Porogen-induced surface modification of nano-fibrous poly(L-lactic acid) scaffolds for tissue engineering

In addition to suitable pore architecture of a tissue-engineering scaffold, surface modification after scaffolding fabrication is often needed to enhance the interactions between cells and the synthetic material. In this study, a novel one-step process was developed to fabricate surface-modified nano-fibrous poly(L-lactic acid) (NF-PLLA) scaffolds. First, gelatin spheres with smooth surface were prepared by non-surfactant emulsification, solvent extraction, and freeze-drying. A three-dimensional NF-PLLA scaffold was then fabricated by using gelatin spheres as porogen. Gelatin molecules were entrapped onto the scaffold surface during the fabrication process. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy analysis demonstrated the existence of gelatin molecules on the surface of the polymer scaffold. The amount of gelatin on the scaffold surface was controlled by the composition of the solvent mixture of gelatin solution. The compressive modulus of scaffold prepared with gelatin spheres was more than three times higher than that prepared with irregular gelatin particles of the same size range. The surface modification significantly improved initial cell adhesion and proliferation over a 2-week culture. SEM images indicated that cells spread on the gelatin-entrapped scaffolds in contrast to spherical or spindle morphology on the control 1 day after cell seeding. Furthermore, more matrix secretion was observed on the surface-modified scaffolds than on the control after 2 weeks of in vitro cultivation. In conclusion, this approach provides a simple one-step process to fabricate surface-modified collagen-like NF-PLLA scaffolds, which have improved cell adhesion and proliferation.