Design And Mechanism Study Of A Probe For Real Time Monitoring Of PH Changes

Intracellular pH is important in regulating various cellular behaviors and pathological conditions. Compared with traditional detection methods, fluorescence probe technique has the advantages of simple operation, high sensitivity, good stability etc. Coupled with the development of modern medicine, molecular biology and all kinds of advanced fluorescence detection techniques and instruments, fluorescence probe technique has been applied in fluorescence imaging, gene diagnosis, medical diagnosis and other fields.Lysosome is an acidic organelle in all eukaryotic cells excluding erythrocytes. Lysosomal pH change may result in the malfunction of lysosomes. The acidic microenvironment in tumour is closely related to the tumor growth, invasion and metastasis. Therefore, imaging of lysosomes as well as tumour and real-time monitoring of pH changes is important. In this paper, a probe (hereafter referred to as RA) with a pKa of 4.10 was synthesized for real time monitoring of pH changes in vivo. The probe exhibited favourable "on-off' reversibility between pH 4.25 and 7.20 for at least six cycles. RA can not only localize in lysosome but also performe well in real-time detection of lysosomal pH induced by artesunate, chloroquine and dexamethasone in MCF-7 cells. The intense fluorescence of RA in ovarian tumour indicated the higher acidity in tumour tissues than in normal tissues. Based on the different fluorescence response in cancer and normal cells, RA can be employed to distinguish cancer cells from normal cells, which provide important information for cancer detection and treatment.Chloroquine led to the alkalisation of the lysosome. Dexamethasone was typically used to induce cell apoptosis and led to pH increase in lysosome. However, very few research were reported about the influences of artesunate (ART) on lysosome. Herein, three dyes (E?B?N) were synthesized to label ART. AE, AB, AN were compared by four methods. There are almost no difference on the spectral properties of AE, AB, AN and E, B, N. Co-localization experiments of MCF-7 cells incubated with AN and Lyso Tracker Red proved that ART preferably accumulates in the lysosomes. Enzyme hydrolysis tests and confocal images showed that AE and AB inside cells are prone to be decomposed. AN coupled with low cytotoxicity is more stable and can be used to study the effect of ART on lysosome.