This proposal is on the macromolecule-mediated assembly of rotaxanes to access higher order organizations of individual molecular motors. Doubly bistable palindromic rotaxanes, a type of mechanically interlocked molecule developed in the Stoddart lab, are capable of switchable and reversible molecular motions that mimic muscular contraction. To achieve macroscale effects from these molecular motions for applications such as artificial muscles and biomedical devices, organized assemblies are required. Three types of macromolecules, DNA, peptides and polymers, will be used to assemble the rotaxanes. It will be possible to access these three distinct architectures by functionalizing the rotaxane structures with the respective macromolecules post-synthesis. The DNA- and peptide-rotaxane conjugates will utilize the known properties of biomolecule self-assembly to form linear rotaxane oligomers. The rotaxane-polymer conjugate will be used to create a rotaxane-crosslinked hydrogel in order to translate the molecular scale motions of the bistable rotaxane to macroscopic effects via a size change of the gel. These assemblies will coordinate the individual molecular motions of the rotaxanes and enable their use in the creation of artificial muscle materials.
The development of artificial muscles is important for biomedical devices, robotics for minimally invasive surgeries, and to aid and replace natural muscles in advanced prosthetic devices. Recently, organic molecules called bistable rotaxanes have been developed that mimic the contraction motion of biological muscles. However, to translate these molecular motions into macroscale effects, a method of higher order organization is needed. This proposal presents three methods for the assembly of bistable rotaxanes using macromolecules in order to coordinate their individual molecular motions and create a truly biomimetic artificial muscle material.
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