Photolabile lipids bilayers and liposomes

描述(申请人提供)：本提案的目标是开发一种适用于制备(I)可包埋生物效应物(如药物)且(Ii)可在照射后释放其内容物的脂质体的一般模块方法。此外，我们的目标是设计这样一种递送系统，对于这种递送系统，光释放是有条件的，即在系统变得对光敏感之前，必须发生触发事件来“武装”系统。PI开发了基于羟基(或氨基)烷基二硫代烷和三硫代烷类化合物的光致碳碳键断裂的方法学，它提供了一条通往各种分子和大分子体系的便捷途径，这些体系能够进行光化学“分解”。这一基本的光化学方法将进一步优化，以适应本研究的目标。我们的一般方法是基于外部敏化系统，本质上适合于这些应用。这是因为潜在的可光裂解的二硫杂环己烷两亲分子本身不是光敏的，但当施加外部刺激时，可以使其光敏，例如，分子识别事件使敏化剂/引发剂更接近二硫杂环-羰基耐光“闩锁”。 该项目的一个组成部分将是合成连接到聚乙二醇聚合链上的耐光性脂类，用于隐形脂质体的制造。这样的脂质体将能够在照射后脱落其聚合涂层，从而显著改变其稳定性。 这些类型的传递囊泡的基本原理将在模型系统上演示，从而将荧光分子探针传递到活细胞，使用RGD-整合素识别作为模型靶向机制。我们将演示辐射后囊泡与细胞壁的对接和探针分子的内化。这些研究将为设计和开发可用于各种分子生物学应用的靶向隐形脂质体奠定基础，以将生物效应器运送到活细胞并在照射时将其内化(一种光诱导的内吞作用)。最终，这些研究将为开发用于药物输送的光敏靶向脂质体铺平道路。

DESCRIPTION (provided by applicant): The goal of this proposal is to develop a general modular approach to photolabile amphiphiles, suitable for preparation of liposomes that (i) can entrap a biological effecter, such as a pharmaceutical, and (ii) can release their content upon irradiation. Furthermore, we aim to design such a delivery system, for which the photorelease is conditional, i.e. before the system becomes light-sensitive, a triggering event has to occur to "arm" the system. The PI has developed methodology, based on photoinduced carbon-carbon bond fragmentation in hydroxy- (or amino) alkyl dithiane and trithiane derivatives, which offers a ready access to various molecular and macromolecular systems capable of photochemical "disassembly". This basic photochemical methodology will be further optimized to suit the goals of this research. Our general approach, which is based on externally sensitized systems, is inherently suitable for these applications. This is because the potentially photocleavable dithiane-based amphiphiles are not light sensitive per se, but can be made light sensitive when an external stimulus is applied, for example, a molecular recognition event brings a sensitizer/initiator closer to the dithiane-carbonyl photolabile "latch". An integral part of this project will be to synthesize photolabile lipids tethered to polyethylene glycol polymeric chains for stealth liposome fabrication. Such liposomes will be able to shed their polymeric coat upon irradiation, thus dramatically changing their stability. The fundamentals of these type delivery vesicles will be demonstrated on a model system, whereby a fluorescent molecular probe will be delivered to a living cell using RGD-integrin recognition as a model targeting mechanism. We will demonstrate docking of the vesicles to the cell wall and internalization of the probe molecules upon irradiation. These studies will lay the groundwork for design and development of targeted stealth liposomes that can be used in various molecular biology applications to deliver biological effecters to living cells and internalize them upon irradiation (a kind of photoinduced endocytosis). Ultimately, these studies will pave way for development of photolabile targeted liposomes for drug delivery.