title: Quantitative evaluation of sonophoresis efficiency and its dependence on sonication parameters and particle size.
abstract: Transdermal drug delivery makes a critical contribution to medical practice and some advantages over conventional oral administration and hypodermic injection. Enhancement of percutaneous absorption or penetration of therapeutic agents (ie, drugs and macromolecules) by ultrasound, termed sonophoresis, has been applied and studied for decades. In this study, the penetration percentage through porcine ear skin specimens was determined quantitatively by measuring the fluorescence from nanoparticles of 60, 220, and 840 nm in size in a receptor chamber at different sonication parameters (ie, duty cycle, 20%-100%; acoustic intensity, 0.3-1.0 W/cm(2); duration, 7-30 minutes; and frequency, 1 MHz). In general, the sonophoresis efficiency increased with the acoustic intensity, duty cycle, and sonication duration but decreased with the particle size (mean ± SD, 62.6% ± 5.4% for 60-nm versus 11.9% ± 1.1% for 840-nm polystyrene nanospheres after 30 minutes of sonication at 0.5 W/cm(2) and a 100% duty cycle; P < .05). On scanning electron microscopy the pore size remained the same (≈100 μm), but more flakes were observed with the progress of sonication. In summary, sonophoresis efficiency is dependent on the ultrasound parameters and particle size. Sufficient sonication would lead to satisfactory penetration of even submicrometer objects through the pores.
authors.affiliation: Division of Engineering Mechanics, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore (K.L.L., Y.Z.); and Key Laboratory of Modern Acoustics, Nanjing University, Nanjing, China (Y.Z.).
authors.forename: Kun Loong
authors.initials: KL
authors.lastname: Lee
authors.affiliation: Division of Engineering Mechanics, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore (K.L.L., Y.Z.); and Key Laboratory of Modern Acoustics, Nanjing University, Nanjing, China (Y.Z.). yfzhou@ntu.edu.sg.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000818:Animals; D004058:Diffusion / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D019220:High-Energy Shock Waves; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011829:Radiation Dosage; D012867:Skin / Q000737:chemistry* / Q000528:radiation effects*; D012869:Skin Absorption / Q000528:radiation effects*; D013010:Sonication / Q000379:methods*; D013552:Swine
keywords: cavitation damage; fluorescent nanoparticles; quantitative drug penetration percentage; sonophoresis; superficial structures; transdermal drug delivery