A colorimetric sensor for chiral recognition and detection of mandelic acid based on the peroxidase-like activity of chiral copper oxide

Chiral copper oxide flowers (S-CuO) with peroxidase-like activity were synthesized by an eco-friendly one-pot method without introducing toxic materials and organic solvents. The chirality of S-CuO arises from the helical arrangement of subnanopetals in a specific pattern rather than any surface modification. S-CuO was found to have a different affinity toward S-mandelic acid (MA) and R-MA, resulting in various impacts on improving the peroxidase-like activity of S-CuO. The mechanism was demonstrated experimentally. Moreover, these findings were used to build a colorimetric sensor for chiral recognition and determination of MA. The utility of the sensor was proved through the detection of MA in acid skincare essences. Additionally, an STM32-based portable device was constructed employing 3D printing technology to achieve on-site determination of MA. Notably, the sensor expands the application of chiral ligand-free materials with chirality in chiral discrimination fields.