两亲性嵌段共聚物胶束的研究进展

综述了两亲性嵌段共聚物胶束的形成机理、组成、结构、理化性质、制备方法、影响因素、药学方面的应用等进展.     

Brushed Block Copolymer Micelles with pH-Sensitive Pendant Groups for Controlled Drug Delivery

Purpose

To investigate the effects of small aliphatic pendent groups conjugated through an acid-sensitive linker to the core of brushed block copolymer micelles on particle properties.

Methods

The brushed block copolymers were synthesized by conjugating five types of 2-alkanone (2-butanone, 2-hexanone, 2-octanone, 2-decanone, and 2-dodecanone) through an acid-labile hydrazone linker to poly(ethylene glycol)-poly(aspartate hydrazide) block copolymers.

Results

Only block copolymers with 2-hexanone and 2-octanone (PEG-HEX and PEG-OCT) formed micelles with a clinically relevant size (< 50 nm in diameter), low critical micelle concentration (CMC, < 20 μM), and drug entrapment yields (approximately 5 wt.%). Both micelles degraded in aqueous solutions in a pH-dependent manner, while the degradation was accelerated in an acidic condition (pH 5.0) in comparison to pH 7.4. Despite these similar properties, PEG-OCT micelles controlled the entrapment and pH-dependent release of a hydrophobic drug most efficiently, without altering particle size, shape, and stability. The molecular weight of PEG (12 kDa vs 5 kDa) induced no change in pH-controlled drug release rates of PEG-OCT micelles.

Conclusion

Acid-labile small aliphatic pendant groups are useful to control the entrapment and release of a hydrophobic drug physically entrapped in the core of brushed block copolymer micelles.     

Safety Evaluation of Amphiphilic Three-Armed Star-Shaped Copolymer Micelles

In our previous work, we had prepared a biodegradable amphiphilic three-armed star-shaped copolymers (SPCE) based on poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG), which could form micelles by self-assembly method and it was a potential carrier for hydrophobic drug. For further application, the safety of SPCE micelles was evaluated in vitro and in vivo here. ¹³C-NMR was used to confirm the formation of the micelles in aqueous solution, and the morphology was observed on transmission electron microscope (TEM). Also, thermostability of blank SPCE micelles was determined by Malvern Nano-ZS 90 laser particle size analyzer. In vitro toxicity evaluation included hemolytic test and cytotoxicity. In vivo acute toxicity tests and histopathological study of SPCE micelles were carried out on BALB/C mice which were administrated SPCE micelles (1 g/kg b.w.) intravenously. In acute toxicity test, the mice were observed continuously for 7 days, obtained their body weight every day, at last the mice was sacrificed for the following study: the blood of the mice was assigned for blood chemistry and routine analysis, the heart, liver, spleen, lung, and kidneys were used for histopathological study. All results indicated that the biodegradable self-assembled SPCE micelles were nontoxic; therefore, it might be used as a safe candidate for drug delivery system     

Novel Polymeric Micelles of Amphiphilic Triblock Copolymer Poly (p-Dioxanone-co-L-Lactide)-block-Poly (ethylene glycol)

PURPOSE: The objective of this study is to characterize the micelles of novel block copolymer of poly (p-Dioxanone-co-L-Lactide)-block-Poly (ethylene glycol) (PPDO/PLLA-b-PEG-) and evaluate its ability to induce gene transfection. METHODS: The ability of the block copolymer to self-assemble was determined by viscometery, dye solublization, NMR spectra and dynamic light scattering. The Trypan blue assay for in vitro biocompatibility of the block copolymer was carried out with NIH 3T3, CT-26 and MCF-7 cells, and beta-glactosidase assay was applied to measure the transfection efficiency of the block copolymer on MCF-7 breast cancer cell. RESULTS: Depending on the block lengths and molecular weights, solubility of the polymeric samples in water was varied. Diluted aqueous solution properties of the copolymer were studied. 1,6-Diphenyl-1,3,5-hexatriene solubilization and 1H NMR spectra carried out in CDCl3 and D2O, were used to prove the existence of hydrophobic domains as the core of micelle. Average particle size of 60-165 nm with low polydispersity, and lower negative zeta potential of -3 to -14 mV were observed on the aqueous copolymer dispersion. Copolymer was found with almost no cytotoxic effect and was able to promote the transfection efficiency (about 3-fold) in MCF-7 cells. CONCLUSIONS: The PPDO/PLLA-b-PEG copolymer has ability to assemble into nanoscopic structures in aqueous environment, which enable to enhance gene transfection.     

