Polymeric Nanocarriers for the Visualization and Quantification of Molecular Release

当前提案的首要目标是开发一种技术平台，该平台可以通过引入能够同时可视化和量化有效载荷递送的可切换荧光部分来跟踪和量化分子释放机制（例如药物释放）。 聚合物纳米颗粒作为药物递送载体的发展促进了各种治疗剂的有效靶向释放策略。当与成像剂组合时，这些纳米颗粒允许可视化分子有效载荷的生物分布。然而，这些系统中的大多数没有报告药物从载体的释放，这是一个重要的方面，这对优化的有效载荷递送系统的设计至关重要，并将使生物学效应的深入理解成为可能。 寻求的项目将开发新型聚合物纳米载体，可以显示在何处，何时以及有多少分子有效载荷被传递到特定的目标位点。具有强大的聚合物化学焦点，这将通过将氮氧自由基-荧光团对掺入到递送系统中来实现。当荧光团保持在紧密接近氮氧自由基时，荧光团进入前荧光状态，并且观察到荧光的完全猝灭。当负载从载体释放时-通过刺激诱导的共价键断裂-将发生氮氧自由基和荧光团部分的分离，并且将观察到荧光的立即增加，从而允许定量递送。分子将被设计成使得一个荧光团的开启将与一个递送分子的释放相关，从而导致释放的可定量测量。为了实现这样的理想，已经确定了一些化学挑战，这些挑战是当前提案的核心，并将得到解决，从而更深刻地理解聚合物纳米载体的递送机制。该概念将在体外和体内研究中得到证明，以证明其实用性。

The overarching aim of the current proposal is to develop a technology platform that can follow and quantify molecular release mechanisms (e.g. drug release) by incorporating a switchable fluorescent moiety which is able to simultaneously visualise and quantify payload delivery. The development of polymeric nanoparticles as drug delivery vehicles has facilitated effective targeted release strategies for a variety of therapeutics. When combined with imaging agents, these nanoparticles allow for the visualization of the biodistribution of a molecular payload. However, the majority of these systems do not report on the release of the drug from the carrier, an important facet which is crucial to the design of optimized payload delivery systems and will enable an in-depth understanding of biological effects. The sought project will develop novel polymeric nano-carriers which can show where, when and how much molecular payload is delivered to a specific target site. Featuring a strong polymer chemical focus, this will be achieved through the incorporation of a nitroxide-fluorophore couple into the delivery system. When a fluorophore is held in close proximity to a nitroxide, the fluorophore enters a profluorescent state and a complete quenching of the fluorescence is observed. When the load is released from the carrier - through stimuli-induced scission of a covalent linkage - separation of the nitroxide and fluorophore moieties will occur and an immediate increase in fluorescence will be observed, thereby allowing the quantification of the delivery. The molecules will be designed such that the switch on of one fluorophore will be related to the release of one delivered molecule, leading to a quantifiable measure of release. In order to realize such an ideal, a number of chemical challenges have been identified that are at the core of the current proposal and will be addressed, leading to a more profound understanding of the mechanisms by which delivery from polymeric nanocarriers is achieved. The concept will be evidenced in in vitro as well as in vivo studies to demonstrate its practical applicability.