Abstract:
Nanotechnology offers a sustainable approach for synthesising materials at the
nanoscale, enhancing their physicochemical and biological properties. This study
investigated the green synthesis of silver nanoparticles (AgNPs) using aqueous
root extracts (AEs) of five Cyperus species, namely C. mindorensis, C. esculentus,
C. alternifolius, C. rotundus, and C. eragrostis. Phytochemical screening revealed
the presence of carbohydrates, saponins, proteins, and quinones in all AEs, while
tannins and carboxylic acids were absent. SEM analysis confirmed spherical
AgNPs of 20–50 nm. Compared to AEs, AgNPs showed significantly higher total
flavonoid content (TFC), total phenolic content (TPC), and total antioxidant
capacity (TAC). C. esculentus AEs showed 746.09 g/QE/100g for TFC, 543.34
g/GAE/100g for TPC, 52.988 g/AAE/100g for TAC, and AgNPs exhibited the
highest TFC level (4.2 g/QE/100g), the highest TAC levels (319 g/AAE/100g), and
the highest TPC levels (2158 g/GAE/100g). The antibacterial potential m of the
synthesised AgNPs was evaluated using the well diffusion method with
gentamycin serving as positive control, revealing significant inhibitory activity
against E. coli and S. aureus. Notable zones of inhibition were observed: C.
esculentus – 11 mm, C. alternifolius – 11 mm, C. rotundus – 10 mm, and C.
eragrostis – 11 mm. But C. mindorensis-AgNPs did not exhibit antibacterial
properties. Cytotoxicity tests using Artemia salina indicated 100% viability across
all AgNP concentrations, confirming biocompatibility. In catalysis studies, AgNPs
facilitated the reduction of para-nitrophenol (PNP) to para-aminophenol (PAP),
with C. esculentus-AgNPs showing the highest rate constant (0.1351 min⁻¹).
Degradation of PNP was observed within 20 min at 420 nm, and formation of PAP
was observed at 320 nm. Photocatalytic degradation experiments were performed
with both methylene blue (MB) and methyl orange (MO). Photocatalytic
degradation of MB and MO was faster with 4000ppm AgNPs, while 267ppm
AgNPs showed enhanced degradation when combined with NaBH4. 4000ppm
showed higher degradation with AgNPs and AgNPs with NaBH4. Bioinformatic
docking analysis revealed silver ion binding with key residues (Ser127, Asn124)
of the TRAF1 (1KZN) protein (pbd_00001kzn), suggesting potential anticancer
applications. These results demonstrate that Cyperus-derived AgNPs possess
multifunctional properties, highlighting their potential use in biomedical and
environmental fields.
