Sensitive Ratiometric Luminescent FRET Probe for the Detection of Riboflavin

The synthesis of two isomorphic 2D MOFs {[Ln(L)(NO3)(DMF)2] DMF} (Ln = Ho and Er, H2L = 2,5-bis(1,2,4-triazol-1-yl) terephthalic acid) by the solvothermal method enables ratio luminescent sensing of riboflavin (RF), based on the Förster resonance energy transfer (FRET) effect. As sensors for RF, both Ho-MOF and Er-MOF have splendid anti-interference effects, a large Stokes shift with 103 nm, excellent visualization effect, and a low detection limit, as low as 1.72 and 3.90 nM. Ho-MOF, with a better anti-interference capability and a relatively lower detection limit, is selected for further investigations. It possesses the advantages of excellent pH stability in the range of 4–12, rapid response time within 50 s, and even achieving five cycles. Ho-MOF also demonstrates exceptional practical detection potential when tested in real-life environments and samples, with urine and serum exhibiting detection limits of 5.26 and 27.27 nM, respectively, and a recovery range of 96–104% in VB2 tablets. Mechanism research discovers that FRET serves as the primary sensing mechanism with a calculated Forster distance (R0) of 3.7 nm, which is consistent with the required distance (1–10 nm). This study successfully achieves rate-luminescent sensing and monitoring of RF in diverse environments.