pH敏感的肿瘤靶向聚合物胶束的体外性质

目的 制备肿瘤微环境敏感、具有肿瘤细胞靶向能力和穿膜能力的融合肽FQSIYPpIKRRRRRRRRHHHHC (FRH)修饰的聚合物胶束,并对其体外性质进行初步考察.方法 采用FRH修饰N-(2-羟丙基)-甲基丙烯酰胺(HPMA)聚合物-β-谷甾醇(β-SITO),形成HPMA聚合物胶束(FRH-M),考察其理化性质、肿瘤细胞的摄取和抑制肿瘤细胞生长的效果.结果 透射电镜显示:胶束为均匀的类球形.FRH-M胶束粒径约为55 nm,阿霉素载药量8.3％.该胶束在pH7.4条件下,Zeta电位为-3.01±0.05 mV,在pH6.4条件下,电荷翻转为5.27-0.32 mV.FRH-M的药物释放速度随释放介质的pH降低而加快.FRH-M的细胞摄取较未经修饰胶束的P-M提升了1.9倍;且在pH6.4条件下的细胞摄取明显高于pH7.4的,FRH-M的IC50值为1.40 ±0.41 μg·mL-1,明显低于未经配体修饰的胶束(5.08±0.33 μg· mL-1).结论 经FRH多肽修饰的聚合物胶束具有良好的肿瘤微环境响应能力,且有更好的细胞摄取能力和体外抗肿瘤活性,极具发展前景.     

温度/pH双敏感嵌段共聚物胶束的体外性质研究

本文采用透析法制备了新型温度/pH双敏感聚组氨酸-聚乳酸羟基乙酸-聚乙二醇-聚乳酸羟基乙酸-聚组氨酸(PHis-b-PLGA-b-PEG-b-PLGA-b-PHis)嵌段共聚物的空白胶束与阿霉素(DOX)载药胶束。采用荧光探针技术测定其临界胶束浓度(CMC);应用光透射法研究了聚合物胶束的温度和pH敏感性质;测定了阿霉素载药胶束的粒径、形态、包封率和载药量;并对阿霉素载药胶束的温度和pH响应释药行为进行了研究。结果表明,制备的嵌段共聚物的临界胶束浓度为7.5×10-3 g.L-1;随胶束溶液温度升高或pH降低,其透光率升高;载药胶束的包封率为(85.2±3.1)%,载药量为(10.4±4.5)%;载药胶束粒径为(91.1±15.8)nm,为类球形结构;与模拟生理条件下(37℃,pH 7.4)释药行为相比,升高温度(41℃)、降低pH(pH 7.0、pH 6.5、pH 5.0)和同时升温并降低pH(41℃,pH 5.0)后胶束释药行为明显加快,表明该胶束的释药行为具有温度和pH敏感性。研究结果可见,PHis-b-PLGA-b-PEG-b-PLGA-b-PHis共聚物胶束具有pH/温度双重响应性质,有望成为抗肿瘤...     

In vitro dissolution of pH sensitive microparticles for colon-specific drug delivery

Objective: The objective of this work is to prepare oral dosage systems based on enteric materials in order to verify their possible use as Colon-Specific Drug Delivery Systems (CSDDSs).

Methodology: In particular, three different copolymers of methyl-methacrylate (MMA) - acrylic acid (AA) are synthesized with increasing percentage of MMA (from 70% to 73%) and they are used to produce microparticles by the double-emulsion solvent evaporation method. The microparticles, loaded using theophylline as model drug, are then tested for drug release under varying pH to reproduce what happens in the human GI tract.

Results: All the investigated systems have shown an effective pH sensitiveness: they show a good gastro-resistance, releasing the model drug only at higher pH, small intestine or colon, depending on the kind of used copolymer.

Conclusion: The results confirm the usefulness of both the materials and the methods proposed in this study for colon-specific delivery applications.     

Epidermal growth factor receptor-targeted peptide conjugated phospholipid micelles for doxorubicin delivery

Specific targeting of tumor cells to achieve higher drug levels in tumor tissue and to overcome side effects is the major goal in cancer chemotherapy. In this study, we used a tumor targeting peptide, GE11, to conjugate onto the surface of doxorubicin encapsulated phospholipid micelles. The GE11 peptide triggered specific binding to epidermal growth factor receptor (EGFR), leading to enhanced cellular uptake and cytotoxicity in vitro and highly accumulation in the tumors in vivo. The results indicated that GE11 conjugated phospholipid micelles should have potential applications in cancer therapy.     

