Bio-fabrication of polymeric silver nanoparticles (Ag-NPs) using polysaccharide extracted from <i>Ulva reticulata</i> : structural and functional characterization

Wound healing is still a major problem for nosocomial and diabetic patients, and the traditional way of healing takes a prolonged time due to the inflammation caused by excessive release of cytokines at the site of the wound. In this regard, the bioactive properties of extracted polysaccharides extracted from the marine macro green alga <i>Ulva reticulata</i> were evaluated, and silver nanoparticles were synthesized. The extraction technique yielded 21.5 mg of the polysaccharide/100 g of the alga. The qualitative analyses revealed the presence of flavonoids (25.12 mg QE/g) and phenols (78.46 mg GAE/g). The antioxidant properties of extracted polysaccharide exhibited an IC₅₀ of 42 μg/mL and good scavenging of DPPH. Polysaccharide extract was able to inhibit α-amylase (IC₅₀ = 62 µg/mL), defining its antidiabetic property. Anti-inflammatory activity was successfully investigated and confirmed through total protein denaturation (% inhibition, IC₅₀ = 43 µg/mL) assay. Silver (Ag) nanoparticles were synthesized and characterized for UV-visible spectroscopy, Fourier Transform Infrared Spectroscopy, zeta potential and size analyzer, X-ray diffraction, and Scanning Electron Microscopy. These findings suggested that the polysaccharide extracted from <i>U. reticulata</i> exhibited strong antioxidant, antidiabetic, anti-inflammatory, antimicrobial, and cytotoxic potential, supporting its development as a natural multi-functional therapeutic agent.