Modifications of Hydroxyapatite by Gallium and Silver Ions—Physicochemical Characterization, Cytotoxicity and Antibacterial Evaluation

Abstract

Hydroxyapatite (HA) powders enriched with silver or gallium ions or both were synthesized by two different routes: standard precipitation and the solid-state method. The powders were characterized by using several methods: inductively coupled plasma optical emission spectrometry (ICP-OES), powder X-ray diffractometry (PXRD), transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). The effects of enrichment of the HAs in Ag+ or Ga3+ or both on in vitro cytotoxicity and microbiological activity were discussed. PXRD experiments showed that the samples obtained by the wet method consisted of single-phase nanocrystalline HA, while the samples prepared via the solid-state method are microcrystalline with a small amount of calcium oxide. The introduction of higher amounts of silver ions was found to be more effective than enriching HA with small amounts of Ag+. Gallium and silver ions were found not to affect the lattice parameters. Ga3+ affected the crystallinity of the samples as well as the content of structural hydroxyl groups. Among samples synthesized by the wet method, only one (5Ag-HAw) was cytotoxic, whereas all Ga-containing samples obtained by the dry method showed cytotoxicity. In the preliminary antimicrobial test all the materials containing “foreign” ions showed high antibacterial activity.

Advancement of Gallium and Gallium-Based Compounds as Antimicrobial Agents

“…The controlled release of gallium ions was consistent with the sustained bacteriostatic activity against P. aeruginosa over 28 days. Other biomaterials, including phosphate glass (Lapa et al, 2020), hydroxyapatite (Pajor et al, 2020), PCL and hydrogel (Rastin et al, 2021), collagen (Xu et al, 2019), poly (4-hydroxybutyrate) (Muller et al, 2021), silk fibroin (Mehrabi et al, 2020), and Ca titanate (Rodriguez-Contreras et al, 2020), have also been proven to compound with gallium for a sustained release of gallium ions and to play an excellent bactericidal effect against common pathogens, such as E. coli, S. aureus, and P. aeruginosa, both in vivo and in vitro.…”

“…On the one hand, hydrogel, bioceramics, and other materials with good biocompatibility can be directly used as tissue engineering scaffolds for the repair of infectious defects. On the other hand, chemical processes, such as electrophoretic deposition, thermochemical treatment (Rodriguez-Contreras et al, 2020), solid-state method (Pajor et al, 2020), radio-frequency magnetron sputtering (Stan et al, 2020), and gel/sol can form antibacterial coatings (Pajor et al, 2020;Rodriguez-Contreras et al, 2020;Stan et al, 2020;Almohandes et al, 2021;Centurion et al, 2021) containing gallium on the surface of implants to prevent and treat iatrogenic infections. The controlled release of gallium by the above materials mainly benefits from their biodegradability, porous network structure, and adjustable porosity.…”

Gallium containing bioactive materials: A review of anticancer, antibacterial, and osteogenic properties

“…Showed antibacterial effect against P. fluorescens . [ 136 ] Solid-state reaction Calcium Phosphate Cement, Ca 10.5-1.5x Ga x (PO 4 ) 7 Characterization of ceramic by NMR, XRD, SEM. In-vivo sheep study.…”

Bioinspired Reactive Interfaces Based on Layered Double Hydroxides-Zn Rich Hydroxyapatite with Antibacterial Activity

“…aeruginosa . Thus, the nanocomposite of HA and nanosphere of elemental gallium and gallium-substituted HA have been proposed as antibacterial materials . In this work, a new strategy to improve the osteoconduction and to confer antibacterial activity to HA is proposed and concerns the use of layered double hydroxides (LDHs) to grow HA.…”

“…18 Thus, the nanocomposite of HA and nanosphere of elemental gallium 19 materials. 20 In this work, a new strategy to improve the osteoconduction and to confer antibacterial activity to HA is proposed and concerns the use of layered double hydroxides (LDHs) to grow HA. This strategy allows the combination of HA with LDH that is able to immobilize a large amount and variety of both therapeutic cations and molecular anions.…”