Inhibitory effect on in vitro Streptococcus oralis biofilm of a soda-lime glass containing silver nanoparticles coating on titanium alloy.

This paper reports the effect of soda-lime-glass-nAg coating on the viability of an in vitro biofilm of Streptococcus oralis. Three strains (ATCC 35037 and two clinical isolates from periodontitis patients) were grown on coated with glass, glass containing silver nanoparticles, and uncoated titanium alloy disks. Two different methods were used to quantify biofilm formation abilities: crystal violet staining and determination of viable counts. The influence of the surface morphology on the cell attachment was studied. The surface morphology was characterized by scanning electron microscopy (SEM) and using a profilometer. SEM was also used to study the formation and the development of biofilm on the coated and uncoated disks. At least a >99.7% inocula reduction of biofilm respect to titanium disks and also to glass coated disks was observed in the glass-nAg coated disks for all the studied strains. A quantitative evaluation of the release of silver was conducted in vitro to test whether and to what extend the biocidal agent (silver) could leach from the coating. These findings suggest that the biofilm formation of S. oralis strains is highly inhibited by the glass-nAg and may be useful for materials which require durable antibacterial effect on their surfaces, as it is the case of dental implants

Scanning electron micrographs at different magnifications after biofilm formation of the CI-1 strain on: a, b) uncoated titanium alloy disk; c, d) titanium alloy disk coated with glass; and e, f) titanium alloy disk coated with glass-nAg.

<p>Scanning electron micrographs at different magnifications after biofilm formation of the CI-1 strain on: a, b) uncoated titanium alloy disk; c, d) titanium alloy disk coated with glass; and e, f) titanium alloy disk coated with glass-nAg.</p

Profilometer characterization of surface topography of the different samples.

<p>Representative height maps in three-dimensional view of: a) uncoated titanium alloy disk, b) glass coated Ti4Al6V disk c) glass-nAg coated Ti4Al6V disk. Representative surface profiles exhibiting variations in R_a of: d) uncoated titanium alloy disk, e) glass coated Ti4Al6V disk and f) glass-nAg coated Ti4Al6V disk. The images correspond to 1 mm×1 mm scan area.</p

Comparison of total biofilm mass for the studied S. oralis strains determined by crystal violet staining among coated (glass or glass-nAg) and uncoated titanium alloy disks.

<p>Comparison of total biofilm mass for the studied S. oralis strains determined by crystal violet staining among coated (glass or glass-nAg) and uncoated titanium alloy disks.</p

Comparison of the viable planktonic bacteria (CFU/mL) for the studied S. oralis strains among coated (glass or glass-nAg) and uncoated titanium alloy disks.

<p>Comparison of the viable planktonic bacteria (CFU/mL) for the studied S. oralis strains among coated (glass or glass-nAg) and uncoated titanium alloy disks.</p

Comparison of the viable adherent bacteria (CFU/mm²) for the studied S. oralis strains among coated (glass or glass-nAg) and uncoated titanium alloy disks.

<p>Comparison of the viable adherent bacteria (CFU/mm²) for the studied S. oralis strains among coated (glass or glass-nAg) and uncoated titanium alloy disks.</p

Average cumulative silver released from glass-nAg coating of titanium alloy disks in the culture at 37°C as a function of time.

<p>Average cumulative silver released from glass-nAg coating of titanium alloy disks in the culture at 37°C as a function of time.</p