Release control of drug-encapsulated liposomes by piezoelectric ultrasonic probe

Abstract

Liposomes as a drug delivery system have been an attracting interest to many researchers. This paper concerns with the study on how to control the release rate of the inner-substances from liposomes by the ultrasonic irradiation. Two kinds of ultrasonic control methods are tested for investigation of the efficiency of the release property of the liposomes. One control method is to increase the input power by fixing its frequency at a frequency near the probe resonant frequencies. Another method is to adjust the input frequency around the probe resonant frequencies but fixing the input power. In the experiments, three kinds of liposomes with different lipid ratio were prepared and calcein as an indicator was enclosed into the liposomes. The release effect was evaluated from the fluorescence intensity changes which was measured by a spectrofluorometer. The results showed that the efficient release property could be achieved both by control of the input power and the input frequency, but adjusting the input frequency around the probe resonant frequency can get higher efficient release performance than that controlled by the input power.