表面修饰二氧化硅的脂质体对阿霉素的包埋与释放性质

背景：脂质体药物载体近年来被用以增加药物的稳定性,提高药效,降低药物的毒副作用。然而研究发现由于稳定性较差,脂质体药物载体难以实现药物缓释与长效给药。大量研究表明,二氧化硅无毒,具有化学惰性和生物相容性,是很好的修饰材料。 目的：为了提高脂质体药物载体的稳定性,延长给药时间,采用二氧化硅对脂质体进行表面修饰并用于抗癌药物盐酸阿霉素的包埋。 设计、时间及地点：体外观察实验,1：200705／2008—06存哈尔滨工业大学生物医学工程中心的纳米医药与生物传感器实验室完成。材料：L-α二棕榈酰磷酯酰胆碱购自南京康森特化工有限公司,正硅酸乙酯购自美国Aldrich公司,盐酸阿霉素购白北京华奉联博科技有限公司,葡聚糖凝胶G-50购自瑞典Amersham公司,其他化学试剂均为分析纯。 方法：通过溶胶凝胶沉积二氧化硅的方法修饰模板L-α二棕榈酰磷酯酰胆碱脂质体。主要观察指标：通过激光粒度仪与Zeta电位仪测定二氧化硅修饰后的脂质体粒径分布与表面电荷;通过透射电镜观察二氧化硅修饰后脂质体的形态;通过傅里叶变换红外光谱表征材料的化学结构;通过荧光光谱仪测定溶液中阿霉素浓度;通过阿霉素浓度回归方程计算脂质体药物包封率与脂质体体外释放速率。 结果：①成功制各了二氧化硅包裹修饰的脂质体。②傅里叶变换红外光谱结果显示在1166cm^-1,1080cm^-1,859cm^-1和526cm^-1存在Si-O-Si振动峰。③：氧化硅修饰的脂质体对阿霉素的包封率为724％。④药物体外释放结果移示二氧化硅包裹修饰的脂质体使阿霉素达到缓释效果。结论：由于在脂质体的表面形成纳米级厚度的无机Si-O-Si网络作为保护层,使得脂质体的稳定性显著提高,并且对阿霉素有缓释效果。     

表阿霉素-白藜芦醇长循环脂质体的制备及其体外释放

目的制备经聚乙二醇(PEG)修饰的表阿霉素-白藜芦醇长循环脂质体,考察长循环脂质体体外释药行为,并对其抗肿瘤作用进行评价。方法采用薄膜分散法-硫酸铵梯度法制备表阿霉素-白藜芦醇长循环脂质体;采用动态透析法考察其体外释药行为;SRB法评价体外抗肿瘤作用。结果采用薄膜分散法-硫酸铵梯度法制备的长循环脂质体中表阿霉素与白藜芦醇包封率可达89.80%、65.01%。体外释放研究表明,表阿霉素-白藜芦醇长循环脂质体较普通脂质体及原料药释药速度更慢,稳定性更好。体外细胞毒试验显示,长循环脂质体对C6胶质瘤细胞具有较强的抑制作用。结论制备长循环脂质体操作简便、重复性好,包封率较高,体外释放具有缓释特征,体外抗肿瘤作用强。     

人转铁蛋白修饰载阿霉素海藻酸钠纳米粒的制备与评价

背景:对抗肿瘤药物靶向治疗和肿瘤细胞多药耐药产生的问题,载阿霉素海藻酸钠纳米粒经改性,偶联人转铁蛋白,生成的人转铁蛋白修饰载药纳米粒,可用于靶向肿瘤药物载体.目的:制备人转铁蛋白修饰的载阿霉素海藻酸钠纳米粒并进行表征鉴定,检测其表面蛋白活性.方法:采用优化的微乳化-离子交联方法制备包覆阿霉素的海藻酸钠复合纳米粒,以水溶性碳二亚胺为交联剂,将载阿霉素海藻酸钠纳米粒与人转铁蛋白连接,制备出人转铁蛋白修饰载阿霉素海藻酸钠纳米粒.透射电镜观察纳米粒的外观大小、形态;高效液相色谱法分析纳米粒的包封率和载药量;流式细胞仪检测其表面人转铁蛋白的活性.结果与结论:人转铁蛋白修饰载阿霉素海藻酸钠纳米粒呈球形,平均粒径为170 nm.阿霉素的加入量可影响纳米粒的包封率,当阿霉素的加入量为纳米粒的10%时,包封率和包裹量均最佳.每毫克载药纳米粒可与约65 μg人转铁蛋白连接.人转铁蛋白修饰的载药纳米粒在流式细胞仪上除去非特异性吸附后还有67 3%荧光显示,说明人转铁蛋白修饰的载药纳米粒大部分都偶联上了人转铁蛋白抗体并能保持抗体活性,从而为载药纳米粒特异性靶向肿瘤细胞提供了足够的靶向动力.微乳化-离子交联方法制备方法简便可靠,制得的人转铁蛋白修饰载阿霉素海藻酸钠纳米粒有望成为具有潜在价值的一种特异性靶向药物载体.     

