Abstract

Cancer cells that survive chemotherapy treatment often develop resistance to the administered chemotherapeutics, as well as to many other types of drugs, because the cancer cells increase their production of efflux pumps in the cell. This undesired phenomenon of resistance to cancer drugs is known as multidrug resistance. This work uses a novel drug carrier, called an eLiposome, to achieve cytosolic drug delivery to kill multidrug-resistant cancer cells. An eLiposome consists of a perfluoropentane (PFC5) emulsion droplet inside of a liposome. Folate attached to the eLiposome facilitates uptake into the cell. The PFC5 droplet is metastable at body temperature, but will rupture the liposome as the droplet expands during vaporization, and will release any drugs encapsulated inside of the liposome directly to the cell cytosol. Laser and ultrasound were examined as triggers to initiate the vaporization of the PFC5 droplet and actuate the release of doxorubicin (Dox) from folated eLiposomes containing Dox (feLD). Gold nanorods (GNRs) were synthesized and transferred to PFC5 droplets. Although GNRs are efficient at converting irradiated laser light to heat, no vaporization of the PFC5 droplets was observed when irradiated with laser light. Further investigation into the energy required for vaporization of PFC5 droplets revealed that there are currently no portable and wearable lasers available to provide enough energy to vaporize PFC5 droplets. Two seconds of ultrasound can release 78% of encapsulated Dox from feLD. Dox-sensitive KB-3-1 cells and Dox-resistant KB-V1 cells treated with feLD (without ultrasound) had cell viabilities of 33% and 60%, respectively. Ultrasound had negligible additional effect on the cell viability of KB-3-1 and KB-V1 cells treated with feLD (33% and 53%, respectively). We hypothesized that the Dox fiber formed during the loading of Dox into the eLiposome is a site for heterogeneous nucleation once the feLD is endocytosed by the cell, and vaporization and drug release occurs with or without ultrasound. Blocking the efflux pumps with verapamil decreases the rate at which Dox is exported from multidrug-resistant cells. When verapamil is co-delivered with feLD, the cell viability of KB-3-1 and KB-V1 cells decreases to 29% and 25%, respectively; thereby reversing the multidrug resistance possessed by KB-V1 cells. The delivery of doxorubicin inside of folated eLiposomes with an efflux pump blocker is a novel way to kill multidrug-resistant cancer cells as effectively as non-resistant cancer cells independent of lasers or ultrasound.

Degree

PhD

College and Department

Ira A. Fulton College of Engineering and Technology; Chemical Engineering

Rights

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