Precisely modulating the chromatin tracker via substituent engineering: reporting pathological oxidative stress during mitosis.

An in-depth understanding of cancer-cell mitosis presents unprecedented advantages for solving metastasis and proliferation of tumors, which has aroused great interest in visualizing the behavior via a luminescence tool. We developed a fluorescent molecule CBTZ-yne based on substituent engineering to acquire befitting lipophilicity and electrophilicity for anchoring lipid droplets and the nucleus, in which the low polarity environment and nucleic acids triggered a "weak-strong" fluorescence and "short-long" fluorescence-lifetime response. Meaningfully, CBTZ-yne visualized chromatin condensation, alignment, pull-push, and separation as well as lipid droplet dynamics, for the first time, precisely unveiling the asynchronous cellular mitosis processes affected by photo-generation reactive oxygen species according to the subtle change of fluorescence-lifetime. Our work suggested a new guideline for tracking the issue of the proliferation of malignant tumors in photodynamic therapy.

A multifunctionally reversible detector: Photoacoustic and dual-channel fluorescence sensing for SO2/H2O2.

In this work, the phenothiazine fragment with powerful electron-donating ability was specifically selected to construct a multifunctional detector (noted as T1) in double-organelle with near-infrared region I (NIR-I) absorption. The changes of SO2/H2O2 content in mitochondria and lipid droplets were observed through red/green channels respectively, which was due to the reaction between benzopyrylium fragment of T1 and SO2/H2O2 to achieve red/green fluorescence conversion. Additionally, T1 was endowed with photoacoustic properties deriving from NIR-I absorption to reversibly monitor SO2/H2O2in vivo. This work was significant for more accurately deciphering the physiological and pathological processes in living organisms.

Bifunctional Single-Molecular Fluorescent Probe: Visual Detection of Mitochondrial SO2 and Membrane Potential.

Mitochondrial membrane potential (MMP) and sulfur dioxide (SO2) significantly affect the mitochondrial state. In this work, TC-2 and TC-8 were constructed through side-chain engineering, in which TC-2 bearing the poorer hydrophobicity could localize on mitochondria better. Interestingly, short-wave emission was captured due to the sensitive response of TC-2 to SO2 (LOD = 13.8 nM). Meanwhile, the probe could bind with DNA, presenting enhanced long-wave emission. Encouragingly, TC-2 could migrate from mitochondria to the nucleus when MMP was decreased, accompanied by the increase of fluorescence lifetime (9-fold). Hence, TC-2 could be used for dual-channel monitoring of mitochondrial SO2 and MMP, which showed a completely different pathway from the commercial MMP detectors JC-1/JC-10. The cellular experiments showed that MMP was gradually decreased due to reactive oxygen species-triggered oxidative stress, and the SO2 level was up-regulated simultaneously. Overall, this work proposed a new method to investigate and diagnose the mitochondrial-related diseases.

Unveiling upsurge of photogenerated ROS: control of intersystem crossing through tuning aggregation patterns.

Photo-induced reactive oxygen species (ROS) generation by organic photosensitizers (PSs), which show potential in significant fields such as photodynamic therapy (PDT), are highly dependent on the formation of the excited triplet state through intersystem crossing (ISC). The current research on ISC of organic PSs generally focuses on molecular structure optimization. In this manuscript, the influence of aggregation patterns on ISC was investigated by constructing homologous monomers (S-TPA-PI and L-TPA-PI) and their homologous dimers (S-2TPA-2PI and L-2TPA-2PI). In contrast to J-aggregated S-TPA-PI, S-2TPA-2PI-aggregate forming "end-to-end" stacking through π-π interaction could generate ROS more efficiently, due to a prolonged exciton lifetime and enhanced ISC rate constant (k ISC), which were revealed by femtosecond transient absorption spectroscopy and theoretical calculations. This finding was further validated by the regulation of aggregation patterns induced by host-guest interaction. Moreover, S-2TPA-2PI could target mitochondria and achieve rapid mitophagy to cause more significant cancer cell suppression. Overall, the delicate supramolecular dimerization tactics not only revealed the structure-property relationship of organic PSs but also shed light on the development of a universal strategy in future PDT and photocatalysis fields.