Evaluation of porous poly(lactide-co-glycolide) scaffold surface-modified by irradiation of nitrogen ion beams

Increase in cellular interaction of poly(lactide-co-glycolide) (PLGA) is very important in tissue engineering, in where initial cell adhesion and subsequent proliferation on a scaffold surface determine the fate of, especially, tissue engineering vascular grafts. Surface modification of a porous PLGA scaffold was performed for induction of higher cell adhesion by irradiating nitrogen ion beams with either 1 or 10 keV. Both energy and intensity of the nitrogen ion beams were in advance determined by utilizing Stopping and Range of Ions in Matter software after inputting the scaffold conditions such as species and density of the PLGA samples as well as its glass transition temperature. Surface modification was evaluated by three methods, i.e. physical and chemical tests and in vitro tests. Extent of surface modification was physically evaluated by observing both its color changes with digital camera and morphological changes with scanning electron microscopy as well as by measuring surface tension with water contact angle. Chemical modification was further evaluated by detecting its chemical structure changes with Fourier transformed infrared spectroscopy and by measuring its atomic composition ratio with X-ray photoelectron spectroscopy. In vitro test was performed on the scaffold surfaces (n = 3) by employing porcine vascular smooth muscle cells for 4 weeks. Further cellular behaviors such as cell proliferation and tissue formation were evaluated by cell counting kit (CCK-8) and by histological staining, respectively. While increase in cellular interaction was clearly observed from the CCK-8 and histological stain data, its surface modification was verified by various physical and chemical changes.