盐酸表阿霉素纳米靶向制剂的缓释效应***◆

背景:盐酸表阿霉素是一种广谱抗生素,目前临床使用的不足多为药物释放快、目标组织药物浓度低,静脉给药后广泛分布于体内各种组织器官,不良反应明显.目的:针对盐酸表阿霉素临床应用的不足,制备盐酸表阿霉素纳米靶向注射制剂.方法:以叶酸偶联牛血清白蛋白为载体,采用乳化-高压匀质法,制备盐酸表阿霉素纳米靶向注射制剂,以激光粒度分析仪测定纳米颗粒的粒径大小、粒径分布及 Zeta 电位,扫描电镜观察纳米颗粒的表面形态,高效液相色谱法分析白蛋白负载盐酸表阿霉素纳米制剂的包封率、载药量和释药性能.结果与结论:制备的盐酸表阿霉素纳米粒外观呈均匀球型,粒径分布较窄,平均粒径为(157.73±0.40) nm,平均 Zeta 电位为(-30.85±0.43) mV,载药量22.78%,包封率可达96.24%.体外模拟释药结果表明药物释放曲线分为两个阶段,突释阶段微球释药量在24 h内达42.6%,缓释阶段纳米粒释药持续时间长,在112 h 时释药量达84.1%,载药纳米粒的药物释放速率持续稳定.结果表明乳化结合高压匀质法制备的盐酸表阿霉素纳米靶向制剂粒径均匀,粒径范围分布窄,载药量和包封率高,具有一定的缓释作用.     

和厚朴酚脂质体的制备及表征

目的:为了提高和厚朴酚的稳定性和溶解性,增强其肿瘤靶向性,制备和厚朴酚脂质体并对其进行表征。方法:采用薄膜水化-挤出法制备和厚朴酚脂质体,通过超滤法测定包封率,以包封率为指标优化和厚朴酚脂质体的制备工艺和处方因素,通过粒径分布和体外释放对其进行表征。结果:优化工艺和处方为磷脂与药物的重量比为60∶1,磷脂与胆固醇的重量比为20∶1,水化介质为pH 6.5磷酸盐缓冲液,超声时间为6 min。所得到的和厚朴酚脂质体平均粒径为150 nm,96 h体外累积释药量为55.2%。结论:优化工艺所制备的和厚朴酚脂质体包封率高,工艺稳定,基本达到了缓释控释及靶向制剂的设计要求。     

整合素αvβ3受体靶向载药脂质体的制备及体外靶向性

背景:含RGD序列的多肽是多种整合素的识别位点,以其相对分子质量小、稳定、易于制备,且无免疫原性等优点被广泛用于纳米靶向药物传递系统的设计.目的:制备以RGD环五肽为配基的整合素αvβ3载药脂质体,通过体外细胞学实验证实其受体靶向性.方法:使用人工合成的RGD环五肽作为靶向分子探针,通过高压均质法制备靶向整合素αvβ3载药脂质体,采用扫描电镜和激光粒度分析仪检测纳米颗粒形态和粒径;以流式细胞分析观察其对血管平滑肌细胞的特异性标记,并考察荷载药物的离体缓释能力以及体外靶向能力.结果与结论:合成的靶向载药脂质体粒径为(175±6) nm,包封率为(96.33±1.02)%,体外溶出时间超过5 d.靶向载药脂质体对整合素αvβ3具有较高的特异性亲和力,可通过受体介导的内吞作用进入细胞内.提示制备的靶向整合素αvβ3载药脂质体,具有较高的药物包封率及缓释性,能与整合素αvβ3受体特异性结合,是一种新型的受体介导靶向制剂.     

