Label-free Colorimetric Sensing of α-Amino Acids Based on Surface-enhanced Photochromic Phenomena of Molybdenum(VI) Oxide Nanoparticles
A. Yamamoto, K. Adachi
Bunseki Kagaku (分析化学), 2017, 66, 639-646.
DOI : 10.2116/bunsekikagaku.66.639

Abstract: Due to the biological importance of α-amino acids and their derivatives, the development of novel colorimetric probes for these molecules has been an active research area in recent years. In this study, surface-enhanced photochromic phenomena by various α-amino acids (L-aspartic acid [Asp], L-leucine [Leu], and L-lysine [Lys]) adsorbed on molybdenum(VI) oxide (MoO3) nanoparticles in an aqueous system were investigated by means of UV-vis absorption spectrometry. No derivatization of α-amino acids is required, and eventually highly accurate determinations are obtained from the UV-induced MoO3 photochromic coloration. Under optimal conditions in this system, limit of quantitation (LOQ) values of 3.45×10-6, 2.08×10-6, and 1.53×10-6 mol dm-3 for Asp, Leu, and Lys, respectively, were achieved at pH 2. During UV irradiation, the detection process could be visually observed by naked eyes. A simple and unique approach to explore sensitive "label-free" colorimetric sensing toward α-amino acids is proposed.