Smartphone-integrated portable platform based on a multicolor fluorescent paper sensor for visual quantification of azithromycin

Abstract

The emergence of “superbugs” caused by the excessive use of antibiotics poses a major threat to human health and safety. Developing sensitive and efficient analytical methods for antibiotic monitoring is therefore essential for addressing issues associated with antibiotic overuse. However, existing detection techniques often rely on expensive instrumentation and trained personnel. In this work, we present a rapid, instrument-free, on-site method for detecting azithromycin (AZM) residues, enabled by a multicolor fluorescence response that allows direct visual quantification. Specifically, AZM effectively and selectively quenches the fluorescence of Y-CDs, and its addition induces a distinct fluorescence color change, enabling highly sensitive detection with a detection limit of 0.86 μM. To support field applications, we further integrated a smartphone-based analytical platform with a paper-based fluorescent strip, achieving visual detection with excellent sensitivity and a detection limit of 1.32 μM. This strategy provides a convenient, low-cost, and user-friendly approach for AZM monitoring. Overall, the results demonstrate the strong potential of Y-CDs as effective fluorescent probes for environmental analysis and offer a practical pathway toward simple and visual antibiotic detection.