An instrument-free photoluminescent sensor array based on “turn-off” bimetallic lanthanide metal–organic frameworks for antibiotic determination

The widespread use of antibiotics results in harmful residues, posing a serious threat to ecosystems and human health. Given synergetic or antagonistic toxicological features often exist among different antibiotics, it is vital to develop methods to synchronously determine these contaminants. Herein, we develop a hand-held photoluminescent sensor array based on "turn-off" bimetallic lanthanide metal–organic frameworks (MOFs) to realize the identification and quantification of six common antibiotics. Three Tb/Eu-MOFs with different bimetallic proportions were synthesized and employed to provide signals toward multiple antibiotics based on their differential contributions to the photoluminescence quenching of these probes. By designing a 3D-printed smartphone-equipped signal capturing platform, tiny luminescence variations induced by different antibiotics were recorded and processed for the classification and identification of these targets via pattern recognition analysis. Compared to conventional sensor arrays requiring cumbersome signal reading instruments and complex sensing units, our platform really enables instrument-free in-field detection of multiple targets with only a basic material. The platform could identify not only single antibiotics in a wide level scope but also various combinations of two, three or even four antibiotics with good discrimination capacity. Differentiation of multiple antibiotics in river water, milk, and urine matrices was also demonstrated. Furthermore, over 90% accuracy was gained for unknown samples in double-blind tests. Our work offers a portable, low-cost, and high-performance tool to determine multiple antibiotics simultaneously, which will stimulate future exploration of hand-held sensor arrays with simple sensing elements for on-site analysis and point-of-care diagnosis.