Temperature-dependent higher order structures of the (Pro-Pro-Gly)₁₀-modified dendrimer.

Collagen is the most abundant protein in mammals and is widely used as a biomaterial for tissue engineering and drug delivery. We previously reported that dendrimers and linear polymers, modified with collagen model peptides (Pro-Pro-Gly)₅, form a collagen-like triple-helical structure; however, its triple helicity needs improvement. In this study, a collagen-mimic dendrimer modified with the longer collagen model peptides, (Pro-Pro-Gly)₁₀, was synthesized and named PPG10-den. Circular dichroism analysis shows that the efficiency of the triple helix formation in PPG10-den was much improved over the original. The X-ray diffraction analysis suggests that the higher order structure was similar to the collagen triple helix. The thermal stability of the triple helix in PPG10-den was higher than in the PPG10 peptide itself and our previous collagen-mimic polymers using (Pro-Pro-Gly)₅. Interestingly, PPG10-den also assembled at low temperatures. Self-assembled structures with spherical and rod-like shapes were observed by transmission electron microscopy. Furthermore, a hydrogel of PPG10-den was successfully prepared which exhibited the sol-gel transition around 45°C. Therefore, the collagen-mimic dendrimer is a potential temperature-dependent biomaterial.