Rapid, sensitive, and selective quantitative detection of pyridine dicarboxylic acid (DPA) as biomarker of anthrax spores is in great demand since anthrax spores are highly lethal to human beings and animals and also potential biological warfare agents. Herein, we prepared a ratiometric fluorescence lanthanide functionalized micelle nanoprobe by "one-pot" self-assembly, with an amphiphilic ligand containing β-diketone derivative which can "immobilize" terbium ions through the coordination interaction and a fluorophore as fluorescence reference (FR). The detection strategy was ascribed to Tb ions in lanthanide functionalized micelle, which can be sensitized to emit the intrinsic luminescence upon addition of DPA due to the presence of energy transfer when DPA chromophore coordinated with Tb ion. The fluorescence intensity of FR remained essentially constant, leading to ratiometric fluorescence response toward DPA. The results demonstrate that the terbium functionalized micelle was able to sensitively detect DPA with a linear relation in the range of 0 μM to 7.0 μM in aqueous solution, which also showed remarkable selectivity to DPA over other aromatic ligands. Our work paves a new way in the design of ratiometric fluorescence lanthanide functionalized micelle nanoprobes which can be promising for selective and sensitive detection of bacterial spores or biomolecules.

The postsynthetic-modified nanoscale metal-organic framework (NMOF) probes selected as potential drug delivery platforms and photodynamic therapy agents to fulfill the effective and safe treatment of neoplastic diseases have attracted increasing attention recently. Herein, a Eu(III)-based NMOF probe elaborately postsynthetically modified with a β-diketonate two-photon-absorbing (TPA) ligand is rationally designed and further functionalized by assembling the photosensitizer molecule (methylene blue, MB) in the pores and a cyclic peptide targeting motif on the surface of the NMOF, which could achieve highly efficient near-infrared (NIR)-triggered and -targeted photodynamic therapy (PDT). On the basis of the luminescence resonance energy transfer process between the NMOF donor and the photosensitizer MB acceptor, the probe can achieve a high tissue-penetrable TPA-PDT effect. Thus, the NMOFs in this study play the role of not only the nanocontainer for the photosensitizer but also the energy-transfer donor. Studies in vitro show enhanced cellular uptake and satisfactory PDT effectiveness toward cancer cells compared to the free photosensitizer MB. It is highly expected that this study contributes to the development of smart luminescent diagnostic and therapeutic probes.

Real-time temperature feedback in tissue based on photothermal therapy is an urgent problem to be solved in cancer treatment. Herein, a smart all-in-one nanoprobe THA@Eu-NMOF@Fe/TA was designed and assembled by postsynthetical functionalization of an Eu­(III)-based nanoscale metal–organic framework (Eu-NMOF) with a two-photon-absorbing β-diketonate ligand 4,4,4-trifluoro-1-(9-hexylcarbazol-3-yl)-1,3-butanedione (HTHA) and Fe­(III)/tannic acid assembly (Fe/TA). Such a functionalized material can simultaneously achieve the temperature-sensing and optical heating under a single beam of near-infrared (NIR) light. Under 808 nm laser excitation, real-time feedback of temperature by monitoring thermoresponsive fluorescence emission ratio (I 616/I 590) and fluorescence lifetime of Eu­(III) ions were realized. Meantime, Fe/TA served as the photothermal agent and antibacterial agent to implement photothermal therapy (PTT) and antibacteria simultaneously. The functions of the nanoprobe were proved with ex vivo experiments, and the antibacterial activity against Gram-positive and Gram-negative bacteria of the probe was also elaborately evaluated. Our work paves a new avenue for engineering a new cancer treatment probe which can achieve real-time temperature sensing feedback during PTT and antibacterial process.