Detection of antibiotics at in situ temperature by Rhodamine B encapsulated in terbium-based metal-organic frameworks

Rhodamine B(RhB) was encapsulated in Tb(btc) (btc = 1,2,4-benzene tricarboxylic acid) frameworks by “one-pot” method, and the complex RhB@Tb(btc) with host-guest dual fluorescence emissions was synthesized. Compared with the stability of Tb3+ emission, the characteristic emission of RhB at 620 nm showed a more sensitive response to ambient temperature. By integrating the different temperature dependence of Tb3+ and RhB emissions, the temperature sensing of RhB@Tb(btc) was determined with relative sensitivity ranging from 0.43 to 0.59% K−1 (temperature range 298–353 K). Among several common antibiotics, RhB@Tb(btc) showed fluorescence quenching response to metronidazole (MDZ) and color transition to levofloxacin (LOFX) respectively with stable reusability. The combination of photoinduced electron transfer and internal filtration effect was confirmed as the contributor to MDZ induced fluorescence quenching. Furthermore, hydrogels and milk, which were added antibiotics on purpose for simulating unsafe foods, were detected at in situ temperature by RhB@Tb(btc) test paper, which achieved highly sensitive and highly selective detection to MDZ and LOFX with limit of detection reaching 10−6 M.