Green synthesis, characterization and antimicrobial efficacy of silver nanoparticles from Kappaphycus alvarezii extract

Silver nanoparticles (AgNPs) synthesized via a green method offer numerous advantages compared to conventional chemical synthesis routes, primarily due to their lower cost, non-toxic nature, and enhanced antimicrobial properties. This study introduces a green method for synthesizing AgNPs with promising antimicrobial properties, using Kappaphycus alvarezii (K. alvarezii), a red seaweed, as the reducing and stabilizing agent. The hydrothermal method was employed, and optimal synthesis conditions were identified at 90 °C for 2 h. The resulting AgNPs were comprehensively characterized using an array of spectroscopic and microscopic techniques including UV–Visible (UV–Vis) spectroscopy, fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscope, and atomic force microscopy. The findings indicated that the functional groups inherent to the seaweed extract played a crucial role in both reducing and stabilizing the AgNPs. The synthesized AgNPs are confirmed based on the presence of the characteristic surface plasmon resonance band within the 380–460 nm range in the UV–Vis spectra. The AgNPs are predominantly composed of silver (82.38 wt