Exploration of novel dual-emission NL-CDs/Cu–Cy–I ratio fluorescent probe for the sensitive detection of amoxicillin

A dual-emission ratio fluorescence probe (NL-CDs/Cu–Cy–I) was fabricated via an electrostatic self-assembly method. NL-CDs served as the reference signal (Em = 433 nm), remaining insensitive to amoxicillin, while Cu–Cy–I acted as the response signal (Em = 601 nm), exhibiting varying degrees of fluorescence quenching with amoxicillin concentration changes. This established a fluorescence sensing platform leveraging internal filtration and static quenching synergistically, ensuring high specificity. Compared to the single-signal Cu–Cy–I fluorescence probe, the detection range expanded from 0.5–15 μmol L−1 to 0.2–30 μmol L−1, with the detection limit decreasing from 0.12 μmol L−1 to 0.073 μmol L−1, demonstrating significant enhancements in both range and limit. The developed ratiometric fluorescent probe was effectively employed for amoxicillin monitoring in environmental water samples, urine samples, and amoxicillin capsules, achieving recovery rates of 96.5–102.9%. This underscores the accuracy and practical applicability of the NL-CDs/Cu–Cy–I ratio fluorescence probe-based fluorescence analysis method for amoxicillin detection.