Colorimetric Sensing Strategy through the Coordination Chemistry between Ascorbic Acid 2-Phosphate and Copper Ions

The coordination chemistry between phosphorylated molecules and metal ions has been reported, while few studies focus on its sensing capability. Herein, we report a colorimetric sensing strategy through the coordination chemistry between ascorbic acid 2-phosphate (AAP) and copper ions. The phosphate group-containing AAP can coordinate with copper ions to induce a visible color change from blue to green in a rapid way, which can be easily read by the naked eye or a smartphone based on the blue-to-green (B/G) ratio. This coordination chemistry provides a facile and convenient strategy for designing colorimetric assays. Alkaline phosphatase can catalyze the hydrolysis of AAP to ascorbic acid (AA), thus modulating the AAP/AA transformation and the AAP-mediated coordination, offering a straightforward way for monitoring the enzymatic activity. This colorimetric sensing strategy shows good performances in stability, sensitivity, cost, and scale-up production, holding great promise as a point-of-care technique for diagnostic applications.