Novel 3D composite polymeric scaffolds for tissue engineering

3D printed poly(lactic acid) (PLA) grids coated with electrospun PLA, chitosan and silk fibroin webs or their composites were fabricated and evaluated for liver tissue engineering applications. United States Food and Drug Administration (FDA) approved biodegradable and biocompatible PLA was chosen for mechanical strength and ease of processibility. It was shown that simple fused deposition method or 3D printing can be used to create not only rigid but also soft structures by changing the printing parameters, without the use of complex procedures or hardware, to match the mechanical properties of soft tissues. As PLA is inherently not cell binding, effect of surface modification by treatment with sodium hydroxide to improve hydrophilicity and cell attachment was investigated. Soft 3D printed PLA grids with 1x1, 3x3 and 5x5 mm pore sizes were produced. PLA webs were also deposited on these grids by electrospinning using various solvent combinations. Effect of fiber surface topographies on wettability, cell attachment and cell viability was investigated. Furthermore, grids were also coated with electrospun PLA/chitosan and PLA/silk fibroin webs to improve cell viability. Calcium modified silk fibroin was blended with PLA and used for liver tissue engineering for the first time in this study. 3D composite scaffolds produced were characterized in terms of surface topography and roughness using Scanning Electron Microscopy (SEM) and White Light Interferometry (WLI) respectively. Wettability was assessed by static water contact angle measurements. Materials were also characterized by FTIR-ATR spectroscopy and XRD measurements. Hep2G cell viability and cell growth was investigated by MTT assay. The cell growth on the scaffolds were demonstrated by SEM imaging. Strong protein adsorption on scaffolds after immersing in DMEM with and without serum protein were shown by SEM images and water contact angle measurements. Biodegradation tests were performed by immersing the scaffolds in PBS and DMEM with serum for 3 weeks. Through these investigations we tried to correlate material type and surface properties and cell viability. Our results indicate that 3D printed PLA grids coated with various electrospun webs were all bioactive and may be suitable for long term in vitro liver tissue modelling and liver tissue engineering applications. Keywords : Liver tissue engineering, 3D bioactive scaffolds, surface modification