Plasmonic Gold Nanocrosses with Multidirectional Excitation and Strong Photothermal Effect

Abstract

We report a facile chemical synthesis of well-defined gold nanocrosses through anisotropic growth along both <110> and <001>, whereas gold nanorods grow only along either <110> or <001>. The multiple branching was achieved by breaking the face-centered-cubic lattice symmetry of gold through copper-induced formation of single or double twins, and the resulting gold nanocrosses exhibited pronounced near-IR absorption with a great extension to the mid-IR region. As studied by discrete dipole approximation (DDA) simulations, the entire nanocross gets excited even when one of the branches is exposed to incident light. The above properties make them useful as octopus antennas for capturing near-IR light for effective photothermal destruction of cells. The cell damage process was analyzed using the Arrhenius model, and its intrinsic thermodynamic characteristics were determined quantitatively. Besides effective photothermal treatment and two-photon luminescence imaging, the near- and mid-IR-absorbing gold nanocrosses may also find applications in IR sensing, thermal imaging, telecommunications, and the like.

Steam generation in a nanoparticle-based solar receiver

“…It has been confirmed both experimentally and theoretically [13,14,16,[23][24][25] that under an intensive laser heating (i.e. > 1000 MW/m 2 ), bubbles can be generated around the heated nanoparticles [26,27].…”

“…Clearly classical nucleation and heat transfer theory does not support the formation of nanobubbles on top of nanoparticles at < 1 MW/m 2 that is typical for a Fresnel Lens, albeit it may be possible under high fluence lasers (i.e., > 1000 MW/m 2 ) [13,14,16,23,24].…”

“…It has been reported recently that certain nanoparticles, especially those with Localized Surface Plasmon Resonance (LSPR) properties [9,10], can absorb solar energy efficiently in a liquid medium [11][12][13][14]. For an aqueous nanoparticle dispersion [15], it would lead to a rapid increase of the particle temperature and steam production, albeit the bulk fluid was still in the subcooled state [16,17].…”

Photothermo-responsive Cu7S4@polymer nanocarriers with small sizes and high efficiency for controlled chemo/photothermo therapy

“…The heat energy (Q 0 ) of the sample container and solvent was measured independently and found to be 60.5 mW. As a result, the heat conversion efficiency (η T ) of the Cu 7 S 4 NCs under 808-nm laser was finally calculated to be 25.4%, which was higher than that of reported gold nanoshells (13%, 800 nm), gold nanorods (21%, 800 nm) [62] and Cu 2−x Se (22%, 980 nm) [63]. It should be mentioned that the polymer shell of the NCs demonstrates a negative impact on the overall photothermal conversion ef- DOX controlled release from nanocomposites DOX as model drugs was loaded onto the polymer matrixes of nanocarriers through physical adsorption and the DOX-loaded NCs were termed as NCs-DOX.…”

Noble Metal Nanoparticle Platform

“…For example, multiple-branched gold nanocrosses showed a pronounced NIR and mid-IR absorption, which enabled effective photothermal destruction of the cancer cells in vitro after irradiation with a 900 nm laser (30 s at 4.2 W/cm 2 or 150 s at 2.6 W/cm 2 ) [94]. The enthalpy and entropy of the photothermal effect were calculated to 229 6 5 kJ mol 21 and 460 6 17 J mol 21 K 21 , respectively.…”