新型多肽聚酰胺-胺型靶向药物载体的载药性能及细胞吸收和毒性

背景:前期研究通过噬菌体展示体内筛选方法获得了一条NCI-H460非小细胞肺癌特异结合的多肽(Lung cancer targetingpe ptide,LCTP),将该多肽与修饰的聚酰胺-胺型(Polyamidoamine,PAMAM)树枝状高分子材料连接制备了纳米靶向药物载体PAMAM-Ac-FITC-LCTP,该载体在体内外对非小细胞肺癌NCI-H460具有很好的靶向性。目的:在前期研究基础上,进一步研究PAMAM-Ac-FITC-LCTP靶向载体对阿霉素的包埋、释放及其细胞吸收和毒性性能。方法:以筛选到的多肽LCTP为靶向剂,构建了PAMAM-Ac-FITC-LCTP靶向载体。采用物理包埋法将PAMAM-Ac-FITC-LCTP与阿霉素连接,通过体外透析实验观察载体对药物的缓释功能,共聚焦显微镜观察细胞对药物的吸收。以游离阿霉素作为对照,MTT法观察载体载药后对NCI-H460细胞的作用。结果与结论:PAMAM-Ac-FITC-LCTP对阿霉素的最大包埋率为7.46%。载体对药物具有明显的缓释作用,离子浓度、pH和温度对药物的释放具有影响,说明PAMAM-Ac-FITC-LCTP主要是通过静电相互作用与阿霉素结合。PAMAM-Ac-FITC-LCTP/阿霉素短时间内较单独药物更高效进入NCI-H460细胞,而复合物24h的细胞毒性与阿霉素对细胞的毒性基本一致。以上结果说明PAMAM-Ac-FITC-LCTP可能是一个肿瘤治疗和诊断中很有用的药物靶向传输载体。     

载脑源性神经营养因子脂质体纳米微粒脂膜微泡超声造影剂的制备与初步评价

目的制备一种新型的载脑源性神经营养因子(BDNF)脂质体纳米微粒脂膜微泡超声造影剂(BDNF-UMCA),并对其应用进行初步评价。方法以冷冻干燥法在"脂氟显"制备的基础上加入与二棕榈酰磷脂酰胆碱等量的含生物素化棕榈酰磷脂酰甘油钠-聚乙二醇2000-生物素,制备含生物素化脂膜超声微泡造影剂,通过链亲和素耦连含生物素化聚乙二醇载BDNF脂质体纳米微粒制备BDNF-UMCA,检测其物理性质、载药量、包封率、稳定性及体内声学特性。结果 BDNF-UMCA平均粒径(4.20±0.79)μm,浓度1.02×109/ml,总药物含量(1.18±1.96)mg/ml,包封率(71.6±2.6)%。在4℃下,BDNF-UMCA平均粒径和包封率各时间点无明显变化;在(24±2)℃下,BDNF-UMCA的平均粒径随时间推移逐渐增大,第1、3、5、7天的粒径与初始粒径比较差异均有统计学意义(均P0.05),包封率在(24±2)℃下各时间点比较差异无统计学意义。BDNF-UMCA能显著增强实验动物肝脏显影,平均峰值强度(21.5±3.5)d B,平均达峰时间(19.2±5.2)s。结论应用生物素-亲和素耦连可成功制备BDNF-UMCA;BDNF-UMCA可为靶向显影及药物通过血脑屏障释放提供工具。     

