Polycaprolactone (PCL) has been widely adopted for biomaterials and biomedical applications due to its slow degradability and good biocompatibility, as well as its good mechanical and thermoplastic characteristics. However, PCL has hydrophobic surface and lacks of functional groups, therefore, it does or can not provide suitable surface for cell adhesion.
In this study, we have deposited poly acrylic acid films on three-dimensional (3D) PCL scaffolds using plasma polymerization and then plasma-polymerized 3D PCL scaffold was immersed into simulated body fluid (SBF) in order to improve the biocompatibility.
The changes in wettability and surface morphology of 3D-PCL surface after plasma treatment were examined by contact angle and field emission scanning electron microscopy. The chemical bonding of acrylic acid plasma polymerized on 3D-PCL surfaces was demonstrated by fourier transform infrared spectroscopy. The biological behaviors were also evaluated for MC3T3-E1 cells proliferation and differentiation using MTT assay and alkaline phosphatase (ALP) activity. The osteo-conductive ability of acrylic acid plasma polymerized on 3D-PCL surfaces was evaluated by SBF immersing test.

From the current findings, the following conclusions were drawn:
1) Acrylic acid plasma polymerization on the PCL films showed the formation of hydrophilic film containing carboxyl groups.
2) In SBF immersing test, acrylic acid plasma polymerized 3D PCL scaffolds presented excellent hydroxyapatite formation ability than untreated 3D PCL scaffolds.
3) Hydroxyapatite coated 3D PCL scaffold showed good proliferation of MC3T3-E1 cells than untreated and plasma-polymerized 3D PCL scaffolds, but the cell differentiation of the experimental group was not significantly different from control group.

These results suggest that the acrylic acid plasma polymerization on the 3D PCL scaffolds has an effect on proliferation of MC3T3-E1 cells and a possibility of potential use in osteo-conductive bone graft scaffolds.