A pH-sensitive supramolecular nanosystem with chlorin e6 and triptolide co-delivery for chemo-photodynamic combination therapy

The combination of Ce6, an acknowledged photosensitizer, and TPL, a natural anticancer agent, has been demonstrated as a useful strategy to reinforce the tumor growth suppression, as well as decrease the systemic side effects compared with their monotherapy. However, in view of the optimal chemo-photodynamic combination efficiency, there is still short of the feasible nanovehicle to steadily co-deliver Ce6 and TPL, and stimuli-responsively burst release drugs in tumor site. Herein, we described ...     

基因转染的pH敏感脂质体的最优处方和制备工艺的研究

目的　寻找用于基因转染的pH敏感脂质体的最佳处方和制备工艺。方法　采用正交设计法 ,考虑制备的pH值、组成摩尔比、制备方法三因素 ;即 1个四水平因素和 2个二水平因素混合状态。选用L16(4 1·2 12 )正交设计表安排试验 ,各水平组合条件下 ,通过基因转染实验 ,以基因转染荧光测定值作为观测指标 ,实验重复 4次。结果　在基因与脂质体重量比为 (1∶8)时 ,组成大豆磷脂与DC 胆固醇摩尔比为 (6∶4)和在超声法制备的特定条件下 ,pH5 .4与pH7.4基因转染荧光测定值之间差别非常显著 ;均值都较大 ,但是以 pH5 .4时基因转染荧光测定值均值最大。 结论　基因转染荧光测定值最高的脂质体为在 pH5 .4、组成大豆磷脂与DC 胆固醇摩尔比为 (6∶4)时采用超声法制备的脂质体。     

载As2O3 pH敏感钙砷复合物脂质体的制备及体外评价

目的制备pH敏感释药的As₂O₃脂质体,并进行体外评价。方法采用薄膜分散法制备含钙离子脂质体,然后用离子沉淀法孵育制备钙砷复合物脂质体(CaAs-LP)。测定CaAs-LP的粒径、Zeta电位及多分散系数(PDI);透射电子显微镜观察脂质体的形态;电感耦合等离子体发射光谱仪测定纳米药物的载药量与包封率;透析袋法考察其体外释药特性。噻唑蓝(MTT)法考察未载药脂质体及CaAs-LP对人源性乳腺癌MCF-7细胞、人源性脑胶质瘤U87细胞和人源性肝癌HepG2细胞的毒性;共聚焦显微镜考察U87细胞对CaAs-LP的摄取效率。结果制备的CaAs-LP呈规整类球型,粒径约为(117.16±1.94)nm,包封率和载药量分别为(74.31±2.11)%、(8.31±0.13)%。体外释放研究表明,CaAs-LP具有明显的缓释以及pH响应释药特征。未载药的脂质体在MCF-7、U87、HepG2和L02细胞中的生物相容性良好;CaAs-LP抑制肿瘤细胞生长的作用较原药有所上升,半数抑制浓度(IC₅₀)值分别为11.91、4.90、19....     

pH-敏感型脂质小囊体外释放特性

探讨表面结合聚（２－乙基丙烯酸）后脂质小囊的体外ｐＨ敏感性。方法将巯基化的聚（２－乙基丙烯酸）连接在含有二肉豆蔻酰－Ｎ－［（４－马来酰亚胺甲基）环己羰基］磷脂酰乙醇胺的类脂双分子层表面,制备ｐＨ－敏感型脂质小囊。以内容物钙黄绿素酸化前后体外释放百分率的变化作为指标,考察不同相对分子质量的聚（２－乙基丙烯酸）和不同离子强度磷酸盐缓冲液对脂质小囊ｐＨ敏感性的影响。结果高相对分子质量聚（２－乙基丙烯酸）表面结合脂质小囊对ｐＨ最敏感;以１００ｍｍｏｌ／Ｌ磷酸盐缓冲液为介质制备的脂质小囊ｐＨ敏感性最好。结论聚（２－乙基丙烯酸）表面结合的脂质小囊具有ｐＨ敏感性     

