title: Molecular dynamics study of the structure and interparticle interactions of polyethylene glycol-conjugated PAMAM dendrimers.
abstract: We performed molecular dynamics (MD) simulations of one or two copies of polyethylene glycol of molecular weight 550 (PEG550) and 5000 (PEG5000) daltons, conjugated to generation 3 (G3) to 5 (G5) polyamidoamine (PAMAM) dendrimers with explicit water using a coarse-grained model. We found the radii of gyration of these dendrimer-PEG molecules to be close to those measured in experiments by Hedden and Bauer (Hedden , R. C. ; Bauer , B. J. Macromolecules 2003 , 36 , 1829.). Densely grafted PEG ligands (>50% of the dendrimer surface) extend like brushes, with layer thickness in agreement with theory for starlike polymers. Two dendrimer-PEG complexes in the box drift away from each other, indicating that no aggregation is induced by either short or long PEG chains, conflicting with a recent view that the cytotoxicity of some PEGylated particles might be due to particle aggregation for long PEG lengths.
authors.affiliation: Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. leeh3@nhlbi.nih.gov
authors.forename: Hwankyu
authors.initials: H
authors.lastname: Lee
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Larson
mesh_terms: D003198:Computer Simulation; D050091:Dendrimers; D015394:Molecular Structure; D011073:Polyamines / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D055672:Static Electricity; D014867:Water / Q000737:chemistry
chemical_list: D050091:Dendrimers; C104700:PAMAM Starburst; D011073:Polyamines; D014867:Water; D011092:Polyethylene Glycols