Preparation and Antibacterial Activity of Silver Ions-Substituted Hydroxyapatite/Titania

Abstract

In this paper a series of silver ions-substituted hydroxyapatites (HA) were prepared. The antibacterial activities of these materials on textiles against bacteria have been investigated. Titania (TiO2) was selectively added into the materials to decrease the silver-ions concentration to get the same active antimicrobial effects. The microstructure, the shape and size, concentration of silver, and the groups of the composite materials were characterized using transmission electron microscopy (TEM), infrared spectroscopy (IR), Atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The results showed that there was a dose dependent-effect of silver-ions concentration from the disk diffusion test. The higher the silver-ions concentration, the better the antibacterial activity of the composite materials was. Keeping silver-ions concentration constant, the antibacterial activity of the materials for adding Titania was better than that of without Titania. Moreover, the addition of Titania would inhibit the discolouration of the composite materials. The antibacterial activities of the composite materials differentiate to some extent with the bacterial strains.

The release properties of silver ions from Ag-nHA/TiO 2 /PA66 antimicrobial composite scaffolds

“…It is reported that the water molecules in the inter-lamellar regions can change the overall crystalline state of the PA matrix [32]. On the other hand, the release of the substituted Ag + ions in the HA lattice should be much slower [10,20]; this may be another reason why the Ag + release from the Ag-nHA/TiO 2 /PA66 composite scaffold can be sustained for a long time. A steady and sustained release of silver ions in a concentration level capable of rendering antimicrobial efficacy is a crucial factor for antibacterial materials [33].…”

“…The nHA (Ca 10 (PO 4 ) 6 (OH) 2 ) slurry with a Ca/P molar ratio of 1.67 was prepared [20]; then, the TiCl 4 solution was slowly dropped into the nHA slurry to form the nHA/TiO 2 slurry. The nHA/TiO 2 precipitate was fully washed with deionized water to remove the chloride ions.…”

“…Titania (TiO 2 ) is incorporated into the composite because, on the one hand, it is conducive to prevent silver from discoloration [17], and on the other hand, a silver-doped titania composite exhibits good bactericidal property due to the synergy between silver ions and titania nano-particles [18,19]. Furthermore, the synergy can keep the same antibacterial activity when fewer silver ions are used, thus reducing the cost of the material [20].…”

Peculiarities of synthesis of Ag-doped hydroxyapatite ceramics

“…These problems may be avoided by using metal ions or nanoparticles such as silver, copper, zinc as an antimicrobial agent [7][8][9][10]. In terms of imparting antimicrobial properties to a bone implant, the effect of silver additives in HA [5,6,[11][12][13][14][15][16][17][18][19][20][21] having a strong inhibitory effect on a wide range of bacteria, was studied in more detail. Literature suggests that regardless of the form in which silver is in the implant -either in the form of ions substituting calcium isomorphically, or in the form of nanoparticles located on the surface of HA particles, or in the intergranular space of silver-containing ceramics, to a concentration about 1.5-2 wt.%, the material exhibits excellent bactericidal properties [5,6,11,12].…”