The Effects of Sedimentation and Dissolution on the Cytotoxicity of Ag Nanoparticles

Abstract

Nanoparticles (NPs) are being employed for various industrial purposes with increasing frequency, yet the adverse health effects associated with the prolonged exposure of humans and the environment to NPs has not been well-established. Particularly, the effects of the extrinsic (or dynamic) physicochemical properties of NPs in aqueous cell culture media (e.g., hydrodynamic size, aggregation, agglomeration, sedimentation, and dissolution of nanoparticles) on the cytotoxicities of the NPs are barely understood. In this study, to investigate the effects of two important extrinsic properties of Ag NPs, namely the sedimentation and dissolution of Ag NPs, we performed MTT cell viability tests for HeLa cells exposed to Ag NPs with varying extrinsic properties. Ag NPs with different hydrodynamic sizes, sedimentation rates, and dissolution rates were prepared via exposure to NaCl and FBS. Sedimentation of aggregated/agglomerated Ag NPs was found to contribute more significantly to the cytotoxicity of Ag NPs during early periods of exposure, whereas the cytotoxicity was more greatly enhanced later during the exposure period due to the increase in silver ions. Therefore, it is offered that any assessment of NP cytotoxicity should consider the extrinsic properties of NPs, and their time-dependent properties, because the dominant processes affecting NP cytotoxicity may change over time and lead to a misunderstanding or poor prediction of NP cytotoxicity.

Effects of Ag Nanoparticle Flow Rates on the Progress of the Cell Cycle Under Continuously Flowing "Dynamic" Exposure Conditions

“…6 The characteristic UV-vis spectrum of the Ag NPs was also observed with an absorption maximum at a wavelength of 400 nm; in addition, the good dispersion stability of the Ag NPs in DMEM cell culture media was also confirmed in a previous study. 6 The MTT cell viability assays performed for the Ag NPs are presented in Figure 1(a), which show a typical dosedependent decrease in cell viability. As shown in Figure 1(b)-(d), cell rounding and reduced cell populations were observed for the cells exposed to higher doses of Ag NPs (10 and 20 g/mL), while in the control cells, cytoid-shaped cells clustered near each other and adhered well to surfaces.…”

“…Prior to investigating the effects of flow rate on the cytotoxicity of Ag NPs, we characterized their physicochemical properties. 6 The core size distribution of the Ag NPs used in this study was found to be 8.3 ± 1.5 nm, and the particles were found to have a spherical shape. 6 The characteristic UV-vis spectrum of the Ag NPs was also observed with an absorption maximum at a wavelength of 400 nm; in addition, the good dispersion stability of the Ag NPs in DMEM cell culture media was also confirmed in a previous study.…”

“…6 The core size distribution of the Ag NPs used in this study was found to be 8.3 ± 1.5 nm, and the particles were found to have a spherical shape. 6 The characteristic UV-vis spectrum of the Ag NPs was also observed with an absorption maximum at a wavelength of 400 nm; in addition, the good dispersion stability of the Ag NPs in DMEM cell culture media was also confirmed in a previous study. 6 The MTT cell viability assays performed for the Ag NPs are presented in Figure 1(a), which show a typical dosedependent decrease in cell viability.…”

“…4,5 Recently, we reported that the physicochemical properties of Ag NPs, such as their degree of agglomerations, hydrodynamic sizes, and dissolution rates in cell culture media, also have strong influences on their cytotoxicity. 6 However, our understanding of the detailed toxicity mechanisms and the roles of these physicochemical properties is still incomplete. In addition, most of these toxicity studies were performed under in vitro systems and the current knowledge on the toxicity mechanisms of Ag NPs under in vivo physiological conditions are limited.…”

“…In addition, most of these toxicity studies were performed under in vitro systems and the current knowledge on the toxicity mechanisms of Ag NPs under in vivo physiological conditions are limited. [6][7][8] There is an urgent need to perform more toxicity evaluations of Ag NPs under in vivo systems or at least in vitro systems that can mimic in vivo conditions.…”