Block Copolymer Micelles for the Encapsulation and Delivery of Amphotericin B

Purpose. To assess the effect of fatty acid substitution of a micelle-forming poly(ethylene oxide)-block-poly(N-hexyl stearate-L-aspartamide) (PEO-b-PHSA) on the encapsulation, hemolytic properties and antifungal activity of amphotericin B (AmB). Methods. PEO-b-PHSA with three levels of stearic acid substitution were synthesized and used to encapsulate AmB by a solvent evaporation method. Size exclusion chromatography and UV spectroscopy were used to confirm and measure levels of encapsulated AmB. The hemolytic activity of encapsulated AmB toward human red blood cells and its minimum inhibitory concentration against Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans were obtained and compared to AmB alone. Results. An increase in the level of stearic acid substitution on PEO-b-PHSA improved the encapsulation of AmB while reducing its hemolytic activity. PEO-b-PHSA micelles having 50% and 70% stearic acid substitution (mol fatty acid: mol reacted and unreacted hydroxyls) were completely non-hemolytic at 22 g/ml. At 11% stearic acid substitution, AmB caused 50% hemolysis at 1 g/ml. AmB in PEO-b-PHSA micelles was as effective as AmB alone against pathogenic fungi. Conclusions. PEO-b-PHSA micelles with a high level of stearic acid side chain substitution can effectively solubilize AmB, reduce its hemolytic activity yet retain its potent antifungal effects.     

Block Copolymer Micelles for Controlled Delivery of Glycolytic Enzyme Inhibitors

Purpose  

To develop block copolymer micelles as an aqueous dosage form for a potent glycolytic enzyme inhibitor, 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO).     

Mixed pH-Sensitive Polymeric Micelles for Combination Drug Delivery

Purpose  

To prepare mixed polymeric micelles that can carry two different drugs, doxorubicin (DOX) and 17-hydroxyethylamino-17-demethoxygeldanamycin (GDM-OH), for combination cancer chemotherapy.     

叶酸介导肿瘤细胞靶向紫杉醇聚合物胶束的制备与表征

以叶酸-聚乙二醇-二硬脂酰磷脂酰乙醇胺(FA-PEG 3350-DSPE)和甲氧基聚乙二醇-二硬脂酰磷脂酰乙醇胺(mPEG 2000-DSPE)(摩尔比1:100)作为混合载体材料,采用固体分散-水化法,制备包载紫杉醇(1)的聚合物胶束,以星点设计-效应面法进行处方优化,并考察了聚合物胶束的理化性质、体外抑制肿瘤细胞生长效果及对巨噬细胞摄取的影响.结果表明,优化所得胶束的包封率为81%、载药量为2.7%、平均粒径为12～16 nm,可持续释放24 h;制品可有效提高1体外抑制肿瘤细胞生长的效果,加入1%的FA-PEG 3350-DSPE可略减弱mPEG 2000-DSPE规避巨噬细胞吞噬的效果.     

Mixed Polymer Micelles of Amphiphilic and Cationic Copolymers for Delivery of Antisense Oligonucleotides

Cationic copolymers were synthesized by conjugation of branched 2 kDa polyethylenimine (PEI) and Pluronic® block copolymers (F38, P85, P123). Compositions of these copolymers mixed with corresponding free Pluronics® at weight ratio 1:9 were used to complex phosphorothioate oligonucleotides (ODN). As a result stable suspensions of small micelle-like particles (<220 nm) were obtained. Incorporation of ODN in these formulations increased uptake of ODN in KBv cells and increased sequence specific activity of antisense ODN targeted against MDR gene in multidrug resistant cells resulting in inhibition of the functional activity of P-glycoprotein (P-gp) in these cells. Furthermore, these formulations increased transport of ODN across model intestinal barrier, Caco-2 cell monolayers, suggesting that they could be useful for oral delivery of biologically active ODN.     

嵌段共聚物胶束作为药物载体的研究进展

嵌段共聚物胶束通过物理和化学方法将难溶性药物和基因治疗药物增溶,可实现主动或被动靶向给药.综述了嵌段共聚物胶束的特点、载体的制备方法、载药能力、药物的释放和研究实例.     

