Dual synergetic approach for targeting dysfunctional cells based on rare-earth-doped forsterite nanoparticles

In recent years, forsterite (Fo, Mg₂SiO₄) has emerged as a promising biomaterial for bone tissue engineering scaffolds, demonstrating efficacy in inhibiting the growth of clinical bacterial isolates. In addition, rare-earth (RE) doped Fo exhibits excitation properties that match the nearinfrared (NIR) biological transparency window (700–1800 nm), facilitating deep penetration into biological tissues. Despite these advantageous properties, data on the toxicity of RE-doped forsterite is lacking, and effects on damaged or dysfunctional cells, such as cancer cells, are not known. The aim of this study was to examine the toxicity of RE-doped forsterite nanoparticles (NPs) in cultures of healthy and tumor skin cells. Specifically, forsterite doped with Er3+, Yb3+, and a combination of Er3+/Yb3+, produced via reverse strike coprecipitation (RSC), was employed in cytotoxicity assays. The influence of solution pH on the toxicity response was also investigated. Data demonstrated that all NPs exhibited biocompatibility with HaCaT keratinocytes, while melanoma B16-F10 cells showed increased cell death. Photoluminescence (PL) analyses found that Fo:Yb displayed enhanced blue emission under 980 nm excitation, whereas Fo:Er/Yb exhibited green and red emissions. Data suggest that combining alkalinization effect of forsterite with the up-conversion (UC) photoactivity of NPs might serve as a dual-attack system for in situ oncological treatment.