基于当归多糖的酶敏肿瘤靶向纳米递药体系的研究

目的构建基于当归多糖(AP)的酶敏肿瘤靶向纳米递药体系:当归多糖-基质金属蛋白酶敏感肽-阿霉素(AP-PP-DOX),研究其理化性质及体外抗肿瘤效果。方法首先将AP用马来酸酐(MA)修饰后得到马来酰化当归多糖(AP-MA),再将APMA和基质金属蛋白酶敏感肽(PP)结合生成当归多糖-基质金属蛋白酶敏感肽(AP-PP),最后将AP-PP和阿霉素(DOX)结合生成当归多糖-基质金属蛋白酶敏感肽-阿霉素(AP-PP-DOX)聚合物。利用FT-IR和1 H-NMR表征各步反应产物;透析法自组装形成纳米粒;粒度分析仪测定纳米粒粒径和电位;TEM观察纳米粒大小及外观形态;紫外分光光度计测定纳米粒载药量;体外模拟释药实验研究纳米粒在MMP-2作用下的酶解释药情况;MTT法研究纳米粒对A549细胞的毒性作用。结果 (1)FT-IR和1 H-NMR表征各步反应产物成功合成;(2)透析法成功制备了AP-PP-DOX纳米粒;(3)测定纳米粒的平均粒径和电位分别是139.00±3.32nm和-28.45±0.22mV;(4)该纳米粒结构圆整,平均粒径为100nm;(5)计算纳米粒载药量为17.00%±1.72%;(6)体外模拟释药结果表明,纳米粒在MMP-2下作用24h累积释药率最高达74.5%;(7)MTT实验表明,当药物质量浓度为9μg·mL-1时,纳米粒对A549细胞的存活率极显著,高于游离DOX(P<0.01),而含有MMP-2的纳米粒对A549细胞存活率极显著,低于不含MMP-2的纳米粒(P<0.01)。结论制备基于AP的酶敏肿瘤靶向纳米递药体系AP-PP-DOX,能够有效实现在MMP-2作用下的酶敏释药及抗肿瘤效果,值得进一步研究。     

pH敏感型纳米递药系统在肿瘤靶向治疗中的作用

目的 综述目前pH敏感纳米递药系统用于肿瘤靶向治疗中的国内外研究进展。方法 在Pubmed和Google上检索近年国内外资料,阐明pH敏感纳米递药系统靶向肿瘤治疗的作用机制,对超顺磁性纳米粒、胶束、树状大分子等相关研究成果进行总结和评价。结果 传统肿瘤化疗药物普遍存在疗效低、副作用大等问题,而近年来研发的pH响应的纳米载体可通过EPR效应积聚于肿瘤组织,并在弱酸性的肿瘤细胞外液或经内吞作用后在细胞质或溶酶体中释放药物。该pH敏感型载体能促进药物的靶向递送,在减少系统性副作用的同时提高肿瘤化疗疗效。结论 pH敏感纳米递药系统在肿瘤靶向治疗中具有广阔的应用前景,开发具有靶向性、高效性、安全性的递药系统是目前该领域研究主要方向之一。     

叶酸受体介导的肿瘤靶向纳米递药系统

叶酸受体在上皮源性的恶性肿瘤细胞膜表面高度表达。叶酸靶向纳米递药系统具有叶酸-叶酸受体主动靶向和纳米递药系统被动靶向的双重优势,可实现化疗药物对肿瘤组织的靶向递送,有效提高药物疗效,减少毒副作用。本文就近年来研究较多的叶酸-脂质体、叶酸-树枝状聚合物、叶酸-聚合物胶束、叶酸-纳米球等叶酸受体介导的肿瘤靶向递药系统进行综述。     

纳米递药系统在三阴性乳腺癌综合靶向治疗中的应用

高度恶性肿瘤三阴性乳腺癌的治疗局限在于肿瘤细胞耐药性克隆的形成和化疗药物常规给药对正常组织的严重毒性。近年来研究显示,三阴性乳腺癌综合靶向治疗中,纳米递药系统借助纳米材料独具的理化性质,负载化疗药物、活性基因片段和免疫增强因子等,通过光热消融效应、化疗药物增效减毒作用、抑制肿瘤增殖基因作用和免疫系统激活作用,有效抑制和杀灭肿瘤细胞。纳米递药系统改变了常规化疗药物药动学特性,明显减轻药物的不良反应。本文就纳米递药系统在三阴性乳腺癌综合靶向治疗中研究进展做一简要综述。     

