Environmental Toxicity and Antimicrobial Efficiency of Titanium Dioxide Nanoparticles in Suspension

Abstract

International audienceThe aim of this work was to evaluate the photokilling efficiency of synthesized titanium dioxide nanoparticles in suspension. Two strains of Escherichia coli, Lactobacillus casei rhamnosus and Staphylococcus aureus were used as probes to test the photokilling activities of the nanoparticles. The toxicity effects of TiO 2 nanoparticles on the environment were determined by a standard test using gram-negative bioluminescent bacteria Vibrio fischeri. The antimicrobial activity of these nanoparticles (NPs) was then investigated versus NPs concentration, UV irradiation time and mi-cro-organism strains. We evaluated the LC50 values of the nanoparticles suspension by counting the Colony-Forming Units. Results highlighted the differences in bacteria sensitivity facing photo-killing treatment induced by the irradiation of anatase TiO 2 nanoparticles suspension. At the concentration of 1 g·L −1 TiO 2 , tested bacteria were killed after 30 minutes of photo-treatment. Using different TiO 2 concentrations, the Staphylococcus aureus gram-positive/catalase-positive bacteria were more resistant than gram-negative/catalase-positive ones or gram-positive/catalase-negative bacteria. An effect of UV irradiation was evaluated by the quantification of hydrogen peroxide generated by the photolysis of water molecules in presence of the nanoparticles with or without the most resistant bacterium (S. aureus). After 30 minutes with UV irradiation in these two conditions , the concentration of hydrogen peroxide was 35 µM in presence of 1.2 g·L −1 TiO 2 suspension. This result suggested that the resistance mechanism of S. aureus was not due to an extracelullar H 2 O 2 enzymatic degradation

Enhancement of the Antibacterial Efficiency of Silver Nanoparticles against Gram-Positive and Gram-Negative Bacteria Using Blue Laser Light

“…S. aureus may have a stronger defence system against Ag-NPs due to the presence of a thicker cell wall that prevents the action of the Ag-NPs, rendering the bacterium comparatively more resistance to the antimicrobial activity of Ag-NPs [32]. Moreover, the cell wall of Gram-negative bacteria possesses a stronger negative charge than Gram-positive bacteria due to the presence of lipopolysaccharides (LPS), which promotes adhesion of Ag-NPs, causing the bacteria to be more susceptible to Ag-NPs' antimicrobial action [33]. Hence, electrostatic attraction between negatively charged bacterial cells and positively charged NPs is crucial for the activity of NPs as bactericidal materials [34].…”

Langmuir monolayer study of phospholipid DPPC on the titanium dioxide–chitosan–hyaluronic acid subphases

“…It has been proven that chitosan can form stable bonds with TiO 2 (Hasmath Farzana and Meenakshi 2014;Raut et al 2016;Gozdecka and Wiącek 2018) and resulting product shows synergy of their properties. Moreover, some studies confirm that both titanium(IV) oxide and chitosan have antimicrobial (antibacterial, antifungal) properties (Krajewska et al 2011;Uranga et al 2019;Desai and Kowshik 2009;Scuderi et al 2016;Jesline et al 2015;Verdier et al 2014;Bonnet et al 2015) and also show non-toxicity (Khojasteh et al 2016;Ji et al 2016;Reis Éde et al 2016).…”

Preparation and investigation of hydrophilic, photocatalytic, and antibacterial polyacrylic latex coating containing nanostructured TiO2/Ag+-exchanged-montmorillonite composite material

“…The inhibitory effect of Ag ions under a complex physiological condition, is believed to be due to its sorption to the negatively charged bacterial cell wall (in both Gram positive and Gram negative bacteria), deactivating cellular enzymes, disrupting membrane permeability, and finally leading to bacteria lysis and death (Colon et al, 2006;Osamu et al, 2004;Zhu et al, 2004;Choi et al, 2008). By the way different results were shown by titanium dioxide nanoparticles in two Gram positive and two Gram negative bacteria (Bonnet et al, 2015). Antibacterial property of TiO 2 /Ag/TiO 2 sandwich films appeared equally potent in eliminating the bacteria when applied to both the Gram positive (S.aureus and Streptococcus pyogenes) and Gram negative (E.coli and Acinetobacter baumannii) bacteria.…”