Chemical characterization of yellow and orange pollen (Helianthus annuus) and its effect in the growth of hydroxyapatite

In this work orange pollen grains (Helianthus annuus) were immersed in a supersaturated ionic solution (similar to human extracellular fluid) during different times at 37 degrees C, atmospheric pressure and pH of 7.4. By Fourier transform infrared spectroscopy (FT-IR) we confirmed the presence of the functional groups carbonyl, amide I, amide II, carboxyl and phosphate in both samples. Nevertheless, yellow pollen owns a greater amount of phosphate groups than orange pollen. By scanning electron microscopy (SEM), differences in the morphology, shape and size of both samples were not observed. In orange pollen grains, amorphous agglomerates can be observed for periods smaller to 14 days and spherical structures formed by nano-crystals of laminar form were observed on their surface at 17 days. By energy dispersive spectroscopy (EDS) confirms the presence of calcium and phosphorous in the agglomerates with different Ca/P ratio and by X-ray diffraction (XRD) the hydroxyapatite (HAp) phase was verified.