载药聚合物胶束的制备和肿瘤靶向性研究进展

聚合物胶束具有增溶难溶性药物、选择性靶向、P-gp抑制以及改变药物摄取途径等特点,作为药物传递系统具有广泛的应用前景。本文着重综述载药聚合物胶束的制备方法与肿瘤靶向策略的研究现状及进展。     

聚合物胶束作为肿瘤靶向给药载体的研究

聚合物胶束是近年来出现的一种新型胶态药物载体,具有很多优良的性能,如体内外稳定性高、良好的生物相容性、难溶性药物的增溶作用等.它可以作为靶向肿瘤的给药载体,通过多种机制,如环境响应的聚合物胶束、特异性配基耦合的聚合物胶束、免疫聚合物胶束、通透性增强与滞留(EPR)效应、肿瘤的血管系统等途径来实现药物靶向给药.现主要讨论肿瘤给药的靶向策略和聚合物胶束作为靶向肿瘤给药载体的研究进展.     

长春西汀两亲性壳聚糖共聚物自组装胶束的制备

目的:制备长春西汀两亲性壳聚糖共聚物自组装胶束载药系统。方法:采用溶剂蒸发法制备载药胶束,考察处方因素及工艺条件对载药共聚物胶束的包封率及平均粒径的影响,并采用L9(34)正交设计法进行优化。结果:制得的载药胶束平均粒径为(127.4±8.0)nm,载药量为7.8%,包封率为75.7%。结论:溶剂蒸发法制备两亲性壳聚糖载药胶束工艺简单可行。     

Polymeric micelles for pH-responsive delivery of cisplatin

Abstract

Methoxy poly(ethylene oxide)-block-poly-(α-carboxylate-ε-caprolactone) (PEO-b-PCCL) was used to develop pH-responsive polymeric micelles for the delivery of cisplatin (CDDP). Micelles were prepared through complexation of CDDP with the pendant carboxyl groups on the poly(ε-caprolactone) core, perhaps through coordinate bonding. The obtained micelles were characterized using dynamic light scattering (DLS) measurement for size and stability. The in vitro release of CDDP at different pHs (7.4, 6.0 and 5.0) was evaluated. The in vitro cell uptake as well as cytotoxicity of developed micelles against two breast cancer cell lines, i.e. MDA-MB-435 and MDA-MB-231, were also assessed and compared to free CDDP as control. DLS results showed PEO-b-PCCL to form stable micelles with an average diameter of <50?nm upon complexation with CDDP. Developed polymeric micelles were capable of slowly releasing CDDP in physiological pH. However, CDDP release from polymeric micelles was triggered upon exposure to electrolytes and/or acidic pHs mimicking that of extracellular tumor microenvironment or intracellular organelles. Consistent with the slow release of CDDP from its polymeric micellar formulation, polymeric micellar CDDP exhibited lower cytotoxicity and CDDP intracellular uptake compared to free drug. The results indicate a great potential for the developed formulation in platinum therapy of breast cancer.     

RGD-modified polymeric micelles as potential carriers for targeted delivery to integrin-overexpressing tumor vasculature and tumor cells

Integrins αvβ3 and αvβ5 are overexpressed in angiogenic tumor endothelial cells and malignant tumor cells, making them attractive targets for cancer therapy. In this study, an integrin αvβ3 and αvβ5 binding tripeptide, RGD (Arg-Gly-Asp), was conjugated with the surface of poly(ethylene glycol)–block–poly(d,l-lactide) (PEG–PLA) micelles. A lipophilic fluorescent probe, DiI, was loaded into both the nontargeted methoxy PEG–PLA (mPEG–PLA) micelles and the targeted RGD-modified PEG–PLA micelles. The DiI-loaded targeted micelles had a size of 24.2?nm. The targeted micelles were stable in phosphate buffered saline and exhibited a negligible leakage in culture medium. Transmission electron microscopy analysis showed that targeted micelles were spherical in shape. Cell uptake of DiI-labeled targeted micelles by human umbilical vein endothelial cells and melanoma B16 cells was investigated by spectrophotofluorometry and confocal microscopy techniques. Results revealed that RGD-modified micelles significantly facilitated the intracellular delivery of the encapsulated agents via integrin-mediated endocytosis. This study suggests that RGD-modified PEG–PLA micelles are promising drug carriers for targeted delivery to both angiogenic tumor endothelial cells and tumor cells and that the targeted micelles may be attractive carriers for combination cancer therapy against both targets.     

