Mechanical, in-vitro biological and antimicrobial characterization as an evaluation protocol of a ceramic material based on alkaline activated metakaolin

Abstract

The study aimed to correlate mechanical, physical and biological properties (in-vitro) of a ceramic material, based on alkaline activated metakaolin (MK) and CaCO3, to be used in the health sector. The designed materials reached compressive strengths in the range of 18 MPa to 29 MPa, after 7 days of curing, and porosity between 50 and 30%. The higher strength materials were subjected to a reactivity test for the formation of a layer of hydroxyapatite in the presence of simulated body fluid (SBF). By means of scanning electron microscopy, the in-situ growth of rounded crystals was identified, indicating the presence of elements such as Ca and P in its chemical composition. For the evaluation of the biological and anti-bacterial response, a system with the capacity to form a calcium phosphate layer on its surface was selected, with an increase in the pH value of the SBF solution and a compressive strength of at least 25 MPa. The results of the biological protocol showed that the material, due to its high pH, generates haemolysis or the rupture of red blood cells, indicating that the developed material needs to be modified in its chemical composition to decrease the high pH or to guarantee, by means of an additional processing stage, to decrease leaching of alkaline elements to the body fluid and thus not cause harmful effects on the human body. On the other hand, after being evaluated against several bacteria it was identified that the material had an inhibitory effect on Pseudomonas aeruginosa which makes suitable the material to be used in external applications.