Thermo-responsive self-assembled polymeric micelles for drug delivery in vitro

Cholic acid (CA) was coupled with amine-terminated poly (N-isopropylacrylamide) (ATPNIPAAm) using N,N'-dicyclohexyl carbodiimide as a coupling agent. Self-assembled CA/PNIPAAm conjugate (abbreviated as CN) micelles were prepared by diafiltration method in water. The CN micelles exhibited the lower critical solution temperature (LCST) at 31.5 degrees C. The CN micelles were observed as spherical shapes and their dried sizes were ranged between 30 and 50 nm by the transmission electron microscope (TEM) images. Hydrated micelle sizes measured by photon correlation spectroscopy (PCS) were ranged 337.5+/-67.8 nm. And reversible size changes of CN micelles were observed with two point temperature 10 and 40 degrees C, respectively. From the fluorescence spectra, fluorescence intensity of pyrene in the CN micelles was increased and red-shifted as the concentration of CN increased, indicating the formation of self-assembled polymeric micelles in water. The critical micelle concentration (CMC) was evaluated as 8.9 x 10(-2) g/l. Much more indomethacin (IN) was released from th CN micelles at 10 than at 40 degrees C due to the thermo-sensitivity of the PNIPAAm in the CN polymer.     

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

A novel polysorbate-80 (PS(80))-attached amphiphilic copolymer comprising a hydrophilic α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA) backbone and hydrophobic squalenyl-C(17) (Sq(17)) 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 (1)H-NMR NOESY experiments. Finally, the capacity of Riv-loaded micelles, versus free drug, to penetrate mouse neuroblastoma cells (Neuro2a) was evaluated. 2D (1)H-NMR NOESY experiments demonstrated that the PHEA-EDA-Sq(17)-PS(80) copolymer self-assembles into micelle structures in water, with a micelle core formed by hydrophobic interaction between Sq(17) alkyl chains. Fluorescence probe studies revealed the CAC of PHEA-EDA-Sq(17)-PS(80) 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-Sq(17)-PS(80) 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.     

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.     

Uptake of anthracyclines in vitro and in vivo in acute myeloid leukemia cells in relation to apoptosis and clinical response

Aims  

To study anthracycline-induced apoptosis in leukemic cells isolated from patients with acute myelogenous leukemia (AML) in vitro and to compare intracellular anthracycline concentrations causing apoptosis in vitro with those obtained in vivo during anthracycline treatment.     

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.     

阿霉素温度/pH双敏型自组装嵌段共聚物胶束的制备

本文用透析法制备了新型温度/pH双敏自组装嵌段共聚物聚组氨酸-聚乳酸羟基乙酸-聚乙二醇-聚乳酸羟基乙酸-聚组氨酸 (OLH-b-PLGA-b-PEG-b-PLGA-b-OLH) 胶束, 采用荧光探针技术测定其不同温度下临界胶束浓度 (CMC); 用透析法测定共聚物胶束的包封率和载药量; 对胶束的粒径、形态和表面电位进行考察, 并对阿霉素胶束的体外释药和pH敏感性进行了研究。CMC介于0.022 4～0.001 7 μg·mL⁻¹, 胶束包封率为92.8%, 载药量为15.7%; 载药胶束粒径为 (61.7 ± 13.4) nm, zeta电位为−9.88 mV; 阿霉素的体外释药速率随pH降低 (pH 7.4～5.0) 而增加。结果表明, 胶束的CMC随温度升高而降低, 体外释药具有明显的pH敏感性, 该载体材料作为抗肿瘤药物的靶向传递系统具有较好的应用前景。     

Uptake and distribution of 4,4'-diacetyl-diphenyl-urea-bis-guanylhydrazone in sensitive and resistant sarcoma 180 cells in vitro

Sarcoma 180cells sensitive to 4,4'-diacetyl-diphenyl-urea-bis-guanylhydrazone (DDUG) were compared with a resistant subline (S-180/DDUG) with respect to crossresistance to methylglyoxal-bis-guanylhydrazone (CH₃G), 2-chloro-4',4″-bis(2-imida-zolin-2-yl)-terephthalanilide (NSC 38280) and vincristine (VCR); they were also compared with respect to the nature and rate of cellular uptake of DDUG and its intracellular distribution and binding.     

pH sensitive alginate-guar gum hydrogel for the controlled delivery of protein drugs

