Preparation, structural characterisation and antibacterial properties of Ga-doped sol–gel phosphate-based glass

Abstract

A sol-gel preparation of Ga-doped phosphate-based glass with potential application in antimicrobial devices has been developed. Samples of composition (CaO) 0.30 (Na 2 O) 0.20-x (Ga 2 O 3 ) x (P 2 O 5 ) 0.50 where x = 0 and 0.03 were prepared, and the structure and properties of the gallium-doped sample compared with those of the sample containing no gallium. Analysis of the 31 P MAS NMR data demonstrated that addition of gallium to the sol-gel reaction increases the connectivity of the phosphate network at the expense of hydroxyl groups. This premise is supported by the results of the elemental analysis which showed that the gallium-free sample contains significantly more hydrogen and by FTIR spectroscopy, which revealed a higher concentration of OH groups in that sample. Ga K-edge EXAFS and XANES data revealed that the gallium ions are coordinated by six oxygen atoms. In agreement with the X-ray absorption data, the high-energy XRD results also suggest that the Ga 3+ ions are octahedrally coordinated with respect to oxygen. Antimicrobial studies demonstrated that the sample containing Ga 3+ ions had significant activity againstStaphylococcus aureus compared to the control.

Biofilm formation on titanium implants counteracted by grafting gallium and silver ions

“…Therefore, gallium inhibits Fe 3+ biological functions by a “Trojan horse” strategy . This strategy can be exploited to interfere with or disrupt the iron metabolism in a large number of bacterial strains, including P. aeruginosa , Mycobacteria , Clostridium difficile , and the methicillin‐resistant S. aureus …”

“…Recently, several inorganic antimicrobial agents have been used as a promising strategy to discourage biofilm formation onto implant surfaces by exploiting their known antibacterial properties to reduce both the systemic antibiotic therapy and the surgical procedures necessary to remove the infected implants . In particular silver (Ag) and gallium (Ga), a semimetallic element in group 13 (3 + ), have been shown to be effective in the prevention of implant surgical infections . Bacteriostatic/bactericide properties of silver are well known and are mainly due to its multiform mechanisms to damage bacteria even at very low concentrations .…”

Preparation and characterization of antibacterial P2O5–CaO–Na2O–Ag2O glasses

“…Pickup et al . 25 investigated the antibacterial activities of a Ga‐doped sol‐gel PBGs of composition (CaO) 0.30 (Na 2 O) 0.20‐ x (Ga 2 O 3 ) x (P 2 O 5 ) 0.50 where x = 0 and 0.03 mol %. They observed a small zone of inhibition (7 mm) for the gallium‐free glass and they attributed it to either a change in pH as the glass dissolves or by reduced water activity as ions leach out.…”

Broad-Spectrum Antibacterial Characteristics of Four Novel Borate-Based Bioactive Glasses

“…Doping bioactive glass with other ions, such as yttrium, selenium, and iodine also show potential for antimicrobial activity [21] [24]. Gallium doped sol-gel phosphatebased glasses have also shown promising antimicrobial activity against S. aureus and Streptococcus mutans [27] and phosphate based glasses doped with both silver and gallium have been shown to be effective against P. aeruginosa biofilm formation [25].…”

“…Further studies have revealed that antimicrobial effects of gallium are likely intracellular and involve disruption of bacterial iron uptake [27] [28].…”