title: Quartz crystal microbalance with dissipation coupled to on-chip MALDI-ToF mass spectrometry as a tool for characterising proteinaceous conditioning films on functionalised surfaces.
abstract: Proteinaceous conditioning films (pCFs) are thought to play a key role in microbial adhesion, leading to the fouling of technical and biomedical devices and biofilm formation, which in turn causes material damage or persistent infections, respectively. However, little is definitively known about the process of surface conditioning via proteins. Herein, we demonstrate the potential of quartz crystal microbalance with dissipation coupled to MALDI-ToF mass spectrometry (QCM-D-MALDI) to investigate protein adsorption on different surfaces, enabling both the monitoring of CF formation and the determination of the molecular composition of CFs. After running QCM-D experiments, a subsequent tryptic on chip digestion step allows the identification of the proteins deposited on the sensor chip surface via MALDI-ToF mass spectrometry. Prominent blood plasma proteins, i.e., human serum albumin (HSA), fibrinogen (FG) and fibronectin (FN), were used. Chemically well defined sensor surfaces were prepared, among others, via self-assembled monolayer (SAM) technology. In cases where protein adsorption was observed by QCM-D, the adsorbed proteins were clearly detected and identified using MALDI-ToF/MS for both single-protein solutions of HSA, FG and FN as well as for protein mixtures. However, for equimolar protein mixtures on TiO2 surfaces, only signals attributed to FG and FN were observed in the mass spectra. No signals indicating the presence of HSA could be detected. This finding leads to the assumption that only FG and FN attach to the TiO2 sensor surface under the given experimental conditions.
authors.affiliation: Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Germany. Electronic address: frank.kirschhoefer@kit.edu.
authors.forename: Frank
authors.initials: F
authors.lastname: Kirschhöfer
authors.forename: Annika
authors.initials: A
authors.lastname: Rieder
authors.forename: Carolin
authors.initials: C
authors.lastname: Prechtl
authors.forename: Boris
authors.initials: B
authors.lastname: Kühl
authors.forename: Kristina
authors.initials: K
authors.lastname: Sabljo
authors.forename: Christof
authors.initials: C
authors.lastname: Wöll
authors.forename: Ursula
authors.initials: U
authors.lastname: Obst
authors.forename: Gerald
authors.initials: G
authors.lastname: Brenner-Weiß
keywords: Conditioning films; On-chip digestion; Protein adsorption; Quartz crystal microbalance with dissipation monitoring; Time-of-flight mass spectrometry