title: Engineering a well-ordered, functional protein-gold nanoparticle assembly.
abstract: The study of interactions between proteins and nanoparticles is important to advancing applications of nanoparticles in biology, medicine, and materials science. Here, we report the encapsulation of a 5-nm diameter gold nanoparticle (AuNP) by thermophilic ferritin (tF), achieved in nearly quantitative yield under mild conditions that preserved the secondary structure, ferroxidase activity, and thermal stability of the native, 4-helix bundle protein subunits. Chromatography-based assays determined that stable protein assembly around AuNPs occurred on long time scales (~48h) and was reversible. Apparent association constants were determined at 25°C for equilibrated tF-BSPP-capped AuNP samples (KA=(2.1±0.4)×10(78)M(-11)) and compared favorably to salt-assembled tF samples (KA=(2.2±0.5)×10(68)M(-11)) at the same protein concentration (0.3mg/mL). Finally, addition of gold ions and mild reducing agent to the tF-AuNP assembly produced 8-nm diameter AuNPs with surface plasmon resonance band unchanged at 520nm, indicative of templating by the protein shell.
authors.affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104-6323, United States.
authors.forename: Jasmina C
authors.initials: JC
authors.lastname: Cheung-Lau
authors.forename: Dage
authors.initials: D
authors.lastname: Liu
authors.forename: Katherine W
authors.initials: KW
authors.lastname: Pulsipher
authors.forename: Weiren
authors.initials: W
authors.lastname: Liu
authors.forename: Ivan J
authors.initials: IJ
authors.lastname: Dmochowski
mesh_terms: D002384:Catalysis; D002942:Circular Dichroism; D005293:Ferritins / Q000737:chemistry* / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D020349:Surface Plasmon Resonance; D013997:Time Factors
chemical_list: D011506:Proteins; D006046:Gold; D005293:Ferritins
keywords: Biomineralization; Ferritin assembly; Nanoparticle–protein interaction; Protein self-assembly; Protein–nanoparticle association constant