Chemical Characterization of Yellow and Orange Pollen <i>(Helianthus annuus) </i>and its Effect in the Growth of Hydroxyapatite

Abstract

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 °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 nanocrystals 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.

Purification of Hollow Sporopollenin Microcapsules from Sunflower and Chamomile Pollen Grains

“…Cyclohexane extraction represented a further mass reduction of 2.6% from the raw pollen mass ( Figure 3 A). The accumulated percent of mass corresponding to the lipid phase of the pollenkitt (~10%, Figure 3 A) was in line with the lipid content previously reported for sunflower pollen [ 26 , 47 ]. After treatment with cyclohexane, the bands assigned to sporopollenin [ 48 ] became evident in the spectra ( Figure 2 E), indicating the successful cleaning of the pollen surface.…”

“…Untreated samples presented the typical morphology of raw sunflower pollen with the surface completely coated with pollenkitt ( Figure 2 A), as well as their characteristic FTIR spectrum [ 26 ] ( Figure 2 E). We analyzed sunflower pollen from two different origins: Spain, and Czech Republic.…”

“…As compared to hot acetone extraction, our low temperature process could be advantageous as it should reduce any thermal alteration of the product. After this step, sunflower pollen became white, indicative of the removal of flavonoids and carotenoid pigments [ 26 ], and product mass was reduced by approximately 8% ( Figure 3 A). Acetone washing was unable to eliminate saturated lipids and proteins, as shown by FTIR bands at 1735 cm −1 ( Figure 2 E).…”

“…FITR technique was employed to explore the different functional groups present in the pollen samples [ 26 ] after each purification step as well as in the obtained eluates. FTIR spectra were recorded in a VARIAN FT-IR 670 (Varian Inc. Scientific Instr., Palo Alto, CA, USA) equipped with an attenuated total reflectance (ATR) accessory (GladiATR, PIKE technologies, Madison, WI, USA) from 400 to 4000 cm −1 at 4 cm −1 resolution using 64 scans.…”