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Anal Bioanal Chem. 2018 Jul;410(18):4555-4564. doi: 10.1007/s00216-018-1114-7. Epub 2018 Jun 4.

Smart app-based on-field colorimetric quantification of mercury via analyte-induced enhancement of the photocatalytic activity of TiO2-Au nanospheres.

Author information

1
Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan.
2
Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 11529, Taiwan.
3
Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan. changht@ntu.edu.tw.
4
Department of Chemistry, Chung Yuan Christian University, Chung Li District, Taoyuan City, 32023, Taiwan. changht@ntu.edu.tw.

Abstract

We have devised a unique strategy for highly sensitive, selective, and colorimetric detection of mercury based on analyte-induced enhancement of the photocatalytic activity of TiO2-Au nanospheres (TiO2-Au NSs) toward degradation of methylene blue (MB). Through electrostatic interactions, Au nanoparticles are attached to poly-(sodium 4-styreneulfonate)/poly(diallyldimethylammonium chloride) modified TiO2 nanoparticles, which then form an Au shell on each TiO2 core through reduction of Au3+ with ascorbic acid. Notably, the deposition of Hg species (Hg2+/CH3Hg+) onto TiO2-Au NSs through strong Au-Hg aurophilic interactions speeds up catalytic degradation of MB. The first-order degradation rates of MB by TiO2-Au NSs and TiO2-Au-Hg NSs are 1.4 × 10-2 min-1 and 2.1 × 10-2 min-1, respectively. Using a commercial absorption spectrometer, the TiO2-Au NSs/MB approach provides linearity (R2 = 0.98) for Hg2+ over a concentration range of 10.0 to 100.0 nM, with a limit of detection (LOD) of 1.5 nM. On the other hand, using a low-cost smartphone app that records the color changes (ΔRGB) of MB solution based on the red-blue-green (RGB) component values, the TiO2-Au NSs/MB approach provides an LOD of 2.0 nM for Hg2+ and 5.0 nM for CH3Hg+, respectively. Furthermore, the smartphone app sensing system has been validated for the analyses of various samples, including tap water, lake water, soil, and Dorm II, showing its great potential for on-line analysis of environmental and biological samples. Graphical Abstract ᅟ.

KEYWORDS:

Mercury; Methylene blue; Photo-degradation; Photocatalyst; Smartphone app; TiO2–Au nanospheres

PMID:
29862429
DOI:
10.1007/s00216-018-1114-7

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