Work

Green synthesis of silver nanoparticles using Catharanthus roseus leaf extract: Characterization and biological activities

Year: 2026

Type: article

Abstract: An environmentally friendly method for creating functional metal nanostructures with biologically active surface chemistry is plant-mediated synthesis. In this instance, the green production of silver nanoparticles (AgNPs) employed Catharanthus roseus leaf extract as a multipurpose reducing and stabilizing agent. The production of AgNPs was verified by a characteristic surface plasmon resonance band at 426.5 nm. A crystalline face-centered cubic (fcc) structure of metallic silver with a dominant (111) orientation was discovered by X-ray diffraction research, while crystallite sizes determined using Debye-Scherrer, Sahadat-Scherrer, Williamson-Hall, Size-Strain Plot, and Halder-Wagner models confirmed the nanocrystalline nature of the synthesized AgNPs. The bulk of the nanoparticles were spherical, and the average particle size was 32.51 nm, according to FE-SEM image analysis using ImageJ. An average hydrodynamic diameter of 152.95 nm was shown by dynamic light scattering (DLS) measurement, and moderate colloidal stability was indicated by the zeta potential value of -20.3 mV. The role of phytochemical functional groups in Ag⁺ reduction and nanoparticle stability were verified by FTIR spectroscopy, whereas EDX analysis demonstrated a high elemental silver content ( 90.15 wt%). The biosynthesized AgNPs exhibited enhanced antioxidant performance ( IC 50 = 16.60 ± 0.10 μg/mL ) compared with crude plant extracts, suggesting synergistic radical scavenging activity arising from nanoscale surface reactivity and phytochemical capping. Additionally, the AgNPs showed strong antibacterial activity against both Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) microorganisms, as well as strong cytotoxicity in the brine shrimp lethality experiment (LC 50 = 3.81 ± 0.006 μg/mL). Notably, antibacterial inhibition was observed against E. coli under conditions where gentamicin showed no detectable effect. Overall, this study demonstrates that C. roseus-mediated synthesis provides a simple and sustainable platform for producing bio-functional AgNPs with promising relevance in antimicrobial and biomedical applications.

Source: South African Journal of Chemical Engineering

DOI: 10.1016/j.sajce.2026.100967