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A novel ratiometric luminescence "dual-key-and-lock" probe based on "ruthenium(II) complex-coumarin" scaffold was constructed for detection and imaging of formaldehyde in lysosomes of living cells and mouse brain tissues. [Display omitted] • A novel ratiometric luminescence probe Ru-COU for formaldehyde was constructed with a large emission shift (Δλ > 100 nm). • Ru-COU can specifically recognize formaldehyde under acidic microenvironment and localize lysosomes in living cells. • Ru-COU was successfully employed in the ratiometric imaging of formaldehyde in living cells and mouse brain tissues. Ratiometric luminescence probes have attracted widespread attention because of their self-calibration capability. However, some defects, such as small emission shift, severe spectral overlap and poor water solubility, limit their application in the field of biological imaging. In this study, a unique luminescence probe, Ru-COU , has been developed by combining tris(bipyridine)ruthenium(II) complex with coumarin derivative through a formaldehyde-responsive linker. The probe exhibited a large emission shift (Δλ > 100 nm) and good water solubility, achieving ratiometric emission responses at 505 nm and 610 nm toward formaldehyde under acidic conditions. Besides, ratiometric luminescence imaging of formaldehyde in living cells and Alzheimer disease mouse's brain slices demonstrates the potential value of Ru-COU for the diagnosis and treatment of formaldehyde related diseases. [ABSTRACT FROM AUTHOR]

The progression of Alzheimer's disease (AD) is accompanied by the increase of copper ions (Cu2+) concentration and decrease of hydrogen sulfide (H 2 S) level in brain tissue, thus, reversible detection of Cu2+ and H 2 S is regarded as an important strategy for the diagnosis and intervention of AD. However, reliable tools for reversible tracking of Cu2+ and H 2 S and demonstrate their dynamic changes in AD are still lacking. Herein, this work developed a novel NIR Ir(III) complex-based probe, named NIR-Ir-DA, for reversible tracking of Cu2+ and H 2 S in AD cells and brain tissues. The newly prepared NIR luminescence probe exhibited fast response, high sensitivity and selectivity, good biocompatibility, which makes it to be used for reversible sensing of Cu2+ and H 2 S in multiple cycles in living cells and assessing AD progression in vitro and in vivo. Furthermore, using NIR-Ir-DA as a probe, we screened the theaflavin-3,3′-digallate (TF3) from polyphenols with an outstanding ability to reduce neuroinflammation, which would be greatly beneficial for AD therapy. These results indicated that NIR-Ir-DA could be a useful tool for understanding the role of "Cu2+-H 2 S seesaw" phenomenon in amyloid-β deposition, as well as for assessing AD progression and screening anti-AD drugs. [Display omitted] • A NIR Ir(III) complex probe for reversible detection of Cu2+ and H 2 S was developed. • Fast response, high sensitivity and selectivity towards Cu2+ and H 2 S was achieved. • Reversible detection of Cu2+ and H 2 S in multiple cycles in living nerve cells. • Assess AD progression in vitro and in vivo was successfully demonstrated. • Screen anti-AD drugs through visualization of the "Cu2+-H 2 S seesaw" phenomenon.. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is an age-related neurodegenerative disorder that devastatingly affects people's lives. Accumulating evidence indicates that the pathological progression of AD is inseparably connected with hypochlorous acid (HClO). However, further exploring the biological function remains an open challenging due to a lack of effective tools to image HClO in AD brains. To this end, a ruthenium(II) luminescence probe, Ru–HClO , is developed for quantitative detection and visualization of HClO in nerve cells and AD brains. Ru–HClO shows quenched luminescence due to the PET process (excited electron transfer from Ru(II) center to diaminomaleonitrile) and the C N bond isomerization in the excited state. The HClO-triggered specific cleavage reaction with Ru–HClO cleaves the C N bond to form highly luminescent Ru–COOH. Ru–HClO shows rapid response speed, high sensitivity and selectivity, excellent biocompatibility, which makes the probe to be applied to semi-quantitative analysis of HClO in nerve cells and high-throughput screening of anti-AD drugs in the AD cell model. Moreover, using Ru–HClO as a probe, present work further validated that the elevated levels of HClO secretion were accompanied by the AD progressed. These findings may provide valuable results for figuring out the biological roles that HClO played in AD but also for accelerating anti-AD therapeutic discovery. A ruthenium(II) complex-based luminescence probe (Ru–HClO) is developed for the detection of HClO. Ru–HClO features rapid response speed, high sensitivity and selectivity, which makes it to be applied to semi-quantitative analysis of HClO in nerve cells, high-throughput screening of anti-AD drugs in the AD cell model and in-situ imaging of the elevated levels of HClO in AD mice. [Display omitted] • A high performance Ru(II) complex-based luminescence probe for HClO was developed. • Semi-quantitative luminescence analysis of HClO in nerve cells was demonstrated. • High-throughput screening of anti-AD drugs was performed in the AD cell model. • Visualization of the elevated levels of HClO in the brain tissues of AD mice. [ABSTRACT FROM AUTHOR]