Cytotoxic effects of zinc oxide nanoparticles on cyanobacterium Spirulina (Arthrospira) platensis

PeerJ

article

Sinouvassane Djearamane¹  Yang Mooi Lim²  Ling Shing Wong³  Poh Foong Lee⁴ 

[1] Department of Biomedical Science, Faculty of Science, Universiti Tunku Abdul Rahman;Department of Pre-Clinical Sciences, Faculty of Medicine and Health Sciences, Universiti Tunku Abdul Rahman;Department of Biotechnology, Faculty of Health and Life Sciences, INTI International University;Department of Mechanical & Material Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman

关键词: Zinc oxide nanoparticles;    Spirulina platensis;    Microalgae;    Cytotoxicity;   

DOI  :  10.7717/peerj.4682

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundThe extensive usage of zinc oxide nanoparticles (ZnO NPs) in industrial and consumer products raises the risk of releasing their residues into the aquatic environment. The presence of ZnO NPs in the aquatic environment could potentially cause cytotoxic effects on aquatic organisms. Thus, investigating the cytotoxic effects of ZnO NPs on microalgae, which form the base for the food web of aquatic biota, is essential to gain information regarding the ecotoxicological effects of metallic oxide nanoparticles in the aquatic ecosystem. Therefore, the present study has investigated in detail the assorted cytotoxic effects of ZnO NPs on S. platensis using various concentrations of ZnO NPs (10–200 mg/L) from 6 to 96 h to explore the dose- and time-dependent cytotoxic effects.MethodsThe cytotoxic effects were all assessed through quantification of loss in cell viability, reduction in biomass and decrease in photosynthetic pigments such as chlorophyll-a, carotenoids and phycocyanin. The surface interactions of nanoparticles and the subsequent morphological alterations on algal cells were examined by optical and scanning electron microscopy (SEM). The intracellular alterations of algal cells were studied using transmission electron microscopy. Furthermore, Fourier transformed infrared (FTIR) spectrum was obtained to investigate the involvement of algal surface biomolecules in surface binding of ZnO NPs on algal cells.ResultsThe treatment of ZnO NPs on S. platensis exhibited a typical concentration- and time-dependent cytotoxicity. Results showed a significant (p < 0.05) cytotoxicity from 24 h onwards for all tested concentrations of ZnO NPs. The maximum cytotoxicity on algal cells was achieved at 96 h of exposure to ZnO NPs. In comparison with control, the algal cells that interacted with 200 mg/L of ZnO NPs for 96 h showed 87.3 ± 1% loss in cell viability, 76.1 ± 1.7% reduction in algal biomass, 92.5 ± 2.2%, 76.2 ± 2.2% and 74.1 ± 3.4% decrease in chlorophyll-a, carotenoids and phycocyanin contents respectively. Our study confirmed the cytotoxicity of ZnO NPs through the algal growth inhibition with 72 h EC10 and EC50 values of 1.29 and 31.56 mg/L, respectively. The microscopic examinations of the algal cells that interacted with ZnO NPs showed severe cell membrane and intracellular damage. The SEM EDX spectrum of ZnO NPs treated algal biomass evidenced the surface accumulation of zinc in the biomass. Finally, the FTIR spectrum confirmed the involvement of amino, hydroxyl and carboxylic groups of algal cell wall in the surface interaction of ZnO NPs on the algal cells.DiscussionThe results showed that the treatment of ZnO NPs on S. platensis triggered substantial cytotoxicity and caused cell death. Hence, S. platensis could be potentially used as a bioindicator for testing toxicity of ZnO NPs in aquatic environment.

【 授权许可】

CC BY