pH敏感电荷反转型姜黄素纳米粒子的制备及体外评价

目的制备pH敏感电荷反转型姜黄素纳米粒子(PCE/Cur NPs),优化制备工艺并考察PCE/Cur NPs的理化性质及其对黑色素瘤(B16)细胞的抑制作用。方法在正电性材料甲氧基聚乙二醇-聚己内酯-聚乙烯亚胺(MPEG-PCL-PEI,PCE)的基础上键合1,2-环己二酸酐使其变成负电性材料,制备带负电的PCE/CurNPs,该纳米粒子具有pH值依赖性,pH值7时,PCE/Cur NPs不发生化学变化,显示负电性,pH值6时,PCE/Cur NPs发生化学反应,水解掉1,2-环己二酸,显示正电性。考察了其形态、粒径、载药量、包封率与体外释放等理化特性;通过MTT法、划痕实验进行检测,验证PCE/Cur NPs对B16细胞的抑制作用、抗增殖侵袭能力。结果获得了PCE/Cur NPs,透射电子显微镜下观察所得纳米粒子形态外观圆整,大小均匀,无黏连,平均粒径为(80±5)nm;包封率为(90.0±2.0)%;载药量为(8.0±1.0)%;48 h时,PCE/Cur NPs释放趋于恒速,释放缓慢,累积释放达到(69.2±5.2)%(pH 7.4)与(71.2±4.3)%(pH 5.0);细胞实验显示,PCE/Cur NPs能够显著抑制B16细胞的生存和增殖能力,具有剂量和时间依赖性。结论成功制备了PCE/CurNPs,对抑制B16细胞增殖效果良好,为开发智能型抗肿瘤给药系统提供了理论依据。     

Strategies for triggered drug release from tumor targeted liposomes

Introduction: Long circulating liposomal drug carriers are widely used in experimental cancer therapy because they avoid excretion and benefit from the enhanced permeability and retention-effect to accumulate at the tumor site while simultaneously limiting systemic exposure to the cytotoxic drug due to their high stability. A drawback of the stability of the formulation is that the unloading of the drug at the target site is very poor. This opens up a new challenge to trigger drug release at the target site, while still retaining most of the drug inside the carrier while it resides in the bloodstream.

Areas covered: A short introduction is given about lipid polymorphism and phase behavior. To illustrate how this can be used to design triggered release systems, the development of delivery systems that are activated by tumor environment, UV or visible light and mild heat are discussed. The most recent triggered release systems have evolved even further, creating a need for more sophisticated triggers, which are as non-invasive and patient friendly as possible.

Expert opinion: Currently the most promising triggered release systems that have advanced furthest are thermosensitive liposomal delivery systems. As mild hyperthermia also increases tissue permeability it appears a suitable trigger for drug release while it also assists in drug accumulation. Combined with an advanced imaging system in the MR-high intensity focused ultrasound, this could be the combination of delivery system and trigger that can achieve clinical success.     

pH-sensitive polymer-liposome-based antigen delivery systems potentiated with interferon-γ gene lipoplex for efficient cancer immunotherapy

Potentiation of pH-sensitive liposome-based antigen carriers with IFN-γ gene lipoplexes was attempted to achieve efficient induction of tumor-specific immunity. 3-Methylglutarylated poly(glycidol) (MGluPG)-modified liposomes and cationic liposomes were used, respectively, for the delivery of antigenic protein ovalbumin (OVA) and IFN-γ-encoding plasmid DNA (pDNA). The MGluPG-modified liposomes and the cationic liposome-pDNA complexes (lipoplexes) formed hybrid complexes via electrostatic interactions after their mixing in aqueous solutions. The hybrid complexes co-delivered OVA and IFN-γ-encoding pDNA into DC2.4 cells, a murine dendritic cell line, as was the case of MGluPG-modified liposomes for OVA or the lipoplexes for pDNA. Both the lipoplexes and the hybrid complexes transfected DC2.4 cells and induced IFN-γ protein production, but transfection activities of the hybrid complexes were lower than those of the parent lipoplexes. Subcutaneous administration of hybrid complexes to mice bearing E.G7-OVA tumor reduced tumor volumes, which might result from the induction of OVA-specific cytotoxic T lymphocytes (CTLs). However, the hybrid complex-induced antitumor effect was the same level of the MGluPG-modified liposome-mediated antitumor immunity. In contrast, an extremely strong antitumor immune response was derived when these liposomes and lipoplexes without complexation were injected subcutaneously at the same site of tumor-bearing mice. Immunohistochemical analysis of tumor sections revealed that immunization through the liposome–lipoplex combination promoted the infiltration of CTLs to tumors at an early stage of treatment compared with liposomes, resulting in strong therapeutic effects.     

