Biogenic synthesis of NiO-SrO nanocomposite using Mangifera indica leaves and its biological and dye adsorptive applications with mechanistic insights

Background: The biosynthesis of metal nanoparticles using plant extracts offered a sustainable alternative to conventional chemical methods. In this study, nickel oxide–strontium oxide nanocomposite (NiO–SrO NC) was synthesied using Mangifera indica leaf extract for the first time, aiming to explore its multifunctional biomedical and photocatalytic applications. Method: The synthesized NiO–SrO NC was characterized by UV–Vis spectroscopy, FTIR, XRD, and SEM–EDX analyses. Phytochemical screening and FTIR results confirmed the presence of polyphenols and terpenoids, which act as natural reducing, stabilizing, and capping agents during nanoparticle formation. The nanocomposite was further evaluated for its biological potential and environmental applications. Findings: Hemolytic studies demonstrated that the NiO–SrO NC exhibited no toxicity at lower concentrations. The nanocomposite showed strong antibacterial activity against S. aureus (8 ± 0.3 mm), E. coli (7.8 ± 0.29 mm), and P. aeruginosa (7 ± 0.27 mm), comparable to the standard control. Furthermore, the results indicated that the NiO–SrO NC possesses significant antidiabetic potential, with 51 % α-amylase inhibition IC₅₀= 193.8 mg/mL. It also exhibited good antioxidant activity, achieving 78 % inhibition in the DPPH and 73 % in the ABTS assay. In addition, the nanocomposite achieved 98 % degradation of methylene blue (MB) within 150 min, confirming its effective photocatalytic performance. These findings suggest that the biosynthesized NiO–SrO NC holds great promise for applications in environmental remediation and biomedical fields.