Design And Synthesis Of Stimuli-Sensitive Dendritic Supramolecular Assemblies

Polymer-based amphiphilic systems that self-assemble into micelles are widely studied, promising molecular designs for the delivery of hydrophobic drug molecules, which are otherwise difficult to deliver due to their poor water solubility. Incorporating stimuli-sensitive character into these polymeric assemblies has elevated the usefulness of these molecular systems in drug delivery applications due to their ability to unload non-covalently encapsulated guest molecules in response to specific stimuli. Among these nano-sized polymeric micelles, dendrimer-based micellar assemblies have received particular attention due to the fact that dendrimers are well-defined-monodispersed molecular architectures. The monodisperse nature of dendrimers provides a unique advantage in studying the structure-property relationship of amphiphilic supramolecular assemblies and stimuli-sensitive disassemblies. In this dissertation, we incorporate stimuli-sensitive characteristics into facially amphiphilic dendrimers designed and synthesized by our group. Our design principle renders these dendrimers responsive to different stimuli such as proteins, redox potential and light. We first study the self-assembly and encapsulation properties of these stimuli-responsive dendrimers in aqueous media. Next, it is demonstrated that these dendritic micellar assemblies disassemble in response to ( i ) an external stimulus such as light, ( ii ) protein-ligand interactions, and (iii ) a combination of an enzymatic reaction and redox potential. In the third molecular design, we show that combination of two stimuli enhances the release kinetics of guest molecules as compared to the independent effect of each stimulus. We also demonstrate that disassembly of these dendritic supramolecular assemblies takes place with a concomitant release of hydrophobic guest molecules trapped within the assembly