Abstract

The physical properties and performance of polymer matrix composites can be significantly improved by the addition of carbon nanotubes (CNTs) as reinforcements. Nanocomposites formed from poly(lactic-co-glycolic acid) (PLGA) and carboxylated multiwall CNTs (MWCNTs) have been recently fabricated in order to generate suitable implant materials for bone tissue engineering. Here, we reported the cellular reactions of osteoblasts grown on PLGA-MWCNTs nanocomposite films, and investigated the molecular mechanisms responsible for the artificial surface of the films-induced modulation of cellular functions. The results showed that interaction with the PLGA-MWCNTs films induced an increased cell proliferation, DNA synthesis and S phase accumulation, and modulated osteogenic differentiation in osteoblasts. The well-defined stress fibers and enhanced phosphorylation of focal adhesion kinase (FAK) were also observed in osteoblasts cultured on PLGA-MWCNTs films. Assessment of signaling molecules suggested that extracellularsignal- regulated kinases (ERK1/2), but not p38 mitogen-activated protein kinases (p38MAPK) or c-Jun-N-terminal kinases (JNK), were selectively phosphorylated in osteoblasts grown on PLGA-MWCNTs film. Pre-treatment of osteoblasts with PD98059, a specific inhibitor of ERK 1/2, resulted in a significant reduction in cell viability and stress fibers formation of osteoblasts cultured on PLGA-MWCNTs film, suggesting the involvement of ERK1/2 in cell viability and stress fibers formation. These results provided the molecular basis for enhanced biocompatibility of osteoblasts response to the surfaces of PLGA-MWCNTs nanocompostie films, which may account for the potential use of PLGA-MWCNTs composites as promising substrates for bone regenerative applications.

Keywords: Carbon nanotubes, poly(lactic-co-glycolic acid), nanocomposite, osteoblasts, focal adhesion kinase, mitogen-activated protein kinases