Colorimetric Sensor Array for Thiols Discrimination Based on Urease–Metal Ion Pairs

Thiols play a crucial role in various physiological functions, and the discrimination of thiols is a significant but difficult issue. Herein, we presented a new strategy for strengthening the discrimination of thiols by a facile colorimetric sensor array composed of a series of urease–metal ion pairs. The proposed sensor array was fabricated based on the interactions between thiols and metal ions and the effective activation of urease by thiols. Different thiols exhibited different affinities toward the metal ions, producing differential retentions of urease activity and generating distinct colorimetric response patterns. These response patterns are characteristic for each thiol and can be quantitatively differentiated by linear discriminant analysis (LDA). Cysteine (Cys), glutathione (GSH), and four other kinds of thiols have been well distinguished on the basis of this sensor array at a low concentration (1.0 μM). Remarkably, the practicability of the proposed sensor array was further validated by high accuracy (96.67%) identification of 30 unknown thiol samples. In this strategy, urease and its metal ion inhibitors were adapted to fabricate the sensor array, offering a facile way to develop sensitive array sensing systems based on inexpensive and commercially available enzymes and their inhibitors.