Au–Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment

Abstract

Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents.

Femtosecond Laser Fabricated Ag@Au and Cu@Au Alloy Nanoparticles for Surface Enhanced Raman Spectroscopy Based Trace Explosives Detection

“…A variety of methods have been introduced to fabricate NPs during the last two decades such as a chemical methods including seed growth method, citrate reduction method, laser ablation in liquids (LAL) and electrochemical methods [1][2][3][4][5][6][7]. In recent years, LAL grown as a promising simple green technique to fabricate NPs in a single experiment.…”

Intracellular Biodegradation of Ag Nanoparticles, Storage in Ferritin, and Protection by a Au Shell for Enhanced Photothermal Therapy

“…18 However, they are generally regarded as unstable and prone to intense and rapid oxidation and subsequent structural degradation in simplified aqueous saline and biological media. [19][20][21] At the increasing degree of complexity, on the cell [22][23] or organism level, [24][25] the studies assessing silver nanoparticles degradation and performance become increasingly complicated.…”

Recent Advances in Nanoparticle Shape and Composition Regulation Based on Galvanic Replacement for Cancer Treatment

“…Hollow nanocages exhibit fascinating characteristics, in that their localized surface plasmon resonances (LSPRs) shift to the near-infrared (NIR) wavelength region owing to the narrowing of the energy gap between the anti-symmetric anti-bonding resonance modes and the symmetric bonding resonance modes depending on shell thickness and diameter [109][110][111][112][113][114][115][116][117][118]. These high-extinction features in the NIR region induce strong exothermic phenomenon caused by the surface plasmon oscillation through laser irradiation in the corresponding wavelength range, which is often referred to as photothermal conversion [119][120][121][122][123][124][125][126][127][128][129][130][131][132][133]. In cancer treatment, photothermal conversion is highly efficient in killing cancer cells vulnerable to hyperthermia.…”