A portable instrument-assisted and dual-model sensor array with distinguished color change for the point-of-care identification of tetracycline antibiotics

Background

The development of a facile sensor array for the identification of multiple tetracyclines (TCs) is highly promising, considering their similar chemical structures and the associated challenges to public health and food safety. Herein, we explored a dual-model sensor array (ratiometric fluorescence and colorimetric method) for detection and identification of multiple TCs.

Results

Three types of ratiometric fluorescent probes based on blue carbon dots (Mg,N-CDs): Mg,N-CDs/MOF-5, Mg,N-CDs/Eu-MOFs, and Mg,N-CDs/Eu-MOFs@Rh-6G, were synthesized as sensing elements. Based on a multi-channel strategy involving the changed signals of the sensing elements, all three probes were able to generate multi-signal fluorescence responses. Under a 365 nm UV lamp, these fluorescence responses were accompanied by obvious color changes (blue to green, blue to red, yellow to red), providing an efficient strategy for on-site quantitative analysis of TCs, including tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), metacycline (MTC), doxycycline (DOX), and doxycycline hyclate (DTC). A handheld portable 3D-printed platform was also constructed to further enhance the convenience and practicality of detection. This platform utilized the unique ratiometric fluorescence and visual responses of the probes to generate different “fingerprints” for each TC. Effective detection and identification of TCs and their mixtures were achieved by linear discriminant analysis (LDA) and hierarchical cluster analysis (HCA).

Significance

The sensitivity of the sensor array based on color change of ratiometric fluorescence was much higher than that of the conventional colorimetric sensor array. Thus, this method not only enriches the techniques for detection of TCs, but also introduces a low-cost, high-performance, dual-model detection tool for on-site analysis.