胆甾醇琥珀酰基壳聚糖锚定脂质体用作表阿霉素载体的体外实验

背景:多糖"锚定"脂质体在抗肿瘤药物、蛋白以及基因的传输领域有着极其重要的理论及应用价值,国外已有较多机构在进行相关的研究.目的:通过"锚定"的方式制备胆甾醇琥珀酰基壳聚糖锚定脂质体,并以表阿霉素作为模型药物,考察其对包载药物体外释放性质的影响.设计、时间及地点:体外实验,于2006-09/2008-05在天津市生物医学材料重点实验室完成.材料:以壳聚糖为原料,合成胆甾醇琥珀酰基壳聚糖,并采用胶体滴定法测定其胆甾醇基取代度.方法:采用pH梯度法制备表阿霉素脂质体,然后通过共孵育的方法合成了取代度为2.80%,5.58%和8.00%的载药胆甾醇琥珀酰基壳聚糖锚定脂质体.主要观察指标:荧光分光光度计检测药物浓度;透射电镜观察脂质体形态;亚微米粒度及电位分析仪检测脂质体的粒径大小、分布和电位;动态透析法考察包载药物表阿霉素在胆甾醇琥珀酰基壳聚糖锚定脂质体中的体外释放特征.结果:胆甾醇琥珀酰基壳聚糖锚定脂质体为规则球状形态,呈现典型的核壳结构,粒径为245.4～279.7nm,zeta电位为 21.09～ 25.48mV;和载药脂质体及壳聚糖包衣脂质体相比,CHCS锚定脂质体能明显延缓表阿霉素的体外释放,在胆甾醇基取代度2.80%～5.85%范围内,表阿霉素的释放速度随着取代度的增加呈降低的趋势.结论:胆甾醇琥珀酰基壳聚糖锚定脂质体有着比普通脂质体及壳聚糖包衣脂质体更高的稳定性,能显著延缓包载药物的释放速度.     

胆固醇改性普鲁兰纳米粒子的制备及其载药性质

背景:多糖经引入疏水基团后,在水中能自组装成胶束,可作为疏水小分子药物及生物活性大分子(多肽、蛋白和基因)的载体,在医药和生物技术领域有着潜在的应用价值.目的:系统考察胆固醇基取代度和普鲁兰多糖相对分子质量对改性普鲁兰纳米粒子性状的影响.方法:将胆固醇修饰到不同相对分子质量的普鲁兰多糖长链上,合成了一系列取代度不同的胆围醇基-普鲁兰改性多糖,使其在水中自组装成纳米粒子,考察胆固醇取代度及多糖相对分子质量对纳米粒子形态的影响,以阿霉素为模型药物.研究了其在胆固醇基-普鲁兰改性多糖纳米粒子中的包封及体外释放行为.结果与结论:随着相对分子质量和取代度的增加,粒子稳定性增强,临界胶束质量浓度降低.胆固醇基取代度越低、多糖相对分子质量越大,载药量和包封率越高:当取代度和相对分子质量相同时,随着投料比的增加,载药量增加而包封率降低.体外释放结果表明,相对分子质量越大,粒子越稳定,载药量越高,药物释放越慢.     

聚乳酸羟基乙酸/纳米羟基磷灰石-5-氟尿嘧啶复合微球的制备及体外释放

背景:由聚乳酸羟基乙酸/纳米羟基磷灰石复合材料制备的微球,在体外磷酸盐缓冲液中能够持续释放药物.目的:制备聚乳酸羟基乙酸/纳米羟基磷灰石-5-氟尿嘧啶复合微球,探讨纳米羟基磷灰石对复合微球的载药量、包封率和体外释放等性质的影响.设计、时间及地点:材料学体外观察,于2009-02/2009-07在华南理工大学材料学院实验室完成.材料:聚乳酸羟基乙酸为济南岱罡生物有限公司产品,纳米羟基磷灰石由华南理工大学特种功能材料教育部重点实验室自制,5-氟尿嘧啶为上海楷洋生物技术有限公司产品.方法:以水溶性抗癌药物5-氟尿嘧啶作为模型药物,先用纳米羟基磷灰石吸附药物,外包裹生物相容性好且可生物降解的聚乳酸羟基乙酸,采用单乳化溶剂挥发法(S/O/W)制备聚乳酸羟基乙酸,纳米羟基磷灰石-5-氟尿嘧啶复合微球.对载药前后的纳米羟基磷灰石进行透射电子显微镜、扫描电子显微镜观察和FTIR分析.采用扫描电镜、激光粒度仪和紫外分光光度计对微球的理化性质及体外释药性质进行分析.主要观察指标:纳米羟基磷灰石与5-氟尿嘧啶分子之间的相互作用,微球载药量和包封率,药物体外释放.结果:FTIR结果表明,纳米羟基磷灰石对5-氟尿嘧啶有较强的吸附作用.聚乳酸羟基乙酸/纳米羟基磷灰石-5-氟尿嘧啶复合微球的载药量和包封率分别为3.83%,86.78%,明显高于单纯的聚乳酸羟基乙酸-5-氟尿嘧啶微球.经过体外释放药物突释后,复合微球比单纯聚乳酸羟基乙酸微球的药物释放慢.在第27天,复合微球和单纯的聚乳酸羟基乙酸微球累积药物释率放分别为84.87%,99.87%.结论:与单纯的聚乳酸羟基乙酸-5-氟尿嘧啶微球相比,由于纳米羟基磷灰石对5-氟尿嘧啶存在较强的吸附作用,使聚乳酸羟基乙酸/纳米羟基磷灰石-5-氟尿嘧啶复合微球的载药量和包封率得到了较大提高,具有更好的药物缓释效果.     

