Infinite Coordination Polymer Nanoparticles Used for Fluorescence Turn-On Sensing of Ascorbic Acid

In this work, a “turn-on” fluorescence assay with sequential recognition based on infinite coordination polymer (ICP) nanoparticles is developed for the highly selective analysis of ascorbic acid (AA). The ICP nanoparticles are easily prepared by self-assembly of reactive Ce4+, fluorescent Tb3+, and the bridging ligand adenosine monophosphate (AMP), which are denoted as AMP-Ce(IV)/Tb ICP nanoparticles. The weak fluorescence of the AMP-Ce(IV)/Tb ICP nanoparticles can be selectively switched on by AA via two sequential recognitions: (1) Ce4+ in the AMP-Ce(IV)/Tb ICPs is regarded as the first recognition component to react with AA through a redox reaction, and (2) Tb3+ is the second recognition site that will be sensitized by the oxidation product of AA, thus emitting strong fluorescence. The principle of dual recognition endows the proposed assay with a high specificity, which can well eliminate the interference caused by similar reductive biomolecules in the detection of AA. The as-proposed turn-on fluorescence assay possesses a wide linear range of 0 to 100 μM and a low detection limit of 190 nM for AA. Furthermore, the levels of AA in vitamin C tablets and serum samples have been precisely determined. The present strategy provides an efficient way to highly recognize AA with merits of direct sensing, simple operation, superior selectivity, and excellent sensitivity, which also creates more possibilities for the application of ICP nanoparticles.