Colorimetric detection of amoxicillin based on querecetagetin coated silver nanoparticles

A different approach to the molecular recognition events consists in synthesis and conjugating silver nanoparticles with flavonoid quercetagetin isolated from T. erecta. In this article we are reporting rapid and feasible procedure for the synthesis of querecetagetin stabilized silver nanoparticle (Qt AgNPs). These nanoparticles were characterized by UV-vis spectroscopy, FTIR, and AFM techniques. The average size of the querecetagetin coated silver nanoparticles was found to be in the range from 25 to 45 nm and are highly robust. Querecetagetin coated silver nanoparticle selectively recognize amoxicillin producing a bathochromic shift along with color change from yellow to reddish. The detection limit was calculated using standard deviation of blank and slope of regression line and was found to be 4.46 μM with a correlation factor R2 equal to 0.993. The binding stoichiometry between Qt AgNPs and amoxicillin was found to be 1:2 (Qt AgNPs: amoxicillin) as revealed by Job's plot. The Qt AgNPs interact selectively with amoxicillin in human blood plasma and tap water sample showing that the ingredients of tap water and blood plasma are inert towards the interaction of Qt AgNPs with amoxicillin.Photophysical events were examined using UV-vis, FTIR spectroscopy and, AFM techniques.