Preparation Of Nanomaterials Based On Natural Polyphenols And Their Application In Cancer Therapy

Natural polyphenol is derived from animals and plants,which has abundant reserves.Because it is a natural reducing agent with high biocompatibility and bioactivity,so that nanomaterials prepared by natural polyphenols have attracted extensive attention in the field of biomedicine.Therefore,in this paper,the natural polyphenolic compound resveratrol and dopamine were used as examples to prepare gold nanomaterials by their reducing abilities.The synthesis mechanism,kinetic control,and application for cancer therapy were studied carefully.In the second chapter,the gold nanorods(GNRs)were first to be synthesized by a seedless method,which have a good size monodispersity and tunable aspect ratio.The longitudinal localized surface plasmon resonance peaks(LSPR)can be adjusted from 570 nm to 950 nm by adjusting the feed ratio of chloroauric acid(HAuCl4),resveratrol,silver nitrate(AgNO3),cetyl trimethyl ammonium bromide(CTAB),and sodium borohydride(NaBH4).The success of our approach is attributed to the aromatic structure and mild reducibility of resveratrol,which enhances the facet-selective absorption of CTAB,and promotes the anisotropic growth of GNRs.In addition,due to the mild reducibility of resveratrol,secondary nucleation during the synthesis process is avoided,which promotes the monodispersity of GNRs.As a chemopreventive agent,the combination of resveratrol in GNRs synthesis will consolidate the theranostic applications of GNRs.In the last chapter,although we have successfully prepared GNRs using resveratrol,the toxic ligand CTAB was still used in the synthesis process.So,in the third chapter,in order to further improve the biocompatibility of nanomaterials,using resveratrol as a reductant cum coating agent to prepare gold nanocomposites in a surfactant-free method,will promote the applications of resveratrol in cancer theranostics.The as-prepared Au@resveratrol hollow nanocomposites(Au@Res HNPs)not only have good photothermal properties of the gold structure,but also have the biological activity of the shell formed by resveratrol.The in vitro experiments indicated that the Au@Res HNPs can block the cell cycle and slow down the growth rate,and cause apoptosis after laser irradiation at 808 nm.Since no toxic surfactant is introduced,the synthesis method avoids the tedious separation of surfactants and complex surface modification,and is a highly feasible method for preparing gold nanocomposites.In the fourth chapter,we focus on polydopamine,its good biocompatibility and light absorption property,are widely used by researchers in the surface modification of nanomaterials and photothermal therapy for cancer.In this chapter,we prepared dendritic Au-Ag@polydopamine nanoparticles(Au-Ag@PDA NPs)using dopamine as a reducing cum coating agent in a surfactant-free method,and developed its mitochondria-targeting therapy and exocytosis inhibition for papillary thyroid cancer,which achieves an enhanced therapeutic effect of papillary thyroid cancer.In order to better understand the nano-bio interaction,the endocytosis pathway and intracellular fate of Au-Ag@PDA NPs in TPC-1 cells are studied.The results indicate that Au-Ag@PDA NPs mainly accumulate in mitochondria and they can hardly be excreted by the TPC-1 cells.This leads to dysfunction of mitochondria,which inhibits the expression of dihydroorotate dehydrogenase and ultimately leads to the S-phase cell cycle arrest.Despite the cancer cells can avoid apoptosis or necrosis through an autophagy-mediated survival,the TPC-1 cells can be killed with the aid of photothermal therapy.