Polymeric Micelles Based on Amphiphilic Scorpion-like Macromolecules: Novel Carriers for Water-Insoluble Drugs

No HeadingPurpose. The objective was to evaluate amphiphilic scorpion-like macromolecules (AScMs) as drug carriers for hydrophobic drugs.Methods. Indomethacin (IMC) was incorporated into two AScM micelles (M₁₂P₅ and M₁₂P₂) by the O/W emulsion technique. The influences of IMC:polymer feed ratio and molecular weight of the hydrophilic block of AScMs on the micelle size, IMC entrapment efficiency and release behavior were investigated. Furthermore, cytotoxicity of the AScMs was evaluated with human umbilical vein endothelial cells (HUVEC).Results. The maximal IMC entrapment efficiency in M₁₂P₅ and M₁₂P₂ micelles (72.3 and 20.2%, respectively) was obtained at ratios of 0.1 to 1 for indomethacin:polymer. The sizes of IMC-loaded M₁₂P₅ and M₁₂P₂ polymeric micelles were <20 nm with a narrow size distribution. In vitro release studies revealed that IMC released from M₁₂P₅ and M₁₂P₂ polymeric micelles showed sustained release behavior during the 24 h of experiment. Additionally, M₁₂P₅ and M₁₂P₂ polymeric micelles did not induce remarkable cytotoxicity against HUVEC cells at concentrations up to 1 and 0.5 mM, respectively.Conclusions. The amphiphilic scorpion-like macromolecules may be useful as novel drug carriers because of their small size, ability to encapsulate hydrophobic drugs and release them in a sustained manner as well as low cytotoxicity.     

Amphiphilogels for Drug Delivery: Formulation and Characterization

PURPOSE: This study examines the microstructure, gelation temperatures, and flow properties of novel amphiphilogels consisting solely of non-ionic surfactants. METHODS: Gels were prepared by mixing the solid gelator (sorbitan monostearate or sorbitan monopalmitate) and the liquid phase (liquid sorbitan esters or polysorbates) and heating them at 60 degrees C to form a clear isotropic sol phase, and cooling the sol phase to form an opaque semisolid at room temperature. Gel microstructure was examined by light and electron microscopy and by small angle neutron scattering (SANS); gelation temperatures were measured by hotstage microscopy, a melting point apparatus, and high sensitivity differential scanning calorimetry (HSDSC). Flow rheograms were performed to establish the zero-rate viscosity of the gels and their performance under shear. RESULTS: Gel microstructures consisted mainly of clusters of tubules of gelator molecules that had aggregated upon cooling of the sol phase, forming a 3D network throughout the continuous phase. The gels demonstrated thermoreversibility. Gelation temperature and viscosity increased with increasing gelator concentration, indicating a more robust gel network. At temperatures near the skin surface temperature, the gels softened considerably; this would allow topical application. CONCLUSIONS: This study has demonstrated the formation/preparation of stable, thermoreversible, thixtropic surfactant gels (amphiphilogels) with suitable physical properties for topical use.     

The Use of Nano Polymeric Self-Assemblies Based on Novel Amphiphilic Polymers for Oral Hydrophobic Drug Delivery

Purpose  

To investigate the use of nano self-assemblies formed by polyallylamine (PAA) modified with 5 or 10% mole fluorenylmethoxy carbonyl (Fmoc₅/₁₀), dimethylamino-1-naphthalenesulfonyl (Dansyl₅/₁₀) and 5% mole cholesteryl group (Ch₅) for oral hydrophobic drug delivery.     

