Phytotoxic effects of seaweed mediated copper nanoparticles against the harmful alga: .

In this study, copper nanoparticles (Cu-NPs) were synthesized using Linnaeus and Areschoug aqueous extracts. Transmission Electron microscope indicated that the biosynthesized Cu-NPs averaged 12.7 nm and 13.6 nm for and , respectively. As reported by the FT-IR analyses, the algal extracts contain phyto-chemicals such as proteins, carboxylic acids, complex carbohydrates; these compounds will act as encapsulating agents and be reduced from copper sulphate to Cu-NPs. Energy-dispersive analyses X-ray (EDX) confirmed the copper composition in the synthesized Cu-NPs. The biosynthesized Cu-NPs arrested the growth of and presented in time and concentration dependent trends. At a concentration of 2 μg/mL, Cu-NPs, synthesized by exerted 85 ± 4% reduction of the algae dry weight. Increasing Cu-NPs concentration led to excellent reduction, which is a very promising result. Cupper-NPs synthesized by produced moderate effects on . The results also indicated that there were sharp decreases in chlorophyll a content in with the increase in Cu-NPs concentrations. Using 4 μg/mL of Cu-NPs derived from , chlorophyll a decreased by 48 ± 5%. On the other hand, lower reductions in chlorophyll a were recorded upon using Cu-NPs synthesized using (36 ± 3% and 41 ± 5% reductions at concentrations of 2 μg/mL and 4 μg/mL, respectively). The results of this study suggested that the bioactive and allelopathic compounds derived from the two algal extracts coating the (Cu) together with (Cu) are responsible for the inhibitive impacts of Cu-NPs on .