Monitoring Hg2+ and MeHg+ poisoning in living body with an activatable near-infrared II fluorescence probe.

Noninvasively imaging mercury poisoning in living organisms is critical to understanding its toxicity and treatments. Especially, simultaneous fluorescence imaging of Hg2+ and MeHg+in vivo is helpful to disclose the mysteries of mercury poisoning. The key limitation for mercury imaging in vivo is the low imaging signal-to-background ratio (SBR) and limited imaging depth, which may result in unreliable detection results. Here, we designed and prepared a near-infrared II (NIR II) emissive probe, NIR-Rh-MS, leveraging the "spirolactam ring-open" tactic of xanthene dyes for in situ visualization of mercury toxicity in mice. The probe produces a marked fluorescence signal at 1015 nm and displays good linear responses to Hg2+ and MeHg+ with excellent sensitivity, respectively. The penetration experiments elucidate that the activated NIR-II fluorescence signal of the probe penetrates to a depth of up to 7 mm in simulated tissues. Impressively, the probe can monitor the toxicity of Hg2+ in mouse livers and the accumulation of MeHg+ in mouse brains via intravital NIR-II imaging for the first time. Thus, we believe that detecting Hg2+ and MeHg+ in different organs with a single NIR-II fluorescence probe in mice would assuredly advance the toxicologic study of mercury poisoning in vivo.

An activatable fluorescent probe enables in vivo evaluation of peroxynitrite levels in rheumatoid arthritis.

An activatable probe able to detect RONS level underlying the development of rheumatoid arthritis (RA) would be far-reaching for the diagnosis and drug efficacy assessment of RA. Despite more and more evidence suggests that ONOO- is an important signaling molecule participating in the RA disease, only rare fluorescent probes can detect ONOO- in this disease with satisfying performance. To this end, we designed and synthesized a novel activatable AIE fluorescent probe (DPPO-PN) for the detection of ONOO- levels in RA. The probe linearly responds to 0-10 µM ONOO- with a significant far-red fluorescence enhancement at 632 nm in 30 s (F/F0 = 161-fold, LOD = 10 nM) upon the excitation of 490 nm, elucidating excellent sensing abilities for ONOO- in cuvettes. Moreover, the fluctuations of intracellular ONOO- levels caused by adscititious adding or stimulant provoking could be real-time captured and visualized with this probe by confocal imaging. Further, the intravital imaging of ONOO- in LPS-induced and CFA-induced RA mouse models also can be achieved with the aid of the probe, substantiating the burst of ONOO- in the RA process. Therefore, this work not only offers an auxiliary tool for the diagnosis of RA but also would benefit our understanding of the ONOO-'s roles in RA.

An Activity-Based Fluorescent Probe for Imaging Fluctuations of Peroxynitrite (ONOO- ) in the Alzheimer's Disease Brain.

Peroxynitrite (ONOO- ) plays a critical role in Alzheimer's disease (AD). To reveal the ONOO- influx in AD brains, an activatable activity-based fluorescence probe Rd-DPA3 was designed by a structure-modulated strategy. Taking advantage of ONOO- -initiated two-step cascade reactions of a novel chemical trigger, Rd-DPA3 specifically responds to ONOO- in 0.3 mM of other reactive oxygen species (ROS) and varied proteins, and gives an intensive fluorescence enhancement (F/F0 =50). Moreover, with its mitochondria-targeting ability, Rd-DPA3 can be used to efficiently monitor the alternations of intracellular ONOO- levels in cerebral cells during oxidative stress. Significantly, due to NIR emission and good blood-brain barrier (BBB) crossing ability, Rd-DPA3 is suitable for in vivo imaging of cerebral ONOO- influx and illustrating an age-dependent accumulation of ONOO- in AD mice brains.