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A chemosensor 3-[(2-hydroxybenzylidene)-amino]-1H-pyridin-2-one (HL) for multi-ions was synthesized and characterized by single-crystal X-ray diffraction. HL is a turn-on fluorescence chemosensor for Al 3+ , F − , and CN − ions in DMSO. F − and CN − anions could be further distinguished by the ratiometric absorption spectrometry method. Job plot and 1 H NMR data showed that the binding stoichiometries of HL with Al 3+ , F − , or CN − all were 1:1. Further observations of 1 H NMR titration and ESI-MS showed that the possible fluorescent species of Al 3+ with HL was [AlL(OH)(DMSO) 2 ] + in DMSO. The spectroscopic observations of the Al(III) complex showed that the two oxygen atoms and one imine nitrogen atom of HL were coordinated to the Al(III) ion. While the crystal structure of the Ni(II)-L complex confirmed the tridentate coordination mode of HL in the complexes. The experimental results revealed that HL and F − ion formed hydrogen bond in DMSO, while CN − attacked the carbon atom at –C N of HL to undergo a nucleophilic addition. The theoretical calculations confirmed that HL showed very weak fluorescence because of the excited-state intramolecular proton transfer (ESIPT). The turn-on sensing of HL to Al 3+ , F − , and CN − ions arose from the inhibition of ESIPT. MTT tests showed that HL was low toxic to cells. Also, HL could probe intracellular Al 3+ and F − ions by bioimaging. [ABSTRACT FROM AUTHOR]

• A fluorescence "turn-on" method was developed for MUC1 detection and targeted cancer imaging. • The specific interaction of MUC1 with its aptamer led to the fluorescence swithching. • Successful detecion of MUC1 in aqueous media was achieved with a detection limit of 0.8 nM. • The method allowed to map the spatial expression of MUC1 in cancer cells with excellent sensitivity. Mucin 1 (MUC1) is an important biomarker that has been shown to participate in the metastasis and invasion of various types of cancers. Simple yet sensitive methods for the detection of MUC1 in liquid and in situ imaging of MUC1 at cellular level are crucial for early diagnosis of cancers as well as monitoring their progression. Herein, a polydiacetylene (PDA) liposome-based sensing system functionalized with Cy3-labeled MUC1 binding aptamer (Cy3-Apt) was developed as a fluorescence "turn-on" nanosensor for the detection of MUC1. In the sensing system, the fluorescence of Cy3-Apt could be directly quenched due to the energy transfer between the fluorogen and PDA conjugated backbone. In the presence of MUC1, the recognition of MUC1 with its aptamer induces the structure switching of both PDA liposomes and the aptamer, recovering the red fluorescence. Sensitive and selective analysis of MUC1 in aqueous media could be achieved with a limit of detection around 0.8 nM. The feasibility of the nanosensor was further demonstrated by mapping the spatial expression of MUC1 in cancer cells with excellent sensitivity. [ABSTRACT FROM AUTHOR]