Characteristics of a micro-biolistic system for murine immunological studies

With an advanced computational fluid dynamics (CFD) technique, we have numerically developed and examined a micro-biolistic system for delivering particles to murine target sites. The micro-particles are accelerated by a high speed flow initiated by a traveling shock wave, so that they can attain a sufficient momentum to penetrate in to the cells of interest within murine skin (or mucosa). In immunization application, powdered vaccines are directly delivered into the antigen presenting cells (APCs) within the epidermis/dermis of the murine skin with a narrow and highly controllable velocity range (e.g., 699+/-5.6 m/s for 1.8 microm modeled gold particles) and a uniform spatial distribution over a diameter of approximately 4 mm target area. Key features of gas dynamics and gas-particle interaction are presented. Importantly, the particle impact velocity conditions are quantified as a function of: stand-off distance (2-15 mm), driver gas species (air/helium mixtures), particle density (1,050 kg/m3 and 19,320 kg/m3) and particle size (1-5 microm for gold particles and 10-50 microm for less dense particles, respectively). The influential parameters--representative of immunotherapeutic (e.g., DNA vaccination) and protein (e.g., lidocaine) biolistic applications--are studied in detail.