Detection of the UV-vis silent biomarker trimethylamine-N-oxide via outer-sphere interactions in a lanthanide metal-organic framework

Trimethylamine- N -oxide (TMAO) is a biomarker of the cardiovascular disease that is one of the leading causes of worldwide death. Facile detection of TMAO can significantly improve the survival rate of this disease by allowing early prevention. However, the UV-vis silent nature of TMAO makes it intricated to be detected by conventional sensing materials or analytical instruments. Here we show a bilanthanide metal-organic framework functionalized by borono group for the recognition of TMAO. Superior sensitivity, selectivity and anti-interference ability were achieved by the inverse emission intensity changes of the two lanthanide centers. The limit of detection is 15.6 μM, covering the clinical urinary concentration range of TMAO. A smartphone application was developed based on the change in R - G - B chromaticity. The sensing mechanism via a well-matched outer-sphere interaction governing the sensing function was studied in detail, providing fundamentals in molecular level for the design of advanced sensing materials for UV-Vis silent molecules. Detection of trimethylamine N -oxide (TMAO) can allow for early intervention of cardiovascular disease, but is challenging to achieve using conventional materials and instruments owing to it being spectroscopically silent in the UV-visible region. Here, a series of bilanthanide metalorganic frameworks functionalised with a borono group are shown to detect TMAO with high sensitivity and selectivity by exploiting the inverse emission intensity changes of the two lanthanide centres.