Stable AgNPs were formed in vitro by reacting AgNO3 (aq) solution with the aqueous plant leaf extract. UV-vis revealed the surface plasmon resonance λmax at 448 nm and the absorbance steadily increased in intensity as a function of reaction time. Transmission electron microscope (TEM) and XRD studies were used to characterize the AgNPs; the size was 4-35 nm. Dynamic light scattering (DLS) was used as supporting evidence to determine hydrodynamic size and zeta potential recorded as 80.27 nm and -24.7 mV, respectively. FT-IR spectra suggest that AgNPs are capped with protein molecules and other water soluble phytocompounds such as saponins and glycosides which also behave as stabilizing agents; TEM images indicate a visible layer surrounding the AgNPs. Prominent absorption bands at 3380 and 1642 cm(-1) are assigned to alcohol and carbonyl groups, respectively. (1)H NMR of the neat aqueous plant extract indicates presence of a complex mixture of compounds; however the chemical shift at δ 6.0-8.0 and 1.0-4.0 ppm indicates the presence of few aromatic but abundant aliphatic compounds, respectively. Toxicity of AgNPs on lung cancer cells (A549) and normal healthy peripheral lymphocytes (PLs) at 10 μg/ml and 50 μg/ml was assessed using the MTT, ATP and lactate dehydrogenase assays. Viability data for A549 cells showed a 21% (10 μg/ml) and 73% (50 μg/ml) cell viability after 6h exposure to AgNPs compared to 117% (10 μg/ml) and 109% (50 μg/ml) cell viability of normal peripheral lymphocytes. Lactate dehydrogenase was only significantly altered at 50 μg/ml AgNPs treated cells from 2.43±0.04 units to 0.77±0.04 units.
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