Carboxymethyl carrageenan immobilized on 3D-printed polycaprolactone scaffold for the adsorption of calcium phosphate/strontium phosphate adapted to bone regeneration.

Three dimensional (3D) substrates based on natural and synthetic polymers enhance the osteogenic and mechanical properties of the bone tissue engineering scaffolds. Here, a novel bioactive composite scaffolds from polycaprolactone /kappa-carrageenan were developed for bone regeneration applications. 3D PCL scaffolds were fabricated by 3D printing method followed by coating with carboxymethyl kappa-carrageenan. This organic film was used to create calcium and strontium phosphate layers via a modified alternate soaking process in CaCl 2 /SrCl 2 and Na2HPO4 solutions in which calcium ions were replaced by strontium, with different amounts of strontium in the solutions. Various characterization techniques were executed to analyze the effects of strontium ion on the scaffold properties. The morphological results demonstrated the highly porous with interconnected pores and uniform pore sizes scaffolds. It was indicated that the highest crystallinity and compressive strength were obtained when 100% CaCl2 was replaced by SrCl2 in the solution (P-C-Sr). Incorporation of Sr onto the structure increased the degradation rate of the scaffolds. Mesenchymal stem cells (MSCs) culture on the scaffolds showed that Sr effectively improved attachment and viability of the MSCs and accelerated osteogenic differentiation as revealed by Alkaline phosphatase activity, calcium content and Real Time-Reverse transcription polymerase chain reaction assays.

Surface mineralized hybrid nanofibrous scaffolds based on poly(l-lactide) and alginate enhances osteogenic differentiation of stem cells.

Surface mineralized nanofibrous scaffolds hold great potential for bone tissue engineering applications. In this study, a new hybrid nanofibrous scaffold composed of alginate/poly(l-lactide) nanofibers was fabricated using electrospinning method and then crosslinking process was employed. Hydroxyapatite crystal formation took place using in situ precipitation by immersion of the scaffolds in simulated body fluid solution for 10 days at 37°C. The morphologies of the scaffolds were observed using scanning electron microscope. Hydroxyapatite crystal formation on the surface of nanofibers was confirmed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis. The biocompatibility of the fabricated scaffolds was evaluated using mesenchymal stem cell culture and MTT assay. According to alkaline phosphatase activity and calcium content assays, it was concluded that the osteogenic differentiation of stem cells was considerable on scaffolds containing hydroxyapatite crystals in comparison with other specimens. The results showed biocompatibility of the scaffolds and their support from stem cell adhesion, growth and osteogenic differentiation, so the hydroxyapatite-coated poly(l-lactide)/alginate hybrid nanofibrous scaffolds hold suitable characteristics for bone tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 586-596, 2019.