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Abstract
Inorganic nanoparticles have gained significant interest because of their exclusive material- and size-dependent properties that can be harnessed for biomedical applications. In particular, gold and iron oxide nanoparticles (IONPs), that display unique response towards light and magnetic stimuli, respectively, have been widely investigated due to their biocompatibility. The nanoparticles can be utilized in diverse applications including hyperthermia therapy, drug delivery and bioimaging. Besides, their reactive surface can be easily functionalized using precisely engineered polymer prepared via living radical polymerization i.e. reversible addition-fragmentation chain transfer (RAFT) process, which endows additional properties to the nanoparticles such as colloidal stability. Collectively, the multifunctional, hybrid polymer-inorganic nanoparticles are envisioned to improve the treatments of current leading causes of death worldwide, i.e. cancer and infectious diseases. This thesis demonstrates the development of hybrid polymer-inorganic nanoparticles for biomedical applications. Using well-defined polymers, a range of hybrid polymer-inorganic nanoparticles were prepared. In Chapter 3, thiol functionalized copolymers were used as reducing-cum-protecting agent for the synthesis of gold nanoclusters. The polymer can be designed to confer reversible thermoresponsive fluorescence property to the gold nanoclusters. The optimal condition for the synthetic approach was studied by varying copolymer arrangement and molar ratio of gold to thiol. In the following chapter, hybrid polymer-gold nanoparticles of different shapes were synthesized to investigate and compare their performance as near-infrared (NIR) photothermal agent and anticancer drug nanocarrier in vitro. Block copolymer was prepared to impart colloidal stability and conjugate doxorubicin via pH-responsive linker. Finally, in the last two chapters, the synthesis of hybrid nanoparticles for the delivery of nitric oxide (NO) was explored. Hybrid nanoparticles composed of block copolymer bearing N-diazeniumdiolate (NONOate) functionalities and gold nanoparticle core was designed for the storage and controlled released of NO. The NO nanocarriers demonstrated toxicity towards biofilm bacteria and cancer cells. An alternative approach using polydopamine coated IONPs was also investigated for encapsulation of NONOate. The nanoparticles displayed colloidal stability and excellent antibacterial activity against biofilm bacteria.