What question did this study set out to answer?

This research aims to synthesize bioactive zinc oxide nanoparticles using Nostoc sp. extract and to evaluate their biomedical applications.

April 15, 2026Open Access

Biogenic synthesis of bioactive zinc nanoparticles from cyanobacterial Nostoc sp. MK-7 for biomedical applications

Key Points

This research aims to synthesize bioactive zinc oxide nanoparticles using Nostoc sp. extract and to evaluate their biomedical applications.
Green synthesis of zinc oxide nanoparticles using Nostoc sp. strain MK-7 extract
Characterization through UV-visible spectroscopy, FTIR, XRD, FESEM, and TEM
Biological evaluations including antioxidant assays and elastase inhibition
Cell viability assays on MDA-MB-231 breast cancer cells using Annexin V-FITC/PI staining
Zinc oxide nanoparticles confirmed with characteristic absorption peak at 312 nm
Average crystallite size calculated at 41.9 nm and high purity of zinc at 82.3%
Antioxidant activity of 89.04% ABTS radical scavenging with IC50 value of 35 ± 5 µg/mL
Demonstrated 50.5% elastase inhibition and significant apoptosis induction in breast cancer cells
Suppressed IL-6 secretion and nitric oxide production, highlighting anti-inflammatory effects

Abstract

This study reports the green synthesis of bioactive zinc oxide nanoparticles (MK-7 ZnO NPs) using Nostoc sp. strain MK-7 extract as a natural reducing and stabilizing agent. The formation of ZnO NPs was confirmed by UV-visible spectroscopy with a characteristic absorption peak at 312 nm. FTIR analysis revealed the involvement of bioactive functional groups (O-H, C = O, C-O, and Zn-O), indicating their role in nanoparticle reduction and stabilization. XRD analysis confirmed the crystalline nature of the nanoparticles with a prominent peak at 36.3°, and the average crystallite size was calculated to be 41.9 nm using the Debye-Scherrer equation. FESEM and TEM analyses demonstrated a well-defined hexagonal morphology, while EDS confirmed high zinc purity (82.3% by weight). Biological evaluations revealed that MK-7 ZnO NPs exhibited significantly enhanced bioactivity compared to the crude extract. The nanoparticles showed strong antioxidant activity, achieving 89.04% ABTS radical scavenging with an IC50 value of 35 ± 5 µg/mL and superior ferric- and cupric-reducing capacities. In elastase inhibition assays, MK-7 ZnO NPs demonstrated notable anti-wrinkle potential (50.5% inhibition at 100 µg/mL; IC50 = 55 ± 5 µg/mL). Importantly, the nanoparticles significantly reduced viability of MDA-MB-231 breast cancer cells by inducing apoptosis, as confirmed by Annexin V-FITC/PI staining and flow cytometry. Furthermore, MK-7 ZnO NPs suppressed nitric oxide production and downregulated IL-6 secretion and mRNA expression, demonstrating potent anti-inflammatory and anticancer effects. Overall, the findings highlight the successful biosynthesis of structurally stable, hexagonal MK-7 ZnO NPs with enhanced antioxidant, anti-inflammatory, anti-wrinkle, and anticancer activities. These results underscore the promising potential of MK-7 ZnO NPs as multifunctional therapeutic agents, warranting further in vivo investigations for clinical translation.

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