A facile method to study the bioaccumulation kinetics of amorphous silica nanoparticles by quantum dot embedding

Abstract

Amorphous silica nanoparticles (AmSiNPs) are one of the most extensively produced NPs in the world. Nevertheless, the bioaccumulation kinetics of AmSiNPs, as an indicator of their toxicity, have rarely been examined, due to the lack of convenient methods of quantification. In this study, AmSiNPs of different sizes embedded with CdSeTe@ZnS–SiO₂ quantum dots (QDs) were synthesized and the kinetics of their bioaccumulation in A549 human lung carcinoma cells were examined using the Cd in the QD core as the tracer. The toxicity of the embedded AmSiNPs was comparable to that of their coreless counterparts. In the bioaccumulation kinetics experiment, the internalization of AmSiNPs of two different size classes (20 and 100 nm) in A549 cells was significant. The Cd-based estimation of NP bioaccumulation was similar to that determined by direct Si-based quantification of both QD-embedded AmSiNPs and to their coreless counterparts. The uptake kinetics of the 20 and 100 nm AmSiNPs at different ambient concentrations were then investigated. Considering the uncertainty regarding the dose metric of NPs, their mass-, particle-number-, and surface-area-based uptake was determined. The difference in the uptake of NPs of different sizes was better explained by the surface-area-based metric. Overall, we developed a facile method to investigate the bioaccumulation kinetics of AmSiNPs. This method allows the environmental and biological behaviors of not only a single type but also a mixture of AmSiNPs to be examined if different Cd isotopes are applied in the core. The resulting information is essential in real applications and toxicity evaluation of AmSiNPs.