Hydroxyapatite-nanosilver composites with plasmonic properties for application in surface-enhanced Raman spectroscopy

Two routes for preparation of nanocomposites based on hydroxyapatite (HA) doped with Ag nanoparticles (HA@AgNPs) were investigated aiming towards the development of novel materials for sensing and biomedical applications. Both routes are based on using commercially available HA and Creighton colloidal silver prepared by reduction of silver nitrate with sodium borohydride. A number of composites with different HA to Ag ratios were synthesized and evaluated by transmission electron microscopy, X-ray diffraction analysis, infrared and Raman spectroscopy. It was found that the position of phosphate band in 940-970 cm-1 range of Raman spectra can be used as an independent marker of successful HA loading with Ag NPs in addition to XRD analysis. The ability of HA@AgNPs nanocomposites to localized surface plasmon resonance was demonstrated by the UV-Vis spectroscopy and surface-enhanced Raman scattering (SERS) study performed with acridine as a test molecule. The grafted SERS activity can be utilized for optical control of bone healing either for identification of various analytes, participating in bone metabolism.