Effects of coating materials on antibacterial properties of industrial and sunscreen-derived titanium-dioxide nanoparticles on Escherichia coli

• Published in: Chemosphere (Oxford) 2018-10, Vol.208, p.196-206
• Main Authors: Baek, Soyoung, Joo, Sung Hee, Blackwelder, Pat, Toborek, Michal
• Format: Article
• Language: English
• Subjects: Antibacterial effect; Carboxymethyl cellulose (CMC); E. coli; polyvinylpyrrolidone (PVP); Reactive oxygen species (ROS); TiO2 nanoparticles
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2018.05.167

Organic or inorganic stabilizers are often used for coating nanoparticles (NPs) in consumer products. However, upon release of stabilized NPs into the environment, uncertainty exists as to the antimicrobial properties of NPs due to stabilizers and the resultant bioaccumulation in organisms. This study investigates antibacterial effects and subsequent mechanisms of TiO2 NPs on Escherichia coli (E. coli) in the presence and absence of stabilizers (CMC, PVP, and SiO2) commonly used in consumer products. Compared with uncoated TiO2 NPs, the presence of any stabilizers tested in this study increased toxicity of NPs and enhanced growth inhibition in E. coli. While the particle sizes of TiO2 were smaller as the result of coating with PVP or CMC and appeared to contribute to E. coli cell damage, the generation of reactive oxygen species (ROS) was independent of stabilizer type. In fact, coating with PVP and CMC exerted ROS scavenging properties. In contrast, increased ROS production was observed at higher concentrations of TiO2 and upon coating with SiO2. This impact of SiO2 can be related to the formation of a TiOSi chemical bond. The results of the present study emphasize the importance of nanoparticle coating to their anti-bacterial activity and toxicity. •The coating with CMC, PVP, or SiO2 enhanced toxicity of TiO2 NPs on E. coli.•Toxicity of CMC or PVP coating was linked to size reduction of TiO2 NPs.•The presence of silica increased the generation of ROS from TiO2 NPs.•More ROS generation by silica was correlated with TiO2 NP toxicity.