Development of Liposome-Based Radiometric Probe for Detection of X-ray Enhancement Due to Gold Nanoparticles

Liposomal delivery of chemotherapeutics has been used for nearly 20 years as a standard in cancer treatment. However, recurrence rates in many cancers still remain high due to ineffective drug release from the liposomes. To address this problem, we are developing a controlled-release drug delivery capsule utilizing gold nanoparticle(GNP)-coated liposomes that are activated using a minimal amount of x-ray radiation. This allows the drug to be released from the liposomes only within the tumor cells and will greatly reduce recurrence rates and side effects.  The GNP coating enhances the amount of energy deposited by the x-rays and destabilizes the liposome, thus releasing the drug. To detect the enhancement due to GNP coating, we have developed dye-filled liposomes that can be used as radiometric probes. Using these probes, we can then optimize our GNP coating and liposome composition to increase the release of drug. Fluorescent dyes loaded within liposomes can be used in measuring the destruction of fluorescence upon x-ray radiation. Several dyes were used including Cy5, Calcein, and Rhodamine 6G.  In liposome control studies, 30% and 60% decreases in the fluorescence of various dyes were observed after 100 and 200 grays of radiation, respectively. Upon completion of the synthesis of the GNP-coated liposomes, the enhancement will be measured. This work will allow for the optimization of the liposome composition as well as the GNP shell that will enable a novel drug release capsule for cancer therapy.