| Dendrimers are well defined, highly branched macromolecules that consist of a core, internal branching units and a multitude of peripheral groups. Dendrimers possess low viscosities, high solubilities, single molecular weights, and a globular shape in solution. As a result, the architecture and physiochemical properties of dendrimers offer specific advantages over linear polymers.; Currently, millions of people in the Unites States seek treatment for the repair of corneal wounds. The standard of care for repairing these wounds involves using sutures, which do not actively participate in healing of the surgical procedure. Another common medical problem involves the degradation of cartilage due to osteoarthritis or trauma. Since cartilage has a limited capacity for self-repair, the current methods of treatment involve the use of non-surgical and/or surgical techniques to reduce pain while maintaining joint function. Consequently, there is interest in synthesizing dendritic macromolecules specifically for these biomedical applications.; Fourth generation, bola-type dendritic macromolecules were synthesized by the divergent method in an iterative process of monomer unit coupling, followed by deprotection. The design of these dendritic macromolecules was based on an ABA triblock architecture, wherein two dendritic arms, or A blocks, flanked a linear linker, or B block, via ester linkages. The dendritic arms consisted of biocompatible materials, while the linear linker was a non-immunogenic poly(ethylene glycol) of three different molecular weights. Degradation of these macromolecules leads to natural metabolites, such as succinic acid and glycerol, thus they are termed biodendritic macromolecules. The same synthetic strategy was used to prepare biodendritic macromolecules containing carbamate linkages, in addition to previous ester linkages, to obtain materials with a different set of physical properties.; Further functionalization of these macromolecules was needed to prepare photocrosslinkable systems for the formation of hydrated networks, or hydrogels. Forming hydrogel networks from highly branched biodendritic macromers offers advantages in preparing hydrogels at low polymer concentration, varying mechanical properties, and developing in situ polymerizing systems for delivery to an irregularly shaped wound site. Consequently, hydrogels based on macromolecules possessing ester linkages were explored as sealants for corneal wounds, while scaffolds for cartilage repair were prepared from macromolecules containing carbamate linkages. |
