Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

Abstract

SummaryThis paper reports the structural and optical properties and comparative photocatalytic activity of TiO2 and Ag-doped TiO2 nanoparticles against different bacterial strains under visible-light irradiation. The TiO2 and Ag-doped TiO2 photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2 has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2 nanoparticles. The decreased band-gap energy of Ag-doped TiO2 nanoparticles in comparison to TiO2 nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2 and Ag-doped TiO2 nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2 nanoparticles. Annealed TiO2 showed zero viability at 80 mg/30 mL whereas doped Ag-TiO2 7% showed zero viability at 40 mg/30 mL culture in the case of P. aeruginosa only.

Increasing the shelf life of pikeperch (Sander lucioperca) fillets affected by low-density polyethylene/Ag/TiO2 nanocomposites experimentally produced by sol-gel and melt-mixing methods

“…These values were close to the present findings that the best inhibition zone for E. coli and S. aureus was 16.76 ± .10 and 18.45 ± 0.15 mm, respectively, with a significantly higher value attained using the melt-mixing method compared to the sol-gel process with the increased dispersion of Ag/TiO 2 gained with 3% Ag. Similarly, Gupta and colleagues [26] documented that an Ag/TiO 2 nanocomposite produced through the sol-gel process completely inactivated bacteria including E. coli and S. aureus when the TiO 2 NPs were doped with 3% Ag. In another study, the efficiency of Ag-TiO 2 NPs to completely kill E. coli populations was increased at an Ag concentration of 2.5%.…”

“…The attachment of Ag + from the TiO 2 NPs may bestow antimicrobial properties. [5,8] Gupta et al [26] reported that Ag-TiO 2 nanocomposites having Figure 11. (a and b) LDPE produced using 0.5% Ag and 2.5% TiO 2 as well as 1% of silver, which were produced by the sol-gel method.…”

Comparison of characteristics of selected metallic and metal oxide nanoparticles produced by picosecond laser ablation at 532 and 1064 nm wavelengths

“…In addition, the peaks at 2h = 32.5°are indicative of the brookite phase of the TiO 2 nanoparticles [20,21]. A strong rutile peak was observed for the 532-nm laser wavelength at 27.5° [22]. In addition, small peaks at 48°and 68.3°were observed at 532 nm which indicate the anatase phase [23,24], and the peaks at 56.25°and 70°represent the rutile phase [23,25] of the TiO 2 nanoparticles.…”

The characteristics of novel bimodal Ag–TiO2 nanoparticles generated by hybrid laser-ultrasonic technique

“…As a result, titanium(IV) hydroxide (Ti(OH) 4 Fig. 11 Relationship between the number of surviving E. coli bacteria as a function of the concentration of Ag-TiO 2 (US) (ultrasonic) and Ag nanoparticles generated by picosecond laser in deionised water with ultrasonic wave assisted.…”

“…Both the hydrophilic and photocatalytic properties of TiO 2 nanoparticles are important for numerous applications, such as antimicrobial activity [4] and self-cleaning [5]. The photocatalytic activity of TiO 2 requires the activation with a UV light, which limits its applications.…”