Preliminary investigation of the potential of mesoporous bioactive glasses to treat hemorrhage

Abstract

Hemorrhage is the primary cause of death in both trauma and war. Commercially available hemostats cannot achieve hemostasis within two minutes of application and cannot inhibit bacterial infection, which are the properties of an ideal hemostatic agent. Organic hemostats are acidic in nature and can lead to inflammation. Inorganic hemostats can achieve hemostasis with fewer complications. Mesoporous bioactive glasses (MBGs) are inorganic agents that possess high surface area, pore volume and ordered channel structure. They have the potential to act as molecular sieves for platelets and other serum proteins to aggregate. Calcination heating rate is a major processing parameter during the synthesis of MBGs. Any variation in calcination heating rate could alter the physical properties of MBGs, affecting their ability to facilitate clotting. A low heating rate is preferred because it can yield more ordered mesoporous channel structures. A series of novel MBGs based on the glass composition (80-x) SiO2- 15 CaO- 5 P2O5- x Ta2O5 (mol%) were synthetized using a 1°C/min calcination heating rate. The effect of Ta incorporation on the glass structure was investigated. X-ray diffraction revealed that all glasses were completely amorphous. Fourier transform infrared spectroscopy showed that higher concentrations of Ta (5 and 10 mol%) in the glass structure acted as a network modifier which disrupts the silica backbone and leads to discontinuities in porous channel structures, confirmed by transmission electron microscopy. Brunauer-Emmett-Teller (BET) theory quantified the effects of the discontinuities through surface area measurement. It was found that MBGs with 0 and 0.5 mol% of Ta2O5 in the glass structure had 373.87 and 373.98 m2/g surface area respectively indicating that such low levels of Ta incorporation did not influence surface area. The addition of further Ta in the glass structure reduced surface area and produced more discontinuities in the channel structure. 1, 5 and 10 mol% Ta had approximately 5, 12 and 20% reduced surface area compared to 0 mol% Ta in the glass structure. The whole blood coagulation study indicated that MBGs with lower concentrations of Ta (0 and 0.5 mol%) could achieve 58% and 46% hemostatic efficiency, which decreased as tantalum content increased. It is concluded that the application of a low heating rate during calcination, of the order of 1°C/min, is more likely to result in mesoporous bioactive glasses with high surface area and pore volume than MBG samples processed at a higher heating rate. MBGs containing 0 and 0.5 mol% Ta could be potential hemostatic agent.