氰基丙烯酸酯包裹胰岛素纳米颗粒的结构

 目的：为得到稳定有效的口服胰岛素制剂,对氰基丙烯酸异丁酯包裹胰岛素的机制进行了一系列的体外研究。方法：用凝胶层析法分离纳米包裹颗粒和游离的胰岛素,结合RIA法、放射标记示踪以及作者设计的“抗体捕捉”实验,以阐明氰基丙烯酸异丁酯包裹胰岛素纳米颗粒的结构。结果：大部分胰岛素分子（80％）与形成的纳米包裹颗粒紧密相连,处于包裹颗粒的表面,可以用RIA法测到,而且对蛋白酶降解有一定抵抗作用。用乙腈溶解包裹颗粒,大部分胰岛素分子（84％）并不在溶液中,而与聚合物相连。用抗胰岛素抗体与包裹胰岛素的颗粒反应,可以在电镜下观察到包裹颗粒被抗体捕获。结论：这些结果表明胰岛素分子并未被包裹于颗粒内部,也不是以简单吸附的方式与包裹颗粒相连,而可能通过共价结合的方式与氰基丙烯酸酯聚合物相结合。     

Ability of Doxorubicin-Loaded Nanoparticles to Overcome Multidrug Resistance of Tumor Cells After Their Capture by Macrophages

Purpose. Investigation of the ability of doxorubicin-loaded nanoparticles (NP/Dox) to overcome multidrug resistance (MDR) when they have first been taken up by macrophages. Methods. The growth inhibition of P388 sensitive (P388) and resistant (P388/ADR) tumor cells was evaluated in a coculture system consisting of wells with two compartments. The tumor cells were seeded into the lower compartment, the macrophages were introduced into the upper part in which the drug preparations were also added. Results. Doxorubicin exerted lower cytotoxicity on tumor cells in coculture compared with direct contact. In P388/ADR, NP/Dox cytotoxicity was far higher than that of free doxorubicin (Dox). Three different formulations of cyclosporin A (either free (CyA), loaded to nanoparticles (NP/CyA) or in a combined formulation with doxorubicin (NP/Dox-CyA)), were added to modulate doxorubicin efficacy. The addition of cyclosporin A to Dox increased drug cytotoxicity. Both CyA added to NP/Dox and NP/Dox-CyA were able to bypass drug resistance. Conclusions. Despite the barrier role of macrophages, NP/Dox remained far more cytotoxic than Dox against P388/ADR. Both NP/ Dox + CyA and NP/Dox-CyA allowed to overcome MDR, but the last one should present greater advantagein vivo by confining both drugs in the same compartment, hence reducing the adverse effects.     

布洛芬聚氰基丙烯酸烷酯纳米粒的制备

目的制备布洛芬聚氰基丙烯酸烷酯纳米粒(IBU-PACA-NP)。方法采用乙醚界面缩聚法制备布洛芬聚氰基丙烯酸烷酯纳米粒;以包封率、载药量为指标,在单因素考察处方及工艺条件基础上,采用正交设计法L9(34)对处方进行优化。结果按优化处方制备的纳米粒平均粒径为166 nm,包封率为96.60%,载药量为17.83%,Zeta电位为-20.2 mV。结论乙醚界面缩聚法制备的布洛芬聚氰基丙烯酸烷酯纳米粒粒径小,包封率和载药量符合要求,可用于口服或注射给药。     

Acute Renal Toxicity of Doxorubicin (Adriamycin)-Loaded Cyanoacrylate Nanoparticles

Acute doxorubicin-loaded nanoparticle (DXNP) renal toxicity was explored in both normal rats and rats with experimental glomerulo-nephritis. In normal rats, 2/6 rats given free doxorubicin (DX) (5 mg / kg) died within one week, whereas all control animals and all rats having received free NP or DXNP survived. A 3 times higher proteinuria appeared in animals treated with DXNP than in those treated with DX. Free NP did not provoke any proteinuria. Two hr post-injection, DXNP was 2.7 times more concentrated in kidneys than free DX (p<0.025). In rats with immune experimental glomerulonephritis, 5/6 rats given DX died within 7 days, in contrast to animals treated by DXNP, NP, or untreated, which all survived. Proteinuria appeared in all series, but was 2-5 times more intense (p>0.001) and prolonged after doxorubicin treatment (400-700 mg / day), without significant difference between DXNP and DX. Rats treated by unloaded NP behaved as controls. These results demonstrate that, in these experimental conditions, DXNP killed less animals than free DX, despite of an enhanced renal toxicity of the former. Both effects (better survival and nephrosis) are most probably related to an enhanced capture of DXNP by cells of the mono-nuclear phagocyte system, including mesangial cells.     

