Optimization of poly(ε-caprolactone) surface properties for apatite formation and improved osteogenic stimulation

A biodegradable polymer with surface properties that promotes cell attachment and host integration is widely recognized as a useful three-dimensional construct for bone tissue engineering applications. In this work, studies were carried out to correlate surface properties of modified polycaprolactone (PCL) films with cell-material interactions. PCL film substrates were subjected to various degrees of chemical hydrolysis using different pretreatment solutions to introduce different densities of carboxylate groups onto the surfaces. The extent of hydrolysis on the films was optimized to allow the deposition of a dense and uniform bone-like apatite layer by an alternate soak treatment, followed by subsequent incubation in simulated body fluid (SBF). The hydrolyzed and apatite-coated PCL films were investigated using scanning electron microscopy, thin film X-ray diffractometer (TF-XRD), water contact angle, and Alizarin red staining. Surface wettability, roughness, and chemistry of various PCL substrates were correlated with cell attachment, proliferation, viability, and alkaline phosphatase activity. Results demonstrated that cell attachment increased with increasing surface hydrophilicity and roughness. The apatite-coated films showed significantly improved surface wettability and enhanced surface roughness, which subsequently led to better cell attachment potential, high-cell viability, and enhanced bone formation capability. Thus, surface modification with an apatite coating layer is a promising approach for enhancing the efficacy of the polymeric scaffold for bone tissue engineering applications.