A Reversible and Dynamic Surface Functionalization for Fluidity Controlled Multivalent Recognition of Lectins and Bacteria

The paper reports the design of multivalent bacterial receptors based on reversible self-assembled monolayers (rSAMs) on gold and glass substrates, mimicking the ligand display on host cells and extracellular matrices. The layers consist of α-(4-amidinophenoxy)alkanes decorated at the ω-position with β-galactose (Gal) or sialic acid (SA). The former acts as a mobile ligand binding to the complementary adhesin, LecA, a key virulence factor of the multi-drug-resistant bacterium Pseudomonas aeruginosa (PA). Binary amphiphile mixtures containing either of these ligands, spontaneously self-assemble on carboxylic acid terminated SAMs on gold or glass surfaces to form rSAMs that are easily tunable with respect to the ligand ratio. It is shown that this results in the ability to construct multi-reusable surfaces featuring strong affinity for the bacterial adhesin and recognitive surfaces for bacteria, the latter demonstrated by incubating a culture of PA or the oral commensal species Streptococcus gordonii (SG) on either Gal or SA functionalized rSAMs. In contrast to the mobile ligand display, surfaces featuring covalently attached "static" ligands exhibited low LecA affinity. This approach to wet chemical surface functionalization is unique in imparting both rapid restorability and adaptability, the latter compatible with heteromultivalent receptor designs for boosting lectin and bacteria affinity and specificity.