Elucidating The Cellular Uptake Mechanism Of Graphene-isolated-Au-nano-crystal

With their unique physicochemical properties, nanomaterials have been extensively studied to construct smart multifunctional nanosystems for cancer therapy, biosensing, and cellular imaging. Nanoparticles are considered as efficient intracellular delivery platforms for such biological cargos as DNA, proteins, and drug molecules for therapy. Elucidating the exocytosis and metabolism of NPs in cells could improve diagnostic sensitivity and therapeutic efficiency. Therefore, a simple and rapid method to establish the cellular uptake mechanism and pathway is necessary.In previous works, we developed a biocompatible nanocrystal nanostructure, graphene-isolated-Au-nano-crystal (GIAN), for combined drug delivery, imaging, and NIR-induced hyperthermia. In this work, the cellular uptake mechanism was explored by utilizing the unique property of dual-model imaging ability, the main contents of this thesis are as follows:(1) The GIAN has strong and unique Raman scattering properties and is demonstrated to be a good Raman tag for cell staining and surface-enhanced-Raman-scattering (SERS) Raman imaging. GIANs have also proven to be good two-photon luminescence (TPL) agents for NIR laser imaging, making GIANs a dual-modal imaging tool. Such dual-modal capability offers an easy, label-free and accurate way to investigate the cellular entry pathways of NPs.(2) We investigated the cellular uptake of aptamer-functionalized GIANs by monitoring the intrinsic Raman and TPL signals of GIANs in live cells pretreated with several types of endocytic inhibitors which selectively block specific uptake pathways. Using multimodal cell imaging, we concluded that cellular entry of the aptamer-functionalized GIANs is mainly via which pathway.(3) To investigate the effect of size on the mechanism of endocytosis on nanoparticles, we synthesised gold nanoclusters (AuNCs) which is only 2 nm in size. We studied cellular uptake of ultrasmall fluorescent gold nanoclusters by HeLa cells using confocal fluorescence microscopy.