Rational design of an “on-off-on” fluorescent assay for chiral amino acids based on quantum dots and nanoporphyrin

Interests in the recognition of chiral amino acids have grown tremendously in recent years, particularly in the fields of food analysis and pharmaceutical studies. Herein, an innovative “on-off-on” fluorescent assay has been developed for the sensitive and selective determination of chiral Proline (Pro), Lysine (Lys), and Serine (Ser). This detection platform is constructed by exploiting the fluorescence quenching ability of chiral self-assembly zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (ZnTPyP) to CdTe quantum dots (CdTe QDs). CdTe QDs can act as signal switches whose fluorescence signals can effectively quenched by chiral nano ZnTPyP and then restored in the presence of enantiomer amino acids. The coupling use of CdTe QDs and chiral nano ZnTPyP also permits quantitative analysis of d-Pro, d-Lys, l-Ser with detection limits of 4.46 × 10−10 mol L−1, 7.13 × 10−11 mol L−1, and 3.35 × 10−11 mol L−1, respectively. The approach is also suitable for the effective detection of the three amino acids in complex biological matrices. This rapid, robust and reliable strategy for recognizing enantiomer amino acids has not been reported. The proposed method can be a powerful and valuable technology in the areas of drug discovery and food chemistry.