Rational design of core-shell Ln-MOF hierarchitecture for ratiometric fluorescent sensing and bioimaging for phosphate or ATP

Mixed hierarchical lanthanide metal-organic framework (Ln-MOF) with core-shell structure has been acquired via a solution-mediated epitaxial growth method, retaining the spatially segregated structure of network and domain fluorescence property. The excellent heterostructured characteristics of Ln-MOFs enable the effective electron modulation, multiple energy transfer and thereby remarkably increase recognizing and sensing capacity in phosphate (Ps) or adenosine triphosphate (ATP). Ln3+ centers coupled with Ps or ATP could trigger a decrease in fluorescence of Ln3+, and further interrupt original fluorescence intensity ratio of Tb3+/Eu3+ (I545/I616) to shape the ratiometric fluorescent register. The optimized Tb/Eu-MOF with Tb/Eu ratio of 1:1 presented good linearity responsive to Ps and ATP with lower detection limit of 84.1 nM and 121.4 nM, respectively. Meanwhile, the interference and toxicity experiments have confirmed its high selectivity and high biocompatibility. Thus, the probe could be applied to detect Ps in real environmental water and biologically imaging ATP in Hela cells. This has provided a new strategy to construct Ln-system heterojunction with multiplexed luminescence selectivity and sensitivity in substance detection.