The main objective of GLYMCE is the bottom-up design of glycocalyx models specifically using sGAG mimetic macromolecules to systematically study their role in infection processes and to potentially use this knowledge as well as the derived molecules and materials to derive new strategies in the fight against infections. Along this concept, the project is divided into three major aims: 1) The synthesis of sGAG mimetics, 2) The assembly of glycocalyx models using sGAG-mimetics and 3) Glycocalyx engineering using sGAG-mimetics.
Aim 1: In the first phase of the project, solid phase polymer synthesis protocols to enable the sequence-defined synthesis of both, sulfated and non-sulfated glycomacromolecules were consolidated to now give access to sGAG mimetics with possible variations in a) the carbohydrate motif, b) the number and density of carbohydrate motifs, c) the number and density of sulfate groups and d) the introduction of oligoproline segments to alter main chain flexibility. Since solid phase protocols are limited in terms of the achievable molecular weights, polymeric sGAG-mimetics have been derived by controlled radical polymer synthesis (linear GAG mimetic polymers) and by combining solid phase and polymer synthesis (brushed GAG mimetic polymers).
Aim 2: In order to make the GAG mimetic macromolecules and polymers developed in Aim 1 accessible for the development of glycocalyx models, these need to be equipped with a so-called membrane anchor. Solid phase synthesis protocols are now established that allow for the controlled installation of different types of membrane anchors in glycomacromolecules. The same protocols also give access to macroinitiators/ -chain transfer agents that are used to then derive the according glycopolymer systems. Both, glycomacromolecules and glycopolymers are then successfully incorporated into giant unilamellar vesicles (GUVs) to derive glycocalyx models. Importantly, glycomacromolecules as well as glycopolymers are fluorescently labelled and thus can be readily used for analysis of membrane incorporation, dynamics and interactions. A key driver of multivalent glycan-mediated binding on cell surfaces is the formation of clusters. Two strategies were already successfully established: 1) Formation of phase-separated GUVs and installation of glycan mimetics selectively in either the ordered or non-ordered membrane phase to create clustered presentation (Blawitzki et al, doi.org/10.1002/anie.202414847) and 2) Incorporation of post-polymerizable diacetylene units to induce cluster formation through receptor interaction and fixation from UV-induced polymerization (Blawitzki et al, doi.org/10.1002/marc.202500567) Currently, both strategies are being extended towards sulfated GAG mimetic macromolecules and polymers.
Aim 3: While the glycocalyx models developed in Aim 2 enable systematic studies into GAG-mediated interactions, these systems are highly simplified and can intrinsically only mimic parts of the complexity of the natural cell surfaces and binding processes. Therefore, in an additional top-down approach, membrane-anchored GAG mimetics are now successfully applied for so-called glycocalyx engineering.
