Biomedical Applications of Gold and Silver Nanoparticles

摘要

Noble nanoparticles have attracted a large amount of attention among researchers due to their brilliant colors, which results from their unique optical properties from the localized surface plasmon resonance (LSPR) effect. Among different kinds of noble nanoparticles, gold and silver nanoparticles have been studied the most because of their superior properties.;The unique optical properties of gold nanoparticles (AuNPs) depend on many different factors, such as the size and shape of the nanoparticles. Besides unique optical properties, AuNPs can be easily modified and conjugated with different kinds of. With these properties, AuNPs have been investigated in various biomedical applications, including cancer imaging and photothermal therapy.;Silver nanoparticles (AgNPs) have been widely investigated as a promising antimicrobial agent after recent advances in nanotechnology. However, AgNPs have been found to cause cytotoxicity to mammalian cells in a dose-dependent manner. Therefore, it is necessary to either reduce the amount of AgNPs needed or combine them with other antimicrobial agents in order to employ the super antimicrobial properties of AgNPs.;In the current study, AuNRs were first synthesized, characterized and tested on healthy mammalian cells and tumor cells. Results showed that synthesized AuNRs were highly toxic towards tumor cells and at the same time had little or no influence on healthy human dermal fibroblasts at a certain concentration range.;Next, silver-coated AuNRs (Ag/AuNRs) were synthesized in order to employ the antimicrobial properties of silver. Their antimicrobial properties were tested on different bacteria species. Furthermore, TEM images showed "pits" on the treated S. aureus membrane. Also, fluorescence assays of the bacteria species treated with Ag/AuNRs showed much less bacteria and no formation of biofilms. The cytotoxicity of the Ag/AuNRs was investigated and no obvious decrease in HDF proliferation was found up to a certain concentration.;Finally, some other shapes of nanoparticles, gold nanospheres and gold nanostars, were synthesized and characterized. Results showed limited tunability of gold nanospheres in their absorption band. However, they have the potential to be used as drug delivery systems. In contrast, the absorption bands of gold nanostars can be tuned to the NIR region for applications involving imaging and photothermal therapy.