A Colorimetric Chemical Nose with Unmodified Gold Nanoparticles for Multiplexed Detection and Discrimination of Catecholamine Neurotransmitteres

Catecholamine neurotransmitters, specifically, dopamine, epinephrine, and norepinephrine, are known as substantial indicators of various neurological diseases. Developing rapid detection methods capable of simultaneously screening their concentrations is highly desired for early clinical diagnosis of such diseases [1-2]. In contrast to single probes, sensor arrays are capable of discriminating different analytes that may possess similar structures and/or exist in complex mixtures [3-5]. We have designed an optical sensor array using gold nanoparticles (AuNPs) with four distinct particle sizes as sensing elements for discrimination and semi-quantitative determination of DA, EP, NE and L-dopa. The aggregation of AuNPs produces changes in both the color and UV–vis spectra of nanoparticles generating a visual molecular fingerprint of each analyte. Using this chemical/nose strategy, four catecholamines can be differentiated by chemometric methods including PCA, HCA and even baked-eye. The proposed array could successfully differentiate the four target analytes in urine samples, suggesting the potential applicability of the nanoarray for analysis of real biological specimens.