Fluorescence, turn-on detection of melamine based on its dual functions as fluorescence enhancer of DNA-AgNCs and Hg(II)-scavenger

Abstract

A new method has been developed for the simple, fluorescence, turn-on detection of melamine, which utilizes DNA-templated silver nanoclusters (DNA-AgNCs) as a key component. In the sensor, melamine exhibits the dual functions: one is to enhance the fluorescence signal of DNA-AgNCs by its specific interaction with thymine residues in DNA template, and the other is to prevent Hg(II)-induced fluorescence quenching of DNA-AgNCs via its strong coordination with Hg(II). These consequently enable the sensitive and selective detection of melamine. By exploiting such novel features of melamine, we significantly increased the fluorescence response up to 360%, compared to the previous counterpart that relies on DNA-AgNCs only, and successfully determined melamine down to ca. 49 nM, a value that is 400 times lower than the safety level of 20 lM set by the US Food and Drug Administration. In addition, it was confirmed that the proposed approach works fine even in the real milk samples without any additional pre-treatment steps.

Label-free DNAzyme for highly sensitive detection of multiple biomolecules in real samples through target-triggered catalytic cleavage reactions with auramine O’s discriminated fluorescence emission

“…In this way, an excessive intake of MA will result in the production of insoluble MA anurate crystals in the kidney and eventually induce renal failure. According to FDA standards for MA interim safety and risk evaluation, a maximum quantity of 20 µM MA can be present in food for human consumption [3][4][5].…”