海藻酸钙凝胶微球的制备和pH敏感释放

背景:大多数蛋白质和多肽药物存在稳定性差、生物利用度低等缺点,为提高其生物利用度,目前常用将蛋白类药物包裹在高分子材料中,制成缓释控释体系.由于蛋白质外层的载体材料能起到一定保护作用,因此可增加此类药物的稳定性.目的:以含水率为指标,通过正交实验设计,找出制备海藻酸钙微球的最佳条件.并以牛血清白蛋白为模型药物,考察微球载药性能及DH环境下的释放规律.设计、时间及地点:对比观察实验,于2007-10/2009-05在四川大学高分子科学与工程实验楼完成.材料:海藻酸钠、无水氯化钙由成都科龙试剂公司提供,牛血清白蛋白由上海伯奥生物科技有限公司提供.方法:采用滴制法制备了海藻酸钙微球,考察了海藻酸钠质量分数、氯化钙质量分数、交联时间对微球含水率的影响.采用牛血清白蛋白作为模型药物,对优化条件下海藻酸钠凝胶微球进行载药量和释放行为的考察.主要观察指标:微球中牛血清白蛋白包封率及在不同pH介质中白蛋白的释放行为.结果:当海藻酸钠质量分数、氯化钙质量分数均为2.0%,交联时间为6 h,所得微球含水率最高能达到70%.pH溶胀实验显示,微球在盐酸溶液,氯化钠溶液中不溶胀,而在磷酸盐缓冲液中溶胀体现一定的pH敏感性.微球载药量约为5%,包封率为70%左右.对药物释放曲线几种模型方程进行拟合,发现释放曲线不符合Higuchi释放模型.结论:滴制法制备海藻酸钠微球条件温和,不接触有机溶剂.微球含水率高具有pH敏感性且能有效载药,适合作为蛋白质和多肽药物包裹材料.     

聚酰胺纳米分子介导survivin反义寡核苷酸诱导结肠癌细胞凋亡

背景:传统的病毒载体及非病毒载体在基因治疗中均存在明显的缺点,采用纳米材料作为反义寡核苷酸载体有望获得更好更安全的基因转导,提高基因治疗的有效性和安全性.实验拟采用聚酰胺纳米分子介导反义寡核苷酸阻断survivin表达,诱导大肠癌凋亡.目的:探讨聚酰胺树形分子高聚合物介导survivin反义寡核苷酸(survivin antisense oligonucleotide,survivin-asODN)转染结直肠癌SW620细胞的可行性以及对结直肠癌SW620细胞survivin表达、细胞凋亡的影响.设计、时间及地点:肿瘤基因治疗体外实验,于2007-09/2008-05在上海交通大学微纳米科学技术研究院生物纳米工程研究室及南方医科大学珠江医院中心实验室完成.材料:人结直肠癌细胞株SW620购自中国科学院上海细胞研究所,聚酰胺树形分子由上海交通大学微纳米研究院生物纳米工程研究室崔大祥教授提供,转染试剂脂质体LipofectamineTM 2000购自美国Invitrogen公司.survivin-asODN由上海生工公司合成.方法:采用300 μg/L survivin-asODN和4.06 μg/L聚酰胺制备聚酰胺反义基因复合物,同时制备阳离子脂质体反义基因复合物作为对照.透射电镜观察复合物的形态,激光散射粒径分析仪测定粒径,zeta电位分析仪测定zeta电位,离心法和紫外分光光度仪测定复合物的的包封率、载药率和体外DNA释放速度.将上述两种基因转染复合物转染结直肠癌细胞,测定其转染效率;Western blotting检测转染后细胞中survivin蛋白的表达:流式细胞术检测两组细胞的凋亡率.主要观察指标:阳离子脂质体-survivin-asODN复合物及聚酰胺-survivin-asODN复合物的粒经,zeta电位,基因载药率,包封率,释放率,转染后survivin表达率及对凋亡的诱导率.结果:聚酰胺-survivin-asODN复合物的粒径小于脂质体-survivin-asODN复合物的粒径(P<0.01),但zeta电位高于后者(P<0.05);基因载药率、包封率两组差异无显著性意义:聚酰胺对DNA持续释放14 d,但脂质体只持续5 d.聚酰胺-survivin-asODN转染结直肠癌细胞的效果强于脂质体survivin-asODN(P<0.05).转染后结直肠癌细胞survivin蛋白的表达低于脂质体复合物(P<0.05),细胞的凋亡率高于脂质体复合物(P<0.05).结论:聚酰胺能将survivin-asODN高效递送到结直肠癌SW620细胞,降低survivin蛋白表达并诱导结直肠癌细胞凋亡.     

