Biological Nanofactories: Altering Cellular Response via Localized Synthesis and Delivery

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Conventional research in targeted delivery of molecules-of-interest involves either packaging of the molecules-of-interest within a delivery mechanism or pre-synthesis of an inactive prodrug that is converted to the molecule-of-interest in the vicinity of the targeted area. Biological nanofactories provide an alternative approach to targeted delivery by locally synthesizing and delivering the molecules-of-interest at surface of the targeted cells. The machinery for synthesis and delivery is derived from the targeted cells themselves. Biological nanofactories are nano-dimensioned and are comprised of multiple functional modules. At the most basic level, a biological nanofactory consists of a cell targeting module and a synthesis module. When deployed, a biological nanofactory binds to the targeted cell surface and locally synthesizes and delivers molecules-of-interest thus altering the response of the targeted cells.

In this dissertation, biological nanofactories for the localized synthesis and delivery of the 'universal' quorum sensing signaling molecule autoinducer-2 are demonstrated. Quorum sensing is process by which bacterial co-ordinate their activities at a population level through the production, release, sensing and uptake of signaling autoinducers and plays a role in diverse bacterial phenomena such as bacterial pathogenicity, biofilm formation and bioluminescence. Two types of biological nanofactories; magnetic nanofactories and antibody nanofactories are presented in this dissertation as demonstrations of the biological nanofactory approach to targeted delivery. Magnetic nanofactories consist of the AI-2 biosynthesis enzymes attached to functionalized chitosan-mag nanoparticles. Assembly of these nanofactories involves synthesis of the chitosan-mag nanoparticles and subsequent assembly of the AI-2 pathway enzymes onto the particles. Antibody nanofactories consist of the AI-2 biosynthesis enzymes self assembled onto the targeting antibody. Assembly of these nanofactories involves creation of a fusion protein that attaches to the targeting antibody. When added to cultures of quorum sensing bacteria, the nanofactories bind to the surface of the targeted cells via the targeting module and locally synthesize and deliver AI-2 there via the synthesis module. The cells sense and uptake the AI-2 and alter their natural response. Prospects of using biological nanofactories to alter the native response of targeted cells to a 'desired' state, especially with respect to down-regulating undesirable co-ordinated bacterial response, are envisioned.