Synthesis And Properties Of Novel Near Infrared Organic Photosensitizers

Photodynamic therapy（PDT）is a kind of technology used to treat malignant tumor infection and other pathological changes,which has attracted more and more attention all over the world.It is applied locally or systemically in pathological tissues based on a light-sensitive compound-photosensitizer（PS）.After the photosensitizer enters the lesion,it absorbs light of the appropriate wavelength,and the singlet oxygen generated has high reactivity,which can cause oxidative stress and damage in different organelles.Normal tissues in the human body that are not exposed to laser radiation are not damaged.H₂O₂ is a very important reactive oxygen species.In the environment,H₂O₂ can be used in the field of water purification;as a product of human metabolism,in life activities,H₂O₂acts as an immune marker in the cells of the organism.Excessive H₂O₂ content can cause cancer,Alzheimer’s and other diseases.Therefore,the real-time detection of H₂O₂ in the environment and organism is of great significance.In this paper,we successfully synthesized a new type of photosensitizer M₁,which has both the functions of fluorescent probe and photodynamic therapy.As a fluorescent probe to realize intramolecular fluorescence switch,fluorescence spectroscopy test shows that M₁ has good selectivity and anti-interference ability in the recognition of H₂O₂ in PBS buffer solution,the detection limit is 10.9μM,the linear detection range is 0-22μM,after H₂O₂ reacts with the molrcular M₁,the borate group was removed and form M₁-OH molecule with a phenolic hydroxyl group.The singlet oxygen yield of M₁-OH is as high as 0.88.It has good photosensitization performance and can be used as a photodynamic therapy agent to provide a new strategy for cancer treatment.Recently,the target moleculer entered the testing process of biological activity.Intracellular pH is an important parameter of cell metabolism and plays an important role in regulating the physiological and pathological processes of cells,such as intracellular proliferation and apoptosis,cell adhesion,signal transduction,etc.Studies have shown that in human cells,different organelles also correspond to different pH.Therefore,sensitive and accurate monitoring of the pH value inside and outside the cell helps to understand the physiological and pathological processes at the molecular level.In this paper,we used salicylaldehyde as the main body,2-aminothiophenol as the fluorophore to synthesize fluorescent probe M₂,and its structure is characterized by analysis methods such as nuclear magnetic and mass spectrometry.Using fluorescence spectroscopy to study the response behavior of M₂ molecules at a pH value of about 5.0-13.0,the results prove that the probe M₂ molecules appear new fluorescence emission peaks in an alkaline environment,and they are not interfered by other common metal cations and anions.At the same time,with the help of the color change under visible light and 365nm ultraviolet lamp to verify M₂’s recognition of alkaline environment,it shows that the probe M₂ can accurately detect the change of pH in the range of 7.0-13.0.The probe synthesis method is simple and has good performance.The photostability and selectivity of pH are also relatively specific,providing a new analytical method for studying the changes of pH inside and outside the cell.