Biosynthesized CuO nanoparticles mediated by red algae Gracilaria textorii: Photocatalytic dye degradation of methylene blue and in vitro antioxidant and antidiabetic activities

In this Current Study, copper oxide (CuO NPs) was synthesized by an eco-friendly, low-cost, and economical synthesis method using Gracilaria textorii algae extract as a reducing and capping agent. The synthesized CuO NPs were characterized by UV–visible spectroscopy showed an absorption edge at 272 nm, and the optical band gap was estimated to be 2.2 eV, confirming the nanoparticles. The FTIR spectrum shows that the band in the range 400–4000 cm−1 confirms the formation of CuO NPs. X-ray diffraction patterns revealed the monoclinic phase of CuO with good crystallinity, and the average crystallite size was calculated as 17.8 nm. The SEM analysis also confirmed that formed nanoparticles had irregular and agglomeration morphology and Elemental analysis and the particle size were confirmed by elemental dispersive X-ray analysis (EDX) and particle size analyzer using confirm the Cu and O nanoparticles. Electrochemical behavior was investigated through cyclic voltammetry, which indicates good redox activity and electron transfer capability of the synthesized CuO NPs. The photocatalytic activities of biosynthetic CuO NPs and chemically prepared CuO NPs were studied using methylene blue upon exposure to sunlight irradiation revealing significant degradation efficiency, with variation between the algae - mediated nanoparticles. Moreover, Antioxidant activity was evaluated using DPPH and hydrogen peroxide (H₂O₂) scavenging assays, indicating concentration-dependent radical scavenging showed strong antioxidant activity. In vitro study showed that significantly inhibited the enzymatic activity of-amylase inhibition assay. The biosynthesized copper oxide nanoparticles method are environment and economically use in various field and biomedical applications.