主动靶向肿瘤的纳米递药系统改善肿瘤免疫治疗研究进展

近年来,免疫疗法在肿瘤临床治疗方面已取得巨大进展,但在免疫治疗药物体内递送过程中仍存在肿瘤特异性差、肿瘤深部渗透率低和细胞摄取率低等问题,导致其疗效和安全性较差,严重限制了免疫疗法的临床效果。通过表面偶联的抗体或配体与靶细胞膜受体间的相互作用,设计构建主动靶向肿瘤的纳米递药系统(aNDDS)可提高药物在靶细胞内的浓度,为实现特异高效的药物递送提供了可行的策略。此外,一些特定类型的细胞膜因具有天然的靶向能力被用于仿生纳米载体的构建,进而提高药物的递送效率。基于主动靶向肿瘤纳米载体的诸多优势,科研人员也设计了一系列用于促进抗肿瘤免疫应答的aNDDS,并证明其可以提高免疫治疗的有效性和安全性。本文回顾了近年来aNDDS改善肿瘤免疫治疗的研究进展,并对该领域的主要挑战和未来的发展进行了展望。     

基于透明质酸的纳米递药系统在肿瘤靶向治疗中的研究进展

近年来,透明质酸（hyaluronic acid,HA）作为一种高效的肿瘤靶向递送载体引起了人们的广泛关注。HA的优越性主要体现在其具备良好的生物相容性、生物可降解性和特殊的CD44受体结合能力。本文针对HA的结构修饰、作为肿瘤特异性药物载体的基础理论以及基于HA纳米递药系统的研究成果进行了综述,并展望了其应用前景。     

肿瘤靶向细胞穿膜肽的设计合成及活性检测

目的合成一种可活化细胞穿膜肽(ACPPs)并初步探索其穿膜活性及亚细胞分布。方法 应用化学合成方法合成ACPPs,采用流式细胞仪检测ACPPs穿膜活性,免疫荧光法及全波长酶标仪检测表达ACPPs的肿瘤靶向性穿膜作用,用荧光显微镜观察ACPPs在细胞内的定位及ACPPs-pc-Ad.egfp复合物的亚细胞分布。结果 成功合成了ACPPs,ACPPs-异硫氰酸荧光素(FITC)组较牛血清清蛋白-FITC组荧光量大,差异有统计学意义(F=4 656.600,P=0.000),ACPPs具有肿瘤靶向性穿膜活性,人肺癌细胞A549、人结肠癌细胞SW480、人卵巢癌细胞OVCAR3细胞质内荧光量较人支气管上皮细胞HBE大,差异有统计学意义(F=37 947.676,P=0.000);ACPPs定位于细胞质并介导ACPPs-pc-Ad.egfp复合物分布于细胞质。结论 成功合成了ACPPs,ACPPs具有肿瘤靶向性穿膜活性并分布于细胞质。     

基于酶敏感机制的可激活细胞穿透肽在靶向输送系统中的应用

细胞穿透肽的细胞膜穿透作用借助于一种非选择性和受体非依赖性的方式。该特点使得细胞穿透肽介导的细胞摄取过程适用于较广泛的细胞类型,而这种普遍性对于癌症治疗和诊断领域的应用无疑是重大障碍。因此,将体循环给药的细胞穿透肽惰化形式在肿瘤等病变区域选择性地转变为活化态成为研究热点。本文重点关注引入酶敏感机制的可激活细胞穿膜肽及其靶向递送系统,对此类传递载体的研究概况进行综述。     

基于靶向纳米递药系统用于胰腺癌化疗中的研究现状

胰腺癌是一种恶性程度较高、诊断和治疗均较困难的消化道系统肿瘤。胰腺癌的传统化疗方案靶向性不高,治疗效率低,存在一系列的药物不良反应。近年来纳米靶向递药系统迅猛发展,为胰腺癌的治疗提供了许多的新思路。本文综述了近年来基于靶向纳米递药系统用于胰腺癌化疗的研究进展,从被动靶向、物理化学靶向、主动靶向和化疗药物的联合运载四个方面中的应用进行介绍,以期为胰腺癌的临床治疗提供新的思路和方法。     

Brain tumor-targeted drug delivery strategies

Despite the application of aggressive surgery, radiotherapy and chemotherapy in clinics, brain tumors are still a difficult health challenge due to their fast development and poor prognosis. Brain tumor-targeted drug delivery systems, which increase drug accumulation in the tumor region and reduce toxicity in normal brain and peripheral tissue, are a promising new approach to brain tumor treatments. Since brain tumors exhibit many distinctive characteristics relative to tumors growing in peripheral tissues, potential targets based on continuously changing vascular characteristics and the microenvironment can be utilized to facilitate effective brain tumor-targeted drug delivery. In this review, we briefly describe the physiological characteristics of brain tumors, including blood–brain/brain tumor barriers, the tumor microenvironment, and tumor stem cells. We also review targeted delivery strategies and introduce a systematic targeted drug delivery strategy to overcome the challenges.Key words: Barriers targeting, Tumor microenvironment, Tumor cells, Systematic targeted drug delivery     

