Biopolymers 95:682 (2011)
Amide-linkage formed between ammonia plasma treated poly(D,L-lactide acid) scaffolds and bio-peptides: enhancement of cell adhesion and osteogenic differentiation in vitro.
Zixing Xu1, Tao Li1, Zhaoming Zhong1, Dingsheng Zha1, Songhui Wu1, Fuqiang Liu1,Wende Xiao1, Xiaorui Jiang2, Xinxin Zhang2 and Jianting Chen1, *
The surface characteristics of scaffolds for bone tissue engineering must support cell adhesion, migration, proliferation and osteogenic differentiation. In the study, Poly (D,L-lactide acid) (PDLLA) scaffolds were modified by combing ammonia (NH3) plasma pre-treatment with Gly-Arg-Gly-Asp-Ser (GRGDS)-peptides coupling technologies. The X-ray photoelectron spectroscopy (XPS) survey spectra showed the peak of N 1s at the surface of NH3 plasma pre-treated PDLLA, which was further raised after GRGDS conjugation. Furthermore, N 1s and C 1s in the high-resolution XPS spectra revealed the presence of -C=N (imine), -C-NH-(amine) and -C=O-NH-(amide) groups. The GRGDS conjugation increased amide groups and decreased amine groups in the plasma-treated PDLLA. Confocal microscope and high performance liquid chromatography verified the anchored peptides after the conjugation process. Bone marrow mesenchymal stem cells were co-cultured with scaffolds. Fluorescent microscope and scanning electron microscope photographs revealed the best cell adhesion in NH3 plasma pre-treated and GRGDS conjugated scaffolds, and the least attachment in un-modified scaffolds. Real-time PCR demonstrated that expression of osteogenesis-related genes, such as osteocalcin, alkaline phosphatase, type I collagen, bone morphogenetic protein-2 and osteopontin, was up-regulated in the single NH3 plasma treated and NH3 plasma pre-treated scaffolds following GRGDS conjugation. The results show that NH3 plasma treatment promotes the conjugation of GRGDS peptides to the PDLLA scaffolds via the formation of amide linkage, and combination of NH3 plasma treatment and peptides conjugation may enhance the cell adhesion and osteogenic differentiation in the PDLLA scaffolds.