Mechanosynthesis of carbonate doped chlorapatite–ZnO nanocomposite with negative zeta potential

Abstract

Carbonate doped chlorapatite–ZnO composite nanopowders with negative zeta potential were synthesized by one step mechanochemical process as a novel bioceramic. Results indicated that the formation of carbonate doped chlorapatite–ZnO composite was varied by incorporation of different ZnO contents. In the presence of 3, 6, 9, 12, and 15wt% ZnO, carbonate doped chlorapatite–ZnO composite nanopowders were produced successfully after 1h of milling. There was no trace of carbonate doped chlorapatite based composite as ZnO content increased to 20wt%. According to the X-ray diffraction data, the average crystallite size, and the degree of crystallinity of the product decreased slightly as ZnO contents increased from 0 to 15wt%. Conversely, lattice strain increased gradually. Subsequent annealing at 800°C for 1h of carbonate doped chlorapatite–12wt% ZnO composite indicated larger crystallite size and the degree of crystallinity. The zeta potential of nanoparticles (12wt% ZnO sample) suspended in physiological saline (0.154M NaCl) was determined. The zeta potential was almost zero for pH=3 and negative values for pH=5–11 and –22.52 ±1.96mV at pH 7.4. Negative zeta potential is reported to favor apatite nucleation, bone regeneration, as well as osseointegration. Microscopic observations illustrated that the final product had a cluster-like structure containing ZnO platelets as well as polygonal and spherical particles with an average particle size of approximately ranged from 20±10 to 50±10nm. To our knowledge, this is the first report of the synthesis of carbonate doped chlorapatite–ZnO composite nanopowders; the nanocomposite reported here can be a promising candidate for use in biomedical applications.