Biosynthesis of Mikania micrantha mediated silver nanoparticles: Its application as a sustainable catalyst for Biginelli reaction and antioxidant capacity

Abstract

The current study focuses on the eco-friendly, bio-synthesis and of silver nanoparticles (AgNPs), utilizing an aqueous extract of Mikania micrantha. A rigorous analysis was performed to investigate the effects of several operational factors on the synthesis of AgNPs, including the various quantities of leaf extract, temperature, contact duration, and pH solution. The outcomes demonstrated that the optimal circumstances for producing nanoparticles are Mikania micrantha leaf extract dosage (5 % v/v), pH 9, and 80 °C temperature, with a duration of 60 min incubation time. The bio-synthesized AgNPs were examined using UV–Vis, FT-IR, X-ray diffraction (XRD), FE-SEM, EDX, TEM, and SAED studies. The FT-IR study proved that phytochemicals were involved in the AgNPs production process, and its spherical morphologies with the size range of 12.35 - 46.83 nm were apparent in the TEM images. The face-centered cubic structure of AgNPs was validated by the XRD spectrum. The XRD investigations also substantiated the SAED spectrum's indication that the AgNPs were crystalline. AgNPs were identified as an eco-friendly heterogeneous catalyst, demonstrating high catalytic efficiency in the Biginelli reaction under acid-free, mild conditions, achieving excellent yields in 30 s. 1,1-diphenyl- 2-picrylhydrazyl (DPPH) and Ferric reducing antioxidant power (FRAP) assays were used to assess the biological efficiency showing 89.8 % inhibition activity with an average IC₅₀ value of 24.99± 0.19 µg mL^-1 and higher reducing power than the positive control, respectively. This confirms that the leaf extract of Mikania micrantha and its biosynthesized nanoparticles also showed promising antioxidant capability.