Toxicological profiles of hollow silica nanoparticles (h-SiO2) as a model for silica-coated systems: A benchmark study against NM-300K silver nanoparticles.

Hollow silica nanoparticles (h-SiO2), serving as a model for evaluating the toxicity of silica-coated systems, are benchmarked against NM-300K silver nanoparticles (AgNP), which have a well-established safety profile. This study systematically investigates the toxicological profiles of h-SiO2 and NM-300K AgNP through in vitro assays on Madin-Darby canine kidney (MDCK) cells and in vivo studies in male BALB/c mice over a 28-day exposure period. Cytotoxicity assays indicated significant cell death at concentrations nearing 100 ppm for both nanoparticles, with no statistically significant differences (p > 0.05). In vivo assessments revealed substantial damage to kidney, liver, and brain tissues, characterized by ballooning degeneration and neuronal vacuolation. Biomarker analysis demonstrated elevated levels of malondialdehyde (MDA) and decreased glutathione (GSH), indicating oxidative stress, while h-SiO2 exposure resulted in increased levels of 8-hydroxy-2'-deoxyguanosine (8-OH-dG), suggesting potential long-term genetic damage. Behavioral assessments, including the Morris water maze, forced swim test, and open-field test, revealed cognitive deficits and increased anxiety-like behaviors in both nanoparticle-treated groups. These findings underscore potential toxicity of thin silica shells, challenging the prevailing assumption of their inertness in biological systems. This calls for a reassessment of the safety profiles of silica-coated nanoparticles, particularly in biomedical applications where their interactions with biological tissues could lead to significant adverse effects.