Biolistic injection of microparticles with high-power Nd:YAG laser

Irradiation of a high-power laser pulse (above 10(9)W/cm(2)) on thin metal foil causes ablation, which is characterized by a strong plasma-shock formation followed by a rapid expulsion of surface matter. The shock propagates through the foil and reverberates on the rear side causing instant deformation of the metal foil, whose surface is treated with microparticles prior to ablation. Based on this principle of microparticle ejection, we develop a laser-based injector that features controllability and stability. We also perform characterization of the penetration depths at varying confinements and energy levels. The confinement media include glass (BK7), water, and ultrasound gel. Biological tissue was replicated by a gelatin-water solution at a 3% weight ratio. Present data show that the confinement effect results in a significant enhancement of penetration depth reached by 5 microm cobalt microparticles. Also, there exists an optimal thickness at each energy level when using liquid confinement for enhanced particle delivery.