Facile Colorimetric Detection of Silver Ions with Picomolar Sensitivity

• Published in: Analytical chemistry (Washington) 2017-03, Vol.89 (6), p.3622-3629
• Main Authors: Gao, Zhuangqiang, Liu, Grace G, Ye, Haihang, Rauschendorfer, Robert, Tang, Dianping, Xia, Xiaohu
• Format: Article
• Language: English
• Subjects: Capping; Catalysis; Color; Colorimetry; Cubes; Dynamic range; Ions; Nanostructure; Oxidation; Peroxidase; Sensitivity; Sensitivity analysis; Silver; Strategy
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.6b05026

Although various colorimetric methods have been actively developed for the detection of Ag+ ions because of their simplicity and reliability, the limits of detection of these methods are confined to the nanomolar (nM) level. Here, we demonstrate a novel strategy for colorimetric Ag+ detection with picomolar (pM) sensitivity. This strategy involves the use of poly­(vinylpyrrolidone)- (PVP-) capped Pt nanocubes as artificial peroxidases that can effectively generate a colored signal by catalyzing the oxidation of peroxidase substrates. In the presence of Ag+ ions, the colored signal generated by these Pt cubes is greatly diminished because of the specific and efficient inhibition of Ag+ toward the peroxidase-like activity of the Pt cubes. This colorimetric method can achieve an ultralow detection limit of 80 pM and a wide dynamic range of 10–2–104 nM. To the best of our knowledge, the method presented in this work shows the highest sensitivity for Ag+ detection among all reported colorimetric methods. Moreover, this method also features simplicity and rapidness as it can be conducted at room temperature, in aqueous solution, and requires only ∼6 min.