After drying at room temperature, the measurement was performed in a
MALDI-TOF/TOF mass spectrometer (ultrafleXtreme, Bruker Daltonik
GmbH, Bremen, Germany) at positive ion mode in a range of m/z
700–3500 Da. The evaluation of the mass spectra was carried out by
the software FlexAnalysis 3.0 (Bruker Daltonik GmbH, Bremen,
Germany).