In situ evading of phagocytic uptake of stealth solid lipid nanoparticles by mouse peritoneal macrophages

Stealth solid lipid nanoparticles (SSLN) were prepared and evaluated for the effect of evading phagocytic uptake by mouse peritoneal macrophages in situ. Fluorescent SSLNs were prepared by emulsion/evaporation with rhodamine B as the fluorescent marker and polyoxyethylene stearate as stealth agent in a stearic acid matrix. Macrophages were induced chemically through intraperitoneally injecting 1% sodium thioglycolate. After 4 days of cultivation, SSLNs suspension was injected intraperitoneally and phagocytosis taken out in situ. At definite time intervals, peritoneal fluid was drawn out and analyzed by flow cytometer. Maximium uptake by macrophages was observed at 2 hr after injection of nanoparticles. At all time intervals, phagocytic uptake of Solid lipid nanoparticles (SLNs) was better than SSLNs. Longer and dense polyethylene glycol chains led to reduced uptake by macrophages. Both SSLNs and SLN had uptake by macrophages to some extent, and the in situ model was suitable for evaluating interactions between cells and nanoparticles.     

Antitumor properties of irinotecan-containing nanoparticles prepared using poly(DL-lactic acid) and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)

Irinotecan-containing nanoparticles (NP) were prepared by coprecipitation with addition of water to acetone solution of poly(DL-lactic acid), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) and irinotecan, and subsequent evaporation of organic solvent. NP were purified by gel filtration and used for experiments after condensation by evaporation. The obtained NP showed the drug content of 4.5% (w/w) and the mean particle diameter of 118 nm with the particle diameter distribution between 80-210 nm. When the antitumor effect was examined at a repeated dose of 20 mg irinotecan eq/kg for 3 d (3 x 20 mg/kg) using mice bearing Sarcoma 180 subcutaneously, only NP suppressed tumor growth significantly. After i.v. injection in rats, NP maintained irinotecan plasma concentration longer than CPT-11 aqueous solution. The present nanoparticle formation is suggested as a possibly useful dosage form of irinotecan against solid tumor.     

聚乙二醇单甲醚接枝壳聚糖自组装纳米球的制备*

目的:合成聚乙二醇单甲醚接枝壳聚糖(monomethoxy poly(ethylene glycol)-grafted-chitosan,mPEG-g- CS),并制备自组装纳米球。方法:利用甲醛连接法将聚乙二醇单甲醚(monomethoxy poly(ethylene glycol),mPEG)接枝干壳聚糖(ehitosan,CS)分子,得到聚乙二醇(poly(ethylene glycol),PEG)改性的壳聚糖衍生物,并通过傅立叶红外光谱仪(Fourier transform infrared spectroscopy,FT-IR),核磁共振仪(proton nuclear magnetic resonance,~1H-NMR)对产物进行结构表征;采用超声透析法制备自组装纳米球,并通过透射电镜(transmission electron microscopy,TEM),动态激光粒度分析仪(dynamic laser light scattering,DLLS)表征了纳米球的形态和粒径;以芘为荧光探针,通过荧光检测分析测定了mPEG-g-CS的临界胶束浓度(critical micellar concentration,CMC)。结果:通过FT-IR,~1H- NMR确证了接枝产物的存在;mPEG-g-CS在水溶液中能够自组装形成球状纳米胶束,平均粒径为250 nm。结论:通过甲醛连接法制备mPEG-g-CS,具有制备方法简捷、反应周期短、易操作的优点。利用该产物制备的纳米球有望成为长循环纳米药物载体。     

聚乙二醇-聚十六烷基氰丙烯酸酯聚合物及其纳米粒的制备

聚乙二醇氰乙酸酯和十六烷基氰乙酸酯聚合得到两亲性的标题聚合物,通过IR、1HNMR及凝胶渗透色谱法等确证结构.将此聚合物用溶剂-非溶剂法所制得的纳米粒粒径为100～400nm,分布均匀.     

