Multivalent carbohydrate interactions at the cell interface play a crucial role in many biological processes, such as cell development, communication or pathogen invasion. Recent work showed that the overall binding strength can be controlled by adjusting the material parameters of carbohydrate ligand presenting polymer scaffolds, e.g. increased ligand spacing and high elastic modulus result in stronger binding. Here we harness these principles in order to design thermosensitive microgel coatings that can bind clinically relevant carbohydrate binding pathogens, such as E. coli, in a stimuli responsive fashion. At elevated temperature, these gels collapse and increase their elastic modulus, as well as ligand spacing, resulting in increased interactions. This process is reversible and potentially allows capturing and releasing carbohydrate binding bacteria by microgel coatings and temperature stimulus. We present the synthesis of thermoresponsive carbohydrate presenting poly(N-isopropylacrylamide) microgels via different synthetic approaches, e.g. copolymerization of ligand monomers or post-functionalization. The influence of charged groups, ligand density and different microgel architecture on temperature dependent receptor binding and E. coli catch and release are investigated in dispersion by Bradford assay and on microgel films using fluorescence microscopy, as well as readout in microwell plates. We noticed that robust microgel films could be readily prepared by physisorption on plastic surfaces, which may stimulate larger scale applications of these materials. Moreover, we perform detailed analysis on the microgel structure and ligand positioning upon temperature transition. We believe that specific protein binding and bacterial adhesion are further enhanced by a smoother microgel surface and enrichment of carbohydrate ligands at the microgel surface above the phase transition temperature. Detailed studies by STED microscopy and AFM colloidal probe are underway to shed light on these phenomena.

Temperature-controlled adhesion of bacteria and lectins to carbohydrate presenting microgel films

256th National Meeting (2018)

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