Bioinspired 8‑hydroxyquinoline-Fe3O4 nanostructures from Citrullus colocynthis exhibit strong antibacterial, antifungal, and anticancer effects.

This study presents a novel green-synthesized iron oxide nanostructure (ION) using Citrullus colocynthis extract (CCE) and functionalized with 8-hydroxyquinoline (8HQ) to enhance antibacterial, antifungal, and anticancer activities. IONs were synthesized via CCE-mediated reduction or chemical coprecipitation, coated with 8HQ, and characterized by FE-SEM, EDAX, and FT-IR. The antimicrobial efficacy was assessed against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Candida albicans through CLSI-guided MIC/MBC assays, while cytotoxicity was evaluated on MCF7 and Hep-G2 cancer cells using MTT assays. Results demonstrated that CCE-ION exhibited enhanced antimicrobial activity compared to chemically synthesized ION. The MIC values for CCE-ION were 125 µg/mL for P. aeruginosa, 250 µg/mL for E. coli, 500 µg/mL for S. aureus and C. albicans, and 1000 µg/mL for E. faecalis, with corresponding MBC values of 250, 250, 500, 500, and 1000 µg/mL, respectively, indicating strong bactericidal and fungicidal properties. FE-SEM analysis confirmed spherical nanoparticles (35–40 nm) with balanced iron oxide and organic composition. The 8HQ@CCE-ION nanocomposite exhibited significant cytotoxicity, with IC50 values of ≈ 489 µg/mL against MCF-7 cells and ≈ 183 µg/mL against Hep-G2 cells (compared to ≈ > 500 µg/mL and ≈ 450 µg/mL for free CCE, respectively), achieving > 80% cell death at 250 µg/mL and highlighting enhanced cellular uptake and synergistic effects. This eco-friendly nanoplatform successfully integrates CCE’s natural bioactivity with 8HQ’s metal-chelating properties, achieving significant pathogen viability reduction at MIC doses while offering promising anticancer potential. The dual-functional approach positions 8HQ@CCE-ION as a potential therapeutic candidate for drug-resistant infections and cancer treatment.