Measuring the Adhesion Forces for the Multivalent Binding of Vancomycin-Conjugated Dendrimer to Bacterial Cell-Wall Peptide

Abstract

Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van) ( n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy. The SPR experiment for these conjugates was performed in a biosensor chip surface immobilized with a bacterial cell-wall peptide Lys-d-Ala-d-Ala. Of these, G5(Van) bound most tightly with a K of 0.34 nM, which represents an increase in avidity by 2 or 3 orders of magnitude relative to a monovalent conjugate G5(Van) or free vancomycin, respectively. By single-molecule force spectroscopy, we measured the adhesion force between G5(Van) and the same cell-wall peptide immobilized on the surface. The distribution of adhesion forces increased in proportion to vancomycin valency with the mean force of 134 pN at n = 4 greater than 96 pN at n = 1 at a loading rate of 5200 pN/s. In summary, our results are strongly supportive of the positive correlation between the avidity and adhesion force in the multivalent interaction of vancomycin nanoconjugates.

Quantification of Multivalent Interactions between Sialic Acid and Influenza A Virus Spike Proteins by Single-Molecule Force Spectroscopy

“…In a correlated case, the binding sites on a receptor are closely coupled laterally; therefore, the failure of one bond triggers the immediate failure of the surrounding bonds within the multivalent complex, and bond rupture is detected as a single event. This type of bond configuration has been reported for other mechanically coupled systems such as dendrimers with different valency and recently virus binding with cells. ,, However, the lack of a significant increase in the magnitude of the rupture forces at higher loading rates when compared to that of the monovalent receptor might suggest that a different binding mode could be involved between the dendritic architecture and H3 protein binding pockets.…”

“…This type of bond configuration has been reported for other mechanically coupled systems such as dendrimers with different valency and recently virus binding with cells. 38,49,50 However, the lack of a significant increase in the magnitude of the rupture forces at higher loading rates when compared to that of the monovalent receptor might suggest that a different binding mode could be involved between the dendritic architecture and H3 protein binding pockets.…”

Multivalent non-covalent interactions lead to strongest polymer adhesion

“…22,[25][26][27][28][29][30][31][32][33][34][35] Additionally, SMFS on systems comprising multivalent interactions have been performed for different biological systems, obtaining detachment forces of up to 1000 pN. [36][37][38][39][40][41][42] However, the individual contributions to the overall force could not be resolved.…”

Structural and physicochemical characteristics of one-step PAMAM dendrimeric nanoparticles

“…Despite the low MW of OS-PAMAM on comparison to PAMAM G6, the similar adhesion force could be due to related surface functional groups between both dendrimers [44,45]. Dendrimers in biomedical applications interact with cargo molecules and cells, and the force of adhesion provides the fundamental basis for the hypothetical notion that high binding avidity [46].…”