Uptake of Nanoparticles by Rat Glomerular Mesangial Cells in Vivo and in Vitro

Glomerular mesangial cells play a major role in the structure of capillary loops, generation of mediators of inflammation, and uptake of macromolecules. We demonstrate here that isobutylcyanoacrylate nanoparticles loaded with actinomycin D (ADNP) concentrate in rat mesangial cells in vitro and in vivo, as compared to the free drug (AD). In normal rats injected with 20 µg of ³H-ADNP or ³H-AD, the uptake ratios ³H-ADNP/³H-AD measured in whole kidneys at 30 and 120 min were 2.2 ± 1.0 and 2.3 ± 0.9, respectively. The same ratios calculated for isolated rat glomeruli and tubules, were 4.1 ± 0.5 and 0.8 ± 0.2 at 30 min, and 2.6 ± 0.5 and 0.6 ± 0.3 at 120 min, respectively. In the glomeruli, the absolute uptake of ³H-ADNP corresponded to 7.5 (30 min) and 1.8 (120 min) % I.D./100 mg of protein. In rats with experimental glomerulonephritis, the uptakes of ³H-ADNP and ³H-AD by the glomeruli were 6.9 and 4.0 times higher than in normal rats, respectively. In vitro experiments demonstrated up to 5 times higher uptake by glomerular mesangial cells than by epithelial cells. Uptake was maximum after 60 min, higher at 37°C than at 4°C, dependent on the presence of fresh serum and inhibited by cytochalasin-B. Drug targeting by nanoparticles is thus possible to renal cells involved in inflammatory processes, especially mesangial cells and macrophages. Nanoparticles could also be useful for lowering drug concentration in tubular cells, to reduce any tubular toxicity. Targetting of the mesangial cells is of particular interest for drugs such as corticosteroids capable of reducing glomerular inflammation in various pathological conditions.     

Drug Targeting by Polyalkylcyanoacrylate Nanoparticles Is Not Efficient Against Persistent Salmonella

Purpose. We have investigated the efficacy of colistin and ciprofloxacin, free or bound to polyalkylcyanoacrylate nanoparticles, for the targeting and eradication of Salmonella persisting in the organs of the mononuclear phagocyte system. Methods. A model of persistent S. typhimurium infection was developed in C57BL/6 mice using IV inoculation of the plasmid-cured strain C53. Results. In vivo and ex vivoexperiments showed that the persisting bacteria seem to evolve to a nongrowing state during experimental salmonellosis. In vivo treatment with free or nanoparticle-bound colistin did not significantly reduce the number of viable Salmonella C53, either in the liver or the spleen of infected mice. In contrast, in vivo treatment with ciprofloxacin led to a significant decrease of bacterial counts in the liver whatever the stage of infection and the form used. However, none of the treatments were able to sterilize the spleen or the liver. In ex vivo experiments, colistin was only active against bacteria recovered during the early phase of infection, whereas ciprofloxacin exerted its activity at all times postinfection. Conclusions. We suggest that the micro-environment in which the bacterial cells persist in vivo probably causes dramatic changes in their susceptibility to antimicrobial agents.     

Degradation and drug release characteristics of monosize polyethylcyanoacrylate microspheres

—Monosize, biodegradable poly(ethylcyanoacrylate) (PECA) microspheres with a diameter of 1.3μm were prepared by a relatively new polymerization method, the so-called phase inversion polymerization. The effects of pH and temperature on the degradation behavior of PECA particles were investigated. PECA microspheres were degraded mainly by surface erosion. The degradation rate increased with increasing pH temperature. A model drug, i.e. 2,4-dinitrophenylhydrazine (DNPH) was loaded into the monosize PECA microspheres during polymerization. The drug incorporation into the PECA microspheres increased with increasing initial drug concentration in the monomer phase. Drug release from the PECA microspheres was investigated at different pH. Higher drug release rates were observed in the neutral and alkaline media as compared with the acidic medium.     

Degradation of poly (isobutyl cyanoacrylate) nanoparticles

Poly(isobutyl cyanoacrylate) nanoparticles were prepared. They were degraded in two enzyme-free media at pH 7 and 12 in the presence of rat liver microsomes. The conventional formaldehyde-producing degradation route was studied, and showed a very low efficiency. Another pathway, consisting of ester hydrolysis, was identified and studied. In contrast to the formaldehyde pathway, ester hydrolysis was shown to be catalysed by enzymes. Finally, the release rate of adsorbed actinomycin from nanoparticles was proved to correlate exactly with the degradation rate of the polymer.     

Polyalkylcyanoacrylate Nanoparticles as Polymeric Carriers for Antisense Oligonucleotides

Adsorption of oligothymidylates on polyisobutyl- or polyisohexylcyanoacrylate nanoparticles was achieved in the presence of hydrophobic cations such as tetraphenylphosphonium chloride or quaternary ammonium salts. Results suggested that oligonucleotide adsorption on the nanoparticles was mediated by the formation of ion pairs between the negatively charged phosphate groups of the nucleic acid chain and the hydrophobic cations. The adsorption efficiency of oligonucleotide–cation complexes on nanoparticles was found to be highly dependent upon several parameters: oligonucleotide chain length, nature of the cyanoacrylic monomer, hydrophobicity of cations used as ion-pairing agents, and ionic concentration of the medium. Carrier capacity of polyisohexylcyanoacrylate nanoparticles for oligothymidylates (16 nucleotides) complexed with cetyltrimetylammonium bromide in the presence of 0.15 M NaCl was determined to be 5 µmol/g polymer. The in vitro protection of oligothymidylates adsorbed to nanoparticles against degradation by a 3-exonuclease (snake venom phosphodiesterase) was also demonstrated. These results showed that nanoparticles can be considered as convenient carriers for the protection and delivery of Oligonucleotides to cells in culture and for future applications in vivo.     

聚氰基丙烯酸烷基酯纳米载体制备工艺的研究进展

综述了聚氰基丙烯酸烷基酯纳米载药系统的制备工艺、载药方式、纯化、灭菌、表面修饰等方面的研究进展.