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A novel AIEE (aggregation-induced emission enhancement)-active conjugated polymer incorporating thiazole and tetraphenylethene (TPE) was designed and synthesized via Pd-catalyzed Sonogashira coupling reaction. The polymer shows typical AIEE phenomena, and emits green fluorescence in the mixed solvent of tetrahydrofuran (THF) and water, reaching a maximum fluorescence intensity when the fraction of water is 90%. In the aqueous phase (fw = 90%), the polymer sensor exhibits “turn-off” fluorescence quenching responses towards Hg2+ and Ag+ over other cations, such as Li+, K+, Ca2+, Mg2+, Ba2+, Zn2+, Cd2+, Co2+, Ni2+, Pb2+, Cu2+, Al3+ and Fe3+. The obvious fluorescence change (bright yellow to weak emission) can be clearly observed by the naked eyes.

Monitoring trace hypochlorite at the organelle level is important for the early diagnosis of diseases caused by abnormal hypochlorite levels. Traditional organelle localization probes require the introduction of specific target groups, which increases the requirements for the molecular structure and complicates the synthesis. Developing non-targeted fluorescent probe for organelle level detection is of great significance. In this study, a novel coumarin-based aggregation-induced emission probe (AIE-CDs) was designed and prepared for OCl− determination with fast response (within 5s) and high sensitivity (detection limit is 0.32 μM). In aqueous solution, probe AIE-CDs emerged as spherical nanostructures which can enter the cell easily and located in mitochondria. In addition, after evaluating the optical properties and toxicity of the probe AIE-CDs, the monitoring and imaging application of hypochlorite in living cells and zebrafish probes are successfully realized, suggesting the potential of probe AIE-CDs as a tool for biological applications.

The near-infrared (NIR) fluorescent probe for rapid, highly sensitive and selective detection of cysteine (Cys) has great significance in both biological and environment sciences. In this work, a novel and specific dicyanoisophorone-based NIR probe for Cys was developed. This probe features remarkably large Stokes shift, with turn-on fluorescence property for highly sensitive and selective detection of Cys over other amino acids including the similar structured homocysteine (Hcy) and glutathione (GSH). The probe based on the conjugate addition-cyclization reaction, and has low detection limit of Cys. Furthermore, this probe shows great potential for Cys detection, which was successfully applied to bioimage Cys in living cells with low cytotoxicity.

Herein, we report a novel fluorescent probe based on coumarin to detect cysteine (Cys). The probe can react rapidly and selectively with Cys but not with the other amino acids. When the Cys was added to the solution of the probe, we could observe obvious color change from pale green to bright green. The detection limit of this probe for Cys was found to be 0.06 μM. Additionally, bioimaging of intracellular Cys by this probe was successfully applied in living cells, which indicating that this probe holds great potential for biological applications.

In this study, a novel carbon dots (CDs) was prepared by using citric acid and 1,2-diaminobenzene as raw materials via hydrothermal reaction. The obtained CDs showed a fluorescence turn-off response to divalent copper ion (Cu2+) with high selectively and sensitively which can be observed by the naked eye. The distribution of CDs is spherical with an average diameter about 2.89 nm, as observed by scanning electron microscopy (TEM) which could easily pass through the cell membrane and can be successfully located in mitochondria. In addition, the CDs was successfully applied to imaging Cu2+ in HeLa cells and zebrafish owing to its excellent optical performance and low toxicity.

As an important reactive carbonyl compound, formaldehyde (FA) existing in various parts of the organism and plays an important role in cognitive ability and memory formation. However, abnormal concentrations of FA could cause many diseases. Herein, a novel 1,8-naphthalimide derivative fluorescent probe (NID) for detecting FA was rationally designed and synthesized. Probe NID showed a rapid response (within 8 s) towards FA with visual detection. More importantly, NID can be used to image FA in MCF-7 cells, which demonstrated its suitability for practical applications of biological systems with low cytotoxicity.