Photothermal effects of gold nanoparticles induced by light emitting diodes

Gold nanoparticles (AuNPs) have a great potential for biomedical application due to the superior photothermal efficiency. The photothermal effects of AuNPs in different heated media under a polychromatic and three monochromatic light emitting diode (LED) illuminations were experimentally investigated to explore the possible use of LED for the thermotherapy treatment. The results show that the noticeable temperature increase of the heated media can be achieved by the injection of AuNPs induced by LED illumination. The selection of the LED wavelength depends not only on the absorption peak wavelengths of the AuNP with different sizes but also on the absorption coefficient of the heated media. Either a smaller AuNP size, higher AuNP concentration, or higher power density can lead to a higher temperature increase. The AuNP aggregation occurred in the heated egg white, agar solution, and blood leads to the lower temperature increase comparing with the heated water. Moreover, the LED light with a wavelength of 635 nm results in better heating for the heated blood and biological tissue in vitro comparing with other selected wavelengths due to the lower light absorption of the blood, deeper penetration in biological tissues, and the light absorption rate of AuNP to a certain degree. (C) 2016 Elsevier Ltd. All rights reserved.