UPCONVERSION NANOPARTICLES FOR STUDY OF LIVE VACCINE TRAFFICKING AND SUBUNIT VACCINE DELIVERY

Abstract

Sub-optimal protection conferred by the limited number of existing vaccines seriously impedes the control of many crucial infectious diseases. New tools are therefore required to accelerate the vaccine development process. This thesis proposes upconversion nanoparticles (UCNs) as a new tool for studying vaccine trafficking and delivery of subunit vaccines. Understanding trafficking of bacterial vaccines is essential for elucidating their safety profiles and protection mechanisms. However, the problems of autofluorescence and photobleaching, encountered when using conventional fluorophores, represent serious limitations for these studies. UCNs can address these caveats by means of their photostability and near-infrared excitation. We thus studied the applicability of UCNs for labelling and trafficking of live bacterial vaccines. Additionally, the lack of suitable delivery systems remains a prevailing issue for subunit vaccines. Encouraged by the increasing evidences suggesting the potential of nanoparticles as vaccine carriers, we thus evaluated the use of mesoporous silica-coated UCNs for the delivery of a subunit vaccine candidate.