Characterization of selected parameters of Chlorella vulgaris microalgae after short-term exposure to gold nanoparticles with different surface properties. Issue 5 (October 2022) - Kula-Maximenko, Monika
Abstract: Enhanced production and exploitation of gold nanoparticles (AuNPs), among others in lateral flow assays for the diagnosis of SARS-CoV-2 infection, motivate for extensive studies on their environmental and biological safety. Therefore, the impact of three types of AuNPs on Chlorella vulgaris was studied after short-term exposure. The AuNPs were prepared using sodium borohydride (SB), cysteamine hydrochloride (CH) and trisodium citrate (TC). Microscopic imaging revealed that the AuNPs were characterized by quasi-spherical shape and an average size within the range 9–12 nm. CHSBAuNPs were positively charged whereas TCAuNPs and SBAuNPs were negatively charged. The results of studies showed that the exposure to each type of AuNPs led to the dose-dependent decrease of growth rate of C. vulgaris biomass. The swelling of the cells was observed especially at concentration of 5 mg L −1 . For all treatments, significant changes in efficiency of the photosystem II were detected. Each type of AuNPs applied in concentration of 1 mg L −1 caused an increase and in concentration of 5 mg L −1 a decrease of photosynthetic pigments content. Based on recorded Raman spectra, it was found that the cell chemical composition was disturbed radically after the treatment with SBAuNPs and CHSBAuNPs. It was established that the changes in the morphology and physiology of C. vulgaris cells, as a result of the exposure on the AuNPs, were strongly dependent on the surface properties of AuNPs. Nevertheless, it was impossible to indicate the most harmful type of AuNPs. Obtained findings did not confirm that the stabilization of AuNPs by molecules of well-documented toxicity lead to the increase of their toxic effects. It was not confirmed that positively charged CHSBAuNPs, stabilized by cysteamine, were more harmful for C. vulgaris than negatively charged TCAuNPs and SBAuNPs. Graphical Abstract: ga1 Highlights: Surface properties and the concentration of AuNPs modify the response of the treated Chlorella vulgaris microalgae AuNPs generate changes in pigments content, chemical composition and photosystem II AuNPs imply a decrease in biomass and swelling of C. vulgaris cells