Quantification of Protein Incorporated into Electrospun Polycaprolactone Tissue Engineering Scaffolds

The surface modification of synthetic tissue engineering scaffolds is essential to improving their hydrophilicity and cellular compatibility. Plasma treatment is an effective way to increase the hydrophilicity of a surface, but the incorporation of biomolecules is also important to control cellular adhesion and differentiation, among many other outcomes. In this work, oriented polycaprolactone (PCL) electrospun fibers were modified by air-plasma treatment, followed by the covalent attachment of laminin. The amount of protein incorporated onto the fiber surface was controlled by varying the reaction time and the protein solution concentration. The protein concentration and coverage were quantified using X-ray photoelectron spectroscopy (XPS), solid-state ultraviolet-visible spectroscopy (UV-vis) and two fluorescence-based assays. XPS results showed a nearly linear increase in protein coverage with increasing protein soaking solution concentration until a monolayer was formed. Results from XPS and the NanoOrange fluorescence assay revealed multilayer protein coverage at protein solution concentrations between 25 and 50 μg/mL, whereas the UV-vis assay demonstrated multilayer coverage at lower protein solution concentrations. The effect of protein concentration on the neurite outgrowth of neuron-like PC12 cells was evaluated, and outgrowth rates were found to be positively correlated to increasing protein concentration.