Effect of PEGylation on Receptor Anchoring and Steric Shielding at Interfaces: An Adhesion and Surface Plasmon Resonance Study with Precision Polymers.

Abstract

This study aims at quantifying the steric shielding effect of multivalent glycoconjugates targeting pathogens by blocking their carbohydrate binding sites. Specifically, PEGylated and non-PEGylated glycoconjugates are studied as inhibitors of lectins and bacterial adhesins evaluating the steric repulsion effect of the nonbinding PEG chains. We use the soft colloidal probe (SCP) adhesion assay to monitor the change in the adhesion energy of mannose (Man)-decorated hydrogel particles on a layer of concanavalin A (ConA) in the presence of sequence-defined multivalent glycoconjugate inhibitors over time. The results show that PEGylated glycoconjugates achieve a stronger adhesion inhibition when compared to non-PEGylated glycoconjugates although the dissociation constants (KD) of the PEGgylated compounds to ConA were larger. These results appear in line with Escherichia coli adhesion inhibition assays showing a small increase of bacteria detachment by PEGgylated glycoconjugates compared to non-PEGylated compounds. This suggests that an increase of sterical shielding via PEGylation may help reduce the invasiveness of pathogens even after they have adhered. Adhesion studies based on electrostatic interactions using amine-linked PEG of varying molecular weight confirm that such sterical shielding effect is not limited to carbohydrate-mediated adhesion.