HA-GMS-INS胰岛素口服纳米给药系统研究

目的:建立透明质酸-单硬脂酸甘油酿-胰岛素(HA-GMS-INS)口服纳米给药系统,并进行成药性研究.方法:利用酿化反应合成载体HA-GMS,单因素法筛选制备工艺,通过红外光谱和核磁共振氢谱对结构进行表征;采用低能乳化法制备HA-GMS-INS,用多分散激光粒度仪和透射电镜测定纳米乳的粒径及形态,并对胰岛素的体外释放性...     

Preparation of folate-modified pullulan acetate nanoparticles for tumor-targeted drug delivery

The purpose of this work was to develop a novel nano-carrier with targeting property to tumor. In this study, pullulan acetate (PA) was synthesized by the acetylation of pullulan to simplify the preparation technique of nanoparticles. Folic acid (FA) was conjugated to PA in order to improve the cancer-targeting activity. The products were characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy. Epirubicin-loaded nanoparticles were prepared by a solvent diffusion method. The loading efficiencies and EPI content increased with the amount of triethylamine (TEA) increasing in some degree. FPA nanoparticles could incorporate more epirubicin than PA nanoparticles. The folate-modified PA nanoparticles (FPA/EPI NPs) exhibited faster drug release than PA nanoparticles (PA/EPI NPs) in vitro. Confocal image analysis and flow cytometry test revealed that FPA/EPI NPs exhibited a greater extent of cellular uptake than PA/EPI NPs against KB cells over-expressing folate receptors on the surface. FPA/EPI NPs also showed higher cytotoxicity than PA/EPI NPs. The cytotoxic effect of FPA/EPI NPs to KB cells was inhibited by an excess amount of folic acid, suggesting that the binding and/or uptake were mediated by the folate receptor.     

Preparation of folate-modified pullulan acetate nanoparticles for tumor-targeted drug delivery

The purpose of this work was to develop a novel nano-carrier with targeting property to tumor. In this study, pullulan acetate (PA) was synthesized by the acetylation of pullulan to simplify the preparation technique of nanoparticles. Folic acid (FA) was conjugated to PA in order to improve the cancer-targeting activity. The products were characterized by proton nuclear magnetic resonance (¹H NMR) spectroscopy. Epirubicin-loaded nanoparticles were prepared by a solvent diffusion method. The loading efficiencies and EPI content increased with the amount of triethylamine (TEA) increasing in some degree. FPA nanoparticles could incorporate more epirubicin than PA nanoparticles. The folate-modified PA nanoparticles (FPA/EPI NPs) exhibited faster drug release than PA nanoparticles (PA/EPI NPs) in vitro. Confocal image analysis and flow cytometry test revealed that FPA/EPI NPs exhibited a greater extent of cellular uptake than PA/EPI NPs against KB cells over-expressing folate receptors on the surface. FPA/EPI NPs also showed higher cytotoxicity than PA/EPI NPs. The cytotoxic effect of FPA/EPI NPs to KB cells was inhibited by an excess amount of folic acid, suggesting that the binding and/or uptake were mediated by the folate receptor.     

Polymeric drugs for efficient tumor-targeted drug delivery based on EPR-effect

For over half a century extensive research has been undertaken for the control of cancer. However, success has been limited to certain malignancies, and surgical intervention is potentially curative for early stage patients. For the majority of patients with advanced stage of cancer, the treatment is limited to chemotherapy or radiation. Chemotherapy in particular has limitations due to the lack of selectivity with severe toxicity. Under these circumstances tumor-targeted delivery of anticancer drugs is perhaps one of the most important steps for cancer chemotherapy. We reported such a drug for the first time, styrene-maleic acid copolymer-conjugated neocarzinostatin (SMANCS) in 1979, and it eventually led to formulate the concept of the enhanced permeability and retention (EPR) effect of solid tumors in 1986. Monoclonal antibody conjugates are another direction, of which interest is increasing recently though with limited success. The EPR-effect appears as a universal phenomenon in solid tumors which warrants the development of other polymeric drugs or nanomedicine.EPR-effect is applicable for any biocompatible macromolecular compounds above 40 kDa, even larger than 800 kDa, or of the size of bacteria; thus complexed molecules like micelles and liposomes containing anticancer drugs are hallmark examples. The drug concentration in tumor compared to that of the blood (T/B ratio) can be usually as high as 10-30 times. In case of SMANCS/Lipiodol given via tumor feeding artery, the T/B ratio can be as high as 2000, a real pin-point targeting. EPR-effect is not just passive targeting for momentary tumor delivery, but it means prolonged drug retention for more than several weeks or longer.This review describes the pathophysiological mechanisms of the EPR-effect, architectural difference of tumor blood vessel, various factors involved and artificial augmentation of EPR-effect with respect to tumor-selective delivery, and then advantages and problems of macromolecular drugs.     

