Fluorometric discrimination of tyrosine isomers based on the inner filter effect of chiral Au nanoparticles on MoS2 quantum dots

TiO2 Nanotubes Decorated with CdSe Quantum Dots: A Bifunctional Electrochemiluminescent Platform for Chiral Discrimination and Chiral Sensing

Chiral analysis is of significant importance for living organisms since chirality is the fundamental phenomenon in nature. In this work, a bifunctional electrochemiluminescent (ECL) platform is constructed for chiral discrimination and chiral sensing. 3-Mercaptopropionic acid-functionalized CdSe quantum dots (CdSe QDs) are combined with aminated TiO₂ nanotubes (NH₂-TiNTs) via amidation. The resultant CdSe QDs/TiNTs display significantly enhanced ECL signals due to the synergistic effect between CdSe QDs and TiNTs, which are then used for the chiral discrimination of the isomers of nine chiral amino acids (AAs) in the presence of d-AA oxidase (DAAO). DAAO can selectively catalyze the oxidation of d-AAs to generate H₂O₂, which acts as the coreaction reagent and triggers the ECL signals of CdSe QDs/TiNTs, and thus, the isomers of the nine chiral AAs can be effectively discriminated. In addition, the as-constructed ECL platform can also be used for the sensitive detection of d-AAs in the presence of DAAO with a wide linear range and a low limit of detection. These findings suggest that the CdSe QDs/TiNTs can work as a bifunctional ECL platform (chiral discrimination and chiral sensing), which might be an advanced ECL platform for biomedical applications.

Electrochemiluminescent chiral discrimination with chiral Ag2S quantum dots/few-layer carbon nitride nanosheets

Well-dispersed chiral Ag₂S quantum dots (Ag₂S QDs) were facilely synthesized by using N-acetyl-L-cysteine (NALC) as the chiral ligand and loaded onto nanosheets of two-dimensional (2D) few-layer carbon nitride (C₃N₄). The resultant nanocomposite (Ag₂S QDs/few-layer C₃N₄) shows enhanced electrochemiluminescence (ECL) while maintaining the chirality of Ag₂S QDs, which can be used for the chiral discrimination of the enantiomers of tyrosine (Tyr). Due to the higher affinity of chiral Ag₂S QDs toward L-Tyr than toward its enantiomer, the ECL intensity of Ag₂S QDs/few-layer C₃N₄ is significantly decreased after its incubation with L-Tyr, and thus the Tyr enantiomers can be discriminated. The developed ECL chiral sensor exhibits high stability and reproducibility. The universality of the ECL chiral sensor for the discrimination of other chiral amino acids is also studied, and the results indicate that it can work only in the case of chiral aromatic amino acids.