pH-sensitive immunoliposomes specific to the CD33 cell surface antigen of leukemic cells

A promising avenue in cancer therapy using liposomal formulations is the combination of site-specific delivery with triggered drug release. The use of trigger mechanisms in liposomes could be relevant for drugs susceptible to lysosomal hydrolytic/enzymatic degradation. Here, we propose a polymeric pH-sensitive liposome system that is designed to release its content inside the endosomes through a polymer structural change following receptor-mediated internalization. Specifically, pH-sensitive immunoliposomes (ILs) were obtained by including a terminally alkylated copolymer of N-isopropylacrylamide (NIPAM) in the liposome bilayer and by coupling the anti-CD33 monoclonal antibody to target leukemic cells. In vitro release of encapsulated fluorescent probes and cytosine arabinoside (ara-C) revealed that pH-sensitivity of the vector was retained in the presence of the antibody upon incubation in plasma. Flow cytometry and confocal microscopy analyses demonstrated that the pH-sensitive ILs were efficiently internalized by various CD33+ leukemic cell lines while limited interaction was found for liposomes decorated with an isotype-matched control antibody. Finally, the pH-sensitive ILs-CD33 formulation exhibited the highest cytotoxicity against HL60 cells, confirming the role of the NIPAM copolymer in promoting the escape of intact ara-C in the endosomes. These results suggest that this pH-sensitive liposomal formulation could be beneficial in the treatment of acute myeloid leukemia.     

Fiber-optic measurement of intracellular pH in intact rat liver using pH-sensitive dyes

The pH-sensitive fluorescent dye 1,3-dihydroxypyrene-6,8-disulfonic acid (DHPDS) was used to measure intracellular pH (pH_i) from the surface fluorescence of the isolated perfused rat liver.Monochromatic light from a fluorometer was focused on the liver with a fiber optic, emitted light was collected with a second fiber bundle and returned to the spectrometer. To correct for changes in intracellular dye concentration, the excitation wavelength was changed between the pH-sensitive excitation peak wavelength and the isosbestic wavelength, then a ratio was computed between fluorescence intensities at these two wavelengths.Intracellular calibration of the dye was performed by clamping the intracellular to the extracellular pH with H⁺/K⁺-ionophore Nigericin.This method was used to monitor transient changes in intracellular pH caused either by addition and removal of NH₄Cl or by changing perfusate CO₂ and HCO₃ ^– concentrations while keeping their ratio constant. The effects of these maneuvers on bileflow were studied, too.Data obtained in the perfused liver were in good agreement with those obtained in isolated liver cells except that the steady-state pH_i (7.46 ± 0.02) was slightly higher than reported values.Measurements in livers of mutant TR^– rats that are defective of dye secretion revealed similar pH_i values, indicating that secretion of the dye into bile canaliculi did not affect measurements.The technique appears adequate to measure pH_i in the liver and will allow to study pH regulatory mechanisms in the intact organ.     

左乙拉西坦pH敏感鼻用凝胶在大鼠体内的药代动力学研究

目的 研究左乙拉西坦(LEV)pH敏感鼻用凝胶在大鼠体内的药代动力学.方法 用高效液相色谱法测定大鼠血中LEV的浓度.色谱柱为Wondasil C18柱(250.0 mm×4.6 mm,5.0μm),流动相为乙腈-水(11:89),检测波长为205 nm,内标为甲硝唑.按照体质量将大鼠随机分为实验组和对照组,每组6只....