Antibacterial activity of gold-titanates on Gram-positive cariogenic bacteria

Abstract

Objective: Gram-positive cariogenic bacteria are etiological agents in dental caries; therefore, strategies to inhibit these bacteria to reduce the incident of this disease have intensified. In this study, we investigated antibacterial activities of titanates and gold-titanates against Lactobacillus casei (Lc) and Streptococcus mutans (Sm). Materials and methods: Monosodium titanate (MST), nanomonosodium titanate (nMST) and amorphous peroxo-titanate (APT), which are inorganic compounds with high-binding affinity for specific metal ions, were used. Total bacterial proteins were measured to represent bacterial cell mass after 24 h incubation with gold-titanates. We further examined the effect of nMST-Au(III) concentrations (10,200,400 mg/L) on Lc and Sm cell viability over time via Live/Dead fluorescent staining and colony forming units (CFUs). Transmission electron microscopy (TEM) was used to determine specific locations on the bacterial cells affected by the nMST-Au(III). Results: We found all gold-titanates and APT alone reduced bacterial protein for Lc (p value <0.001) while only MST-Au(III) and nMST-Au(III) affected Sm growth (p value <0.001). Overall, nMST-Au(III) showed the most effectiveness against both Lc and Sm at 400 mg/L. The Live/Dead staining showed all concentrations of nMST-Au(III) affected Lc growth but only 200 and 400 mg/L nMST-Au(III) interrupted Sm growth. The growth curves based on CFUs/mL showed all nMST-Au(III) concentrations affected growth of both Lc and Sm. TEM images showed nMST-Au(III) attached to Lc and Sm cell wall and were internalized into both cells. Conclusions: nMST-Au(III) demonstrated potential antimicrobial activity against Gram-positive cariogenic bacteria. These results support further development of nMST-Au(III) as a potential novel material to prevent dental caries.

Nanoengineering the antibacterial activity of biosynthesized nanoparticles of TiO2, Ag, and Au and their nanohybrids with Portobello mushroom spore (PMS) (TiOx/PMS, Ag/PMS and Au/PMS) and making them optically self-indicating

“…This again may reflect on the strength of the Au-PMS interaction. One would expect that NPs/PMS would bind through several metals ions or atoms in the microbial cell [24] .…”

“…Such properties make NPs powerful tools for vast and diverse applications (e.g. antimicrobial, diagnosis, imaging, and thereby drug delivery (because NPs provide unprecedented opportunities to molecular process and interrogate cellular clinical application [24] )). NPs have recently emerged as unique anti-microbial agents due to their shape, size and high surface area to volume ratio; NPs are of the same dimensions as proteins, nucleic acid, membrane of receptors, antibodies and other biomolecules [25] .…”

“…They also show good biocompatibility, being compatible with human body cells and being resistance to corrosion [34] . Au NPs show a significant anti-bacterial activity depending on their size and shape and also the type of bacteria [24] . They strongly bind to the bacterial cell wall, allowing them to disrupt the bacterial cell membrane, causing leakage of nucleic acids and cytoplasm [17,35] , induce photo-mutagenic processes causing damage to DNA and essential proteins [15] , increase in ATP (where ATP generation is a significant part in the respiration chain of bacteria via the NAD + /NADH reaction) intercellular ATP levels, leading to bacterial death and catalyze oxidation reactions, producing ROS that lead to the death of bacteria [35] .…”

Chemical, biological, and antibacterial characterization of silica glass containing silver and gold nanoparticles

“…[25][26][27] However, it was observed that as the concentration of silver oxide increased from 0.5 to 2 wt%, the growth inhibition of P. aeruginosa increased from 72% to 85%, while the growth inhibition of S. epidermidis decreased from 89% to 47%. Initially, we measured the antibacterial activity of silicate glasses with increasing percentages of silver oxide (0.5-1-1.5-2 wt%) It is clear from the figure that significant growth inhibition was observed for both strains.…”

“…It is due to the known antibacterial activity of Ag + on both gram-positive and gram-negative bacteria. [25][26][27] However, it was observed that as the concentration of silver oxide increased from 0.5 to 2 wt%, the growth inhibition of P. aeruginosa increased from 72% to 85%, while the growth inhibition of S. epidermidis decreased from 89% to 47%. The different responses can be ascribable to the different cell wall structures of both model bacteria, gram-positive, and gram-negative.…”