Ultrasound-mediated content release from doxorubicin-loaded polymersomes

Polymersomes are nanometer-sized vesicles coated by amphiphilic polymers. Like lipid vesicles (liposomes), polymersomes can also be loaded with drugs in their aqueous core for delivery to target tissues. The component polymers can be designed to offer better tunability and improved stability. This preliminary study investigates the ultrasound-mediated release of the cancer drug, doxorubicin, from polymersomes. The doxorubicin-filled polymersomes were placed in a 24-well cell plate and were subjected to ultrasound stimulation from an immersed unfocused 2.25 MHz transducer. The stimulation was executed at 2 MHz excitation frequency, 20% duty cycle, 1 ms pulse repetition period, and 1 W/cm2. The doxorubicin release was quantified by measuring the absorbance of the post-ultrasound exposure samples using a spectrophotometer at a wavelength of 485 nm. The preliminary findings showed that ultrasound exposures of 1 and 2 min yielded increases in doxorubicin release by 13.2% and 31.5%, respectively, compared to the control. The initial findings showed a promising possibility of utilizing polymersomes for ultrasound-induced controlled drug release. Future work will focus on covering a wider range of ultrasound parameters (intensity, frequency, duty cycle) to optimize content release from polymersomes.