Biosynthesized Silver Nanoparticles for Colorimetric Detection of Fe3+Ions

In this study, the biosynthesis and characterization of silver nanoparticles (AgNPs) from orchid tree (Bauhinia variegata) leaf extract were firstly carried out, and then, the usability of AgNPs as a colorimetric sensor for detection of Fe(3+)ions in aqueous solutions was evaluated. The characterization studies showed that the synthesized particles were determined to be AgNPs in nanoscale and face-centered cubic structure. Besides, the total phenolic content ofB. variegataextract was determined to be 1.826 +/- 2.1 mg gallic acid equivalents/g dry leaf. Also, the biosynthesized AgNPs showed a strong surface plasmon resonance (lambda(SPR)) around 430 nm and lambda(SPR)intensity decreased with the increasing in Fe(3+)concentration in aqueous solution. Based on the linear relationship between the change of lambda(SPR)intensity and Fe(3+)ion concentration, AgNPs can be used for the sensitive and selective detection of Fe(3+)ions in aqueous solutions with a linear range of 6-100 mu M and a detection limit of 2.08 x 10(-6)M.