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Antifouling activities of pristine and nanocomposite chitosan/TiO₂/Ag films against freshwater algae

Natarajan, Saravanan, Lakshmi, D. Shanthana, Bhuvaneshwari, M., Iswarya, V., Mrudula, P., Chandrasekaran, N., Mukherjee, Amitava
RSC advances 2017 v.7 no.44 pp. 27645-27655
Chlorella, Scenedesmus, adhesion, antifouling activities, biofouling, biomass, chitosan, freshwater, interspecific variation, microalgae, nanocomposites, nanoparticles, nanosilver, silver, titanium dioxide, toxicity, ultraviolet radiation
Adhesion of microalgae or biofouling on submerged artificial surfaces is a universal problem in freshwater environments. Herein, we developed Ag and TiO₂ nanoparticle (NP)-incorporated nanocomposite and pristine films using chitosan for antifouling applications in freshwater environments. Both TiO₂ and Ag NPs are known for their algaecide activity. Hence, nanocomposite (Ag/TiO₂ and TiO₂/Ag) and pristine (Ag, TiO₂) films containing a range of concentrations of both particles were tested against two freshwater algae, specifically, Scenedesmus sp. and Chlorella sp. under different photo conditions. The toxicity assays show that Scenedesmus sp. is more sensitive to all the films tested than Chlorella sp. under both UV-C exposure and dark conditions. The slime formation, biomass (%), LPO, and uptake of the NPs are correlated well with their toxicity data. EPS release is noted to be higher for Scenedesmus sp. than Chlorella sp. due to the higher toxicity of this algal species. This indicates that the species variation substantially influences the antifouling action of both the pristine and nanocomposite films.