Design of a pH sensitive alginate-guar gum hydrogel crosslinked with glutaraldehyde was done for the controlled delivery of protein drugs. Alginate is a non-toxic polysaccharide with favorable pH sensitive properties for intestinal delivery of protein drugs. Drug leaching during hydrogel preparation and rapid dissolution of alginate at higher pH are major limitations, as it results in very low entrapment efficiency and burst release of entrapped protein drug, once it enters the intestine. To overcome these limitations, another natural polysaccharide, guargum was included in the alginate matrix along with a cross linking agent to ensure maximum encapsulation efficiency and controlled drug release. The crosslinked alginate-guar gum matrix is novel and the drug loading process used in the study was mild and performed in aqueous environment. The release profiles of a model protein drug (BSA) from test hydrogels were studied under simulated gastric and intestinal media. The beads having an alginate to guar gum percentage combination of 3:1 showed desirable characters like better encapsulation efficiency and bead forming properties in the preliminary studies. The glutaraldehyde concentration giving maximum (100%) encapsulation efficiency and the most appropriate swelling characteristics was found to be 0.5% (w/v). Freeze-dried samples showed swelling ratios most suitable for drug release in simulated intestinal media ( approximately 8.5). Protein release from test hydrogels was minimal at pH 1.2 ( approximately 20%), and it was found to be significantly higher ( approximately 90%) at pH 7.4. Presence of guar gum and glutaraldehyde crosslinking increases entrapment efficiency and prevents the rapid dissolution of alginate in higher pH of the intestine, ensuring a controlled release of the entrapped drug.     

Novel self-assembled micelles based on palmitoyl-trimethyl-chitosan for efficient delivery of harmine to liver cancer

Backgroud: Polymeric micelles is a safe and effective delivery system, which belong to the targeted delivery system (TDS). An anticancer drug, harmine(HM) is a hydrophobic drug with much adverse effects when used for treatment of liver cancer. Chitosan (CS) is a polysaccharide and can be modified to be an amphiphilic polmer which could self-assemble into micelles and be applied for delivery of hydrophobic drugs.

Objectives: To synthesize three kinds of novel biodegradable polymers, designated as palmitoyl-trimethyl-CS (TPCS)1, TPCS2 and Lac-TPCS2, and investigate their efficiency and mechanism of delivery HM to liver tumors in vitro and in viro.

Results: The self-assembled micelles presented satisfactory particle size (～ 200 nm) and drug release characteristics in vitro. It's proved that Lac-TPCS2/HM may enter HepG2 cell through endocytosis. Antitumor experiments in vivo revealed that Lac-TPCS2/HM could significantly inhibit tumor growth and extend the lifetime of mice bearing H22 tumors after intravenous administration. Subsequently in vivo near-infrared fluorescence imaging results demonstrated a satisfactory liver tumor-targeting effect of Lac-TPCS2/HM.

Conclusion: Three novel polymers hold great potential in the development of nanomedicine for treatment of liver tumors, in particular Lac-TPCS2 exhibits the greatest antitumor potential through active target effect.     

Site-directed delivery of anthracyclines for treatment of cancer

The efficacy of cancer treatment is often limited by the lack of selectivity of anticancer agents for malignant cells. A promising approach for increasing both the efficacy and therapeutic index of anticancer agents is to utilize antibodies, directed against tumor-associated antigens, to selectively deliver anticancer agents to tumor cells. Antibodies have been used to deliver a variety of anticancer agents including chemotherapeutic drugs, plant and bacterial toxins, and radionuclides. This review concentrates on the chemistry and preclinical biology of immunoconjugates made with members of the anthracycline group of antibiotics. © 1995 Wiley-Liss, Inc.     

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.     

Enhanced cytotoxicity of core modified chitosan based polymeric micelles for doxorubicin delivery

In this study, the cytotoxicity of doxorubicin (DOX) loaded stearic acid grafted chitosan oligosaccharide (CSO-SA) micelles and its core modified drug delivery systems were investigated in vitro. The in vitro drug release experiments using cellular culture medium, Roswell Park Memorial Institute 1640 (RPMI-1640) medium as a dissolution medium confirmed that the DOX release from CSO-SA micelles was successfully delayed by the core modification of CSO-SA micelles with stearic acid (SA). The cell viability assay against A549 cells indicated the 50% inhibition concentration (IC(50)) of blank CSO-SA micelles and the core modified CSO-SA micelles was 369 +/- 27 microg/mL and 234 +/- 9 microg/mL, respectively. The entrapment of DOX by CSO-SA micelles could decrease the IC(50) of DOX from 3.5 to 1.9 microg/mL, and a further reduction to 0.7 microg/mL could result by the core modification of CSO-SA micelles. The fluorescence image observations of DOX and DOX concentration measurements inside A549 cells demonstrated that the DOX concentration inside cells was increased by the entrapment of CSO-SA micelles, and further enhanced by the core modification of CSO-SA micelles. The results indicated that the CSO-SA micelles with modified cores could be useful as a drug delivery vehicle for cancer chemotherapy.