title: Quantification of Internalized Silica Nanoparticles via STED Microscopy.
abstract: The development of safe engineered nanoparticles (NPs) requires a detailed understanding of their interaction mechanisms on a cellular level. Therefore, quantification of NP internalization is crucial to predict the potential impact of intracellular NP doses, providing essential information for risk assessment as well as for drug delivery applications. In this study, the internalization of 25 nm and 85 nm silica nanoparticles (SNPs) in alveolar type II cells (A549) was quantified by application of super-resolution STED (stimulated emission depletion) microscopy. Cells were exposed to equal particle number concentrations (9.2 × 10(10) particles mL(-1)) of each particle size and the sedimentation of particles during exposure was taken into account. Microscopy images revealed that particles of both sizes entered the cells after 5 h incubation in serum supplemented and serum-free medium. According to the in vitro sedimentation, diffusion, and dosimetry (ISDD) model 20-27% of the particles sedimented. In comparison, 10(2)-10(3) NPs per cell were detected intracellularly serum-containing medium. Furthermore, in the presence of serum, no cytotoxicity was induced by the SNPs. In serum-free medium, large agglomerates of both particle sizes covered the cells whereas only high concentrations (≥ 3.8 × 10(12) particles mL(-1)) of the smaller particles induced cytotoxicity.
authors.affiliation: Leibniz-Institute for New Materials (INM), Campus D2 2, 66123 Saarbruecken, Germany.
authors.forename: Henrike
authors.initials: H
authors.lastname: Peuschel
authors.affiliation: Leibniz-Institute for New Materials (INM), Campus D2 2, 66123 Saarbruecken, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ruckelshausen
authors.affiliation: Leibniz-Institute for New Materials (INM), Campus D2 2, 66123 Saarbruecken, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Cavelius
authors.affiliation: Leibniz-Institute for New Materials (INM), Campus D2 2, 66123 Saarbruecken, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Kraegeloh
mesh_terms: D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008853:Microscopy; D053758:Nanoparticles / Q000009:adverse effects / Q000737:chemistry*; D010316:Particle Size; D011650:Pulmonary Alveoli / Q000187:drug effects; D012822:Silicon Dioxide / Q000009:adverse effects / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide