The immobilization of recombinant human bone formation protein-2 (rhBMP-2) on polycaprolactone (PCL) scaffolds was performed by plasma polymerization. RhBMP-2, which induces osteoblast differentiation in various cell types, is a growth factor that plays an important role in bone formation and repair. The surface of the PCL scaffold was functionalized with the carboxyl groups of plasma-polymerized acrylic acid (PPAA) thin films. Plasma polymerization was carried out at a discharge power of 60 W at an acrylic acid flow rate of 7 sccm for 5 min. The PPAA thin film exhibited moderate hydrophilic properties and possessed a high density of carboxyl groups. Carboxyl groups and rhBMP-2 on the PCL scaffolds surface were identified by attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The alkaline phosphatase activity assay showed that the rhBMP-2 immobilized PCL scaffold increased the level of MG-63 cell differentiation. Plasma surface modification for the preparation of biomaterials, such as biofunctionalized polymer scaffolds, can be used for the binding of bioactive molecules in tissue engineering.
In this work, protein adsorption and cell adhesion on three-dimensional (3D) polycaprolactone (PCL) scaffolds treated by plasma etching and deposition were performed. The 3D PCL scaffold used as a substrate of a bone tissue was fabricated by recent rapid prototype techniques. To increase surface properties, such as hydrophilicity, roughness, and surface chemistry, through good protein adhesion on scaffolds, oxygen (O 2 ) plasma etching and acrylic acid or allyamine plasma deposition were performed on the 3D PCL scaffolds. The O 2 plasma etching induced the formation of random nanoporous structures on the roughened surfaces of the 3D PCL scaffolds. The plasma deposition with acrylic acid and allyamine induced the chemical modification for introducing a functional group. The protein adsorption increased on the O 2 plasma-etched surface compared with an untreated 3D PCL scaffold. MC3T3-E1 cells adhered bioactively on the etched and deposited surface compared with the untreated surface. The present plasma modification might be sought as an effective technique for enhancing protein adsorption and cell adhesion.
Superporous hydrogels (SPHs) with interconnected pores of several hundreds
micrometers were prepared using radical polymerization of acrylic acid (AA) and acrylamide
(AAm) in the presence of N,N’-methylenebisacrylamide (BIS). A gas blowing method using
bicarbonate as a foaming agent was applied to introduce the porous structure under different pH
conditions (pH 2~7). The pore structures of the prepared SPHs were examined by a scanning
electron microscope. The SPHs obtained at pHs of 4.5 and 4.75 were observed to have a
interconnected pore structure with homogeneous distribution and swell to an equilibrium state
within several minutes. The O2 plasma reactor has been used for surface modification of SPHs. The
plasma-treated SPHs showed much faster swelling behavior due to the improvement of surface
hydrophilicity. The swelling ratio of SPHs was also enhanced by using a wetting agent, such as
triacetin and glycerol, during a washing procedure.
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