Synthesis And In Vitro Antitumor Activity Of Theranostic Agents With Aggregation-induced Emission Characteristics

Cancer has always been one of the major diseases that threaten human health,the main treatment methods are surgery,chemotherapy,radiotherapy and photodynamic therapy?PDT?.Surgery can't remove all tumor cells in many cases,chemotherapy and radiotherapy can lead to serious side effects due to lack selectivity for cell tissue.PDT is a therapeutic method that uses photosensitizer?PS?to produce reactive oxygen species?ROS?under illumination and induce apoptosis.At present,photosensitizers?such as porphyrin derivatives?that used in clinical research have low ability to produce singlet oxygen?¹O₂?in aqueous media due to the aggregation-caused quenching?ACQ?,which severely limits the PDT effect.Aggregation-induced emission luminogens?AIEgens?are a class of materials that exhibit a weak or non-emission in a dilute solution but emit strong fluorescence in an aggregate or solid state.Under light irradiation,AIEgens can transfer energy to adjacent triplet oxygen?³O₂?to produce ¹O₂.Therefore,AIEgens can be used as PDT agents,and can also solve the problem of low efficiency of ROS production in traditional aqueous photosensitizers in aqueous media,and has extremely high research value in the field of PDT.Because AIEgens produce ROS during PDT,it will continue to consume oxygen in the cells,which will lead to a more hypoxic microenvironment in tumor cells.If this hypoxic microenvironment is used to activate prodrugs,reduce the side effects of chemotherapy drugs on normal cells,thus the purpose of the combination therapy will be achieved.In order to favor separation of highest occupied molecular orbital?HOMO?and lowest unoccupied molecular orbital?LUMO?distribution to improve the efficiency of ROS,TPE was used as the AIE parent,methoxy group was used as electron donor,cyano and nitro group were used as electron acceptors,and lactose was used to increase biocompatibility,then LAC-TPE-DB-NO₂ was designed and synthesized.In order to utilize the extremely hypoxic microenvironment caused by the PDT process to achieve specific release of gemcitabine?GMC?in the tumor region,PDT PS?TPE-DB-NO₂?and GMC were coupled through covalent bond,then the theranostic agent GMC-TPE-DB-NO₂ was synthesized.LAC-TPE-DB-NO₂ and GMC-TPE-DB-NO₂ were characterized by NMR,HRMS and SEM.The stability and ROS production efficiency were determined by UV-vis and confocal fluorescence microscopy.MTT assay and live-dead cell staining assay were used to determine the cell viability.Flow cytometry was used to determine the apoptosis of HeLa cells.Confocal fluorescence microscopy was used to study the uptake of theranostic agent on HeLa cells.That results show that the nanoparticles formed by self-assembly of LAC-TPE-DB-NO₂ and GMC-TPE-DB-NO₂ in aqueous medium have a particle size of about 100 nm,LAC-TPE-DB-NO₂ and GMC-TPE-DB-NO₂ can be stably existed under physiological conditions;the ROS production efficiency of LAC-TPE-DB-NO₂and GMC-TPE-DB-NO₂ is much higher than that of Bengal Rose Bengal;the fluorescence intensity of LAC-TPE-DB-NO₂ and GMC-TPE-DB-NO₂ in HeLa cells were incubation time-dependent;the toxicity of LAC-TPE-DB-NO₂ on tumor cells was dose-and light time-dependent.The viability of HeLa cells was 11.7%when exposed to light for 7 min.GMC-TPE-DB-NO₂ was no toxicity to cells under dark conditions.Under hypoxic conditions,it showed the highest toxicity on HeLa cells,incubation for 48 h,the survival rate of HeLa cell was 37.0%,and 51.1%cells were induced apoptosis.LAC-TPE-DB-NO₂ has dual functions of diagnosis and treatment,it can efficiently produce ROS whice can induce apoptosis.GMC-TPE-DB-NO₂has a hypoxic response characteristic,which reduces the toxic side effects of GMC on normal cells,the combination of PDT and chemotherapy achieves the greatest inhibition of tumor cells and provides a new idea for the combination treatment of tumors.