Glass - Back to the Future!

Presenting Author:
Leena Hupa

article posted 1 April 2016

Professor Leena Hupa heads the Combustion and Materials Research Group in the Johan Gadolin Process Chemistry Centre, a Centre of Excellence in Research at Åbo Akademi University. The main research areas of her group are within the bioenergy, cleantech, and medical materials technologies. Within the medical field, tailoring of bioactive glasses for tissue engineering scaffolds is one of the main research focuses. Professor Hupa´s research activities include physical, chemical and in vitro properties of bioactive glasses, properties of soda-lime glasses, manufacture and characterization of ceramic glazes and functional coatings. Her recent research activities include also high-temperature performance of metals and refractories in combustion devices. She is a co-author of 140 scientific papers and reports. She has written four sections on bioactive glasses in books dealing with biomaterials.

Robocasting of S53P4 Bioactive Glass Scaffolds
for Bone Tissue Engineering

Siamak Eqtesadia, Leena Hupaa*, Azadeh Moteallehb ,Pedro Mirandab, Antonia Pajaresb, Timo Närhic

Bioactive glasses are among the most promising biomaterials for application in bone tissue engineering. Today, intense research efforts are paid to develop highly porous 3D structures of bioactive glasses, especially for bone tissue engineering applications. Robocasting, an extrusion-based direct writing technique, utilizes highly solid loaded paste-like colloidal suspensions (inks) to build 3D structures through a layer-wise deposition of extruded cylinders. The robocasting technique provides a means to produce bioactive glass scaffolds with a customized external geometry and internal pore architecture with compressive strengths that are far superior to any previously reported values. The enhancement in the mechanical performance is associated with the novel pore architecture; thicker struts and wider interconnections. Typically, the strength of the bioactive glass-based scaffolds produced by the robocasting technique is more than one order of magnitude higher than the strength of the 3D scaffolds manufactured through other approaches. Most important, the strength data of the robocasted scaffold is well within, or even surpassing, the strength range of cancellous bone.

In this work, we report for the first time production of amorphous 3D tissue engineering scaffolds from the glass S53P4 through robocasting. The silicate-based bioactive glass S53P4 is a commercial biocompatible osteoconductive and osteostimulative bone substitute approved for certain clinical applications. Glass S53P4 is prone to crystallize at relatively low temperatures, which challenges its utilization in procedures where any longer thermal treatments, such as sintering, above the glass transition temperature, are required to fabricate amorphous products with 3D porosity of appropriate mechanical durability. The scaffolds were sintered at as sufficiently low temperature to give amorphous structures and to maintain the well-reported bioactivity of S53P4. The mechanical integrity of the scaffolds was sufficient for practical use, partly due to the thick struts. Therefore, robocasting seems to be a suitable technique for development of patient-specific porous scaffolds of bioactive glass S53P4. In the presentation, the mechanical, in vitro properties, and the cell response of the robocast S53P4 scaffolds will be discussed in detail.


a Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Piispankatu 8, FI-20500 Turku, Finland

b Departamento de Ingeniería Mecánica, Energética y de los Materiales, Universidad de Extremadura, Escuela de Ingenierías Industriales, Avda. de Elvas s/n, 06006 Badajoz, Spain

c Timo Närhi, Department of Prosthetic Dentistry and Turku Clinical Biomaterials Centre – TCBC, Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, FI-20520 Turku, Finland