Instantaneous detection of melamine by interference biosynthesis of silver nanoparticles

Instantaneous detection of melamine, a potential milk adulterant has been demonstrated at room temperature by means of interference biosynthesis of silver nanoparticles. The sensing mechanism is based on the colorimetric change observed during the synthesis of silver nanoparticles due to the presence of melamine added during the biosynthesis. Presence and absence of melamine led to either inhibition of nanoparticle formation or enable partial synthesis of nanoparticles which is detected spectrally. A limit of detection (LOD) of 0.1 ppm in water and 0.5 ppm in raw milk was detected by the proposed technique at room temperature. UV-vis spectroscopy and High Resolution Transmission Electron Microscopy (HR-TEM) have been used to detect the spectral Surface Plasmon Resonance (SPR) and morphological changes of synthesized silver nanoparticle with and without the presence of the analyte melamine. Further, interference synthesis based sensing of melamine was done with caffeic acid as a reducing agent which confirms the role of caffeic acid a major constituent of Parthenium leaf extract for interference biosynthesis based sensing. Melamine is detected from raw milk by interference biosynthesis based sensing after a facile milk pre-processing step. Thus the method can be converted into a workable handheld prototype for detection of melamine for in-situ field applications. (C) 2016 Elsevier B.V. All rights reserved