Chiral Surface Engineering–Boosted Catalytic Activity of CuO Nanomaterials on Luminol–H2O2 Chemiluminescence for Facile Discrimination of Alanine Enantiomers

Abstract

Facile chiral discrimination without relying on chromatographic techniques is extremely intriguing and useful. Herein, we report a chemiluminescence (CL) strategy for discriminating alanine (Ala) enantiomers using chiral CuO nanomaterials as selector. L-CuO and D-CuO were synthesized via a wet-chemical method with cysteine as chiral inducers. The catalytic activity of chiral CuO on luminol–H2O2 CL reaction was approximately 20 times higher than that of achiral CuO, and a positive correlation was observed between the catalytic activity and the chiral asymmetry factor of the chiral CuO. Notably, D-CuO selectively adsorbed l-Ala, and L-CuO selectively adsorbed d-Ala. More interestingly, the catalytic activity of chiral CuO was significantly boosted after adsorbing Ala enantiomer. The chiral CuO–catalyzed CL system achieved rapid discrimination of Ala enantiomers within 6 min. The linear range of chiral CuO–catalyzed CL for detecting d-Ala or l-Ala was 10–100 nM, and the limit of detection (LOD) was estimated to be 3.3 nM for l-Ala or 3.8 nM for d-Ala. The CL intensity varied linearly with enantiomeric excess (ee) across the full range from −100% to 100%. Mechanistic investigations reveal that chiral CuO nanomaterials induce spin polarization of interfacial electron transfer through the chiral-induced spin selectivity (CISS) effect, thereby significantly enhancing its capacity for H2O2 activation and subsequent CL emission. This work not only provides a facile strategy for the discrimination of Ala enantiomers but also elucidates the critical role of chiral surface engineering in modulating the catalytic activity of nanomaterials via the CISS effect.