Abstract
A four-member homogenous quadrumer composed of silver core-shell nanostructures is tailored to enhance photothermal heat generation efficiency in sub-nanosecond time scale. Calculating the plasmonic and photothermal responses of metallic cluster, we show that it is possible to achieve thermal heat flux generation of 64.7 μW.cm-2 and temperature changes in the range of ΔT = 150 K, using Fano resonant effect. Photothermal heat generation efficiency is even further enhanced by adding carbon nanospheres to the offset gap between particles and obtained thermal heat flux generation of 93.3 μW.cm-2 and temperature increase of ΔT = 172 K. It is also shown that placement of dielectric spheres gives rise to arise collective magnetic dark plasmon modes that improves the quality of the observed Fano resonances. The presented data attests the superior performance of the proposed metallodielectric structures to utilize in practical tumor and cancer therapies and drug delivery applications.
Highlights
Photothermal heat generation in metallic subwavelength structures in a short time scale has been extensively utilized in biological applications [1], photothermal cancer and tumor therapies [2,3,4], photothermal imaging [5], bubble formation for surgery [6], control of enzyme reaction [7], optoacoustic thermal therapy [8], and nanodrug delivery [9]
For the noble metallic particles, localization of surface plasmon resonances (LSPRs) in nanosize structures with absorptive behavior leads to tremendous dissipation of an incident optical energy [10]
Ag provides a remarkable absorption of optical energy in the visible to the near infrared region (NIR) due to ohmic losses and the plasmon resonances excitation here depending on the complexity of the aggregate [21]
Summary
Photothermal heat generation in metallic subwavelength structures in a short time scale has been extensively utilized in biological applications [1], photothermal cancer and tumor therapies [2,3,4], photothermal imaging [5], bubble formation for surgery [6], control of enzyme reaction [7], optoacoustic thermal therapy [8], and nanodrug delivery [9]. For the noble metallic particles, localization of surface plasmon resonances (LSPRs) in nanosize structures with absorptive behavior leads to tremendous dissipation of an incident optical energy [10] This large amount of light absorption can be achieved in an extremely short time interval by the free electron gas through electron-electron scattering in a picosecond time scale at the metal-dielectric boundary, and results in photothermal heat generation [11]. Fano resonance (FR) appears as a pronounced and distinct minimum at a certain frequency in the scattering spectra which strongly depends on the position and quality of dark and bright modes At this point a high amount of optical energy accumulates in the structure and can be controlled based on application. It is verified that this structural modification can result in a dramatic enhancement in the temperature
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