A highly sensitive plasmonic sensor for detection of selenium based on the shape transformation of silver nanoprisms

We report on a plasmonic probe for detection of ultra-trace amounts of Se(IV) based on morphological transformation of silver nanoprisms (AgNPRs). AgNPRs were synthesized in a mild condition and characterized by UV-vis absorption spectroscopy and transmission electron microscopy (TEM). It was found that in the presence of Se(IV), SPR peak of AgNPRs at 720 nm shifts to lower wavelengths and the color of solution changes from light blue to violet. This is due to the shape transformation of AgNPRs to nanodisks which is proved by TEM images, and probably results from the etching of corners of NPRs by selenite ions. Based on this phenomenon, a sensitive colorimetric probe was developed for determination of Se(IV) in the concentration range of 2.5-100 mu g L-1 with a detection limit of 1.2 mu g L-1. The developed method was applied for analysis of water and food samples.