Portable bifunctional kits for polychromatic visual assay of tetracycline and copper(II)

Contamination from tetracycline (TC) and copper ions (Cu 2+ ) poses a significant threat to aquatic ecosystems and human health. Developing an efficient platform to achieve ultrasensitive and on-site synchronous detection of TC and Cu 2+ is urgently needed. Herein, a dual-channel fluorescent nanoprobe (Eu-CDs@Eu-MOF) was elaborately designed based on europium ions (Eu 3+ ) decorated green-fluorescent carbon dots (CDs) cooperating with red-fluorescent Eu-MOF. This bifunctional nanoprobe exhibited specific response to Cu 2+ in the 275 nm channel, and special recognition ability for TC in the 385 nm channel due to the “antenna effect”. Ultrasensitive cross-interference-free detection of TC and Cu 2+ were realized with the LOD of 3.70 and 6.13 nM, respectively. Satisfactory results were achieved in various real samples detection. Moreover, smartphone-assisted portable paper- and hydrogel kit-based sensors were constructed for fast and on-site visual assay of TC and Cu 2+ . This study provided an effective method for ultrasensitive and simultaneous detection of TC and Cu 2+ , and offered some references for the construction of portable and multifunctional nanosensors for facile use in daily life.