MXene catalytic amplification-fluorescence/absorption dimode aptamer sensor for the detection of trace Pb 2+ in milk.

Lead ion (Pb ²⁺ ) is a toxic heavy metal, which is very harmful to organisms. Therefore, the establishment of a rapid, simple, and sensitive method is of great significance to food safety and human health. It was found that MXeneTi ₃ C ₂ nanosheet (NS) has a strong catalytic effect on the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) via H ₂ O ₂ to form the oxidized product (TMB _OX ); it has a strong fluorescence peak at 415 nm and an absorption (Abs) peak at 295 nm. The aptamer of Pb ²⁺ (Apt _pb ) can be adsorbed on the surface of an NS to form MXene-Apt conjugates, which reduces its catalytic active sites and inhibits its catalytic activity. When the target Pb ²⁺ is added, it specifically binds with Apt _pb to release MXene NSs to enhance the dimode signals. Therefore, a new MXene catalytic fluorescence/absorption dimode aptamer biosenering platform was fabricated for the determination of trace Pb ²⁺ in milk and water samples, with the fluorescence assay linear range (LR) of 5.0 × 10 ^-2 -2.0 nmol/L.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2022 Zhi, Wei, Zhang, Yi, Li and Jiang.)