title: Probing protein adsorption onto mercaptoundecanoic acid stabilized gold nanoparticles and surfaces by quartz crystal microbalance and zeta-potential measurements.
abstract: The adsorption characteristics of three proteins [bovine serum albumin (BSA), myoglobin (Mb), and cytochrome c (CytC)] onto self-assembled monolayers of mercaptoundecanoic acid (MUA) on both gold nanoparticles (AuNP) and gold surfaces (Au) are described. The combination of quartz crystal microbalance measurements with dissipation (QCM-D) and pH titrations of the zeta-potential provide information on layer structure, surface coverage, and potential. All three proteins formed adsorption layers consisting of an irreversibly adsorbed fraction and a reversibly adsorbed fraction. BSA showed the highest affinity for the MUA/Au, forming an irreversibly adsorbed rigid monolayer with a side-down orientation and packing close to that expected in the jamming limit. In addition, BSA showed a large change in the adsorbed mass due to reversibly bound protein. The data indicate that the irreversibly adsorbed fraction of CytC is a monolayer structure, whereas the irreversibly adsorbed Mb is present in form of a bilayer. The observation of stable BSA complexes on MUA/AuNPs at the isoelectric point by zeta-potential measurements demonstrates that BSA can sterically stabilize MUA/AuNP. On the other hand, MUA/AuNP coated with either Mb or CytC formed a reversible flocculated state at the isoelectric point. The colloidal stability differences may be correlated with weaker binding in the reversibly bound overlayer in the case of Mb and CytC as compared to BSA.
authors.affiliation: Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Kaufman
authors.forename: Jennifer
authors.initials: J
authors.lastname: Belyea
authors.forename: Marcus C
authors.initials: MC
authors.lastname: Johnson
authors.forename: Zach M
authors.initials: ZM
authors.lastname: Nicholson
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Ricks
authors.forename: Pavak K
authors.initials: PK
authors.lastname: Shah
authors.forename: Michael
authors.initials: M
authors.lastname: Bayless
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Pettersson
authors.forename: Zsombor
authors.initials: Z
authors.lastname: Feldotö
authors.forename: Eva
authors.initials: E
authors.lastname: Blomberg
authors.forename: Per
authors.initials: P
authors.lastname: Claesson
authors.forename: Stefan
authors.initials: S
authors.lastname: Franzen
mesh_terms: D000327:Adsorption; D000818:Animals; D015374:Biosensing Techniques; D002417:Cattle; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry; D004563:Electrochemistry; D005227:Fatty Acids / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D053768:Metal Nanoparticles / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D011791:Quartz; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D005227:Fatty Acids; D009211:Myoglobin; D011506:Proteins; C016173:undecanoic acid; D011791:Quartz; D012710:Serum Albumin, Bovine; D006046:Gold; D045304:Cytochromes c