(171g) Photo-Activated Drug Release of a Liposomal Carrier, Comparison Between Hollow Gold Nanoparticles and Sulfide Nanoparticles

Liposomes, lipid bilayer capsules, have been widely evaluated as drug nanocarriers, however, they are often limited by slow and non-specific release. A novel strategy is to initiate drug release by an external agent such as near infra-red pulsed laser light adsorbed by encapsulated or tethered nanoparticles. The light energy is rapidly converted into thermal energy that generates nanobubble formation that can mechanically disrupt the liposome membranes, thereby releasing the drug with temporal and spatial control. This study presents a comparison of the photoactivated liposomal drug release induced by two different types of nanoparticles (NPs): hollow gold nanoshells (HGN) and cupper sulfide nanoparticles (CSN). Both NPs exhibit strong absorption of near infra-red (NIR) light and offer the opportunity to convert optical energy into thermal energy. The absorbance of NIR light is desirable because it causes minimal thermal injury to normal tissues with optimal light penetration. A picosecond pulsed NIR laser is used to trigger and target the release of the drug. The photothermal heating of the nanoparticles generated by short laser pulses results in large temperature gradients that leads to the formation of transient vapor nanobubbles in aqueous solution. The collapse of the nanobubbles induces the rupture of the liposome membrane and the subsequent drug release with minimal damage to the surroundings. We are particularly interested in the relative light intensity necessary to initiate nanobubble formation for the ~ 10 nm diameter CSN and the ~ 50 nm diameter HGN.  We are also interested in the ease of encapsulating the smaller CSN compared to the larger HGN within 100 nm liposomes most used for drug delivery. The study will lead to a better understanding of the capabilities of multi-functional nanomaterials for NIR laser-controlled drug release in order to facilitate the development of more complex therapeutic studies.