(664f) Synthesis of Chitosan Based Hyper-Branched Polymers for Biomedical Applications

Aggrecan is an important molecule in the extracellular matrix of articular cartilage; it contributes to the high compressive modulus of cartilage and to joint lubrication. Aggrecan has a bottlebrush structure made up of a core protein and highly charged glycosaminoglycan (GAG) side chains. One such GAG is chondroitin sulfate (CS), which is a strong polyanion and is very hydrophilic. Chitosan has many unique properties that make it an ideal material for tissue engineering applications. It is a natural polysaccharide, structurally similar to GAGs, it is antimicrobial, and promotes wound healing. CS side chains are grafted onto chitosan to form a nanostructured polymeric bottlebrush that mimics aggrecan. These nano-assemblies are synthesized for use as viscosupplements and as carriers to stabilize and deliver therapeutic proteins. Pendant amine groups along the chitosan chain are thiolated and reacted with a maleimide-activated CS. This strategy enables one to tune the degree of substitution of chitosan with CS side chains. The effects of these parameters on solution dynamics and emergent biochemical properties of these new aggrecan-mimetic polymers can then be studied.