Galactomannan‐Stabilized Gold Nanoparticles: A Sustainable Nanoplatform for Biomedical and Environmental Applications

Gold nanoparticles (Au NPs) were prepared for the first‐time using galactomannan from Lepidium sativum seeds as a reducing and capping agent for biomedical and environmental applications. Upon mixing galactomannan hydrogel (1.0%) and gold chloride (20 mM) solutions, the mixture's color changed from brown to purple within 2.0 h. A surface plasmon resonance peak at 545 nm in the UV‐visible spectrum and a characteristic band in the FTIR spectrum at 486 cm −1 confirmed the successful synthesis. XRD and SEM analyses revealed a crystalline nature and an average particle size of 62.26 ± 4.30 nm, respectively. EDX revealed Au (28.07%), carbon (24.99%), and oxygen (22.73%) as the main elements. The Au NPs exhibited potent antibacterial activity with prominent zones of inhibition, minimum inhibitory concentrations (MICs), and minimum bactericidal concentrations (MBCs) values. The Au NPs healed the wound within 10 days, surpassing neomycin treatment. Under optimized pH (approximately 10), photocatalyst dosage (5.0 mg), and dye concentration (20 ppm), Au NPs degraded 90.9% methylene blue (MB) and 87.5% methyl orange (MO), following a pseudo‐first‐order kinetics and adsorption capacities between 680.27 and 719.42 mg/g, respectively. The results highlight the prominent biomedical and environmental applications of galactomannan polysaccharide‐derived Au NPs.