纳米高聚合物转导Survivin反义寡核苷酸对大肠癌的体内杀伤作用

背景:近年来纳米载体已被视为突破基因转移瓶颈最有前途的技术之一.聚酰胺-胺型树枝状高聚合物(polyamidoamine,PAMAM)是一种新型的纳米材料,体内外实验表明,PAMAM比其他阳离子载体的基因转染效率高、细胞毒性低.目的:探讨PAMAM介导Survivin反义寡核苷酸(Survivin antisense oligonucleotide,Survivin-asODN)对结直肠癌裸鼠移植瘤的抑制作用.设计、时间及地点:肿瘤基因治疗体内实验,于2008-02/08在上海交通大学微纳米科学技术研究院生物纳米工程研究室及南方医科大学珠江医院中心实验室完成.材料:人结直肠癌细胞株SW620购自中科院上海细胞所,PAMAM树形分子由上海交通大学微纳米研究院生物纳米工程研究室提供,脂质体Lipolifectmain~(TM)2000购自美国Invitrogen公司.Survivin-asODN 由上海生工公司合成.方法:将PAMAM和阳离子脂质体分别与Survivin-asODN混合得到载反义基因转染复合物.透射电镜观察复合物的形态,激光散射粒径分析仪测定粒径,zeta电位分析仪测定复合物的zeta电位,离心法和紫外分光分度仪测定复合物的包封率和体外DNA释放速度.将对数生长期的人结直肠癌细胞SW620细胞接种于18只Balb/C裸鼠皮下建立结直肠癌裸鼠皮下移植瘤模型.随机均分为脂质体组、PAMAM组和空白对照组.分别注射脂质体-survivin-asODN转染复合物、PAMAM-survivin-asODN转染复合物、血清培养液,观察两组移植瘤体积,Western bloting方法检测移植瘤组织中survivin基因的表达.主要观察指标:阳离脂质体-survivin-asODN复合物及PAMAM-survivin-asODN复合物的粒经,zeta电位,基因载药率,包封率,释放率,转染后survivin表达率及对凋亡的诱导率,种植肿瘤生长抑制率,移植瘤细胞Survivin蛋白的表达及活性.结果:PAMAM-survivin-asODN复合物的粒径小于脂质体-survivin-asODN复合物的粒径(P<0.01),而zeta电位高于PAMAM-survivin-asODN复合物zeta电位(P<0.05),基因包封率两组差异无显著性意义.PAMAM对DNA持续释放达14 d,但脂质体复合物只持续5 d.PAMAM-survivin-asODN复合物治疗组裸鼠移植瘤survivin蛋白表达低于脂质体-survivin-asODN复合物组(P<0.05).PAMAM-survivin-asODN复合物治疗组移植瘤体积低于脂质体-survivin-asODN复合物组(P<0.05).结论:PAMAM能将Survivin-asODN高效递送到结直肠癌移植瘤细胞,降低survivin蛋白的表达,抑制移植瘤生长.     

UV-induced drug release from photoactive REV sensitized by suprofen.

