Antibacterial properties and mechanisms of toxicity of sonochemically grown ZnO nanorods

Okyay, Tuğba Onal; Bala, Rukayya K.; Nguyen, Hang N.; Atalay, Ramazan; Bayam, Yavuz; Rodrigues, Débora F.

doi:10.1039/c4ra12539h

Cited by 65 publications

(41 citation statements)

References 39 publications

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“…Compared with traditional organic anti-mold agents, inorganic agents have attracted more attention due to their unique features, such as earth-abundance, chemical-stability, and low-cost [11,12]. Nano-Ag/TiO 2 is recognized as one of the best inorganic anti-mold agents [13,14]. Ag nanoparticles can significantly enhance the photocatalytic activity of TiO 2 by restraining the recombination of electron-hole pairs, which can lead to the improvement of the anti-mold effect of TiO 2 under natural light, weak light, and dark conditions [15,16].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Anti-Mold Property and Mechanism Description of Ag/TiO2 Wood-Based Nanocomposites Formation by Ultrasound- and Vacuum-Impregnation

et al. 2020

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Ag/TiO2 wood-based nanocomposites were prepared by the methods of ultrasound impregnation and vacuum impregnation. The as-prepared samples were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), mercury intrusion porosimetry (MIP), and water contact angles (WCAs). The anti-mold properties of the Ag/TiO2 wood-based nanocomposites were improved by 14 times compared to those of the original wood. The nano-Ag/TiO2, which was impregnated in the tracheid and attached to the cell walls, was able to form a two-stage rough structure and reduce the number of hydroxyl functional groups on the wood surfaces. The resulting decline of wood hydrophobic and equilibrium moisture content (EMC) destroyed the moisture environment necessary for mold survival. Ag/TiO2 was deposited in the wood pores, which reduced the number and volume of pores and blocked the path of mold infection. Thus, the anti-mold properties of the Ag/TiO2 wood-based nanocomposite were improved by cutting off the water source and blocking the mold infection path. This study reveals the anti-mold mechanism of Ag/TiO2 wood-based nanocomposites and provides a feasible pathway for wood-based nanocomposites with anti-mold functions.

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Section: Introductionmentioning

confidence: 99%

Enhanced Anti-Mold Property and Mechanism Description of Ag/TiO2 Wood-Based Nanocomposites Formation by Ultrasound- and Vacuum-Impregnation

et al. 2020

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“…A number of naturally occurring surfaces bearing spiky nanotextures (e.g., cicada wings, dragonfly wings, and gecko skin) have been reported to exhibit bactericidal efficacy, attributed to puncturing or stretching of the bacterial membrane, although the detailed mechanisms remain to be fully understood [3,11,[73][74][75][76]. Hence, we suggest that the ZnO urchin surfaces could prevent bacterial growth by combining synergistically the inherent chemical activity of ZnO and the spiky morphology of the urchins that inhibit the bacteria from colonizing on the surface of the ZnO urchins [18,[77][78][79]. The sharp topography of the nanoneedles is particularly effective in disrupting the bacterial cell wall by imparting localized stress on the bacterial membrane [80].…”

Section: Resultsmentioning

confidence: 91%

Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

Tripathy

Wąsik

Sreedharan

et al. 2018

Colloids and Interfaces

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Functional ZnO nanostructured surfaces are important in a wide range of applications. Here we report the simple fabrication of ZnO surface structures at near room temperature with morphology resembling that of sea urchins, with densely packed, µm-long, tapered nanoneedles radiating from the urchin center. The ZnO urchin structures were successfully formed on several different substrates with high surface density and coverage, including silicon (Si), glass, polydimethylsiloxane (PDMS), and copper (Cu) sheets, as well as Si seeded with ZnO nanocrystals. Time-resolved SEM revealed growth kinetics of the ZnO nanostructures on Si, capturing the emergence of "infant" urchins at the early growth stage and subsequent progressive increases in the urchin nanoneedle length and density, whilst the spiky nanoneedle morphology was retained throughout the growth. ε-Zn(OH) 2 orthorhombic crystals were also observed alongside the urchins. The crystal structures of the nanostructures at different growth times were confirmed by synchrotron X-ray diffraction measurements. On seeded Si substrates, a two-stage growth mechanism was identified, with a primary growth step of vertically aligned ZnO nanoneedle arrays preceding the secondary growth of the urchins atop the nanoneedle array. The antibacterial, anti-reflective, and wetting functionality of the ZnO urchins-with spiky nanoneedles and at high surface density-on Si substrates was demonstrated. First, bacteria colonization was found to be suppressed on the surface after 24 h incubation in gram-negative Escherichia coli (E. coli) culture, in contrast to control substrates (bare Si and Si sputtered with a 20 nm ZnO thin film). Secondly, the ZnO urchin surface, exhibiting superhydrophilic property with a water contact angle ∼ 0 • , could be rendered superhydrophobic with a simple silanization step, characterized by an apparent water contact angle θ of 159 • ± 1.4 • and contact angle hysteresis ∆θ < 7 • . The dynamic superhydrophobicity of the surface was demonstrated by the bouncing-off of a falling 10 µL water droplet, with a contact time of 15.3 milliseconds (ms), captured using a high-speed camera. Thirdly, it was shown that the presence of dense spiky ZnO nanoneedles and urchins on the seeded Si substrate exhibited a reflectance R < 1% over the wavelength range λ = 200-800 nm. The ZnO urchins with a unique morphology fabricated via a simple route at room temperature, and readily implementable on different substrates, may be further exploited for multifunctional surfaces and product formulations.

