Silver Nanoplates for Thermal Therapy of Cancer

E. ZELAYA; J. C. AZCARATE; D. O. MÁRTIRE; M. B. RIVAS AIELO; P. D. GARA

Villa Carlos Paz

Congreso; XIII Encuentro Latino-Americano de Fotoquímica y Fotobiología; 2017

Universidad Nacional de Santiago del Estero

Utilization of thermal therapy (hyperthermia) is defined as the application of exogenous heat induction for treating various diseases. In general, hyperthermia is applied as adjuvant means in therapeutic protocols combining chemotherapy and/or irradiation both of which can induce irreversible cellular DNA damage [1].New prospects for light-activated therapies have been emerged in recent years by exploiting the unique optical properties of noble-metal nanoparticles. When the incoming light couples with the oscillation frequency of the conduction electrons in noble-metal nanoparticles, a so called localized surface plasmon resonance (LSPR) arises, which is manifested as a strong absorption band along with an efficient photo-to-heat conversion (photothermal effect) [2]. More specifically, when localized in the tumor, the plasmonic nanoparticles can act as efficient photothermal transducers by converting the light absorbed by surface plasmon resonances into heat, leading to a localized rise of temperature, thereby achieving therapeutic cell killing [3,4].We have synthesized silver nanoplates with PEG (polyethylene glycol) and PVP (polyvinylpolypyrrolidone) cappings. TEM images allow us to see the shape and size of the particles. UV-visible absorption spectra showed that the LSPR maxima of the three nanoparticles are located between 700 and 800 nm. These wavelengths are within the near-infrared (NIR) window, where light has its maximum depth of penetration in tissue. ATR-FTIR spectra of the nanoplates were measured to confirm the effective coating.Suspensions of different concentration of each nanoparticle were irradiated with a 800 nm laser and the temperature was measured at different irradiation times. Results showed that there is a photothermal effect for the suspensions of the nanoplates. The temperature increase for the suspensions of the nanoparticles is larger than those observed upon irradiation of water and a calorimetric reference, used as controls. These in vitro assays seem to indicate that the nanopaltes are good candidates to be employed in photo-thermal therapy.