The effect of carbon nanodots and graphene quantum dots on the green microalga Scenedesmus quadricauda

Carbon dots are a new type of carbon-based material with some unique properties which are attractive for agricultural, biological, medical and nanotechnological applications. The widespread production of graphene for composite materials as well as the formation of carbon dots as by-products (industry, food heat treatment etc.) leading to inevitable environmental pollution. However, the environmental impact posed by them on living organisms is still insufficient investigated. We studied the effects of carbon dots synthesized in our laboratory via electrochemical (classified as graphene quantum dots), hydrothermal and microwave (classified as carbon nanodots) methods on the green microalga Scenedesmus quadricauda . The microalgae were exposed to different concentrations of carbon dots for 6 days. Our results showed that carbon dots did not induce oxidative stress and affect the photosynthetic activity of microalgae. However, carbon dots could decrease the growth rate of microalgae mainly due to reducing light, which occurred via the shading of microalgae by nanoparticles. The obtained results contribute to the understanding of the interaction of carbon dots and microalgae.