Bioinspired nanocoatings for biofouling prevention by photocatalytic redox reactions

Abstract

Aquaculture is a billion dollar industry and biofouling of aquaculture installations has heavy economic penalties. The natural antifouling (AF) defence mechanism of some seaweed that inhibits biofouling by production of reactive oxygen species (ROS) inspired us to mimic this process by fabricating ZnO photocatalytic nanocoating. AF activity of fishing nets modified with ZnO nanocoating was compared with uncoated nets (control) and nets painted with copper-based AF paint. One month experiment in tropical waters showed that nanocoatings reduce abundances of microfouling organisms by 3-fold compared to the control and had higher antifouling performance over AF paint. Metagenomic analysis of prokaryotic and eukaryotic fouling organisms using next generation sequencing platform proved that nanocoatings compared to AF paint were not selectively enriching communities with the resistant and pathogenic species. The proposed bio-inspired nanocoating is an important contribution towards environmentally friendly AF technologies for aquaculture.

Toxicity of Different Zinc Oxide Nanomaterials at 3 Trophic Levels: Implications for Development of Low‐Toxicity Antifouling Agents

“…Our results suggested that morphology and size affect the toxic potential of the nanostructure tested, with ZnO nanorods (NRG and NRS) being the least toxic among all of the tested nanostructures. Thus, our data support the hypothesis that supported ZnO nanorods can be used as a more environmentally friendly antifouling solution (Sathe et al 2017). Previously, it was shown that size, morphology, concentration, and bioavailability of nanostructures affect their toxicity (Ann et al 2015;Juganson et al 2015;Gonçalves et al 2018).…”

“…Although there are large numbers of studies about toxicity of ZnONPs (Reddy et al 2007), there are no data about toxicity of ZnO nanorods with respect to different aquatic organisms belonging to different trophic levels. Because the use of supported ZnO nanorods (ZnONRG) has been proposed for the prevention of marine biofouling (Al-Fori et al 2014;Sathe et al 2017), we have attempted to compare the toxicity of ZnONPs, ZnO nanorods, and Zn 2+ ions on saltwater organisms including a producer (alga D. salina), a consumer (crustacean A. salina), and a decomposer (bacterium B. cereus). We observed a clear dose-response relationship for all nanostructures with respect to all tested organisms.…”

“…The antifouling and antialgal properties of supported ZnO nanorods have been investigated (Al-Fori et al 2014;Sathe et al 2016). In our previous studies, we suggested that supported ZnO nanorods could be used to prevent marine biofouling (Al-Fori et al 2014;Sathe et al 2017) as a low-toxicity alternative to highly toxic biocides currently used as antifouling agents (Yebra et al 2004). To design lowtoxicity antifouling solutions, it is important to understand the toxicity of supported ZnO nanorods and compare it with the toxicity of other ZnO nanostructures on different aquatic organisms of different trophic levels.…”

“…We hypothesized that supported nanocoatings, like ZnO nanorod coatings (Al-Fori et al 2014;Sathe et al 2017), possess significant advantages over spherical NPs because of their increased stability, lower toxicity and lower rate of dissolution of Zn 2+ ions, ease of synthesis, and the possibility of using a large variety of support materials. In the present study, the acute toxicity of spherical ZnONPs, ZnO supported (on glass), unsupported ZnO nanorods, and Zn 2+ ions in the form of ZnSO 4 was compared.…”

Chlorination disadvantages and alternative routes for biofouling control in reverse osmosis desalination

“…The photocatalytic properties of ZnO nano rods have also been investigated against marine micro and macro fouling organisms in laboratory, 143 mesocosm 144 , and field experiments. 145 Photocatalytic compounds such as TiO 2 , ZnO can be nanostructured at low cost and the results they have shown for water purification are promising, leading to prospective applications to disinfect water in homes, as well as in small and large industries. However, the bandgap of these semiconductors pushes their light absorption range in the UV light band, so they can only be activated by a high-energy UV source, whereas the power distribution of the solar spectrum is split between 46% visible light, 47% infrared radiation, and only 7% UV light.…”