Smartphone Sensing Platform Based on CdTe-Al3+ Quantum Dots Fluorescent Nanosensor for Visual Detection of Norfloxacin in Real Samples

A rapid and sensitive ratiometric fluorescence nanosensor for the detection of norfloxacin was obtained, where the yellow-emitting CdTe quantum dots (QDs) were as an internal reference and aluminium ion (Al³⁺) chelated on the QDs surface as the sensing unit. The nanosensor was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. As the concentration of norfloxacin increased, the sensor exhibited a continuous fluorescence color transition from yellow to blue. The CdTe-Al³⁺ QDs sensor demonstrated a low limit of detection of 6.6 nM. The ratiometric fluorescence sensor was also integrated with a smartphone color recognizer for visual and quantitative detection of norfloxacin with a limit of detection of 1.57 µM. This sensing platform exhibits excellent sensitivity, selectivity, and anti-interference performance, and it has great potential for on-site and quantitative analysis.