Self-assembled hydrogel nanoparticles composed of dextran and poly(ethylene glycol) macromer

Biodegradable hydrogel nanoparticles were prepared from glycidyl methacrylate dextran (GMD) and dimethacrylate poly(ethylene glycol) (DMP). GMD was synthesized by coupling of glycidyl methacrylate to dextran in the presence of 4-(N,N-dimethylamino)pyridine (DMAP) using dimethylsulfoxide (DMSO) as an aprotic solvent. DMP was synthesized from poly(ethylene glycol) (PEG) and methacryloyl chloride. GMD/DMP (abbreviated as DP) hydrogel was prepared by radical polymerization of GMD and DMP using ammonium peroxydisulfate (APS) as an initiator and UV curing. DP hydrogel nanoparticles were obtained by diafiltration method using DMSO solution. The GMD and DMP were characterized by fourier transform infrared spectroscopy. Fluorescence probe technique was used to investigate the self-assembly of DP in water using pyrene as a hydrophobic probe. The critical association concentration (CAC) was determined to be 5.6 x 10(-2) g/l. The shape of DP hydrogel nanoparticles was spherical when observed by transmission electron microscope (TEM). The size range of DP hydrogel nanoparticles was about 20 approximately 50 nm. The hydrodynamic size of DP hydrogel nanoparticles was measured by photon correlation spectroscopy (PCS) and gradually increased with time in PBS (0.1 M, pH 7.4). Drug release study was performed using clonazepam (CNZ) as a hydrophobic model drug. In vitro release rate of CNZ from the DP hydrogel nanoparticles was dependent on the existence of dextranase and the pH of the release medium.     

Preparation of biodegradable polycaprolactone/poly (ethylene glycol)/polycaprolactone (PCEC) nanoparticles

Biodegradable polyetherester copolymer (PCL/PEG/PCL, PCEC) was synthesized by ring-opening polymerization of epsilon-caprolactone initiated by poly(ethylene glycol) (PEG). The PCEC nanoparticles were prepared by solvent diffusion method or w/o/w double emulsion method. The obtained particles' morphology was observed on scanning electron microscopy, and the particle size distribution was determined using Malvern laser particle sizer. Bovine serum albumin was used as the model water-soluble protein drug, which was successfully encapsulated in PCEC nanoparticles, the drug release behavior was studied in detail. The hydrolytic degradation behavior of the PCEC nanoparticles was also studied.     

Evaluation of polymeric nanoparticles composed of cholic acid and methoxy poly(ethylene glycol)

Amphiphilic polymeric conjugate based on cholic acid (CA) as the hydrophobic component and methoxy poly(ethylene glycol) (MPEG) as the hydrophilic component was synthesized using a 1,1'-carbonyldiimidazole (CDI) mediated conjugation. Fluorescence spectroscopy measurements suggested that CA and MPEG (abbreviated as CE) conjugate was associated in water to form polymeric core-shell type nanoparticles with a critical association concentration (CAC) value of 0.063 g l(-1). From the transmission electron microscope (TEM) observation, CE nanoparticles were almost spherical with a size range of approximately 10-30 nm in the dried state, which was in agreement with the result from particle size measurement using photon correlation spectroscopy (PCS). Clonazepam (CNZ) was physically loaded into the CE nanoparticles with a 16.2 wt.% loading. CNZ release was pseudo zero-order in kinetic terms for up to 3 days.     

Production of insulin-loaded poly(ethylene glycol)/poly(l-lactide) (PEG/PLA) nanoparticles by gas antisolvent techniques.