Physicochemical,pharmaceutical and biological approaches toward designing optimized and efficient hydrophobically modified chitosan-based polymeric micelles as a nanocarrier system for targeted delivery of anticancer drugs

Abstract

Hydrophobically modified chitosan-based polymeric micelles (CBPMs) are formed through self-aggregation of chitosan amphiphilic derivatives. Their core-shell structure, diversity and the fact that all of their properties are adjustable through reconciling the interactions among their three main constituents: chitosan, hydrophilic segment and hydrophobic segment as well as with the outside medium through changing the ratio and chemical structure of each component's, chemical structure distinguish them from other chitosan-based drug delivery systems (DDSs) and give rise to these promising candidates for targeted delivery of lipophilic anticancer drugs. The majority of review articles conducted previously on chitosan-based DDSs have only made simple differential comparisons between such systems and the anticancer drugs that have been delivered through them. In this review article, all the basic properties of CBPMs including physicochemical, pharmaceutical and biological properties are technically detailed and discussed. The intention of this article is to outline and discuss salient features of CBPMs to contribute to the understanding of optimized strategies for the design of stable and efficient CBPMs.     

Self-assembled micelles based on gambogenic acid-phospholipid complex for sustained-release drug delivery

Abstract

Objective: To improve the water solubility and enhance the oral bioavailability of gambogenic acid (GNA).

Methods: GNA-phospholipid complex (GNA-PLC) micelles were successfully prepared by anti-solvent method.

Results: The encapsulation efficiency of GNA-PLC micelles can reach 99.33 % (w/w). The average particle size of the GNA-PLC micelles was 291.23?nm which was approximate agreed with the transmission electron microscopy (TEM). In vitro release profile showed the GNA-PLC and GNA-PLC micelles have significant sustained-release of GNA compared with crude GNA. Pharmacokinetic parameters indicated that the area under concentration–time curve (AUC_0→t) of GNA in cases of GNA-PLC and GNA-PLC micelles are 2.04- and 3.92-fold higher than crude GNA, respectively.

Conclusions: The better water solubility and higher bioavailability of GNA in GNA-PLC micelles with significant sustained-release of GNA endow the nanoparticle with great potential in GNA delivery system.     

Mucoadhesive buccal films containing phospholipid-bile salts-mixed micelles as an effective carrier for Cucurbitacin B delivery

Abstract

Cucurbitacin B (Cu B), a potent anti-cancer agent, suffers with the problems of water-insoluble, gastrointestinal side effects and non-specific toxicity via oral administration and drawbacks in patient’s compliance and acceptance through injections. An integration of nanoscale carriers with mucoadhesive buccal films drug delivery system would resolve these issues effectively with greater therapeutic benefits and clinical significance. Thus, the drug loaded mucoadhesive buccal film was developed and characterized in this study and the carboxymethyl chitosan (CCS) was chosen as a bioadhesive polymer, glycerol was chosen as a plasticizer and phospholipid-bile salts-mixed micelles (PL-BS-MMs) was selected as the nanoscale carriers. The CCS-films containing Cu B loaded PL-SDC-MMs was evaluated for the mechanical properties, mucoadhesion properties, in vitro water-uptake, in vitro release and morphological properties, respectively. The optimal CCS-films containing Cu B loaded PL-SDC-MMs was easily reconstituted in a transparent and clear solution with spherical micelles in the submicron range. The in vivo study revealed a greater and more extended release of Cu B from nanoscale CCS-films compared to that from a conventional CCS films (C-CCS-films) and oral marketed tablet (Hulusupian). The absorption of Cu B from CCS-films containing Cu B loaded PL-SDC-MMs resulted in 2.69-fold increased in bioavailability as compared to conventional tablet formulation and 10.46 times with reference to the C-CCS-films formulation. Thus, this kind of mucoadhesive buccal film might be an alternative safe route for delivery of Cu B with better patient compliance and higher bioavailability for the treatments.     

