Poly (ε-caprolactone) grafted with nano-structured chitosan enhances growth of human dermal fibroblasts

Polyester films are modified with their bioactivity for tissue engineering by grafting a nano-structured bioactive material, nano-structured chitosan (nano-CS), on a model polymer, poly (epsilon-caprolactone) (PCL). The nano-CS was duplicated using a solvent-etched PCL mold and then grafted onto PCL using a selected solvent. The structure of the nano-CS/PCL surface was characterized using an atomic force microscope to observe the topography and determine the roughness. The centerline average roughness, Ra, of the surface of the nano-CS/PCL film is 106.0 +/- 4.0 nm whereas that of the surface of the CS-grafted PCL film (CS/PCL) is 3.6 +/- 0.4 nm. The latter is therefore very smooth. CS is known to swell following hydration, so the Ra values were determined again after immersion for 12 h in phosphate buffered saline. Although the centerline average roughness of the nano-CS/PCL was lower, it still markedly exceeded that of the CS/PCL film. Cells grown on nano-CS/PCL, CS/PCL, nano-structured PCL (nano-PCL), and PCL films were observed by fluorescent staining and analyzed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) viability assay following 3 and 7 days of culture, to evaluate the effects of the design on the growth of fibroblasts. The viability assay of the cells reveals that the growth rate of cells on both CS/PCL and nano-CS/PCL films significantly exceeds (P < 0.001) those of PCL and nano-PCL films on both cultural days. Additionally, the growth rate and proliferation of fibroblasts on nano-CS/PCL films significantly exceed (P < 0.001) those on CS/PCL films after both periods of culturing, suggesting that the bioactive surface following a nano-structured treatment promotes the growth rate of cells. However, nano-PCL films do not have the same effects as nano-CS/PCL films do. In conclusion, a novel biomaterial, nano-CS/PCL, is developed by grafting a nano-structured bioactive surface, CS, onto the PCL surface to promote the the growth rate of fibroblasts. This work elucidates a new concept for designing films or scaffolds for tissue engineering-the grafting of nano-structured bioactive biomaterials to the films or scaffolds to promote the growth of cells.