title: Structure Tuning of Electrostatically Self-Assembled Nanoparticles through pH.
abstract: pH can be used to tune the self-assembly of cationic polyelectrolyte dendrimers and oppositely charged dyes and to produce particles with a desired shape and size in aqueous solution. We present fundamental insight into the effect of pH on electrostatic self-assembly of poly(amidoamine) dendrimers of generation 4 and di- and trivalent anionic organic dyes. The solution pH is used as a key to turn on the interaction and to control the association by regulating the macroion charge. Stable and well-defined nanoparticles are formed in solution, being more stable at low pH where the dendrimer protonation is complete. Nanoparticle stability was correlated with ζ-potential measurements. We prove that the assemblies are electrostatically stabilized and elucidate the importance of the surface charge density. pH was also used as a key to nanoparticle dimension and shape. For example, smaller particles form at a lower pH. The nanostructures have been characterized using dynamic light scattering and small-angle neutron scattering. A "phase diagram" has been developed for each dye, showing the assembly size, shape, and instability regions dependent on the pH. Overall, a pH-responsive nanoparticle shape is a key step toward the design of novel smart therapeutic carrier systems.
authors.affiliation: Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstraße 3, D-91058 Erlangen, Germany.|Institut Laue-Langevin, DS/LSS , 71 Avenue des Martyrs, F-38000 Grenoble, France.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Mariani
authors.affiliation: Institut Laue-Langevin, DS/LSS , 71 Avenue des Martyrs, F-38000 Grenoble, France.
authors.forename: Ralf
authors.initials: R
authors.lastname: Schweins
authors.affiliation: Department of Chemistry and Pharmacy and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstraße 3, D-91058 Erlangen, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Gröhn
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D050091:Dendrimers / Q000737:chemistry*; D000067493:Dynamic Light Scattering; D006863:Hydrogen-Ion Concentration; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D033363:Neutron Diffraction; D053838:Scattering, Small Angle; D055672:Static Electricity
chemical_list: D004396:Coloring Agents; D050091:Dendrimers; C104700:PAMAM Starburst