Green valorization of Carica papaya seed waste for biogenic silver nanoparticles: Physicochemical characterization and in vitro antibacterial and antidiabetic activities

The present study investigated the green synthesis of silver nanoparticles using Carica papaya seed extract (Ag-CPSE-NPs) and evaluated their physicochemical characteristics, antibacterial activity, and in vitro antidiabetic potential. The green-synthesized Ag-CPSE-NPs prepared using Carica papaya seed extract as a reducing and stabilizing agent, were characterized by UV–Vis, FTIR, DLS, SEM, TEM and XRD. Antibacterial activity was evaluated against Staphylococcus aureus and Escherichia coli by the agar disc diffusion and agar well diffusion method. Antidiabetic potential was assessed via in vitro glucose uptake, α-amylase, and α-glucosidase inhibition assays. DLS analysis of the synthesized Ag-CPSE-NPs indicated a polydispersity index of 0.194 and a mean particle size of 232.3 nm, indicating moderate agglomeration in the biosynthesized nanoparticles, while SEM and TEM confirmed their morphology with particle sizes ranging from 12 to 38 nm (mean 19.74 ± 7.94 nm). XRD analysis demonstrated the crystalline nature of Ag-CPSE-NPs, with characteristic Bragg reflections at 2θ ≈ 38.12° and 77.55° corresponding to the (111) and (311) planes of face-centered cubic silver. Ag-CPSE-NPs exhibited significant concentration-dependent antibacterial activity against the tested microorganisms. At higher concentrations (800 µg/mL to 1000 µg/mL), Ag-CPSE-NPs demonstrated significant glucose uptake (52.77–62.19%), as well as α-amylase (40.85–46.21%) and α-glucosidase (36.03–46.95%) inhibition, compared with the standard drug Acarbose. These findings demonstrate that CPSE seed waste can be successfully valorized for the green synthesis of multifunctional Ag-CPSE-NPs with promising antibacterial and in vitro antidiabetic properties, supporting their potential for future pharmaceutical and nanomedicine applications. Further in vivo and mechanistic studies are warranted to establish their therapeutic potential and facilitate their translation into pharmaceutical and nanomedical applications.