This goal of this project is to synthesize nanoparticles that can convert incident near infrared (NIR) light energy into mechanical motion to propel themselves through viscous fluids and soft gels. The mechanical motion of the nanoparticles is the result of nanoparticle heating which causes the formation and collapse of bubbles, known as cavitation. When the bubble collapses, the nanoparticle is propelled forward with great energy and velocity. This project will study the effects of particle structure on the efficiency of converting light energy into mechanical motion. Next, the nanoparticles will be synthesized with an asymmetric structure, which will allow them to be aimed in specific directions. The effects of the surrounding medium properties on nanoparticle propulsion will be examined. The results of this series of experiments will used to assess the system as a drug delivery technology in which drug-laden nanocarriers are propelled directly into tissue structures, which would help overcome a major barrier in disease treatment.
The overall goal of this project is to design nanostructures that can convert light into cavitation for high energy and velocity propulsion into tissue and other biological fluids. Rather than simply allowing the particles to accumulate near a boundary of a target that contains a mass-transfer barrier, cavitation-mediated propulsion will cause the nanoparticles to rapidly move into the interior of a target. This propulsion will produce two very important effects that will benefit molecular delivery: (a) the nanoparticle itself will be able to penetrate deeply into otherwise-inaccessible tissue, and (b) the path cleared by the nanoparticles will allow the perfusion of small molecules (e.g. drugs) and macromolecules (e.g. antibodies) whose transport would be restricted by the presence of viscous fluids, overgrowth matrix, or high interstitial pressure. In this project, core-shell nanostructures capable of converting light into mechanical motion will be designed by growth of mesoporous silica shells around gold nanorods (AuNRs). Because the ability of the oxide shell to stabilize the cavitation process is mediated by the lipophilic ligands on the oxide surface, it should be possible for the AuNR to convert near infrared (NIR) light to thermal energy, which in turn will be converted to mechanical energy by the formation and collapse of a cavitation bubble. Next, asymmetry will be imparted to the AuNR-shell structure so that the nanostructures can be spatially oriented to penetrate into specific regions. The structure-property relationships underpinning the conversion of light energy into mechanical motion will be examined, as well as validated in viscous and viscoelastic media. This project will also advance several broader impacts to meet the mission of NSF. First, this project will address how to facilitate drug delivery through major transport barriers in the body, such as solid tumors and mucosal membranes. Second, the PIs will make a commitment to recruit trainees that promote diversity. Third, the PIs will develop a course in advanced technical communication that will teach skills that students will utilize over their graduate career and beyond.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
