Au Nanorod Design as Light-Absorber in the First and Second Biological Near-Infrared Windows for in Vivo Photothermal Therapy

Abstract

Photothermal cancer therapy using near-infrared (NIR) laser radiation is an emerging treatment. In the NIR region, two biological transparency windows are located in 650-950 nm (first NIR window) and 1000-1350 nm (second NIR window) with optimal tissue transmission obtained from low scattering and energy absorption, thus providing maximum radiation penetration through tissue and minimizing autofluorescence. To date, intensive effort has resulted in the generation of various methods that can be used to shift the absorbance of nanomaterials to the 650-950 nm NIR regions for studying photoinduced therapy. However, NIR light absorbers smaller than 100 nm in the second NIR region have been scant. We report that a Au nanorod (NR) can be designed with a rod-in-shell (rattle-like) structure smaller than 100 nm that is tailored to be responsive to the first and second NIR windows, in which we can perform hyperthermia-based therapy. In vitro performance clearly displays high efficacy in the NIR photothermal destruction of cancer cells, showing large cell-damaged area beyond the laser-irradiated area. This marked phenomenon has made the rod-in-shell structure a promising hyperthermia agent for the in vivo photothermal ablation of solid tumors when activated using a continuous-wave 808 m (first NIR window) or a 1064 nm (second NIR window) diode laser. We tailored the UV-vis-NIR spectrum of the rod-in-shell structure by changing the gap distance between the Au NR core and the AuAg nanoshell, to evaluate the therapeutic effect of using a 1064 nm diode laser. Regarding the first NIR window with the use of an 808 nm diode laser, rod-in-shell particles exhibit a more effective anticancer efficacy in the laser ablation of solid tumors compared to Au NRs.

Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

“…Similarly, Ag nanowires have been widely exploited as templates for the preparation of hollow nanotubes via the GRR [86,97,[100][101][102][103][104]. Other structures commonly obtained through the GRR between HAuCl 4 and the corresponding Ag template include nanorings [105,106], nanoframes [107][108][109], and nanorattles [110][111][112][113][114]. A set of hollow AuAg nanostructures are shown in Figure 3.…”

Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

“…15,16 A great variety of LNPs have been applied in biomedical research, not only for imaging but also for other purposes including drug delivery and in vitro and in vivo photothermal therapies. 17 Quantum dots (QDs), 18,19 gold NPs, 20 carbonbased NPs (C-NPs), 21,22 organic NPs, 23 and rare earth-doped nanocrystals (RENPs) 24 are among the nanoparticle-based fluorescent probes that have been successfully used in biomedicine.…”

Thermal stability of mesoporous silica-coated gold nanorods with different aspect ratios

“…The plasmonic properties of gold nanorods allow them to be used in photothermal therapy [1,2], imaging techniques [3,4], theranostics [5,6], sensing applications [7][8][9][10] and optical memories [11,12].…”

“…in photothermal therapy [1,2] and photoacoustic imaging [36][37][38]. It was shown that embedding the nanorods into a titaniumoxide matrix [39], or coating with carbon [40] or other materials [7,25] can protect them from shape transformations during heating up to ~690 °C.…”