Cold Triggered Drug Release from Polymersomes

Cold triggered drug release stands to be more advantageous due to lower cost and greater accessibility. The goal of this project is to develop a cold triggered drug delivery system. The platform has 3 elements: the drug, cold therapy, and thermo-responsive polymersomes. To model this type of platform, three methods were tested. In the first method, a polymer was mixed with a fluorescein solution, cooled, and then put in a dialysis tube inside of a centrifuge tube with 14 mL of 37 C Phosphate Buffer solution (PBS), which was exchanged at given time intervals. At each time interval, the amount of drug released was measured as a cumulative percentage calculated to better compare the cold triggered intervals with those at the standard 37 C. These percentages were found by obtaining concentration values from an average of relative absorbances. Another method tested this with direct injection of fluorescein solution into a sample vial, no longer requiring a dialysis tube. The measurements were taken in the same manner but from the supernatant of the mixture, only replacing that volume of PBS at each interval. The final method was also with direct injection, into a 24 wells plate, yet differed from the other two methods by measuring the relative fluorescence instead of absorbance. The results from the fluorescence method proved to be the most promising, showing a steady cumulative release over time that was noticeably increased at the cold triggered intervals. Future testing is necessary for the long term work yet this shows great possibility in the application of thermo-responsive polymers. The significance of this finding is to develop a platform to remotely trigger drug release on demand.