Glass - Back to the Future!

Presenting Author:
Ifty Ahmed

article posted 18 March 2016

Dr Ifty Ahmed’s research has centred on manufacture of resorbable biomaterials for tissue engineering and regenerative medicine applications. The research work has spanned resorbable glasses, biopolymers and biocomposites as resorbable implant materials. His main interests have focussed on manufacture and characterisation of phosphate-based glasses and fibres and more recently on microspheres. Phosphate-based glasses have been investigated for hard and soft tissue repair applications and these glasses are unique amorphous biomaterials due to their fully resorbable characteristics. They can be made to completely dissolve in aqueous environments with controllable degradation rates (from days, weeks/months to several years).

Novel Microstructural Features in Phosphate Glass Microspheres for Cell and Biomaterial Interactions

Ifty Ahmed*1, Zakir Hossain1, Virginie Sottile2, David Grant1 & Brigitte Scammell3
1: Advanced Materials Research Group, Faculty of Engineering, University of Nottingham
2: Division of Cancer and Stem Cells, School of Medicine, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
3: Academic Orthopaedics, Trauma and Sports Medicine, University of Nottingham, Queen’s Medical Centre, Nottingham, UK

There is a major on-going shift in emphasis from tissue repair to tissue regeneration as a solution to the ever-growing need for long-term orthopaedic care. The main aim of this work was to investigate the feasibility of manufacturing resorbable phosphate-glass microspheres as cell carriers for applications in bone regenerative medicine.
Phosphate-based glasses were investigated due to their easily controlled degradation profiles. The glass composition investigated was based on the system 40 P2O5, 16 CaO, 24 MgO and 20 Na2O (in mol%) produced using the following precursors, NaH2PO4, CaHPO4 and MgHPO4.3H2O (Sigma Aldrich, UK). The precursors were mixed together and melted at 1150°C for 1·5 h. Molten glass was poured onto a steel plate and cooled to room temperature. The glass was then ground and sieved into varying particle size ranges for manufacture into microspheres via the flame spheroidisation process.
The main advantages for this technology are; (1) the degradation profiles for these amorphous CaP microspheres can easily be tailored (from days, weeks to several months), (2) these glasses can easily be doped with osteoporotic positives such as strontium to inhibit bone resorbtion, (3) the microspheres can be loaded with biological components to provide a potent combinatorial effect of bone repair and regeneration and (4) can provide a minimally invasive delivery route through simple mechanisms such as syringes or cannulas.
Early trials confirmed that bulk microsphere production was totally feasible (see Figure 1 below) and yields of approximately 95% were achieved. In addition, human mesenchymal stem cells (hMSCs) were seen to successfully attach to the microspheres produced.

Figure 1: Bulk microspheres produced