Surface modification of poly(lactic acid) fibers via aminolysis and type-l collagen immobilization for bone tissue engineering

Abstract

By the reaction of poly (lactic acid) (PLA) in the form of electrospun fibrous membranes with 1,6-hexanediamine (HMD), free amino groups were interoduced onto PLA surface, through which a biocompatible macromolecule, collagen, was covalently immobilized by employing N,N-disuccinimidylcarbonate (DSC) as a coupling agent. The existence of the free amino groups on the aminolyzed PLA surface was verified quantitatively by the ninhydrin analysis method, which revealed that the free amino group density were influenced by the HMD concentration and aminolyzing time. Water contact angle measurement confirmed that the hydrophilicity of the PLA fibrous membranes was enhanced with the aminolysis and the further immobilization of collagen. In addition, surface alteration of modified espun fibrous scaffolds was also studied by ART-FTIR and XPS techniques. In vitro indirect cytotoxicity evaluation performed with mouse fibroblast (L929) and preosteoblastic cells (MC3T3-E1) revealed that both the neat and the modified PLA fibrous scaffolds released no substances at levels that were harmful to these cells. Scanning electron microsocopy observation showed an evidence of the extension of cell cytoplasm on all types of the modified PLA fibrous surface even at 4 h after cell seeding. The culture MC3T3-E1 in vitro proved that the cell proliferation and cell activity of modified PLA e-spun fibers were improved compared with the neat PLA fibers. Among the various types of modified PLA scaffolds, colloagen-immobilized PLA showed the greatest ability to support cell proliferation and alkaline phosphatase (ALP) activity. Therefore, it is promising material to accelerate bone regeneration.