Development of dendritic and polymeric scaffolds for biological and catalysis applications

• Main Author: Goyal, Poorva
• Published: Georgia Institute of Technology 2008
• Subjects: Dendrimers; Polymers; Catalysis; Biological; Synthesis; Organic; Scaffolding; Tissue engineering
• Online Access: http://hdl.handle.net/1853/24826

This thesis hypothesizes that the introduction of facile functional handles on the periphery and cores of dendrimers can lead to novel highly functional dendrimers useful for modular surface modifications of dendrimers with biological units of choice for tunable delivery devices and for high-end imaging applications respectively. The first functional handles introduced were on the periphery of poly(amide)-based dendrimers. The dendrimers were built by convergent strategies and were equipped with one and/or two selective, robust, and orthogonal functional handles for modular attachment to and transformation of dendrimer surface. By using azides, alkynes and aldehydes as robust functional handles and investigating their orthogonality and activity by high yielding couplings with small organic and biologically significant molecules a strategy and methodology for development of tunable dendrimer surfaces for numerous future applications was facilitated. Our second functional handles were introduced in the core of poly(amidoamine) based dendrimers. Raman labels such as triple bonds and carbon-deuterium bonds with vibrational frequencies in the background free vibrational zone of 2100-2500 cm-1 were introduced in the core of dendrimers for scaffold specific labeling. By encapsulationg Ag nanodots within these dendrimers, high fluorescence and scaffold specific Raman labeling could be achieved. This strategy lays the foundation for the creation of ultrabright, scaffold specific information containing biological labels for studying single cell dynamics. Finally, the use of dendritic frameworks in heterogeneous solid supported catalysis for enhanced cooperativity in reactions involving bimetallic transition states is explored and applied. Prior to this thesis work, heterogeneous resin supported catalysts for HKR reactions suffered from high catalyst loadings and low enantioselectivities induced by the solid support. With the use of flexible linker and dendron framework supporting the catalysts, both of these problems were addressed. This method opens up new routes for creation of highly active heterogeneous solid catalysts involving a bimetallic intermediate. In the end, the current status of dendritic frameworks is reviewed and methodological extensions to this work are suggested. Conceptions of how our functional dendritic architectures would be useful for future biological and catalytic applications are explored and detailed.