Hyaluronic acid-modified didecyldimethylammonium bromide/ d-a-tocopheryl polyethylene glycol succinate mixed micelles for delivery of baohuoside I against non-small cell lung cancer: in vitro and in vivo evaluation

Baohuoside I is an effective but a poorly soluble antitumor drug. In this study, we prepared baohuoside I-loaded mixed micelles with didecyldimethylammonium bromide (DDAB) and d-a-tocopheryl polyethylene glycol succinate (TPGS) (DTBM) and active targeting mixed micelles (HDTBM) with hyaluronic acid (HA) as the targeting ligand on the surface of the mixed micelles. We performed a systematic comparative evaluation of the antiproliferative effect, cellular uptake, antitumor efficacy, and in vivo tumor targeting of these micelles using A549 cells. HDTBM showed improved cellular uptake and had a greater hypersensitizing effect on A549 cell lines than baohuoside I; half-maximal inhibitory concentration (IC₅₀) was 8.86 versus 20.42?μg/mL, respectively. Results of the antitumor efficacy study and the imaging study for in vivo targeting showed that the mixed-micelle formulation had higher antitumor efficacy and achieved effective and targeted drug delivery. Therefore, our results indicate that HA/baohuoside I-M may be used as a potential antitumor formulation.     

Amphiphilic polyaspartamide copolymer-based micelles for rivastigmine delivery to neuronal cells

A novel polysorbate-80 (PS₈₀)-attached amphiphilic copolymer comprising a hydrophilic α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) backbone and hydrophobic squalenyl-C₁₇ (Sq₁₇) portions was synthesized and characterized; the formation of polymeric micelles was also evaluated. Rivastigmine free-base (Riv), a hydrophobic drug employed to treat Alzheimer’s disease, was chosen as model drug to investigate micelle’s ability to incorporate hydrophobic molecules and target them to neuronal cells. Micelle formation was studied through analyses including fluorescence spectroscopy and 2D ¹H-NMR NOESY experiments. Finally, the capacity of Riv-loaded micelles, versus free drug, to penetrate mouse neuroblastoma cells (Neuro2a) was evaluated. 2D ¹H-NMR NOESY experiments demonstrated that the PHEA-EDA-Sq₁₇-PS₈₀ copolymer self-assembles into micelle structures in water, with a micelle core formed by hydrophobic interaction between Sq₁₇ alkyl chains. Fluorescence probe studies revealed the CAC of PHEA-EDA-Sq₁₇-PS₈₀ micelles, which was 0.25?mg mL^?1. The micelles obtained had a nanometric hydrodynamic diameter with narrow size distribution and negative surface charge. The PHEA-EDA-Sq₁₇-PS₈₀ micelles incorporated a large amount of Riv, and the system maintained the stability of Riv after incubation in human plasma. An in vitro biological assay evidenced no cytotoxic effects of either empty or loaded micelles on the neuronal cell lines tested. Moreover, the micelles are internalized by neuroblastoma cell lines with drug uptake depending on the micelles concentration.     

Self-assembled nanoparticles based on galactosylated O-carboxymethyl chitosan-graft-stearic acid conjugates for delivery of doxorubicin

A novel polymer, i.e. galactosylated O-carboxymethyl chitosan-graft-stearic acid (Gal-OCMC-g-SA) was synthesized for liver targeting delivery of doxorubicin. The chemical structure was characterized by FT-IR, ¹H NMR and elemental analysis. Gal-OCMC-g-SA could self-assemble into nanoparticles with diameter of 160 nm by probe sonication in aqueous medium and exhibited a low critical aggregation concentration of 0.047 mg/mL. The DOX-loaded Gal-OCMC-g-SA (Gal-OCMC-g-SA/DOX) self-assembled nanoparticles were almost spherical in shape with an average diameter of less than 200 nm and zeta potential of around −10 mV. In vitro release revealed that the Gal-OCMC-g-SA/DOX nanoparticles exhibited a sustained and pH-dependent drug release manner. Furthermore, the hemolysis test demonstrated the good safety of Gal-OCMC-g-SA in blood-contacting applications. These results indicated that Gal-OCMC-g-SA/DOX nanoparticles were highly potential to be applied in cancer therapy.     