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“…Hence, we suggest that the ZnO urchin surfaces could prevent bacterial growth by combining synergistically the inherent chemical activity of ZnO and the spiky morphology of the urchins that inhibits the bacteria to colonise on the surface of the ZnO urchins 18,[72][73][74] . The sharp topography of the nanoneedles are particularly effective in disrupting the bacterial cell wall by imparting the localised stress on the bacterial membrane 75 .…”

Section: Resultsmentioning

confidence: 99%

Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

Tripathy¹,

Wąsik²,

Sreedharan³

et al. 2018

Preprint

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Functional ZnO nanostructured surfaces are important in a wide range of applications. Here we report facile fabrication of ZnO surface structures at near room temperature with morphology resembling that of sea urchins, with densely packed, μm-long, tapered nanoneedles radiating from the urchin centre. The ZnO urchin structures were successfully formed on several different substrates with high surface density and coverage, including silicon (Si), glass, polydimethylsiloxane (PDMS), and copper (Cu) sheets, as well as Si seeded with ZnO nanocrystals. Time-resolved SEM revealed growth kinetics of the ZnO nanostructures on Si, capturing the emergence of “infant” urchins at the early growth stage and subsequent progressive increase in the urchin nanoneedle length and density, whilst the spiky nanoneedle morphology was retained throughout the growth. ε-Zn(OH)2 orthorhombic crystals were also observed alongside the urchins. The crystal structures of the nanostructures at different growth time were confirmed by synchrotron X-ray diffraction measurements. On seeded Si substrates, a two-stage growth mechanism was identified, with a primary growth step of vertically aligned ZnO nanoneedle arrays preceding the secondary growth of the urchins atop the nanoneedle array. The antibacterial, anti-reflective, and wetting functionality of the ZnO urchins—with spiky nanoneedles and at high surface density—on Si substrates was demonstrated. First, bacteria colonisation was found to be suppressed on the surface after 24 h incubation in Gram-negative E. coli culture, in contrast to control substrates (bare Si and Si sputtered with 20 nm ZnO thin film). Secondly, the ZnO urchin surface, exhibiting superhydrophilic property with a water contact angle ~0°, could be rendered superhydrophobic with a simple silanization step, characterised by a water static contact angle θ of 159° ± 1.4° and contact angle hysteresis ∆θ < 7°. The dynamic superhydrophobicity of the surface was demonstrated by bouncing-off of a falling 10 μL water droplet, with a contact time of 15.3 milliseconds (ms), captured using a high-speed camera. Thirdly, it was shown that the presence of dense spiky ZnO nanoneedles and urchins on the seeded Si substrate exhibited a reflectance R < 1% over the wavelength range λ = 200–800 nm. The ZnO urchins with unique morphology via a facile fabrication route at room temperature, readily implementable on different substrates, may be further exploited for multifunctional surfaces and product formulations.

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Antibacterial properties and mechanisms of toxicity of sonochemically grown ZnO nanorods

Cited by 65 publications

References 39 publications

Enhanced Anti-Mold Property and Mechanism Description of Ag/TiO2 Wood-Based Nanocomposites Formation by Ultrasound- and Vacuum-Impregnation

Enhanced Anti-Mold Property and Mechanism Description of Ag/TiO2 Wood-Based Nanocomposites Formation by Ultrasound- and Vacuum-Impregnation

Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

Facile Fabrication of Multifunctional ZnO Urchins on Surfaces

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