Lung toxicities of core–shell nanoparticles composed of carbon, cobalt, and silica

Mohammed T Al Samri,^1,* Rafael Silva,^2,* Saeeda Almarzooqi,³ Alia Albawardi,³ Aws Rashad Diab Othman,¹ Ruqayya SMS Al Hanjeri,¹ Shaikha KM Al Dawaar,¹ Saeed Tariq,⁴ Abdul-Kader Souid,¹ Tewodros Asefa<sup>2,5

1</sup>Department of Pediatrics, United Arab Emirates University, Abu Dhabi, United Arab Emirates; ²Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; ³Department of Pathology, ⁴Department of Anatomy, United Arab Emirates University, Abu Dhabi, United Arab Emirates; ⁵Department of Chemical Engineering and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA

^*These authors contributed equally to this work

Abstract: 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: carbon nanoparticles, cobalt nanoparticles, silica nanoparticles, cobalt oxide nanoparticles, biocompatibility, nanotoxicology