Carbon–SiO₂ Hybrid Nanoparticles with Enhanced Radical Stabilization and Biocide Activity

Nanocarbon and nanosilica are widely-used nanomaterials of significant industrial interest. Herein, a library of {carbon–SiO 2 } hybrid nanoparticles, with controlled nanocarbon content and sp 3 /sp 2 profile, was engineered by a flame spray pyrolysis (FSP) process in one step. Their structure–function relationship was evaluated by studying their radical-generation and radical-stabilization activities, using electron paramagnetic resonance spectroscopy in tandem with their biocide activity toward marine bacteria Aliivibrio fischeri . The surface properties of the C–SiO 2 hybrids were studied by Raman spectroscopy and surface-charge analysis by zeta potential measurements. Raman spectroscopy indicates that the FSP process, as designed and used herein, allows the progressive incorporation of nanocarbon moieties into the SiO 2 nanostructure, which may lead to distortion of the siloxane matrix. Concurrently, the C–SiO 2 hybrids’ surface charge profile reveals a trend correlated with the acute biocide activity toward Aliiv. fischeri . Interestingly, we find no correlation between the stable radical population and the nanohybrids’ biocide activity. Within this context, we discuss the role of surface charge, radical properties, and SiO 2 lattice distortions by the nanocarbon, all of them parametrized via FSP process protocols. Thus, the present study’s findings provide critical insight into the structure–biocide activity relationship of carbon–SiO 2 hybrid nanoparticles. Technology-wise, the present work exemplifies a scalable FSP process for the industrial production of applied nanomaterials, such as C–SiO 2 nanostructures.