Hydrogel Containing Silica Shell Cross-Linked Micelles for Ocular Drug Delivery

Poly(2-hydroxyethyl methacrylate–methacrylic acid–ethylene glycol dimethacrylate) hydrogels loaded with silica shell cross-linked methoxy(polyethylene glycol)-block-polycaprolactone (MePEG-b-PCL) micelles with rod-like morphology were prepared as a potential soft contact lens material for the sustained release of ocular drugs. The silica shell cross-linked methoxy micelles (SSCMs) comprising a polycaprolactone core surrounded by a silica shell were synthesized and their size, morphology, stability, and drug release kinetics were evaluated. The relationships between the composition of the SSCM-loaded poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogels and their transparency, surface wettability, and equilibrium water content were determined. Scanning electron microscopy (SEM) images of SSCM–hydrogel systems showed the presence of intact SSCMs within the hydrogel matrix. Dexamethasone acetate (DMSA), a hydrophobic ophthalmic drug, was loaded into the SSCMs prior to their incorporation into the hydrogels. In vitro release of DMSA from the SSCM–hydrogels, with varying drug loading levels, was observed for up to 30 days. Overall, the incorporation of rod-like SSCMs within pHEMA-based hydrogels provided sustained release over prolonged periods while maintaining optical transparency. This delivery system may be suitable for use as a therapeutic soft contact lens material.     

Novel Platforms for Oral Drug Delivery

The aim of this review is to provide the reader general and inspiring prospects on recent and promising fields of innovation in oral drug delivery. Nowadays, inventive drug delivery systems vary from geometrically modified and modular matrices, more close to “classic” pharmaceutical manufacturing processes, to futuristic bio micro-electro-mechanical systems (bioMEMS), based on manufacturing techniques borrowed from electronics and other fields. In these technologies new materials and creative solutions are essential designing intelligent drug delivery systems able to release the required drug at the proper body location with the correct release rate. In particular, oral drug delivery systems of the future are expected to have a significant impact on the treatment of diseases, such as AIDS, cancer, malaria, diabetes requiring complex and multi-drug therapies, as well as on the life of patients, whose age and/or health status make necessary a multiple pharmacological approach.     

Hyaluronan: Pharmaceutical Characterization and Drug Delivery

Hyaluronic acid (HA), is a polyanionic polysaccharide that consists of N-acetyl-D-glucosamine and β-glucoronic acid. It is most frequently referred to as hyaluronan because it exists in vivo as a polyanion and not in the protonated acid form. HA is distributed widely in vertebrates and presents as a component of the cell coat of many strains of bacteria. Initially the main functions of HA were believed to be mechanical as it has a protective, structure stabilizing and shock-absorbing role in the body. However, more recently the role of HA in the mediation of physiological functions via interaction with binding proteins and cell surface receptors including morphogenesis, regeneration, wound healing, and tumor invasion, as well as in the dynamic regulation of such interactions on cell signaling and behavior has been documented. The unique viscoelastic nature of hyaluronan along with its biocompatibility and nonimmunogenicity has led to its use in a number of cosmetic, medical, and pharmaceutical applications. More recently, HA has been investigated as a drug delivery agent for ophthalmic, nasal, pulmonary, parenteral, and dermal routes. The purpose of our review is to describe the physical, chemical, and biological properties of native HA together with how it can be produced and assayed along with a detailed analysis of its medical and pharmaceutical applications.     

PEG-poly(amino acid) Block Copolymer Micelles for Tunable Drug Release

Purpose  

To achieve tunable pH-dependent drug release in tumor tissues.     

阿霉素共聚物胶束的制备及体外性质研究

目的制备阿霉素共聚物胶束并研究其体外性质。方法采用开环聚合法合成聚乙二醇单甲醚-聚乳酸羟基乙酸（mPEG—PLGA）嵌段共聚物;用透析法、溶剂蒸发法制备空白及载阿霉素胶束;动态光散射仪（DLS）测定其粒径分布;采用紫外分光光度法测定胶束的包封率和载药量。通过体外释药实验研究了载阿霉素胶束的释药特性。结果采用透析法制备载阿霉素胶束大小均匀,平均粒径为（91．1±15．8）nm;药物胶束的包封率为85．2％,载药量为10．4％;与市售阿霉素注射剂相比,载阿霉素胶束具有良好的缓释性能。结论共聚物胶束可作为疏水性药物阿霉素的载体。     

聚合物胶束在经皮给药系统中的应用

摘 要 目的：综述聚合物胶束作为药物载体在经皮传递系统中的应用进展。方法: 根据国内外发表的最新文献,对聚合物胶束的制备方法、促进皮肤渗透的机制、释药过程及其在经皮给药系统中的应用进行分析与讨论。结果: 聚合物胶束具有增加难溶性药物的溶解度,促进药物的经皮吸收等作用,作为药物载体在经皮传递系统的应用越来越广泛。结论:聚合物胶束可作为药物载体被广泛用于经皮给药系统的研究中,具有较好的发展前景。