Multicolor Achiral Carbon Dot-Based Fluorescent Sensors for Chiral Recognition and Visual Detection of Basic Amino Acid Enantiomers

Abstract

Chiral recognition is fundamentally pivotal in biomedicine, yet simultaneous discrimination of enantiomers of multiple structurally analogous molecules remains a key challenge. Herein, multicolor achiral carbon dots (CDs) (B-CDs, G-CDs, and Y-CDs) were successfully synthesized and employed for chiral recognition and quantitative detection of basic amino acid (Lys, His, and Arg) enantiomers. Systematic characterizations verified that the as-prepared CDs possessed abundant surface functional groups, thereby endowing them with unique optical properties. B-CDs, G-CDs, and Y-CDs exhibited selective fluorescence enhancement, concentration-dependent emission blue shift, and ratiometric fluorescence responses toward l-Lys with detection limits of 0.37 μM, 64.3 nM, and 0.57 μM, respectively. By integrating RGB/Lab color models with smartphone-assisted imaging, a convenient colorimetric method was established for visual recognition and rapid quantitative detection of l-lys. Furthermore, a three-channel fluorescent sensor array based on the three CDs was constructed, realizing 100% accurate discrimination of three basic amino acids and their six enantiomers. Chiral recognition mechanism studies revealed that differential binding affinities and stereochemical matching between CDs and l-Lys accounted for the chiral selectivity. Finally, the proposed sensing system is successfully validated in complex biological matrices with satisfactory recoveries (94.73% to 112.90%) and strong anti-interference capacity. Therefore, this achiral CD-based fluorescent platform enables efficient chiral recognition and quantification of basic amino acid enantiomers, offering significant potential for advanced chiral analysis.