Hyaluronic acid modified MPEG-b-PAE block copolymer aqueous micelles for efficient ophthalmic drug delivery of hydrophobic genistein

The ophthalmic drug delivery is a challenge in the clinical treatment of ocular diseases. The traditional drug administration usually shows apparent limitations, such as the low bioavailability from the reason of low penetration of the cornea and the short survival time of drug in the eyes. To overcome these shortcomings, we propose an amphiphilic polymer micelle modified with hyaluronic acid (HA) for high efficient ophthalmic delivery of genistein, a widely used hydrophobic drug for treatment of ocular angiogenesis. The MPEG-b-PAE copolymer was synthesized by the Michael addition reaction, and the final drug carrier MPEG-b-PAE-g-HA was obtained by the process of esterification. Then, genistein was packaged in this drug carrier, getting the final micelles with size of about 84.5?nm. The cell viability tests showed that the micelles take no obvious cytotoxicity to the human cornea epithelium cells. The functionalities of drug slow release and cornea penetration ability were demonstrated in a series ex vivo experiments. Further, the vascular inhibition test illustrated that the micelles could significantly inhibit the angiogenesis of human umbilical vein endothelial cells. These results indicate that the constructed polymer has high feasibility to be used as drug carrier in the treatment of ocular diseases.     

Targeted delivery of quercetin by biotinylated mixed micelles for non-small cell lung cancer treatment

Lung cancer is the leading cause of cancer death world-wide and its treatment remains a challenge in clinic, especially for non-small cell lung cancer (NSCLC). Thus, more effective therapeutic strategies are required for NSCLC treatment. Quercetin (Que) as a natural flavonoid compound has gained increasing interests due to its anticancer activity. However, poor water solubility, low bioavailability, short half-life, and weak tumor accumulation hinder in vivo applications and antitumor effects of Que. In this study, we developed Que-loaded mixed micelles (Que-MMICs) assembled from 1,2-distearoyl-sn-glycero-3-phosphoethanolamine–poly(ethylene glycol)–biotin (DSPE–PEG–biotin) and poly(ethylene glycol) methyl ether methacrylate–poly[2-(dimethylamino) ethyl acrylate]–polycaprolactone (PEGMA–PDMAEA–PCL) for NSCLC treatment. The results showed that Que was efficiently encapsulated into the mixed micelles and the encapsulation efficiency (EE) was up to 85.7%. Cellular uptake results showed that biotin conjugation significantly improved 1.2-fold internalization of the carrier compared to that of non-targeted mixed micelles. In vitro results demonstrated that Que-MMICs could improve cytotoxicity (IC₅₀ = 7.83 μg/mL) than Que-MICs (16.15 μg/mL) and free Que (44.22 μg/mL) to A549 cells, which efficiently induced apoptosis and arrested cell cycle. Furthermore, Que-MMICs showed satisfactory tumor targeting capability and antitumor efficacy possibly due to the combination of enhanced permeability and retention (EPR) and active targeting effect. Collectively, Que-MMICs demonstrated high accumulation at tumor site and exhibited superior anticancer activity in NSCLC bearing mice model.     

Solubilization of flurbiprofen into aptamer-modified PEG–PLA micelles for targeted delivery to brain-derived endothelial cells in vitro

Abstract

Novel aptamer-functionalized polyethylene glycol–polylactic acid (PEG–PLA) (APP) micelles were developed with the objective to target the transferrin receptor on brain endothelial cells. Flurbiprofen, a potential drug for therapeutic management of Alzheimer’s disease (AD), was loaded into the APP micelles using the co-solvent evaporation method. Results indicated that 9.03% (w/w) of flurbiprofen was entrapped in APP with good retention capacity in vitro. Targeting potential of APPs was investigated using the transferring receptor-expressing murine brain endothelial bEND5 cell line. APPs significantly enhanced surface association of micelles to bEND5 cells as quantified by fluorescence spectroscopy. Most importantly, APPs significantly enhanced intracellular flurbiprofen delivery when compared to unmodified micelles. These results suggest that APP micelles may offer an effective strategy to deliver therapeutically effective flurbiprofen concentrations into the brain for AD patients.     