Bile acid-conjugated chondroitin sulfate A-based nanoparticles for tumor-targeted anticancer drug delivery

Chondroitin sulfate A-deoxycholic acid (CSA-DOCA)-based nanoparticles (NPs) were produced for tumor-targeted delivery of doxorubicin (DOX). The hydrophobic deoxycholic acid (DOCA) derivative was conjugated to the hydrophilic chondroitin sulfate A (CSA) backbone via amide bond formation, and the structure was confirmed by ¹H-nuclear magnetic resonance (NMR) analysis. Loading the DOX to the CSA-DOCA NPs resulted in NPs with an approximately 230 nm mean diameter, narrow size distribution, negative zeta potential, and relatively high drug encapsulation efficiency (up to 85%). The release of DOX from the NPs exhibited sustained and pH-dependent release profiles. The cellular uptake of DOX from the CSA-DOCA NPs in CD44 receptor-positive human breast adenocarcinoma MDA-MB-231 cells was reduced when co-treated with free CSA, indicating the interaction between CSA and the CD44 receptor. The lower IC₅₀ value of DOX from the CSA-DOCA NPs compared to the DOX solution was also probably due to this interaction. Moreover, the ability of the developed NPs to target tumors could be inferred from the in vivo and ex vivo near-infrared fluorescence (NIRF) imaging results in the MDA-MB-231 tumor-xenografted mouse model. Both passive and active strategies appear to have contributed to the in vivo tumor targetability of the CSA-DOCA NPs. Therefore, these CSA-DOCA NPs could further be developed into a theranostic nanoplatform for CD44 receptor-positive cancers.     

Active tumor-targeted delivery of PEG-protein via transferrin-transferrin-receptor system

Transferrin (Tf) holds promise as a drug carrier because of overexpress transferring receptors (TfRs) on the surface of tumor cells. The purpose of this work was to conjugate Tf to PEGylated protein (Tf-PEG-protein) to improve tumor-targeted delivery of PEG-protein. After a model protein, beta-lactoglobulin B (LG), was modified by the heterobifunctional polyethyleneglycol (PEG), Tf was covalently linked to the distal end of the PEG chains on the PEG-LG (PL) conjugate. The purified Tf-PEG-LG (TPL) contained 1.4 of Tf ligand on one LG molecule. The specificity and affinity of TPL to TfR on two kinds of tumor cells (K562 and KB cells) were assessed. The results demonstrated that, TPL can bind specifically to the TfR on the tumor cell surface and the affinity of the conjugate to TfR was similar to that of native Tf. The pharmacokinetics and biodistribution studies in rodents found that TPL exhibited a significantly delayed blood clearance, the longest tumor resident time and the greatest tumor accumulation, as compared with LG and PL. Such design of the Tf conjugate would suggest a promising approach for active tumor targeting of therapeutic proteins or peptides to target cells.     

Folate-decorated maleilated pullulan–doxorubicin conjugate for active tumor-targeted drug delivery

A novel folate-decorated maleilated pullulan–doxorubicin conjugate (abbreviated as FA–MP–DOX) for active tumor targeting was set up. The structure of this conjugate was confirmed by ¹H NMR analysis. Furthermore, the conjugation efficiency, drug release property and stability of the conjugate were determined. The cellular uptake and cytotoxicity were assessed by using ovarian carcinoma A2780 cells as in vitro cell model. In vitro DOX release from FA–MP–DOX conjugate occurred at a faster rate at acidic pH compared to neutral pH (7.4). After 30 h of incubation at pH 2.5, 5.0 and 7.4 the released free DOX was about 68.71%, 50.08% and 26%, respectively. Based on the IC₅₀ values, the conjugate was found more effective with ovarian carcinoma A2780 cells than the parent drug after 48 h culture. These results suggested that FA–MP–DOX conjugate could be a promising doxorubicin carrier for its targeted and intracellular delivery.