We present here comparative assessments of murine lung toxicity (biocompatibility) after in vitro and in vivo exposures to carbon (C-SiO2-etched), carbon-silica (C-SiO2), carbon-cobalt-silica (C-Co-SiO2), and carbon-cobalt oxide-silica (C-Co3O4-SiO2) nanoparticles. These nanoparticles have potential applications in clinical medicine and bioimaging, and thus their possible adverse events require thorough investigation. The primary aim of this work was to explore whether the nanoparticles are biocompatible with pneumatocyte bioenergetics (cellular respiration and adenosine triphosphate content). Other objectives included assessments of caspase activity, lung structure, and cellular organelles. Pneumatocyte bioenergetics of murine lung remained preserved after treatment with C-SiO2-etched or C-SiO2 nanoparticles. C-SiO2-etched nanoparticles, however, increased caspase activity and altered lung structure more than C-SiO2 did. Consistent with the known mitochondrial toxicity of cobalt, both C-Co-SiO2 and C-Co3O4-SiO2 impaired lung tissue bioenergetics. C-Co-SiO2, however, increased caspase activity and altered lung structure more than C-Co3O4-SiO2. The results indicate that silica shell is essential for biocompatibility. Furthermore, cobalt oxide is the preferred phase over the zerovalent Co(0) phase to impart biocompatibility to cobalt-based nanoparticles.
Keywords: biocompatibility; carbon nanoparticles; cobalt nanoparticles; cobalt oxide nanoparticles; nanotoxicology; silica nanoparticles.