Anticancer drug delivery of PEG based micelles with small lipophilic moieties

Herein, we reported a new type of self-assembly micelles based on amphiphilic polymers of cinnamate and coumarin derivatives modified PEG for drug delivery applications. Lipophilic cinnamic acid (CIN) and 7-carboxyl methoxycoumarin (COU) were immobilized on the terminal groups of poly(ethylene glycol) (PEG) to prepare amphiphiles. The amphiphiles self-assembled into micelles. The amphiphiles and micelles were characterized by ¹H NMR, FT-IR, DLS and TEM. Doxorubicin (DOX) was used as a model drug to investigate the lipophilic moieties effects on the drug release behaviors. The DOX loaded micelles were incubated with HepG2 liver cancer cells to study the in vitro anticancer activities. The results showed that DOX could be encapsulated in the micelles efficiently. The mean diameter of the drug loaded micelles was around 100 nm. Drug release profile revealed that the release rate of DOX loaded COU-PEG-COU micelles was significantly slower than that of CIN-PEG-CIN micelles. The DOX loaded micelles could be internalized in HepG2 cells. Both CLSM and flow cytometry results showed that the DOX loaded CIN-PEG-CIN micelles exhibited better anticancer efficacy.     

N-辛基-O,N-羧甲基壳聚糖聚合物胶束对紫杉醇的增溶、缓释及其安全性初步评价

本文合成了一系列两亲性壳聚糖衍生物N-辛基-O,N-羧甲基壳聚糖(OCC)，以透析法制备紫杉醇(PTX)-OCC载药聚合物胶束，并考察疏水烷基取代度对包封率、载药量、粒径和zeta电位的影响，通过透射电镜(TEM)观察其形态结构，并以市售制剂为对照；通过体外溶血实验、豚鼠急性过敏实验及小鼠尾静脉注射急性毒性实验初步评价其安全性。结果表明，OCC对PTX有良好的增溶效果，在疏水基取代度为37.9%～58.6%时，载药量为24.9%～34.4%，包封率为56.3%～89.3%，且随着疏水辛基取代度的增加，载药量和包封率皆显著提高。疏水烷基链进一步提高则可能破坏胶束亲水疏水平衡而导致载药能力降低；载药胶束粒径为186.4～201.1 nm，随疏水烷基取代度的增加而减小， zeta电位为-47.5～-50.9 mV，疏水烷基取代度对其无显著影响，TEM照片显示该聚合物胶束为规则球形结构，粒径分布均匀。OCC对紫杉醇具有优良的缓释效果，未见突释，15 d累计药物释放量在60%～95%，缓释能力随疏水基取代度的增加而增强。溶血实验、 豚鼠急性过敏实验和小鼠尾静脉注射急性毒性实验结果表明，PTX-OCC溶血性和急性过敏反应低于市售制剂， PTX-OCC小鼠尾静脉注射的LD₅₀及95%可信限为134.4(125.0～144.6) mg·kg^-1，为市售制剂LD₅₀的2.7倍。初步认为PTX-OCC是安全可靠的静脉注射用纳米制剂。     

Mechanisms of drug release in pH-sensitive micelles for tumour targeted drug delivery system: A review

During the past decades, chemotherapy has been regarded as the most effective method for tumor therapy, but still faces significant challenges, such as poor tumor selectivity and multidrug resistance. The development of targeted drug delivery systems brings certain dramatic advantages for reducing the side effects and improving the therapeutic efficacy. Coupling a specific stimuli-triggered drug release mechanism with these delivery systems is one of the most prevalent approaches for targeted therapy. Among these approaches, pH-sensitive micelles are regarded as the most general strategy with advantages of increasing solubility of water-insoluble drugs, pH-sensitive release, high drug loading, etc.This review will focus on the potential of pH-sensitive micelles in tumor therapy, analyze four types of drug-loaded micelles and mechanisms of drug release and give an exhaustive collection of recent investigations. Sufficient understanding of these mechanisms will help us to design more efficient pH-sensitive drug delivery system to address the challenges encountered in targeted drug delivery systems for tumor therapy.     

mPEG-b-PCL/TPGS mixed micelles for delivery of resveratrol in overcoming resistant breast cancer

Objective: Drug resistance remains a major challenge for effective breast cancer chemotherapy. Resveratrol (Res) is a promising candidate for overcoming cancer chemoresistance, but it has low bioavailability due to poor absorption, and ready metabolism limits its application. This study aims to develop a Res-loaded mixed micelle system to be effective on drug resistance of breast cancer cells.

