Design And Application Of Ratiometric PH Probes Targeting Organelles

Fluorescence technology has played an important role in the exploration of life sciences.With the continuous upgrade of fluorescence microscopes and the continuous improvement of time resolution,fluorescent probes as the carrier of fluorescent signals are playing an increasingly important role in exploring biology and medicine.The pH of the organelles must be maintained within a certain range to ensure the normal physiological activity of the cells.Abnormal changes in pH often cause a series of diseases,so it is very important to detect pH.In order to achieve quantitative detection of pH in subcellular organelles,the ratiometric pH probes BDP-RhB and TBSR-CHO based on the FRET mechanism and having lysosomal targeting or mitochondrial targeting were designed.Firstly,we designed the ratiometric pH probe BDP-RhB using BODIPY and reduced rhodamine.The probe shows good lysosomal localization ability,it has a wide response range from pH 8.0 to 4.0 and the ratio(I₅₈₂/I₅₁₈)change significantly from 0.6 to 3.4 simultaneously.The probe has good reversibility and stability.Through the construction of macrophage inflammation model and fluorescence imaging experiments,we used BDP-RhB visualization to indicate the decrease of lysosomal pH of macrophages during inflammation.Secondly,in order to construct a bifunctional platform molecule with fluorescence ratio and organelle positioning,we constructed the pH probe TBSR-CHO by using1,3,5-Tris（azidomethyl）benzene（T）as the core,BODIPY and tetramethyl sulfonate rhodamine as signal donor and acceptor and 4-diphenylphosphinobenzaldehyde as the mitochondrial targeting and immobilization group.Spectral experiments showed that the ratio of TBSR-CHO(I₅₈₈/I₅₂₂)changed from 0.9 to 0.2 with the increase of pH from 5.5 to 8.5.Fluorescence imaging experiments prove that the probe can be positioned and fixed in mitochondria,and the probe has great potential in mitochondrial pH detection.