Insulin and insulin/poly(ethylene glycol) (PEG)-loaded poly(l-lactide) (PLA) nanoparticles were produced by gas antisolvent (GAS) CO(2) precipitation starting from homogeneous polymer/protein organic solvent solutions. Different amounts of PEG 6000 (0, 10, 30, 50, 100, and 200% PEG/PLA w/w) or concentration of 30% PEG/PLA with PEGs with different molecular weight (MW; 350, 750, 1900, 6000, 10,000, and 20,000) were used in the preparations. The process resulted in high product yield, extensive organic solvent elimination, and maintenance of > 80% of the insulin hypoglycemic activity. Nanospheres with smooth surface and compact internal structure were observed by scanning electron microscopy. The nanospheres presented a mean particle diameter in the range 400-600 nm and narrow distribution profiles. More than 90% of drug and PEG were trapped in the PLA nanoparticles when low MW PEGs were used in the formulation, whereas the addition of high MW PEGs significantly reduced the loading yield. In all cases, in vitro release studies showed that only a little amount of drug was released from the preparations. However, formulations containing low MW PEGs allowed for a slow but constant drug release throughout 1500 h, whereas a burst was obtained by increasing the PEG MW. In conclusion, the GAS process offers a mean to produce protein-loaded nanoparticles possessing the prerequisites for pharmaceutical applications. The PEG added to the formulation was found to play a key role in the simultaneous solute precipitation phenomena and in determining the release behavior and the chemical-physical properties of the formulation.     

Treatment of glioblastoma with poly(isohexyl cyanoacrylate) nanoparticles

Glioblastomas belong to the most devastating cancer diseases. For this reason, polysorbate 80 (Tween 80)-coated poly(isohexyl cyanoacrylate) (PIHCA) (Monorex) nanoparticles loaded with doxorubicin were developed and tested for their use for the treatment of glioblastomas. The preparation of the nanoparticles resulted in spherical particles with high doxorubicin loading. The physico-chemical properties and the release of doxorubicin from the PIHCA-nanoparticles were analysed, and the influence on cell viability of the rat glioblastoma 101/8-cell line was investigated. In vitro, the empty nanoparticles did not show any toxicity, and the anti-cancer effects of the drug-loaded nanoparticles were increased in comparison to doxorubicin solution, represented by IC(50) values. The in vivo efficacy was then tested in intracranially glioblastoma 101/8-bearing rats. Rats were treated with 3 × 1.5mg/kg doxorubicin and were sacrificed 18 days after tumour transplantation. Histological and immunohistochemical analyses were carried out to assess the efficacy of the nanoparticles. Tumour size, proliferation activity, vessel density, necrotic areas, and expression of glial fibrillary acidic protein demonstrated that doxorubicin-loaded PIHCA-nanoparticles were much more efficient than the free drug. The results suggest that poly(isohexyl cyanoacrylate) nanoparticles hold great promise for the non-invasive therapy of human glioblastomas.     

Study of phase behavior of poly(ethylene glycol)-polysorbate 80 and poly(ethylene glycol)-polysorbate 80-water mixtures

Mixtures of poly(ethylene glycols) (PEGs) with polysorbate 80 are often used to dissolve poorly water-soluble drugs in dosage forms, where polysorbate 80 helps either in enhancing dispersion or in inhibiting precipitation of drugs once the solution is mixed with water. Binary phase diagrams of polysorbate 80 with several low molecular weight PEGs and a ternary phase diagram of polysorbate 80 with PEG 400 and water are presented. Two phases were observed in the binary mixtures when the concentration of PEG 200, PEG 300, PEG 400, or PEG 600 was >55%(w/w). The miscibility of the binary mixtures increases with an increase in temperature; the upper consolute temperatures of PEG 200-polysorbate 80, PEG 300-polysorbate 80, PEG 400-polysorbate 80, and PEG 600-polysorbate 80 mixtures were 100, 85, 75, and 40 degrees C, respectively. The upper consolute temperature of PEG 1000-polysorbate 80 could not be determined because the melting temperature of the mixtures is approximately 40 degrees C and the consolute temperature appeared to be less than this temperature. The decrease in upper consolute temperature with an increase in PEG molecular weight indicated a greater miscibility of the two components. In the ternary system, phase separation of polysorbate 80 was observed when the concentration of PEG 400 was >50-60 % (w/w), possibly because of the high exclusion volume of PEG 400.