Eu3+doped bismuth metal-organic frameworks with ultrahigh fluorescence quantum yield and act as ratiometric turn-on sensor for histidine detection

The abnormal levels of histidine in the human body have been regarded as indicator of many neurological diseases. However, it is still a significant challenge to detect histidine with high selectivity and sensitivity in complex biological matrix. Herein, a luminescent material has been synthesized via Eu3+ doped bismuth metalorganic frameworks (Eu/Bi-MOF). After the introduction of Eu3+ ions in the lattice nodes of Bi-MOF, the Eu/BiMOF generates a strong red luminescence induced by antenna effect, with an exceptionally high quantum yield (59.3 %). Interestingly, a luminescence-silent system was successfully constructed through Eu/Bi-MOF dispersed in water due to the inhibition of energy transfer from the ligand to Eu3+ ions. Upon addition of histidine to Eu/BiMOF aqueous solution, the luminescence-silent system was awakened owing to recovering of energy transfer from the ligand to Eu3+ ions in Eu/Bi-MOF, while the fluorescent emission derived from the ligand decreases. Therefore, Eu/Bi-MOF could detect histidine as a ratiometric fluorescence sensor with ?turn?on? response. More importantly, the proposed sensor exhibited fast response, high selectivity and low detection limit (0.18 ?M) toward histidine. Based on these findings, the luminescent film was also prepared and achieved rapid response to histidine. To the best of our knowledge, this is the first example of MOFs as ratiometric luminescent turn-on sensor for histidine detection.

Automated summary

A luminescent material Eu/Bi-MOF was synthesized for selective and sensitive detection of histidine, showing a ratiometric fluorescence response with fast, selective, and low detection limit. The system demonstrated a unique luminescence-silent state in water and could be awakened by histidine, making it a promising turn-on sensor for histidine detection.