Destruction of Recombinant Tissue Plasminogen Activator (rtPA) -Loaded Echogenic Liposomes under Dual Frequency Sonication

Background:echogenic liposomes (elips) encapsulate drugs and gas bubbles within lipid vesicles. the destruction of elips in response to mhz and khz ultrasound waves has been studied previously. applying ultrasound above a certain threshold causes encapsulated gas bubbles destruct rapidly by fragmentation or more slowly by acoustically driven diffusion. this study compares the destruction of recombinant tissue plasminogen activator (rtpa) -loaded echogenic liposomes using three frequency protocols: 130 khz, 1 mhz and dual (130 khz + 1 mhz). method:in gel phantom, elips were imaged by diagnostic ultrasound system and simultaneously destructive ultrasonic fields were applied at different intensities in each protocol. images were analyzed. results:according to the results, 80% decline in mgv (mean of gray value) relative to initial mgv was associated with elips fragmentation. at 130 khz, results showed an 80% decline in mgv and fragmentation happened at all applied ultrasound intensities (0.01 w/cm2 as fragmentation threshold). in mhz and dual protocols, on average, less than 50% decline in mgv was observed which indicated an acoustically driven diffusion. conclusion:our study shows that khz protocol fragments elips more effectively than other two protocols. for better results, dual frequency protocols need optimized combination of frequencies and phases.