Fabrication of bioactive glass scaffolds by stereolithography for bone tissue engineering

• Main Author: Sabree, Israa
• Other Authors: Derby, Brian; Gough, Julie
• Published: University of Manchester 2014
• Subjects: 610.28
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618003

Bone tissue engineering aims to regenerate the bone structure and therefore recover the functions of bone tissue rather than replacing it alone. Regenerative medicine focuses on using biomaterials as three-dimensional (3D) porous scaffolds, specifically designed to mimic the nature of host tissue and hence to promote cell growth and tissue regeneration. For such purposes, 3D bioactive glass scaffolds are one of the most studied types of scaffolds for bone tissue engineering because of their excellent bioactivity and potential for stimulating osteogenesis and angiogenesis. In the present study stereolithography has been used to fabricate negative moulds for use with the gel casting process to produce porous 3D 70%SiO2-30%CaO2 bioactive glass-ceramic scaffolds with three different pore sizes and identical porosity. A scaffold with 50 vol. % solid loading suspension was successfully manufactured in two different 3D external shapes and three pore sizes. The bioactive glass powder was crystallized at a temperature of 865.5°C. The mechanical behaviour of the scaffolds sintered at 1200⁰C was found to be influenced by pore size despite the similarity in porosity and the scaffold compressive strength decreased, and the failure probability increased, with increasing pore size. This behaviour was found to be consistent with the predictions of Weibull statistics. All three scaffold types exhibited a compressive strength within the strength range of human trabecular bone. The indentation hardness of the scaffold struts was found to be close to that of cortical bone. In vitro investigation of the scaffolds’ bioactivity was achieved through examining changes in the composition of the immersion solution. Biological tests showed that all scaffolds significantly enhanced cell proliferation, deposition of collagen, alkaline phosphatase activity and the expression of osteocalcin with an increasing rate of mineralisation throughout the culture period; this is believed to be due to the action of released ions from the bioactive glass which induces osteoblast cells from their proliferation phase to a mineralisation stage. A 3D sliced scaffold was produced from an assembly of quasi-2D slices to investigate cell behaviour throughout the scaffold. The goal of in vitro studies of the sliced scaffolds with different pore size is to improve the understanding of how scaffold pore size impacts on initial cell attachment, tissue ingrowth and mass transfer through the scaffold. The results confirmed that a scaffold with bigger pore size provided more space for tissue ingrowth and mass transfer throughout the scaffold over long culture periods. The findings suggest that the fabricated 3D 70%SiO2-30%CaO2 bioactive glass-ceramic scaffolds have potential for use in bone tissue engineering applications.