Investigation of Microbubble Response to Long Pulses Used in Ultrasound-Enhanced Drug Delivery

Abstract

Abstract: In current drug delivery approaches, microbubbles and drugs can be co-administered while ultrasound is applied. The mechanism of microbubble interaction with ultrasound, the drug and the cells is not fully understood. The aim of this study was to investigate microbubble response to long ultrasonic pulses used in drug delivery approaches. Two different in vitro set-ups were considered: with the microbubbles diluted in an enclosure and with the microbubbles flowing in a capillary tube. Acoustic streaming, which influences the observed bubble response, was observed in “typical” drug delivery conditions in the first set-up. With the capillary set-up, streaming effects were avoided and accurate bubble responses were recorded. The diffraction pattern of the source greatly influences the bubble response and in different locations of the field different bubble responses are observed. At low nondestructive pressures, microbubbles can oscillate for thousands of cycles repeatedly. At high acoustic pressures (at 1 MHz), most bubble activity disappeared within about 100 µs despite the length of the pulse, mainly due to violent bubble destruction and subsequent accelerated diffusion. Copyright &y& Elsevier]

Copyright of Ultrasound in Medicine & Biology is the property of Elsevier Science Publishing Company, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)