Synthesis And Properties Of Long-Wavelength Fluorescent Dyes And Probes With Oxidation-Reduction Properties

Fluorescent dye-based fluorescence analysis and imaging technology has the characteristics of non-destructive,high sensitivity,high spatio-temporal resolution,and easy operation.The technology has been widely used in life science,environ-mental science,drug development,and diagnostic medicine.Long-wavelength near-infrared light has the characteristics of deep penetration in the body,small scat-tering,and low background fluorescence interference.It can meet the requirements of long-term and high-intensity excitation during the imaging process on the stability of the dye.Fluorophores with good photostability are particularly important for fluores-cence imaging.This paper focuses on the preparation of long-wavelength fluorescent dyes and their application in the detection of redox species,and aims to develop new long-wavelength fluorescent probes with high stability through the design of molecu-lar structures to achieve targets in the field of biochemistry research on imaging visu-alization such as markers.Based on this,this paper mainly carried out the following work:（1）The phenothiazine structure was introduced into the molecular structure,and PZ series（PZS,PZSe,PZS-1）fluorescent dyes with near-infrared emission were de-signed and synthesized by extending theπconjugation.Comparing with the classic Rhodamine dyes,the emission wavelengths of the PZ series dyes are in the near in-frared region（730 nm-741 nm）,which has high photostability,good cell membrane permeability and low biological toxicity.While,it retains the characteristic of the classic spirolactone structure to control the fluorescent signal"off-on".Because the structure itself contains the S/Se site,which is the reaction site,it can be used as a fluorescent detection probe for hypochlorous acid（HOCl）without any dye modifica-tion.At the same time,the introduction of selenium atom realized the redox reversi-bility detection of substance（HOCl-GSH）.Based on the characteristic that the spiro-lactone structure controls the"off-on"fluorescence signal,a fluorescence-enhanced probe for detecting metal ions(Hg²⁺)and biologically active substances（NO）was further designed and synthesized.（2）In order to achieve the directional detection of HOCl in mitochondria,methylphenylthio groups and triphenylphosphine functional groups with mitochon-drial targeting labels were introduced with naphthalene diimide as the matrix.We have synthesized a HOCl fluorescent probe Mito-NA with s pecific selectivity and a fast response time（<5 s）,high sensitivity（LOD=1 n M）,wide p H range（p H=2-12）,strong specificity and significant fluorescence turn-on signal.The introduction of tri-phenylphosphine group enables the fluorescence imaging detection of mitochondria HOCl（Pearson coefficient 0.91）,and the probe can be used for the detection of actual water samples.（3）By modifying the structure of naphthalene fluorescein,a xanthene fluores-cent dye TFNF⁰ with near infrared emission（700 nm）was designed and synthesized.Through the study of its performance,it is found that the introduction of fluorine at-oms makes its absorption wavelength and emission wavelength significantly red-shifted,and has a high selectivity for p H.According to the different optical re-sponse signals of the dye to the acid-base signal,a half-add and half-subtract logic circuit with two inputs and two outputs were constructed.