PhD defence: Chemical Synthesis and Biological Properties of Extra Cellular Matrix Components

This thesis investigates the extracellular matrix (ECM) as a dynamic microenvironment in which biochemical and mechanical cues synergistically direct cell behavior. Glycan structures, especially glycosaminoglycans (GAGs) such as hyaluronan (HA), are central as a basis for advanced biomaterials.

Chapter 2 introduces an HA hydrogel formed by metal-free click chemistry (azide–BCN) and containing a PEG-based, photolabile linker with o-nitrobenzyl azides. This linker combines rapid photodegradation with hydrolytic stability and enables integration of RGD peptides and protease-sensitive tethers. MSCs, ECFCs, and bmMSCs were viably cultured in 3D; UV (365 nm) enabled cell harvesting, while 405 nm light softened the biomaterial inducing phenotypical changes. 

Chapter 3 develops spatiotemporal control over protein localization and release in HA hydrogels. Using rationally engineered peptidyl ligases, proteins were region-specifically modified at the N terminus with an azide or aldehyde and a photolabile group, covalently anchored, and released on demand by light. GFP showed week-long release governed by diffusion and polymer relaxation. IFN-α and EGF retained bioactivity while IFN-α functionalized biomaterials showed a persitentent bioactivity, meintaing the ppluripotency of Neural Stem cells for a prolonged period of time.

Chapter 4 describes a route to well-defined glycopolypeptides via NCA polymerization of a serine derivative with N-methyl aminooxy side chains, followed by oxime ligation with reducing oligosaccharides. Conjugation of 6'-sialyllactose and NMR confirmed structure and homogeneity.

Together, this forms a platform to tune mechanics, adhesion, enzyme sensitivity, and controlled, spatially targeted biomolecule release in GAG matrices for 3D cell culture, organoids, regenerative medicine, and glycomaterials.