Evaluation of the antibacterial and cytotoxic activity of gallium doped bioactive glass versus 45S5 Bioglass®

Abstract

In the healthcare setting, approximately 2 million bioinert devices are implanted into patients on an annual basis. However, interfacial instability of bioinert implants leads to reduced implant survivability and as a result revision surgery. Implant related infections are also a major concern which are associated with considerable repercussions for both the patient and healthcare system. Therefore, to overcome these failures materials that stimulate growth, repair and regeneration of tissues whilst simultaneously preventing infections need to be developed. A growing body of clinical data demonstrates that bioactive glasses offer great hope as they endorse these properties. Melt quench derived 3 mol% gallium doped bioactive glass was tested for antibacterial and cytotoxic activity. The results were compared with archetypal 45S5 Bioglass®, prepared and processed under identical conditions to allow a direct comparison. The antibacterial activity was studied using Escherichia coli (NCTC 10538) and Staphylococcus aureus (ATCC 6538). The cytotoxic activity was evaluated using osteosarcoma Saos-2 cells and bone marrow derived mesenchymal stem cells. The group IIIa metal, gallium is known to possess antibacterial, antiresorptive and osteogenic properties and is therefore of interest for biological and tissue engineering applications. Results of the current work illustrated that 3 mol% gallium doped bioactive glass behaves in a similar manner to 45S5 Bioglass®. The antibacterial studies demonstrated that 3 mol% gallium doped bioactive and 45S5 Bioglass® do not possess a broad-spectrum antibacterial activity, as growth inhibition was only observed for E. coli; they were also rendered ineffective following pH neutralisation. Additionally studies with mammalian cells revealed that 3 mol% gallium doped bioactive glass did not exhibit significant osteogenic activity, in comparison to 45S5 Bioglass®, after pH neutralisation.