Lipid-Based Nanocapsules and Nano Fusion Machines

本项目的目的和范围细分为两个具体目标，具体如下：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(亲水性)药剂包埋在其内部水室中，并将水不溶性(疏水性)药剂包埋到膜中。脂质体包埋的药物不受外界条件的失活影响，但不会引起不良的副作用。此外，脂质体有能力将药物输送到细胞内，甚至在单个细胞隔间内。此外，脂质体的尺寸、电荷和表面性质可以通过在脂质体制备前向脂类混合物中添加新成分和/或通过改变制备方法来改变。具有高度柔性链的表面特异性配体和亲水性聚合物可以附着到脂质体上，从而形成长循环的脂质体。此外，加入带正电的脂类衍生物或带正电的聚合物允许DNA结合和有效的细胞转染。某些蛋白质和多肽(通常是单抗或其Fab片段)附着在脂质体表面，可能会将纳米颗粒靶向体内或细胞内的特定病理区域。我们利用我们对病毒融合机制的理解，通过开发一种新的融合相关小跨膜蛋白来设计纳米融合机器。具体目标2：开发多功能触发方式有效给药的一个重要要求是治疗药物在靶点的精确空间和时间释放。已经设计了各种化学和物理化学方法来创造基于脂质的纳米颗粒，这种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刺激(如热或光)触发的系统和由生物提供的刺激(如pH下降、酶裂解或氧化还原电位变化)触发的系统。对这些刺激作出反应并导致脂质体泄漏的化学成分包括可电离脂质、具有所需相变温度(熔化温度)的脂类、可分解脂类、功能性可电离聚合物和多肽、可电离洗涤剂、顺反异构化以及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包裹的药物优先在温和的局部热疗所能达到的温度下释放。我们设计了直接激活针对跨膜蛋白的疏水性细胞抑制剂的策略。闪烁体晶体将被用作介体，将电离辐射转化为可见的紫外光，进而激活细胞抑素以杀死肿瘤细胞。

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.