Green synthesis of gold nanoparticles using Halymenia pseudofloresii extracts and their antioxidant, antimicrobial, and anti-cancer activities

Gold nanoparticles (AuNPs) have a numerous biomedical applications including their antioxidant, antimicrobial, and anticancer applications. We have synthesized AuNPs laced with the extracts of red algae Halymenia pseudofloresii using the green method (Hp-AuNPs). The synthesized nanoparticles were characterized by UV spectroscopy, XRD, FTIR, and SEM. In UV spectroscopy, Hp-AuNP's surface plasmon resonance (SPR) peak was discovered to be at 545 nm, which initially confirmed the formation of nanoparticles. The X-ray diffraction analysis confirmed the biosynthesized Hp-AuNP structures to be crystal in nature. Bioactive molecules, such as phenolic compounds and carboxylic groups, were identified by FTIR analysis as contributing to the reduction of Hp-AuNPs. The scanning electron microscope (SEM) analysis was used to identify the Hp-AuNP morphology as cubic and rectangular structures with 27 nm size. The antioxidant activity demonstrated that H. pseudofloresii extract (61.3%) and synthesized Hp-AuNPs (71.87%) effectively inhibited the DPPH radicals at 50 mu g/mL concentration. The Hp-AuNPs exhibited efficient antibacterial effects against Staphylococcus aureus (24 mm), Lactobacillus (23 mm), and Pseudomonas aeruginosa (22 mm). The biosynthesized Hp-AuNPs showed potential cytotoxic activity against A549 lung cancer (IC50 = 19.02 mu g/mL) than LN-18 glioblastoma cancer cells (IC50 = 32.46 mu g/mL). Hence, further anticancer screening was tested against lung cancer cells. In the clonogenic assay, Hp-AuNPs effectively control the lung cancer cell colony formation at the concentration of 30 mu g/mL, whereas the Hp-AuNPs induce apoptotic activity in lung cancer cells was confirmed through reactive oxygen species (ROS) generation assay. Therefore, the unique biologically synthesized Hp-AuNPs have the ability to function as an anticancer agent, and they may further be used for a variety of biomedical purposes.