Thesis (MSc) - Cyprus International University. Institute of Graduate Studies and Research Chemistry

The leaf extract of Brassica rapa subsp. narinosa (tatsoi) is used in this study to
investigate the green production of silver nanoparticles (AgNPs) and assess their
antibacterial, antioxidant, and dye-catalytic degradation properties. Phytochemicals
were used in the fast synthesis process as reducing and stabilizing agents; a color shift
to dark brown signified successful creation. The presence and characteristics of the
nanoparticles, such as a prominent UV absorption peak at 460 nm and a zeta potential
of -21.85 mV, indicating stability, were confirmed by characterization techniques such
as UV-visible spectroscopy, Fourier Transform-Infrared Spectroscopy (FT-IR),
Scanning Electron Microscope (SEM), Zeta sizer, and X-ray diffraction (XRD). Under
specified conditions, the produced AgNPs showed substantial catalytic activity,
reaching 60% degradation of methylene blue and 90% degradation of safranin. The
DPPH assay was also used to evaluate the antioxidant activity. The results showed that
the plant extract had higher antioxidant activity than the nanoparticles, with IC50
values of 8.409 μg/ml and 13.40 μg/ml, respectively. Gram-positive Bacillus subtilis
(B. subtilis) and Gram-negative Escherichia coli (E.coli) were efficiently stopped from
growing by AgNPs, according to antimicrobial tests, but the plant extract by itself
showed no antibacterial action. This work demonstrates the possibility of ecologically
friendly nanoparticle production for useful uses in antioxidant therapy, antibacterial
treatments, and dye pollution cleanup in the environment.