Release control of drug-encapsulated liposomes

Liposomes as a drug delivery system has 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 the probe resonant frequency of 28.18 kHz. Another method is to adjust the input frequency around the probe resonant frequency but fixing the input power. In the experiment, instead of the drug, calcein is enclosed into the liposomes and the release effect is evaluated from the fluorescence intensity changes which is measured by a spectrofluorometer. The experiment results showed that the efficient release property can be achieved both by control of the input power and 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.