Phosphate glasses as bioresorbable materials for bone tissue regeneration and drug delivery
a B.A. Kyffin, aS.E. Taylor, bF.N.S Raja, bR.A. Martin, aD. Carta
aDepartment of Chemistry, University of Surrey, Guildford, GU2 7XH, UK
bAston research Centre for Healthy ageing, Aston University, Birmingham, B4 7ET, UK
In recent years interest in bioresorbable phosphate glasses for regeneration or repair of hard and soft tissues has grown significantly.1 In contrast to bioactive silicate-based glasses which dissolve relatively slowly phosphate-based glasses react rapidly and dissolve in the physiological environment and they are eventually totally replaced by regenerated hard or soft tissue. Thanks to their complete solubility, phosphate glasses can be used both as tissue regeneration temporary implants and as controlled local delivery systems of drugs/medicines.2 In particular, antibacterial ions such as Ag+, Cu2+, Zn2+ can be incorporated in the glass allowing a combination of bioactivity and efficient local drug release at the implant site thereby avoiding the systematic conventional antibiotic administration treatment.3,4
The conventional method to prepare phosphate glasses is the high temperature melt quenching technique, which often leads to non-homogeneous systems that cannot be used for hosting temperature sensitive molecules. More recently, the lower temperature sol-gel technique has been gaining increased attention.5 However this method uses organic solvents that require removal by calcination.
In this work, we have prepared a series of antibacterial silver-doped phosphate glasses in the system P2O5-CaO-Na2O-Ag2O using the coacervate method. This technique is based on the formation of a colloidal polyphosphate system (coacervate) by slow addition of Ca2+ to a sodium polyphosphate water solution at room temperature. Phosphate glasses having similar structural to the melt-quenched are obtained by drying the coacervate under vacuum. Structural characterisation of the glasses using a multi-technique approach (thermal analysis, X-ray diffraction, Raman spectroscopy) and dissolution tests in water and simulated body fluid will be presented. The antibacterial activity of glasses containing various amounts of silver (Ag2O up to 10 mol%) assessed against Staph. aureus is also presented.
1) Sharmin and Rudd, J. Mater. Sci., 2017, 52, 8733; 2) Abou Neel et al., J. Mater. Chem., 2009, 19, 690; 3) Ahmed et al., J. Biomed. Mater. Res. Part A, 2006, 79, 618; 4) Abou Neel et al. Biomaterials, 2005, 26, 2247; 5) Owens et al. Prog. Mater. Sci., 2016, 77, 1.