Methods: A mixed micelle system made of methoxy poly (ethylene glycol)-b-polycaprolactone (mPEG-PCL) and d-α-Tocopherol polyethylene glycol succinate was prepared and Res was encapsulated to form Res-loaded mixed micelles. Furthermore, the antitumor activity against doxorubicin (Dox)-resistant breast cancer MCF-7/ADR cells was studied and the possible mechanism was elucidated.

Results: The mixed micellar formulation increased drug uptake efficiency of Res by Dox-resistant breast cancer MCF-7/ADR cells, and induced higher rates of apoptotic cell death, as assessed by the accumulation of Sub G1 phases of cell cycle, nucleus staining and Annexin-FITC/propidium iodide assay. Moreover, Res-loaded mixed micelles also markedly enhanced Dox-induced cytotoxicity in MCF-7/ADR cells and increased the cellular accumulation of Dox by downregulating the expression of P-glycoprotein (P-gp) and inhibiting the activity thereof.

Conclusion: The cumulative evidence indicates that Res-loaded mixed micelles hold significant promise for the treatment of drug-resistant breast cancer.     

Pharmaceutical evaluation of genistein-loaded pluronic micelles for oral delivery

The purpose of the present study was to determine whether Pluronic F127 polymeric micelles could improve the oral bioavailability of a poor water-soluble drug, such as genistein. Genistein is a phytoestrogen that has estrogenic activity. F127 triblock copolymer consists of PEO100-PPO65-PEO100. Genistein was incorporated in the Pluronic F127 polymeric micelles by a solid dispersion method. The genistein release of genistein-loaded polymeric micelles was studied in vitro (in pH 1.2 and pH 6.8). And the oral bioavailabilities of genistein powder and genistein-loaded micelles were estimated at a dose of 4.0 mg/kg as genistein in rats. Drug loading amount and drug loading efficiency were 11.18% and 97.41%, respectively. The average size of the genistein-loaded polymeric micelles was 27.76 nm. And genistein release of the genistein-loaded polymeric micelles in vitro was 58% (pH 1.2) and 82% (pH 6.8). The bioavailability of genistein-loaded polymeric micelles was better than genistein powder. Consequently, Pluronic F127 polymeric micelles are an effective delivery system for the oral administration of genistein.     

A new peptide ligand for colon cancer targeted delivery of micelles

Abstract

Ligands are an imperative part of targeted drug delivery systems, and choosing a ligand with high affinity is a subject of considerable interest. In this study, we first synthesized a 12-residue peptide (TK) that interacts with integrin α₆β₁ overexpressed on colonic cancer cells. The molecular binding affinity assay indicated that TK had a high binding affinity for integrin α₆β₁. The results of cellular and tumor spheroid uptake suggested that TK peptide not only increases Caco-2 cells uptake, but also effectively increases penetration of the tumor spheroids. TK-conjugated PEG-PLA was synthesized to prepare a novel PEG-PLA micelles loading DOX or coumarin-6 (TK-MS/DOX or TK-MS/C6). The obtained TK-MS/DOX exhibited uniform, spherical shape with a size of 23.80?±?0.32?nm and zeta potential of 12.21?±?0.31 mV. The release behavior of DOX from micelles were observed no significant changes after TK modification, however, the release profile exhibited pH-sensitive properties. Compared with MS/DOX, TK-MS/DOX exhibited significantly stronger cytotoxicity for Caco-2. Confocal laser microscopy and flow cytometry data further indicated that the targeting micelles not only had higher uptake by Caco-2 cells, but also more effectively penetrated the tumor spheroids. Therefore, TK peptide appears to be suitable as a targeting ligand with potential applications in colonic targeted therapy.