At present, few synthetic systems can achieve robust, on-demand spatial and temporal control of micro or nanovesicle permeabilization in biological environments. We propose to build upon proof-of-principle experiments establishing the feasibility of such a membrane permeabilization system and to apply this technology towards: 1) triggering drug release in tumors and 2) capturing tumor microvasculature contents via a remote loading and retrieval approach. Several methods for cargo release driven by external stimuli driven have been proposed; whereas to our knowledge the concept of remote capture and retrieval of microvessel contents using triggered permeability in nanovesicles has not yet been explored. So far, essentially all biocompatible approaches for externally triggered membrane permeabilization from nanocarriers comprise systems that release their contents when the surrounding temperatures are raised by a few degrees above body temperature via direct or indirect heating. However, such mechanisms are not amenable to trigger-side release modulation and the narrow thermal operating window precludes carrier stability at physiological temperatures. Furthermore, the lack of stability in physiological conditions prevents more demanding applications of these materials such as triggered release at later time points as well as remote loading and recovery. Here, we propose a fundamentally new controlled release system based on porphyrin- phospholipid doped (PoPD) liposomes transiently permeabilized directly by near infrared (NIR) light, a clinically-applicable stimulus that has negligible actuatin in the off state and minimal interference with biological tissues. The ability to open and close nanovesicles in the body with precise spatial and temporal control could lead to entirely new approaches to treating and understanding cancer. We synthesized a novel light-absorbing monomer esterified from clinically approved components that gave rise to highly stable porphyrin bilayer. Remarkably, rapid and complete cargo release was induced upon brief exposure to mild NIR irradiation using an optimal porphyrin-phospholipid (but not free porphyrin) doping. Unlike previously described systems, release occurred in the absence of bulk solution photothermal heating or chemical reactions. In physiological conditions in vitro, NIR irradiation induced a 25,000 fold increase in the release rate of actively loaded doxorubicin, orders of magnitude greater than previously described triggered release methods. Induced permeability could be used for both unloading and loading cargo, and could be modulated by varying porphyrin doping, irradiation intensity and irradiation duration for highly tunable manipulation of permeabilization. This project has three specific aims.
Aim 1 : Develop micro and nanovesicles that open and close on demand in response to NIR light;
Aim 2 : Use near infrared light to deliver cancer therapeutics to tumors;
Aim 3 : Sample tumor microvasculature contents using a capture and retrieve strategy.
The ability to open and close nanovesicles in the body with precise spatial and temporal control could lead to entirely new approaches to treating and understanding cancer. We have demonstrated proof of principle for a new class of organic nanoparticles (PoPD-liposomes) that can be temporarily permeabilized in response to near infrared light, a safe and clinically proven stimulus. We will optimize PoPD liposomes to open and close on demand and apply this enabling technology to deposit a commonly used anti-cancer drug directly in tumors and to capture and retrieve the contents of the tumor microvasculature for analysis.
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