Melanoma cells cytotoxic response to different upconversion nanoparticles and hyperthermia

• Autor(a) principal: Brandão, David Pinto
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/30962
• topic: Hyperthermia; Melanoma; NaYF4:Yb; Er (20/2%)@mSiO2; Gd2O3:Yb; Er; Cytotoxicity; Upconversion nanoparticles

Melanoma is one of the most aggressive types of skin cancer with a high mortality rate. Therefore, there has been an increasing demand for new therapeutic approaches to counteract such elevated rates. Hyperthermia is a therapeutic approach that works by raising the temperature inside of the tumour, ranging between 41 and 45 ºC. The temperature increase may disrupt the biochemical processes of the tumour cells, which in turn can translate into cellular death either by apoptosis or necrosis. However, this promising therapeutic therapy has some hurdles, especially regarding the homogeneous distribution of heat throughout the tumour. Because of the limitations of this technique, there is a need to create new ways of applying it with higher efficiency. Nanoparticles can be used to induce hyperthermia, and they have the upside of being able to be fine-tuned in order to specifically target the tumour and apply heat from inside-out. Various types of nanoparticles have been used to generate hyperthermia, but more recently upconversion nanoparticles (UCNPs) have garnered a lot of interest due to their unique characteristics. The objective of this work was to develop the groundwork needed to apply hyperthermia by using UCNPs. To achieve this objective four different melanoma cells lines were used, MNT-1, B16-F10, A375 and SK-MEL-28, along with 2 different types of UCNPs, NaYF4:Yb,Er(20/2%)@mSiO2 (NaYF4UCNPs@mSiO2) and Gd2O3:Yb,Er (Gd2O3UCNPs). Prior to every assay, both types of UCNPs were dispersed in ultrasound bath for 20 minutes. Physicochemical characterization of nanoparticles was performed by dynamic light scattering (DLS) for NaYF4UCNPs@mSiO2 nanoparticles size and morphology was also assessed by Scanning transmission electron microscopy (STEM). DLS results of Gd2O3UCNPs showed high values of hydrodynamic diameter and polydispersity index, indicating agglomeration of the nanoparticles. Furthermore, zeta potential showed a low value, indicating the instability of the nanoparticles and tendency to aggregate. DLS results of NaYF4UCNPs@mSiO2 showed acceptable values of hydrodynamic diameter, with low values of polydispersity index indicating a more uniform size of nanoparticles. Zeta potential of NaYF4UCNPs@mSiO2 indicate that they have incipient stability at 25 μg/mL, and lower stability at 100 μg/mL. STEM imaging and analysis indicated size of 77.78 ± 3.53 nm. Cytotoxicity of both UCNPs were tested by WST-8 protocol, with Gd2O3UCNPs being tested on MNT-1 and A375 cell lines, and NaYF4UCNPs@mSiO2 being tested on the four cell lines mentioned above. In both cases, cells were exposed to 12,5, 25, 50, 100 and 200 μg/mL of UCNPs. Gd2O3UCNPs caused a decrease in the viability of A375 at the highest concentrations after 48 hours of exposure, compared to the control group. NaYF4UCNPs@mSiO2 caused a decrease in cell viability for all cell lines for 100 and 200 μg/mL after 24 and 48 hours, with MNT-1 cells also having a decrease of viability at 25 and 50 μg/mL for 48 hours after the exposure. A375 cells have a decrease of viability for 50 μg/mL at 48 hours after the exposure. Cellular uptake of NaYF4UCNPs@mSiO2 only happened on MNT-1 and SK-MEL-28 cell lines. Hyperthermia sensitivity profile of MNT-1 and A375 cell lines was performed by exposure to 43 and 45 ºC during 30, 60 and 120 minutes, and cell viability measured 24, 48 and 72 hours after exposure through the MTT assay. In almost every case MNT-1 cell viability decreased with the increase of exposure time where, after 120 minutes of exposure, cell viability was below 60% for all the exposure times in both of the tested temperatures. Comparatively, A375 cells exposed to 43 ºC did not have viability lower than 60% in all cases. Finally, MNT-1 cells exposed to 45 ºC for 120 minutes showed viability values below 20% after 48 and 72 hours, while on the other hand, A375 cells viability ranged from 40 to 60%, depending on the exposure time. This work allowed to set a range of concentrations of UCNPs that can be used without compromising cell viability, being good candidates for near-infrared induced hyperthermia to melanoma cells. This work also allowed to conclude which temperatures and exposure times to apply in order to potentiate the effect of hyperthermia in melanoma cells. The conditions defined in the current work (UCNPs concentrations and temperatures) can be replicated to generate near-infrared light-triggered hyperthermia in melanoma cells using UCNPs.