine oxidation and asparagine deamidation and aggregation did occur on storage of the freeze-dried solid. Decomposition via methionine oxidation was significant. A combination of mannitol and glycine, where the glycine remains amorphous, provided the greatest protection against decomposition and aggregation. It is postulated that an excipient system that remains at least partially amorphous is necessary for stabilization. However, the observation that dextran 40 formulations showed poor stability toward aggregation demonstrates that an amorphous excipient system is not a sufficient condition for stability. Stability of the solid was optimal when produced from solutions in the pH range, 7–7.5, with severe aggregation being observed at high pH. The level of sodium phosphate buffer affected stability of the solid, although this relationship was complex. Freeze-drying in the presence of NaCl produced severe aggregation and precipitation during the freeze-drying process as well as acceleration of oxidation and/or deamidation.     

Estimation of the Degree of Crystallinity of Cefazolin Sodium by X-Ray and Infrared Methods

The pentahydrate ( form) of cefazolin sodium (CEZ) exhibited sharp X-ray diffraction peaks, while the dehydrated form showed weak but distinct diffraction peaks. As expected the amorphous form exhibited a diffuse and halo diffraction pattern. The X-ray procedure to estimate the degree of crystallinity of CEZ was based upon the measurement of the total scattering and the scattering from the crystalline region of the drug. The major difference in the infrared (IR) spectra among the three forms of CEZ was the absence of a spectral band at 1542 cm^–1 in the amorphous form. The IR procedure was based upon the measurement of the peak percentage area ratio between the bands at 1542 and 1760 cm^–1, where the latter was used as a normalizing peak. The degree of crystallinity of CEZ samples, obtained by either freeze-drying aqueous CEZ solutions or storing the crystalline forms under different humidity conditions, was determined by these two methods. Although the correlation of results by the two methods was good, the X-ray procedure appears to be superior since it can differentiate among the three solid CEZ forms, whereas IR could distinguish between only crystalline and amorphous CEZ, reproducibly.     

Decreased Protein-Stabilizing Effects of Cryoprotectants Due to Crystallization

The stabilizing effects of various additives against inactivation of an enzyme (-galactosidase from Aspergillus oryzae) during freeze-drying were studied, with a focus on their crystallinity. The crystalline morphology of mannitol and inositol in freeze-dried cakes depended on the solute concentrations before freezing and the freeze-drying method used. The additives in their amorphous state showed concentration-dependent stabilization of the enzyme, whereas additive crystallization during freeze-drying decreased their effects. Heat treatment before freeze-drying also caused crystallization and diminished the stabilizing effects. Noncovalent soluble aggregates were observed in the inactivated enzyme solution. These results show the importance of maintaining the amorphous state of additives used as stabilizing agents during freeze-drying.     

鬼臼毒素二棕榈酰磷脂酰胆碱前体脂质体的研制及特性观察

目的 研制鬼臼毒素二棕榈酰磷脂酰胆碱(PPT-DPPC)前体脂质体,提高PPT-DPPC脂质体的稳定性。方法 采用冷冻干燥法,选择海藻糖做冻干剂制备PPT-DPPC前体脂质体,并考察PPT-DPPC前体脂质体水合后的形态、粒径分布、包封率和稳定性。结果 PPT-DPPC前体脂质体经水合后在电镜下呈多层多室脂质体,脂质体粒径分布均匀,平均粒径(1.45±0.38)μm,药物包封率为72.3%。分别在4℃、20℃、40℃贮存1、3、6个月,脂质体形态、粒径及包封率均无明显变化。结论 冷冻干燥法制备PPT-DPPC前体脂质体,方法简便易行,制剂粒径分布均匀、包封率高、有良好稳定性。     

Effect of drying processes and curing time of chitosan-lysine semi-IPN beads on chlorpheniramine maleate delivery

Abstract

Beads of semi-interpenetrating polymer network (semi-IPN) have been synthesized from chitosan and lysine with varying amounts of glutaraldehyde solution used as a cross-linker. The cross-linked beads are dried by different drying processes such as air-drying, oven-drying and freeze-drying. These semi-IPNs are characterized under a scanning electron microscope (SEM). Swelling studies of these beads are carried out in different pH (2.0 and 7.4) solutions. The effect of concentration of cross-linking agent and curing period on the swelling as well as on the drug release is analysed. The results indicate that the size of matrix depend on the curing time of beads, concentration of glutaraldehyde and technique of drying. The freeze-dried beads exhibit a relatively higher percentage of swelling in the range of 66–89% as compared to oven-dried beads (53–74%) and air-dried beads (39–61%). The drug loaded beads which are cured for different time intervals followed by drying are tested for in-vitro release of chlorpheniramine maleate (CPM) drug. The rate of drug release from freeze-dried beads is much faster than that from the oven-dried and air-dried beads.     

Recoverability of freeze-dried doxorubicin-releasing chitosan embolic microspheres

The purpose of this study is to investigate the recoverability of freeze-dried chitosan microspheres (MS). The factors influencing the integrity of chitosan MS during freeze-drying and rehydration procedures were determined, with focusing on choosing a suitable rehydration method and a freeze-drying excipient. Mean MS size, size distribution and sphericity of recovered chitosan MS were evaluated. Furthermore, the impacts of freeze-drying and rehydration procedure on the elasticity of chitosan MS were explored and the release profiles were evaluated. The recoverability of lyophilized chitosan MS was largely dependent on rehydration method and freeze-drying excipients. When using the optimized recovery processes, deformable drug-loaded chitosan MS can be rapidly recovered to exhibit the initial physico-mechanical properties such as elasticity. Release profiles also were not significantly changed after rehydration procedure. It is therefore expected drug-loaded chitosan MS can be stably freeze-dried with the prevention of drug release during storage and rapidly recovered to be used as deformable embolic materials possibly applicable for anti-cancer embolotherapy.     

天然药物材料白及胶制备生物支架材料的实验研究

目的 探索采用中药天然成分制备多孔支架材料用于骨缺损修复生物材料的可行性,考察用于骨骼组织修复的白及胶支架材料的制备方法及其性能.方法 从中药材白及中提取白及胶并精制,然后进行醛基化反应,与其他赋形剂共混、交联,冷冻干燥得到支架材料.结果 利用水提醇沉法及酶法精制纯化能得到较高纯度的白及胶;经氧化后发生Schiff碱缩合反应,形成良好的网状结构,冷冻干燥制得多孔支架材料.结论 以白及胶为主要原料制备的生物支架材料,各项性能表征符合多孔支架材料要求.