title: Dependence of Gold Nanoparticle Radiosensitization on Functionalizing Layer Thickness.
abstract: Gold nanoparticles functionalized with polyethylene glycol of different chain lengths are used to determine the influence of the capping layer thickness on the radiosensitizing effect of the particles. The size variations in organic coating, built up with polyethylene glycol polymers of molecular weight 1-20 kDa, allow an evaluation of the decrease in dose enhancement percentages caused by the gold nanoparticles at different radial distances from their surface. With localized eradication of malignant cells as a primary focus, radiosensitization is most effective after internalization in the nucleus. For this reason, we performed controlled radiation experiments, with doses up to 20 Gy and particle diameters in a range of 5-30 nm, and studied the relaxation pattern of supercoiled DNA. Subsequent gel electrophoresis of the suspensions was performed to evaluate the molecular damage and consecutively quantify the gold nanoparticle sensitization. In conclusion, on average up to 58.4% of the radiosensitizing efficiency was lost when the radial dimensions of the functionalizing layer were increased from 4.1 to 15.3 nm. These results serve as an experimental supplement for biophysical simulations and demonstrate the influence of an important parameter in the development of nanomaterials for targeted therapies in cancer radiotherapy.
authors.affiliation: a   Departments of Physics and Astronomy.
authors.forename: Cedric
authors.initials: C
authors.lastname: Spaas
authors.affiliation: b   Oncology.
authors.forename: Rüveyda
authors.initials: R
authors.lastname: Dok
authors.forename: Olivier
authors.initials: O
authors.lastname: Deschaume
authors.affiliation: a   Departments of Physics and Astronomy.
authors.forename: Bert
authors.initials: B
authors.lastname: De Roo
authors.affiliation: a   Departments of Physics and Astronomy.
authors.forename: Mattias
authors.initials: M
authors.lastname: Vervaele
authors.affiliation: c   Materials Engineering and.
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Seo
authors.affiliation: a   Departments of Physics and Astronomy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Bartic
authors.affiliation: d   Public Health and Primary Care, Environment and Health, Katholieke Universiteit Leuven, Belgium; and.
authors.forename: Peter
authors.initials: P
authors.lastname: Hoet
authors.affiliation: b   Oncology.|e   CRUK/MRC Institute for Radiation Oncology and Biology, University of Oxford, Oxford OX3 7DQ, United Kingdom.
authors.forename: Frank
authors.initials: F
authors.lastname: Van den Heuvel
authors.affiliation: b   Oncology.
authors.forename: Sandra
authors.initials: S
authors.lastname: Nuyts
authors.affiliation: a   Departments of Physics and Astronomy.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Locquet
mesh_terms: D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry* / Q000494:pharmacology*; D053768:Metal Nanoparticles; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D011838:Radiation-Sensitizing Agents / Q000737:chemistry* / Q000494:pharmacology*; D013499:Surface Properties
chemical_list: D004278:DNA, Superhelical; D011838:Radiation-Sensitizing Agents; D011092:Polyethylene Glycols; D006046:Gold