Eco-friendly Cobalt Oxide Nanoparticles for the Control of Harmful Cyanobacterial Bloom (Oscillatoria sp.) in Aquatic Systems

Abstract

Harmful cyanobacterial blooms have become a significant environmental concern in freshwater ecosystems due to their adverse effects on water quality, aquatic biodiversity, and public health. The excessive proliferation of cyanobacteria such as Oscillatoria sp. leads to oxygen depletion, toxin production, and deterioration of aquatic environments. In the present study, cobalt oxide (Co₃O₄) nanoparticles were synthesized through an eco-friendly green synthesis approach using ginger extract as a reducing and stabilizing agent. The synthesized nanoparticles were characterized using various physicochemical techniques to confirm their functional group and morphological properties. The anti-blooming potential of Co₃O₄ nanoparticles was evaluated against the cyanobacterium Oscillatoria sp. by assessing growth parameters including chlorophyll content and growth rate under different nanoparticle concentrations. The results revealed a significant concentration-dependent inhibition of cyanobacterial growth. Exposure to Co₃O₄ nanoparticles caused a marked reduction in chlorophyll pigments and biomass productivity, indicating disruption of photosynthetic activity and cellular metabolism. The inhibitory effects are likely associated with nanoparticle–cell interactions that impair physiological processes in cyanobacterial cells. These findings demonstrate that green synthesized Co₃O₄ nanoparticles can effectively suppress cyanobacterial proliferation and may serve as a promising eco-friendly strategy for controlling harmful algal blooms in aquatic systems and improving water quality.