The design, synthesis, relationship between structure and property of stimuli-responsive poly (amino acids)

　　Stimuli-responsive properties of traditional polymers and poly (amino acids) were combined to prepare stimuli-responsive poly (amino acids) materials. The molecular design and the technique of controllable polymerization were emphasized during the preparation. Compared to conventional stimuli-responsive polymers, the properties of polypeptide not only depended on chemical structure of subunits but also replied on the chiral percentage of monomers. As shown below, stimuli-responsive poly (amino acids) are synthesized through direct ring-opening polymerization of functional NCA monomers and post-modification of preformed functional polypeptides.

(a) Thermo-responsive poly (amino acids)

　　Two novel kinds of thermo-responsive poly (amino acids) were successfully synthesized through molecular design and controlled polymerization. As shown below, the side chains of these two types of thermo-responsive polymers are connected to the main chains via ester bonds, and these polyers can be easily hydrolyzed to poly(aspartic acids) or poly(glutamic acids) in the physiological environment, showing good biodegradability and biocompatibility. These thermo-responsive poly (amino acids) are expected to replace the traditional bio-undegradable polymers, such as PNIPAM,  in the biomedical field.

 (1).Zhang, S.; Li, Z. J. Polym. Sci., Part B: Polym. Phys. 2013,51, 546-555.

 (2).Zhang, S.; Chen, C.; Li, Z. Chin. J. Polym. Sci. 2013, 31, 201-210.

 (3).Fu, X.; Shen, Y.; Fu, W.; Li, Z. Macromolecules 2013, 46, 3753-3760.

 (4).Luo, C.; Zhao, B.; Li, Z. Polymer 2012, 53, 1725-1732.

 (5).Chen, C.; Wang, Z.; Li, Z. Biomacromolecules 2011, 12, 2859-2863.

 (6).Luo, C.; Liu, Y.; Li, Z. Macromolecules 2010, 43, 8101-8108.

(b) The design and synthesis of functional poly (amino acids) molecular brushes.

　　We have already prepared a series of molecular brushes with different lengths and side chains, by designing and synthesizing new monomers and controlled ring-opening polymerization. Those side chains are stimuli-responsive.

　　Combining DNA to the poly (amino acid)s backbone, molecular brushes that own DNA as side chains, and DNA- poly (amino acids) hybrid hydrogels are prepared.

 

(1) Luo, C.; Chen, C.; Li, Z. Pure Appl. Chem. 2012, 84, 2569-2578.

(2) Liu, Y.; Chen, P.; Li, Z. Macromol. Rapid Commun. 2012,33, 287-295.

(3) Han, Y.; Xia, L.; Zhu, L.; Zhang, S.; Li, Z.; Wang, Y. Langmuir 2012, 28, 15134-15140.

(4) Chen, P.; Li, C.; Liu, D.; Li, Z. Macromolecules 2012, 45, 9579-9584.