Fabrication of highly biocompatible SiO2@Au-BSA nanoconjugates: Towards a promising thermal therapy route.

SiO₂@Au nanoshells have gained relevance in recent years, especially in biomedical areas, acting as thermal therapy agents due to their high capacity to absorb light and transform it into heat that increases the temperature of the medium. Therefore, it is important to develop methodological strategies to obtain stable, highly specific and biocompatible nanoparticles. In this work, the synthesis of core-shell structures based on SiO₂@Au is reported, where the growth a thin shell ⁓ 46 nm on silica platform was possible. Subsequently, optimal conditions were developed for the binding of a bovine serum albumin (BSA) protein using a thiolated linker such as mercaptoethanol. Likewise, the photothermal conversion capacity was investigated using thermal lens spectroscopy. Thermal diffusivity values were reported for the first time during the conjugation process of gold nanoshells, where an increase of 37.5 % was recorded as the conjugation was completed. Finally, the cytotoxic potential of the developed nanoconjugates was evaluated through their hemolytic rate in human red blood cells. The findings suggest high hemocompatibility of the SiO₂@Au-BSA complex because they did not cause significant oxidative stress and are classified as nonhemolytic. Therefore, in this work we propose a synthesis route for a thermal agent based on SiO₂@Au and bovine serum albumin, highly biocompatible and with high photothermal conversion. The results of this work aim to clarify the safety of using gold nanoshells as a thermal therapy agent.