Antibacterial mechanisms of a novel type picosecond laser-generated silver-titanium nanoparticles and their toxicity to human cells

Abstract

In this study, we explored the antibacterial mechanisms for a novel type of Ag-TiO 2 compound nanoparticles (NPs) produced from an Ag-TiO 2 alloy using a picosecond laser and evaluated the toxicity of the Ag-TiO 2 NPs to a range of human cell types. Transmission electron microscopy was used to determine the morphology, shapes, and size distribution of the laser-generated Ag-TiO 2 NPs. UV-visible spectrometer was used to confirm the shift of light absorbance of the NPs toward visible light wavelength. Results showed that the laser-generated Ag-TiO 2 NPs had significant antibacterial activities against both Gram-negative and Gram-positive bacterial strains, including Escherichia coli, Pseudomonas aeruginosa , and the methicillin-resistant Staphylococcus aureus . Increased level of reactive oxygen species was produced by E. coli after exposure to the Ag-TiO 2 NPs, which was accompanied with lipid peroxidation, glutathione depletion, disintegration of cell membrane and protein leakage, leading to the cell death. Five types of human cells originated from lung (A549), liver (HePG2), kidney (HEK293), endothelium cells (human coronary artery endothelial cells [hCAECs]), and skin (human dermal fibroblast cells [HDFc]) were used to evaluate the cytotoxicity of the laser-generated Ag-TiO 2 NPs. A weak but statistically significant decrease in cell proliferation was observed for hCAECs, A549 and HDFc cells when co-cultured with 2.5 µg/mL or 20 µg/mL of the laser-generated Ag-TiO 2 NPs for 48 hours. However, this effect was no longer apparent when a higher concentration of NPs (20 µg/mL) was used after 72 hours of co-culture with human cells, suggesting a possible adaptive process in the cells had occurred. We conclude that picosecond laser-generated Ag-TiO 2 NPs have a broad spectrum of antibacterial effect, including against the drug-resistant strain, with multiple underlying molecular mechanisms and low human cell toxicity. The antimicrobial properties of the new type of picoseconds laser-generated Ag-TiO 2 compound NPs could have potential biomedical applications.

Size‐dependent antibacterial activity for laser‐generated silver nanoparticles

“…Nanoparticle production by pulsed laser ablation was described in previous work by the authors (Korshed et al, ; Korshed et al, ). Briefly, an Ag plate (dimensions of 25 mm × 25 mm × 2 mm, purity 99.99%) was sterilized by immersing into ethanol and then autoclaved in deionized water (dH 2 O).…”

“…Primary human dermal fibroblast cells (HDFc) C0135C were purchased from Invitrogen (Ramachandran et al, ) and cultured in DMEM/F12 media. The cell viability was tested using MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] assay (Mosmann, ) to test the toxicity of three different sizes of laser‐generated Ag NPs (average size of 19, 21, and 42 nm, respectively) as described in our previous publications (Korshed et al, ; Korshed et al, ).…”

Enhancement of Antibacterial Performance of Silver Nanowire Transparent Film by Post-Heat Treatment

“…Accordingly, disinfectants such as antibacterial agents and antibiotics have been developed [6]. Silver nanomaterials (AgNMs) as antibacterial agents have a wide range of potential applications in the medical, scientific, food, and pharmaceutical industries, thanks to their effective antibacterial activity against Gram-positive bacteria and Gram-negative bacteria [7] and their low toxicity to human cells at a low concentration [8]. Nanomaterials are commonly defined as materials which are 1-100 nm in size in at least one dimension [9].…”

Antibacterial effect of TiO2:Cu:Ag thin coatings on Pseudomonas strain measured by microbiological and ATP assays

“…These facts support further in-depth studies of this component composition of thin film coatings with antibacterial activity. The probable cause for the observed effect is the greater surface area of the smaller silver and copper nanoparticles, as evidenced by other authors [2,3,5,24].…”