Biodegradable Polyrotaxanes for Tissue Engineering

1 Preparation of a Biodegradable Polyrotaxane with Ester Linkages and its Chemical Modification 

New synthetic methods have been investigated over the past two decades in order to design intelligent or smart materials which exhibit large property changes in response to small physical or chemical stimuli. Stimuli-responsive polymers have been studied as smart materials aiming at the applications in biomedical fields or chemomechanical devices. The representatives of the stimuli-responsive polymers are poly(jV- 

1 Synthesis and Characterization of a Polyrotaxane Consisting ofp-Cyclodextrins and a Poly(ethylene glycol)-Poly(propylene glycol) Triblock-Copolymer 

A polyrotaxane, in which many p-CDs are threaded onto PEG-block-P. G-block-PEG triblock-copolymer (Mn = 4200, PPG segment Mn = 2250, PEG segment Mn = 975 x 2) named Pluronic P-84 capped with fluorescein-4-isothiocyanate (FITC), was S5mthesized as a model of stimuli-responsive 

It was foimd that the association number of the polyrotaxane was decreased although that of the model triblock-copolymer was slightly increased from 35 °C to 50 °C . These results indicate that the dissociation behavior of the polyrotaxane may be related to the localization of P-CDs along the triblock-copolymer. Stimuli-responsive polyrotaxanes can be one of candidates to create novel smart materials acting in a similar manner to natural chemomechanical proteins of myofibrils where myosin headpeices slide along actin filaments to initiate the contraction process. 

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