title: Layer thickness of hydrophobin films leads to oscillation in wettability.
abstract: In nanobiotechnology, the properties of surfaces are often key to sensor applications. If analytes possess a low tolerance or affinity regarding the sensory substrate (surface), then the setup of mediators may be indicated. Hydrophobins enable biocompatible surface functionalization without significant restrictions of the physicochemical substrate properties. Because of the imperfect formation of hydrophobin films, a high variation in surface properties is observed. In this study, we report on the relation between the film thickness of hydrophobin-coated solid surfaces and their wettability. We found that the wettability of protein-coated surfaces strictly depends on the amount of adsorbed protein, as reflected in an oscillation of the contact angles of hydrophobin-coated silicon wafers. Fusion proteins of Ccg2 and HFBI, representatives of class I and II hydrophobins, document the influence of fused peptide tags on the wettability. The orientation of the first crystal nuclei plays a decisive role in the formation of the growing hydrophobin layers. Here, a simple method of deducing the film thickness of hydrophobin assemblies on solid surfaces is presented. The determination of the static contact angle allows the prediction of which part of the protein is exposed to possible analytes.
authors.affiliation: Institute of Genetics, Technische Universität Dresden, 01217 Dresden, Germany. leopold.gruner@mailbox.tu-dresden.de
authors.forename: Leopold J
authors.initials: LJ
authors.lastname: Gruner
authors.forename: Kai
authors.initials: K
authors.lastname: Ostermann
authors.forename: Gerhard
authors.initials: G
authors.lastname: Rödel
mesh_terms: D000327:Adsorption; D005656:Fungal Proteins / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D012822:Silicon Dioxide / Q000737:chemistry; D014242:Trichoderma; D017155:Wettability
chemical_list: D005656:Fungal Proteins; D012822:Silicon Dioxide