Combined biocidal action of silver nanoparticles and ions against Chlorococcales (Scenedesmus quadricauda, Chlorella vulgaris) and filamentous algae (Klebsormidium sp.)

Abstract

Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40-70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag(+) concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists, physical chemists, and biologists.

Effects of Nanoparticles on Algae: Adsorption, Distribution, Ecotoxicity and Fate

“…Comparison of the toxicity of Ag NPs to Chlorococcales and filamentous algae showed that the filamentous algae Klebsormidium sp. was able to uptake more NPs under the same conditions [40].…”

“…The algae cell walls are semipermeable, and usually porous in their structure [26]. The diameter of these pores is in the range of 5-20 nm [39,40]. Generally, only the NPs in the size smaller than the maximal pore size can easily pass through the cell wall, while limiting the passage of larger molecules [30].…”

NanoTiO2 materials mitigate mercury uptake and effects on green alga Chlamydomonas reinhardtii in mixture exposure

“…We hypothesized that both IHg and MeHg will be adsorbed onto the nanoTiO2, which will result in a decrease of the cellular concentrations of IHg or MeHg and thus alleviation of the oxidative stress and membrane damage. The hypothesis is based on previous knowledge showing that nanoTiO2 tends to form micrometric aggregates (Allouni et al, 2009;Brunelli et al, 2013), which can not pass through the pores of algal cell walls (Chen et al, 2016;Zouzelka et al, 2016).…”

Toxicity of TiO2, ZnO, and SiO2 Nanoparticles in Human Lung Cells: Safe-by-Design Development of Construction Materials

“…From the above, it is obvious that when developing any nanoparticle-based technology, the toxicological impact of nanoparticles needs to be taken into account [16]. However, this aspect is generally neglected, with nanoparticles often selected only on the basis of their functions.…”