Research progress on STORM ultra-high resolution imaging of photocontrolled fluorescent dyes in JACS

Enzymes are indispensable biological macromolecules in the human body that regulate the normal function of cells by catalyzing chemical reactions of substrates. However, abnormal catalytic activity of enzymes is closely related to the occurrence and development of major human diseases (such as cancer, cellular senescence, etc.).
In 2020, the Feringa Nobel Joint Research Center for Scientists of East China University of Science and Technology, in collaboration with the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, the National Center for Protein, the University of Texas at Austin and the University of Bath in the United Kingdom, made important progress in ultra-high-resolution imaging of enzyme-activated light-controlled fluorescent dyes, and the research results were named "Photochromic Fluorescent Probe Strategy for the Super-resolution Imaging of." Biologically Important Biomarkers" was published in the Journal of the American Chemical Society (JACS).

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Research Introduction (Excerpt)

In the previous study, the research team realized targeted photocontrolled fluorescence imaging of hepatoma cells by constructing a spiropyran-naphthimide photocontrolled fluorescence dye system (Nat.Commun. 2017, 8, 987), and through the introduction of human serum albumin (HSA), a light-controlled probe/protein complex was constructed, which improved the double fluorescence emission performance of the probe and realized the targeted double fluorescence cycle imaging of hepatoma cells (J. Am. Chem. Soc. 2018, 140, 8671−8674）。

On the basis of the above, the researchers introduced a β-galactose group that can be hydrolyzed by β-galactosidase (β-Gal) into the structure of spiropyran, which simultaneously inhibited the photochromic properties and fluorescence properties of spiropyran, and further combined the probe with HSA to form a protein complex with enhanced optical properties. After the complex probe is internalized by cells, it is hydrolyzed by β-galactose residues catalyzed by β-Gal, thereby synchronously activating the photochromic and fluorescence properties of spiropyran molecules.
Based on the probe's unique light-controlled "fluorescence scintillation" performance, the researchers used ultra-high-resolution imaging technology (STORM - random optical reconstruction microscope) to increase the diffraction limit of the probe (resolution 74-80 nm), and realized the activity distribution of β-Gal in ovarian cancer cells and senescent cells at the subcellular level.

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Results of the study (partial)

Experiments have shown that the β-Gal of ovarian cancer cells tends to be evenly distributed in the cytoplasm and lysosomal distribution in senescent cells. The parallel application of membrane detection algorithm analyzes the data information of enzyme distribution in two different cells, constructs polygonal model maps in two different pathological states, and provides a new chemical tool for subcellular-level accurate imaging of enzyme-catalyzed dynamic modification of biological macromolecules.

The above research work was mainly completed by Dr. Chai Xianzhi, Dr. Han Haihao and Dr. Adam C. Sedgwick under the guidance of Associate Professor Zhang Junjiao, Professor He Xiaopeng of the School of Chemical and Molecular Engineering, East China University of Science and Technology, and Professor Li Jia of the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, and under the careful guidance of Academician Tian He.
The ultra-high-resolution imaging experiment was guided by teachers Li Na, Li Yao and Yu Yang of the National Protein Center. His research work has been supported by the National Natural Science Foundation of China "Dynamic Modification and Chemical Intervention of Biological Macromolecules", the Outstanding Youth Science Foundation, the Shanghai Daystar Program, and the Shanghai Major Science and Technology Project.

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