title: Enhanced cellular uptake of size-separated lipophilic silicon nanoparticles.
abstract: Specific size, shape and surface chemistry influence the biological activity of nanoparticles. In the case of lipophilic nanoparticles, which are widely used in consumer products, there is evidence that particle size and formulation influences skin permeability and that lipophilic particles smaller than 6 nm can embed in lipid bilayers. Since most nanoparticle synthetic procedures result in mixtures of different particles, post-synthetic purification promises to provide insights into nanostructure-function relationships. Here we used size-selective precipitation to separate lipophilic allyl-benzyl-capped silicon nanoparticles into monodisperse fractions within the range of 1 nm to 5 nm. We measured liposomal encapsulation and cellular uptake of the monodisperse particles and found them to have generally low cytotoxicities in Hela cells. However, specific fractions showed reproducibly higher cytotoxicity than other fractions as well as the unseparated ensemble. Measurements indicate that the cytotoxicity mechanism involves oxidative stress and the differential cytotoxicity is due to enhanced cellular uptake by specific fractions. The results indicate that specific particles, with enhanced suitability for incorporation into lipophilic regions of liposomes and subsequent in vitro delivery to cells, are enriched in certain fractions.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
authors.forename: Aubrey E
authors.initials: AE
authors.lastname: Kusi-Appiah
authors.affiliation: Department of Chemistry, University of Toronto, Toronto, Canada.
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Mastronardi
authors.affiliation: Department of Chemistry, University of Toronto, Toronto, Canada.
authors.forename: Chenxi
authors.initials: C
authors.lastname: Qian
authors.affiliation: Department of Chemistry, University of Toronto, Toronto, Canada.
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Chen
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
authors.forename: Lida
authors.initials: L
authors.lastname: Ghazanfari
authors.affiliation: Department of Physics, Florida State University, Tallahassee, Florida, USA.
authors.forename: Plengchart
authors.initials: P
authors.lastname: Prommapan
authors.affiliation: Institute of Nanotechnology and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Kübel
authors.affiliation: Department of Chemistry, University of Toronto, Toronto, Canada.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Ozin
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, Florida, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Lenhert
mesh_terms: D001692:Biological Transport; D002470:Cell Survival; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008081:Liposomes; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D010316:Particle Size; D012825:Silicon / Q000737:chemistry
chemical_list: D008081:Liposomes; D012825:Silicon