Electronic-Tongue Colorimetric-Sensor Array for Discrimination and Quantitation of Metal Ions Based on Gold-Nanoparticle Aggregation.

Sensor arrays, called "electronic tongues", provide an alternative to time-consuming detection approaches. In this work, a colorimetric-sensor array composed of three recognition receptors (cysteine, l-glutathione, and melamine) was developed for fast discrimination of toxic metal ions. Different recognition receptors exhibited different binding affinities toward metal ions, causing diverse gold-nanoparticle (AuNP)-aggregation behaviors and generating distinct colorimetric response patterns. As "fingerprints", these response patterns can be quantitatively analyzed by linear-discriminant analysis (LDA). The sensor array achieved good discrimination of six kinds of metal ions (Ti, Cr, Mn, Fe, Pb, and Sn) in deionized water and real samples. It possessed good reproducibility and exhibited a linear range of 100-900 nM ( R = 0.97) for Ti, 100-900 nM ( R = 0.97) for Cr, 100-900 nM ( R = 0.98) for Mn, 100-1000 nM ( R = 0.92) for Sn, 100-800 nM ( R = 0.94) for Fe, and 100-900 nM ( R = 0.97) for Pb. The sensor array shows feasible potential in environmental monitoring and simplification of water-quality analysis.