title: On the molecular interaction between albumin and ibuprofen: An AFM and QCM-D study.
abstract: The adsorption of proteins on surfaces often results in a change of their structural behavior and consequently, a loss of bioactivity. One experimental method to study interactions on a molecular level is single molecular force spectroscopy that permits to measure forces down to the pico-newton range. In this work, the binding force between human serum albumin (HSA), covalently immobilized on glutaraldehyde modified gold substrates, and ibuprofen sodium salt was studied by means of single molecular force spectroscopy. First of all, a protocol was established to functionalize atomic force microscopy (AFM) tips with ibuprofen. The immobilization protocol was additionally tested by quartz crystal microbalance with dissipation (QCM-D) and contact angle measurements. AFM was used to characterize the adsorption of HSA on gold substrates, which lead to a packed monolayer of thickness slightly lower than the reported value in solution. Finally, single molecule spectroscopy results were used to characterize the binding force between albumin and ibuprofen and calculate the distance of the transition state (0.6 nm) and the dissociation rate constant (0.055 s(-1)). The results might indicate that part of the adsorbed protein still preserves its functionality upon adsorption.
authors.affiliation: CIC nanoGUNE Consolider, Tolosa Hiribidea 20018 Donostia/San Sebastian, Spain; Biosurfaces Unit, CIC biomaGUNE, Miramon Pasealekua 182, 20009 Donostia/San Sebastian, Spain. Electronic address: a.eleta@nanogune.eu.
authors.forename: Aitziber
authors.initials: A
authors.lastname: Eleta-Lopez
authors.affiliation: Biofunctional Nanomaterials Unit, CIC biomaGUNE, Miramon Pasealekua 182, 20009 Donostia/San Sebastian, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Etxebarria
authors.affiliation: Biofunctional Nanomaterials Unit, CIC biomaGUNE, Miramon Pasealekua 182, 20009 Donostia/San Sebastian, Spain; CIBER-BBN, Miramon Pasealekua 182, 20009 Donostia/San Sebastian, Spain.
authors.forename: Niels-Christian
authors.initials: NC
authors.lastname: Reichardt
authors.affiliation: Charité-Universitätsmedizin Berlin, Institute of Transfusion Medicine, Charitéplatz 1, 10117 Berlin, Germany; Department of Medical Physics, Biophysics and Radiology, Medical Faculty, Trakia University,, ul. Armeiska 11, 6000 Stara Zagora, Bulgaria.
authors.forename: Radostina
authors.initials: R
authors.lastname: Georgieva
authors.affiliation: Charité-Universitätsmedizin Berlin, Institute of Transfusion Medicine, Charitéplatz 1, 10117 Berlin, Germany.
authors.forename: Hans
authors.initials: H
authors.lastname: Bäumler
authors.affiliation: Biosurfaces Unit, CIC biomaGUNE, Miramon Pasealekua 182, 20009 Donostia/San Sebastian, Spain; Institute for Biophysics, Department of Nanobiotechnology, University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 11, A-1190 Vienna, Austria. Electronic address: jose.toca-herrera@boku.ac.at.
authors.forename: José L
authors.initials: JL
authors.lastname: Toca-Herrera
mesh_terms: D006801:Humans; D007052:Ibuprofen / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D058525:Quartz Crystal Microbalance Techniques; D012709:Serum Albumin / Q000737:chemistry*
chemical_list: D012709:Serum Albumin; D007052:Ibuprofen
keywords: Albumin; Atomic force microscopy; Ibuprofen; Protein functionality; Quartz crystal microbalance; Unbinding force