A low-fouling, self-assembled, graft co-polymer and covalent surface coating for controlled immobilization of biologically active moieties

• Published in: Applied surface science Vol. 584; p. 152525
• Main Authors: Mertgen, Anne-Sophie, Guex, Anne Géraldine, Tosatti, Samuele, Fortunato, Giuseppino, Rossi, René M., Rottmar, Markus, Maniura-Weber, Katharina, Zürcher, Stefan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2022
• Subjects: Cell adhesive surface; Graft copolymer; Low-fouling; RGD; Strain promoted azide-alkyne click chemistry SPAAC; Surface Modification; Low-fouling; Graft copolymer; Cell adhesive surface; RGD; ECM; Strain promoted azide-alkyne click chemistry SPAAC; SPAAC; PEG; ToF-SIMS; DBCO; VASE; Surface Modification; HUVEC; PAcrAmTM-g-(PEG-N3NH2,Si)
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.152525

[Display omitted] •Specific molecular building blocks were grafted to a PAcrAmTM backbone.•Functionalities include non-covalent and covalent binding and non-fouling properties.•Biomolecules were immobilized in a specific conformation with confirmed functionality.•RGD and biotin were co-immobilized spatially defined and concentration-controlled.•Endothelial cells attached and formed confluent monolayers on an RGD coating. Current biointerfaces aiming to steer specific biological responses frequently lack either stability due to purely electrostatic interactions, bioactivity due to unspecific conjugation chemistries, specificity due to uncontrolled biological interactions such as fouling, or cytocompatibility due to harsh and toxic coating procedures. Here, we report a versatile surface modification platform for covalent tethering of selected biomolecules. New in this approach is the particular combination of modular binding blocks as graft co-polymer. Grafted to the backbone of PAcrAmTM multiple functionalities are strategically combined: covalent (silane) and non-covalent (lysine) surface binding groups for stability and self-assembly in mild buffered solution, PEG-azide chains for low fouling properties, and specific, controlled, covalent, linking of biologically active molecules. This modular strategy overcomes the previously mentioned limitations, for instance regarding bioactivity of the biological moiety due to highly specific strain-promoted azide-alkyne cycloaddition. The successful grafting of the copolymer was confirmed by 1H NMR. The immobilization of RGD peptides was characterized by combining surface analytical techniques, such as ToF-SIMS and ellipsometry, allowing quantification of immobilized molecules over an extensive range of concentrations (0.008–1.95 pmol·cm−2). The bioactivity over this range of concentrations was confirmed by in vitro cell studies, presenting a differential endothelial cell attachment and spreading. The modified substrates enabled the formation of an interconnected monolayer of endothelial cells. Furthermore, the modular platform allowed the co-immobilization of two bioactive functional groups, RGD and biotin, on the same surface, which could be exploited for the further development of controlled multi-functional biointerfaces for diverse biological applications in the future.