Toxicity of Nd2WO6 nanoparticles to the microalga Dunaliella salina: synthesis of nanoparticles and investigation of their impact on microalgae

Abstract

The presence of nanoparticles in the environment and their impact on existing organisms is one of the main concerns of researchers working in this field. In this research, Nd₂WO₆ nanoparticles were prepared by an ultrasonic procedure for the first time. X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDS) analyses were applied to identify and prove the purity of these particles. In addition to increasing the reaction rate and efficiency with the help of a radical generation mechanism, ultrasound was able to aid the synthesis of these particles. After confirming nanoparticle formation, the optimal nanoparticles in view of scale and morphology were selected by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Optimal particles at three concentrations (25, 50, and 100 ppm) were mixed into the algae growth medium to investigate the effects of the nanoparticles on Dunaliella salina growth. Biological parameters, including the number of cells, biomass, specific growth rate, pigments, and malondialdehyde (MDA), were measured after ten days. Growth parameters showed an increasing trend in concentrations up to 50 ppm; however, at a concentration of 100 ppm, a significant decrease was observed in contrast to the nanoparticles-free treatment. The MDA content showed a linear relationship with enhanced concentration of the nanoparticles. The examination of biological parameters showed that the algae response to stress was dependent on the concentration of nanoparticles. The results showed that 50 ppm of nanoparticles are suitable for increasing algae and achieving a suitable growth rate for commercial purposes. However, in higher concentrations, algal growth inhibition occurs, which is of great importance from a biotechnological point of view.