2020 Volume 36 Issue 11 Pages 1407-1413
A grey system based on the principle of complementary colors was constructed as an activatable probe for the sensitive and specific ratio-colorimetric detection lead ions (Pb2+) in a complex food matrix. This grey system was prepared by mixing purple-red AuNP-capped glutathione (GSH) and green-blue sulfonated pigment green 7 (SPG7), to create the SPG7/AuNP probe. In the presence of Pb2+, the strong chelation of Pb2+ with GSH could trigger the aggregation of AuNPs, leading to the color activation of SPG7. Hence, the absorbance ratio A523nm/A628nm of AuNPs at ∼523 nm and SPG7 at ∼628 nm could be used for highly specific reporting of Pb2+ levels with a low detection limit of 0.33 μg/L. Moreover, this probe exhibited promising practical applications in real preserved egg samples with recoveries of 89.2 to 107.5% and relative standard deviations (RSD) in the range of 0.28 to 2.12%, revealing its great potential for harmful substance detection.