Interactive Polymer Gels as Biomimetic Sensors for Carbohydrate Interactions and Capture–Release Devices for Pathogens

Abstract

Adhesive processes mediated by carbohydrate‐decorated interfaces play a crucial role in many biological processes such as cell development or pathogen invasion. The involved carbohydrate scaffolds are soft and present multiple subsites forming complex and dynamic bonds to carbohydrate binding proteins. New tools and data are needed to understand how ligand presentation and mechanical properties drive these binding processes. This article highlights recent developments in the area of adhesion assays with a focus on soft biomimetic carbohydrate scaffolds as probes of adhesion forces. Key findings state that carbohydrate functionalized polymer networks largely show additive multivalency (statistical effects) and that the overall interaction forces are strongly affected by the stiffness of the network. These results indicate that phase transitions of carbohydrate bearing polymer gels may enable tunable affinity toward carbohydrate binding proteins. As an example, polymer networks undergoing large changes in mechanical rigidity, density, and spacing of carbohydrate ligands upon temperature stimulus are shown to bind or release carbohydrate binding bacteria such as Escherichia coli. The presented adhesion assays and the developed responsive systems can provide new insights into the mechanism through which carbohydrates mediate adhesion processes and establish new avenues toward scaffolds for the capture or release of cells or pathogens.

Glycan Nanobiosensors

“…Ligand-modified surfaces are probably enhanced due to multivalent interactions between surface-anchored clusters composed of many saccharide units. This phenomenon is denoted as a glycocluster effect and is able to multiply avidity and activity in biologic systems [ 19 ]. On the other hand, the mechanical properties and mobility of a ligand can affect the biorecognition process to a great extent.…”

“…In the next study from the same group, AuNPs were rendered responsive towards lectins and Ca 2+ ions [89]. A similar strategy using microgels instead of AuNPs was used in the detection of Con A and E. coli, which could be separated after binding by filtration [19,90]. Many pathogen-related diseases are caused by food-borne bacterial strains.…”

Temperature‐Controlled Adhesion to Carbohydrate Functionalized Microgel Films: An E. coli and Lectin Binding Study

“…[ 39 ] Quite similarly to thermosensitive polymers, by increasing the temperature above the LCST carbohydrate functionalized microgels form polymer−polymer contacts and collapse, thereby decreasing the steric repulsion while increasing the carbohydrate density and the elastic modulus, [ 34,35,40 ] which increases E. coli clustering in solution and carbohydrate binding overall. [ 38,41,42,43 ] The temperature dependent shifts in the microgels’ elastic modulus and surface roughness can be used to create switchable cell culture surfaces that enable the controlled attachment and detachment of cells even without addressing specific cell adhesion receptors. [ 35,40,44 ] However, microgel coatings specifically targeting selected cells, e.g.…”

Lectin and E. coli Binding to Carbohydrate-Functionalized Oligo(ethylene glycol)-Based Microgels: Effect of Elastic Modulus, Crosslinker and Carbohydrate Density

“…on multivalent macromolecular glycoconjugates presenting many carbohydrate subunits, thus binding to bacterial lectins with high avidity [20][21][22][23][24][25]. Microgel scaffolds have recently been developed as a platform to study carbohydrate-lectin interactions and to capture carbohydrate-binding bacteria [26][27][28][29][30]. In addition to their straightforward synthesis, microgels allow for preparing robust surface coatings through simple physisorption methods, e.g., via drop-casting, spin coating or dip-coating [31] Carbohydrate-functionalized microgels are highly hydrated and soft, thus mimicking properties of the extracellular matrix or glycocalyx, which sets them apart from other glycan-presenting scaffolds.…”