Design And Synthesis Of Aie Pyridine Salt Molecules For Near-infrared Emission And Their Application In Photodynamic Therapy

Aggregation-induced emission(AIE)has developed rapidly in recent years and has been used in many areas,such as fluorescent probes,fluorescent imaging,biological detection,and stimulus-responsive smart materials.The understanding of the AIE mechanism is also deepened,and the Restriction of Intramolecular Motions(RIM)is considered as the main factor.Based on this,we can design AIE molecules that meet the needs.Cancer,in view of the disadvantages of traditional methods of treating cancer,many research scholars are constantly researching,constantly looking for new methods,and developing new methods of treating cancer are urgently needed.Photodynamic therapy(PDT)has attracted much attention because of its advantages of high spatiotemporal selectivity,non-invasiveness and non-invasiveness,minimal side effects,and reduced risk of recurrence.With the rapid development of photosensitizers in recent years,photodynamic therapy has been shown to have significant effects in anti-cancer treatments such as head and neck cancer,skin cancer and its early obstructive lung cancer.Currently,more than a dozen related drugs have been approved for sale and application.AIE molecules have become a research focus in photodynamics because they can generate singlet oxygen and perform fluorescence imaging.At the same time,it has great clinical application potential in tumor treatment and photodynamic antibacterial.However,current photosensitizers generally suffer from shortcomings such as low singlet oxygen generation efficiency,insufficient photosensitizer targeting,and low imaging signal-to-noise ratio,making PDT clinically limited.In view of the above problems,this paper designed and synthesized a tetraphenylethylene-based fluorescent AIE photosensitizer,and used the photosensitizer to target the organelles to achieve tumor treatment.Through molecular design,the singlet oxygen production efficiency is improved,and the effect of PDT treatment is improved.This thesis focuses on the following topics:(1)In terms of photodynamic therapy,we have designed cationic probes TPEPy-I and TPEPy-PF6 based on tetraphenylethylene and pyridinium salts.The entire structure forms an electronic push-pull system,so that the emission wavelength reaches the near infrared region.This is conducive to deeper imaging depth,less background fluorescence interference,and high signal-to-noise ratio.Cationic probes have targeted mitochondria and have a colocalization coefficient of 0.96-0.97.Compared with the commercial photosensitizer RB,the probe has excellent singlet oxygen generation ability.It can show good photodynamic effect under low light source(30m W/cm~2)and low concentration(1?M).(2)In terms of photodynamic antibacterial,the AIE probe has excellent structure,small band gap and its ability to generate active oxygen.The antibacterial effect of the probe showed that at a low concentration(0.5?M),it can show a good antibacterial effect against S.aureus,and at a slightly higher concentration(5-10?M),it can exhibit antibacterial capacity against E.coli.This is mainly due to the cationic electrostatic binding of the probe molecule and its excellent active oxygen generating ability.(3)In the aspect of solid-state/solution multiple stimulus-response fluorescence switching of AIE probes,we designed a responsive material SFX-2SP based on nuclear spiro[fluorene-9,9`-xanthene](SFX)-spiropyran.Experimental results show that SFX-2SP can respond to light,acid/base and ions in solution state.In the solid state,the powder can also exhibit fluorescent switching characteristics.The PMMA film load shows high contrast and high emission characteristics different from solid powder.At the same time,switching between a variety of different state colors provides applications for information encryption,anti-counterfeiting mate rials,and the like.