Lipid-based Nanocapsules and Nano Fusion Machines

该项目的目的和范围可细分为以下两个具体目标：具体目标1：开发具有靶向和成像能力的多功能脂质体，脂质体具有生物相容性，可以将水溶性（亲水）药物试剂捕获在其内部水腔中，并将水不溶性（疏水）试剂捕获在膜中。脂质体掺入的药物不受外部条件的失活作用的保护；但不会引起不良的副作用。此外，脂质体具有将药物输送到细胞内甚至单个细胞室内的能力。此外，脂质体的大小、电荷和表面性质可以通过在脂质体制备前向脂质混合物中添加新成分和/或通过改变制备方法来修饰。脂质体表面特异性配体和具有高柔性链的亲水性聚合物可以形成长循环的脂质体。此外，加入带正电的脂质衍生物或带正电的聚合物允许DNA结合和有效的细胞转染。某些蛋白质和肽（通常是单克隆抗体或它们的Fab片段）附着在脂质体表面，可以将纳米颗粒靶向到体内或细胞内的某些病理区域。我们利用我们对病毒融合机制的理解，通过开发一类新的融合相关的小跨膜蛋白来设计纳米融合机器。开发多功能触发模式有效药物递送的一个重要要求是治疗剂在目标部位精确的空间和时间释放。各种化学和物理化学方法已经被设计用于制造基于脂质的纳米颗粒，这些纳米颗粒可以被触发以受控的方式释放其内容物。诱导释放的刺激可分为由外部施加的刺激（如热或光）触发的系统，以及由生物提供的刺激（如pH值下降、酶解或氧化还原电位的变化）触发的系统。对这些刺激作出反应并诱导脂质体泄漏的化学成分包括可电离的脂质、具有所需相变温度（熔化温度）的脂质、可切割的脂质、功能性可电离的聚合物和肽、可电离的洗涤剂、顺-反异构化和作为光传感器的自由基生成化合物。聚焦超声技术的现代进步将使捕获的药物优先在局部轻度热疗可达到的温度下释放。我们设计了直接激活针对跨膜蛋白的疏水细胞抑制剂的策略。闪烁晶体将被用作介质，将电离辐射转化为可见的紫外线，从而激活细胞抑制剂来杀死肿瘤细胞。

The purpose and scope of this project is subdivided in two specific aims that are detailed below: Specific Aim 1: Develop Multifunctional Liposomes with Targeting and Imaging Capabilities Liposomes are biocompatible and can entrap water-soluble (hydrophilic) pharmaceutical agents in their internal water compartment and water-insoluble (hydrophobic) reagents into the membrane. The liposome-incorporated pharmaceuticals are protected from the inactivating effect of external conditions; yet do not cause undesirable side reactions. Moreover, liposomes have the ability to deliver pharmaceuticals into cells or even inside individual cellular compartments. In addition, the size, charge and surface properties of liposomes can be modified by adding new ingredients to the lipid mixture before liposome preparation and/or by variation of preparation methods. It is possible to attach to the liposome surface specific ligands and hydrophilic polymers with highly flexible chains results in long-circulating liposomes. Moreover, incorporation of positively charged lipid derivatives or positively charged polymers allows for DNA binding and efficient cell transfection. Attachment of certain proteins and peptides (usually monoclonal antibodies or their Fab fragments) to the liposome surface may target nanoparticles to certain pathological areas in the body or inside cells. We use our understanding of viral fusion mechanisms to devise nano fusion machines by exploiting a new class of fusion-associated small transmembrane proteins. Specific Aim 2: Develop Multifunctional Triggering Modalities An important requirement for effective drug delivery is the precise spatial and temporal release of therapeutic agents at the target site. A variety of chemical and physicochemical approaches have been devised to create lipid-based nanoparticles that can be triggered to release their contents in a controlled fashion. The stimuli to induce release can be divided into systems triggered by an externally applied stimulus such as heat or light, and those triggered by a biologically supplied stimulus such as the drop of pH, enzymatic cleavage, or change of a redox potential. The chemical components that respond to these stimuli and induce the liposome leakage include ionizable lipids, lipids with a desired phase transition temperature (melting temperature), cleavable lipids, functional ionizable polymers and peptides, ionizable detergents, cis-trans isomerization, and free-radical-generating compounds as photosensors. The modern advances in focused ultrasound technology will enable the release an entrapped drug preferentially at temperatures attainable by mild local hyperthermia. We have designed strategies to directly activate hydrophobic cytostatic agents that target trans-membrane proteins. Scintillator crystals will be used as mediators that will convert the ionizing radiation into visible UV light which in turn will activate cytostatic to kill tumor cells.