In this study, a colorimetric sensor array that can simultaneously detect and identify multiple heavy metal ions (Hg2+, Cd2+, Fe3+, Pb2+, Al3+, Cu2+, and Cr3+) in water was reported, to our knowledge for the first time. The colorimetric sensor array utilizes 11-mercaptoundecanoic acid (MUA)-capped gold nanoparticles (AuNPs) and five amino acids (lysine, cysteine, histidine, tyrosine, and arginine). Each AuNP and amino acid couple generates a sensor component of the array. In the absence of amino acids MUA capped AuNPs are aggregated non-selectively by metal ions depending on the type and concentration of the metal ion. On the other hand, presence of amino acids in the assay, either enhance or prevent the aggregation of the MUA capped AuNPs. The combinatorial colorimetric response of all channels of the sensor array (i.e., color change in each of AuNP and amino acid couples) enables naked-eye discrimination of all of the metal ions tested in this study with excellent selectivity (see the Figure). Also, by analyzing the combinatorial response of the sensor array components using a data analysis method, all of the tested metal ions were discriminated in a broad concentration range. In addition, the response of the colorimetric sensor array is highly reproducible; it discriminated all tested metal ions for three separate experiments without a mistake.

Identification of toxic metal ions in water using a gold nanoparticle based colorimetric sensor array

249th National Meeting (2015)

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