Surface functionalization and analysis thereof by ambient mass spectrometry

A challenge in the global healthcare is the lack of suitable diagnostic tools for early disease detection. One possible solution is the use of biosensors in diagnostic tests. By definition, a biosensor is a bioanalytical device that detects the presence of a compound (analyte) in the sample. The detection relies on the specific interactions between the ligands that are attached onto the biosensor surface and the analytes in the sample.

This PhD dissertation is focused on developing an optimal protocol for attachment of ligands onto the biosensing surface. A step-wise approach was established for the versatile and reproducible modification and functionalization of a silicon nitride-based biosensor. This approach included the application of bioorthogonal copper-free reactions as a useful tool for oriented attachment of biomolecules. Additionally, a novel surface sensitive analytical method was developed for the identification of covalently bound molecules in monolayers. The method, which is fast and easy to apply, uses DART ionization coupled to a high-resolution mass spectrometer. The nm-thin layers were analysed, and interpretation rules for the obtained mass spectra were formulated. The method was applied in the identification of commercially available nm-thin coatings and biochips.