l-Pyroglutamic Acid-Modified CdSe/ZnS Quantum Dots: A New Fluorescence-Responsive Chiral Sensing Platform for Stereospecific Molecular Recognition

Abstract

Stereoselective recognition of amino acids is extremely important due to its high chirality-dependent interactions and physiological activities in life activities. We herein report a novel functionalized chiral fluorescent nanosensor prepared from surface modification of CdSe/ZnS quantum dots (QDs) with pyroglutamic acid derivatives, which could serve as a chiral recognition module for fluorescence detection of chiral molecules. The sensor exhibited a unique stereoselective fluorescence response to histidine (His), glutamate (Glu), and dihydroxyphenylalanine (Dopa) and had preferable response performance to l-enantiomers. The enantiomeric fluorescence difference ratios of His, Glu, and Dopa enantiomers were 3.90, 3.40, and 2.49, respectively. The mechanism for the enantiomeric fluorescence recognition was systematically studied through a fluorescence spectrum, fluorescence life, and density functional theory (DFT) calculation. Presumably, the different hydrogen bonding capacity of the chiral recognition module with two enantiomers mainly contributed to the difference in fluorescence signals. As a result, a broader application of the pyroglutamic acid derivative-coated QDs as a fluorescence-responsive chiral sensing platform for enantiomeric detection would be expected.

Nitrogen-Doped Chiral CuO/CoO Nanofibers: An Enhanced Electrochemiluminescence Sensing Strategy for Detection of 3,4-Dihydroxy-Phenylalanine Enantiomers

“…Therefore, it is of great significance to realize the recognition and detection of l -DOPA. Recently, some methods such as chromatography (high-performance liquid chromatography, gas chromatography, mass spectrometry), , spectroscopy (UV–visible spectroscopy, fluorescence spectroscopy, circular dichromatography), − and electrochemical methods have been used for the recognition of chiral molecules . Among them, electrochemical methods have received much attention of researchers due to their advantages such as high sensitivity, low cost, simple operation, and real-time online detection. , However, for nonelectroactive isomers, it is still difficult to achieve chiral detection by electrochemical methods.…”

Natural deep eutectic solvent assisted synthesis and applications of chiral carbon dots

“…Since the fluorescence lifetime is closely related to the surface states, size, and other properties of CCDs, which in turn affects the fluorescence intensity and fluorescence lifetime, the fluorescent lifetimes of CCDs were separately recorded in the presence and absence of Lys enantiomers to reveal the fluorescence response mechanism. 32 As shown in Fig. 7C, after adding L-Lys, the fluorescence lifetime increases.…”

“…The enantioselectivity (F L /F D , the fluorescence intensity ratio of L-Lys and D-Lys) reaches 5.46, which is superior to previously reported enantiomeric recognition methods. 6,31,32 Moreover, the effects of coex- isting amino acids on the fluorescence response of CCDs to L-Lys were also evaluated. As shown in Fig.…”

Theoretical Investigation on the Complexation Characteristics and Spectral Properties of CdTe QDs With Four Capping Agents

“…The in uence of different organic ligands on the uorescence properties of quantum dots is mainly related to the electron-donating or electron-absorbing properties of coordination groups [28]. When the surface ligands with electrondonating groups are coordinated with the surface of quantum dots, the surface defects of quantum dots can be effectively removed, resulting in uorescence enhancement [29]. The above analysis of charge transfer ability may explain the phenomenon that the uorescence intensity of MPA-capped QDs reported in the experiment is slightly larger than that of GSH-capped QDs [19].…”

“…According to the analysis by Zhu et al [29], MPA, GSH, TG and MES have strong coordination with QDs, which changes the surface state of QDs and causes the change of UV-Vis absorption intensity of CdTe QDs. However, compared with Fig.…”