CYTOTOXICITY, RELEASING PROPERTY AND ANTI BACTERIAL ACTIVITY OF ZINC DOPED HYDROXYAPATITE

Abstract

Hard tissue repair materials with excellent biological activity are currently the most widely used bioactive materials in clinical practice. Zinc plays diverse roles in biological functions, like enzyme activity, nucleic acid metabolism, membrane structure maintenance, hormonal activity, bio mineralization etc. Incorporation of Zinc into hydroxyapatite (HAp) is energetically favoured in the tetrahedral coordination of Ca2+ site with signiifcant local structural distortion over Ca2+ site. Zn2+ ions were doped into HAp using co-precipitation method at 37 ◦C, 60 ◦C and 80 ◦C. When characterizing ZnHAp it was noticed that with the increase of Zn dopant amount, the shape of particles changed to rod-like shape and the sizes of crystal became smaller. Using size exclusion it was concluded that the samples are below 100 nm in size. Cytotoxicity of the samples was quantified measuring the UV absorbance at 450 nm against L929 cells. When the dopant amount is ≤ 5%, the cytotoxicity grade was always zero. It was noticed the cell viability also increased with increasing the temperature. Linearity of the method could be achieved with 0.975 correlation coefficient. ANOVA tests revealed that there were no any significant variances between Zn doped HAp samples and pure HAp samples. Compelling releasing property was observed at higher temperature which facilitates potent antibacterial property. It is because at high temperatures, higher crystalinity of the nanoparticles will be occurred. This may lead to have an increase in releasing property. In this study 0.9115 mg l-1, 1.1365 mg l-1, 1.6365 mg l-1 amounts of Zn2+ ions were released from 5% ZnHAp synthesized at 37 ◦C, 60 ◦C and 80 ◦C respectively. In addition, more than 95% of antibacterial effect of ZnHAp against Staphylococcus aureus bacteria was observed.