Significance of Non-Thermal Effects in LIPUS Induced Drug Release from Gold Nanoparticle Drug Carriers

In this work a low intensity pulsed ultrasound (LIPUS) targeted drug delivery system was used to induce the release of curcumin, as a natural drug, from the surface of gold nanoparticle (GNP) drug carriers in an ex vivo tissue model. It is hypothesized that a combination of thermal and non-thermal mechanisms are responsible for the curcumin release. To test these mechanisms, drug release was induced with: (1) heating with a hot water needle (thermal mechanism only), and (2) low intensity pulsed ultrasound (LIPUS) exposure (combined thermal and non-thermal mechanisms). When comparing curcumin release between the two treatments there was an 85% increase in curcumin release when using LIPUS over hot water heating. In treatment 1 a water temperature was selected which yielded a similar temperature profile in the region of interest containing the GNP dug carriers as that seen with LIPUS exposure. This suggests that non-thermal effects present in LIPUS exposure, such as acoustic radiation force and acoustic streaming, are significant in LIPUS targeted drug release from GNP drug carriers.