In order to achieve local administration of drugs, calcein (CAL) encapsulated reverse phase evaporation vesicles (REV) carrying photoactive destabilization agent suprofen (SPF) in the lipid bilayer were prepared. Effect of both UV-A and UV-B photoactivation of liposomal membrane incorporated SPF on the destabilization of the liposome bilayer and the release of encapsulated CAL was investigated. Standard REV of phosphatidylcholine (PC):cholesterol (CHOL) in 7:3 molar ratio, and photoactive REV of PC:CHOL:SPF, and DPPC:CHOL:SPF in 7:3:3 molar ratio were prepared. CAL encapsulation efficiency (EE (%)) and in situ release was studied. SPF incorporation in the PC REV membrane led to approximately 5% increase in the EE (34%) in comparison to standard REV (29%). EE decreased (21%) when DPPC was used to replace PC. Exposure to UV-B caused the highest CAL release. The lowest release was from the unexposed REV. DPPC led to a higher liposomal membrane stability (lower CAL release) than PC. A linear relationship was observed between UV-B exposure duration and REV permeability. This study revealed that membrane destabilization of SPF incorporated REV was best achieved upon photoactivation of the membrane-localized SPF by a 40 min exposure to UV-B.     

Efficient tumor regression by a single and low dose treatment with a novel and enhanced formulation of thermosensitive liposomal doxorubicin

We have developed a novel and simplified thermosensitive liposomal formulation (HaT: Hyperthermia-activated cytoToxic) composed of DPPC lipid and Brij78 (96:4, molar ratio). The HaT nanoparticles were loaded with doxorubicin (DOX) with > 95% efficiency when a pH gradient method and a drug/lipid ratio of 1/20 (w/w) were applied. Drug release from the HaT formulation was significantly faster at 40-41 °C (100% release in 2-3 min) with 3.4-fold increased membrane permeability compared to the LTSL (lyso-lipid temperature sensitive liposomes; DPPC: MSPC: DSPE-PEG₂₀₀₀ = 86:10:4, molar ratio), a formulation that is currently in clinical trials. Both formulations displayed similar stability at 37 °C in serum (10-20% release in 30 min), which corresponds to their comparable pharmacokinetics in the unheated mice. An approximately 1.4-fold increased drug delivery to the locally heated tumor (~ 43 °C) was detected with HaT-DOX compared to LTSL-DOX. Moreover, when compared with free DOX, HaT enhanced drug uptake in the heated tumor by 5.2-fold and reduced drug delivery to the heart by 15-fold. A single i.v. treatment with HaT-DOX at 3 mg DOX/kg in combination with localized hyperthermia demonstrated enhanced tumor regression compared to LTSL-DOX and free DOX, and exhibited little toxicity.     

新型多肽聚酰胺-胺型靶向药物载体的载药性能及细胞吸收和毒性

背景：前期研究通过噬菌体展示体内筛选方法获得了一条NCI-H460非小细胞肺癌特异结合的多肽（Lung cancer targetingpe ptide,LCTP）,将该多肽与修饰的聚酰胺-胺型（Polyamidoamine,PAMAM）树枝状高分子材料连接制备了纳米靶向药物载体PAMAM-Ac-FITC-LCTP,该载体在体内外对非小细胞肺癌NCI-H460具有很好的靶向性。目的：在前期研究基础上,进一步研究PAMAM-Ac-FITC-LCTP靶向载体对阿霉素的包埋、释放及其细胞吸收和毒性性能。方法：以筛选到的多肽LCTP为靶向剂,构建了PAMAM-Ac-FITC-LCTP靶向载体。采用物理包埋法将PAMAM-Ac-FITC-LCTP与阿霉素连接,通过体外透析实验观察载体对药物的缓释功能,共聚焦显微镜观察细胞对药物的吸收。以游离阿霉素作为对照,MTT法观察载体载药后对NCI-H460细胞的作用。结果与结论：PAMAM-Ac-FITC-LCTP对阿霉素的最大包埋率为7.46%。载体对药物具有明显的缓释作用,离子浓度、pH和温度对药物的释放具有影响,说明PAMAM-Ac-FITC-LCTP主要是通过静电相互作用与阿霉素结合。PAMAM-Ac-FITC-LCTP/阿霉素短时间内较单独药物更高效进入NCI-H460细胞,而复合物24h的细胞毒性与阿霉素对细胞的毒性基本一致。以上结果说明PAMAM-Ac-FITC-LCTP可能是一个肿瘤治疗和诊断中很有用的药物靶向传输载体。     

