title: Formation Mechanism for Stable Hybrid Clusters of Proteins and Nanoparticles.
abstract: Citrate-stabilized gold nanoparticles (AuNP) agglomerate in the presence of hemoglobin (Hb) at acidic pH. The extent of agglomeration strongly depends on the concentration ratio [Hb]/[AuNP]. Negligible agglomeration occurs at very low and very high [Hb]/[AuNP]. Full agglomeration and precipitation occur at [Hb]/[AuNP] corresponding to an Hb monolayer on the AuNP. Ratios above and below this value lead to the formation of an unexpected phase: stable, microscopic AuNP-Hb agglomerates. We investigated the kinetics of agglomeration with dynamic light scattering and the adsorption kinetics of Hb on planar gold with surface-acoustic wave-phase measurements. Comparing agglomeration and adsorption kinetics leads to an explanation of the complex behavior of this nanoparticle-protein mixture. Agglomeration is initiated either when Hb bridges AuNP or when the electrostatic repulsion between AuNP is neutralized by Hb. It is terminated when Hb has been depleted or when Hb forms multilayers on the agglomerates that stabilize microscopic clusters indefinitely.
authors.affiliation: †INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Sebastian T
authors.initials: ST
authors.lastname: Moerz
authors.affiliation: †INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Kraegeloh
authors.affiliation: ‡Physikalische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: Munish
authors.initials: M
authors.lastname: Chanana
authors.affiliation: †INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Kraus
mesh_terms: D000067493:Dynamic Light Scattering; D006046:Gold / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D006454:Hemoglobins; D012710:Serum Albumin, Bovine; D006046:Gold
keywords: agglomeration; clusters; dispersion stability; electrosteric stabilization; particle stability; protein corona; protein−nanoparticle mixtures; time-dependent Smoluchowiski agglomeration model