Contributed Talk  - Thursday, 16 September I 14:55 PM (CEST)

Dr. Marcela Dendisova: "Nanosopic study of polydopamine monolayers"

Marcela Dendisova ᵃ, Martin Kral ᵃ, Jan Svoboda ᵇ, Ognen Pop-Georgievski ᵇ, Pavel Matejka ᵃ
ᵃ Department of Physical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, 166 28, Prague 6, Czech Republic
ᵇ Department of Chemistry and Physics of Surfaces and Interfaces, Institute of Macromolecular Chemistry, Czech Academy of Sciences, 162 06, Prague 6, Czech Republic

Dopamine is synthetic melanin, which tends to polymerize and form „smart“ chains on virtually any surface; it may be used to modify solid substrates to anchor other compounds ¹. The mechanism of the polymerization is definitely not simple, and to this day, it still has not been fully clarified ². In this study, the dopamine molecules were polymerized on the Si/SiOx, N-TiO₂, and Au surfaces with various polymerization time intervals. The products and/or intermediates of the polymerization were characterized using the Grazing Angle Attenuated Total Reflection Fourier-Transform Infrared spectroscopy (GAATR) and the topographies of the layers were obtained by Atomic Force Microscopy in the tapping mode. In addition, the distribution of the products and intermediates of the complex reaction was recorded using nanoscopic technique Scanning Near-field Infrared Microscopy ³.


Utilizing these techniques, it was found out that dopamine forms small islands, which grow with increasing time of polymerization. The GAATR analysis revealed changes in catechol and quinone band intensities in the spectra of polydopamine on all substrates. The results showed that dopamine first adsorbs on the surfaces via carbonyl groups and then starts to form longer polymer chains. The polydopamine layer formation proved to be significantly substrate-dependent in the early stages of polymerization; however, after longer polymerization intervals, the resulting layers were highly uniform and independent on the type of substrate. The main differences were observed between polydopamine layers formed on the gold surface and surfaces terminated with oxides/reactive hydroxides (Si/SiOx, N-TiO₂). The results were supported by multivariate statistical methods based on Principal Component Analysis.


Acknowledgement


This work was supported by the Czech Science Foundation (GACR) - Project No. 20-08679S.


References:
1. Svoboda, J.; Sedláček, O.; Riedel, T.; Hrubý, M.; Pop-Georgievski, O., Poly(2-oxazoline)s One-Pot Polymerization and Surface Coating: From Synthesis to Antifouling Properties Out-Performing Poly(ethylene oxide). Biomacromolecules 2019, 20 (9), 3453-3463.
2. Svoboda, J.; Král, M.; Dendisová, M.; Matějka, P.; Pop-Georgievski, O., Unraveling the influence of substrate on the growth rate, morphology and covalent structure of surface adherent polydopamine films. Colloids and Surfaces B: Biointerfaces 2021, 205, 111897.
3. de los Santos Pereira, A.; Cernescu, A.; Svoboda, J.; Sivkova, R.; Romanenko, I.; Bashta, B.; Keilmann, F.; Pop-Georgievski, O., Conformation in Ultrathin Polymer Brush Coatings Resolved by Infrared Nanoscopy. Analytical Chemistry 2020, 92 (7), 4716-4720.