Liposome-based nanocapsules for the controlled release of dietary curcumin: PDDA and silica nanoparticle-coated DMPC liposomes enhance the fluorescence efficiency and anticancer activity of curcumin

Nanosystems with various compositions and biological properties are being extensively investigated for drug and gene delivery applications. Many nanotechnology methods use novel nanocarriers, such as liposomes, in therapeutically targeted drug delivery systems. However, liposome matrices suffer from several limitations, including drug leakage and instability. Therefore, the surface modification of liposomes by coating them or adding polymers has advanced their application in drug delivery. Hence, the prevention of drug release from the liposome bilayers was the main focus of this work. For this purpose, liposomes were synthesized according to a thin film hydration method by applying various surface modifications. Three different nanocapsules, N1, N2, and N3, were prepared using 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), poly(diallyldimethylammonium)chloride (PDAA) polymer, and silica nanoparticles. PDDA and silica nanoparticles were coated on the surface of liposomes using a layer-by-layer assembly method, completely encapsulating curcumin into the core of the liposome. Fluorescence spectroscopy, TGA, DLS, XRD, SEM, and zeta potential methods were used to characterize the prepared nanocapsules. Interestingly, the fluorescence of curcumin showed a blue shift and the fluorescence efficiency was extraordinarily enhanced ∼25-, ∼54-, and ∼62-fold in the N1, N2, and N3 nanocapsules, respectively. Similarly, encapsulation efficiency, drug loading, and the anticancer activity of dietary curcumin were investigated for the different types of DMPC nanocapsules. The drug efficiencies of the liposomes were established according to the release of curcumin from the liposomes. The results showed that the release of curcumin from the nanocapsules decreased as the number of layers at the surface of the liposomes increased. The release of curcumin follows the Higuchi model; thus, a slow rate of diffusion is observed when a number of layers is added. The better encapsulation and higher anti-cancer activity of curcumin were also observed when more layers were added, which is due to electrostatic interactions inhibiting curcumin from being released.

Nanosystems with various compositions and biological properties are being extensively investigated for drug and gene delivery applications.     

Encapsulation of doxorubicin into thermosensitive liposomes via complexation with the transition metal manganese.

In the present study, doxorubicin was encapsulated into two thermosensitive liposome formulations which were composed of DPPC/MSPC/DSPE-PEG(2000) (90/10/4 mole ratio) or DPPC/DSPE-PEG(2000) (95/5 mole ratio). Doxorubicin loading was achieved through the use of a pH gradient or a novel procedure that involved doxorubicin complexation with manganese. Regardless of the initial drug-to-lipid ratios (D:L), the final D:L reached a maximum of 0.05 (w/w) when doxorubicin was encapsulated via a pH gradient for both thermosensitive liposome formulations. In contrast, the final maximum D:L achieved through manganese complexation was 0.2 (w/w), and this loading method did not affect temperature-induced drug release, with 85% of drug released from MSPC-containing liposomes within 10 min at 42 degrees C but <5% released over 60 min at 37 degrees C. When the thermosensitive liposomes prepared via the two different loading methods were injected into mice, similar plasma elimination profiles were observed. Cryo-transmission electron microscopy analysis indicated the presence of doxorubicin fiber bundles in liposomes loaded via pH gradient, compared to a stippled and diffuse morphology in those loaded via manganese complexation. To investigate the effect of intraliposomal pH on drug precipitate morphology, the A23187 ionophore (mediates Mn(2+)/H(+) exchange) was added to liposomes loaded with doxorubicin-manganese complex, and the stippled and diffuse appearance could be converted to one exhibiting fiber bundles after acidification of the liposome core. This suggests that the formation of doxorubicin-manganese complex is favored when the intraliposomal pH is >6.5. During the conversion to the fiber bundle morphology, no doxorubicin release was observed when A23187 was added to liposomes exhibiting a 0.05 (w/w), whereas a significant release was noted when the initial D:L was 0.2 (w/w). Following acidification of the liposomal interior and establishment of an apparent new D:L equilibrium, the measured D:L ratio was 0.05 (w/w). In conclusion, the manganese complexation loading method increased the encapsulation efficiency of doxorubicin in thermosensitive liposomes with no major impact on temperature-triggered drug release or pharmacokinetics.