Synthesis And Properties Of Photoacid Based On Tumor Acidity Modulation

Intracellular pH(pHi)is one of the indicators of abnormal metabolism of cancer cells.Alkaline pHi plays an important role in promoting the proliferation and metastasis of cancer cells.Photoacid(PA)is one of the photosensitive compounds,which can produce acidic substances under light irradiation,then improves the concentration of hydrogen protons in solution,and finally regulates the pH of environment.In this study,two photoacid SP and B-I-Cl were synthesized by using photoswitching molecules spiropyran and BODIPY photocage.Their ability to regulate pHi and inhibit the survival rate of cancer cells were investigated subsequently.A spiropyran molecule SP was synthesized.Under 365 nm LED illumination(20mW/cm~2),the protonated SP was switched from open-ring merocyanine to closed spiropyan.The photoisomerization of SP induced fluorescence increasing and pHi changing.The MTT assay proved the pHi changes,which led to the death of cancer cells.Furthermore,a photocage B-I-Cl was presented as an excellent PDT/PA multifunctional reagent,which exhibited a wide absorption from 540 nm to 580 nm,a high singlet oxygen yield(78.0%)and photoacid quantum yield(64.6%).By liquid phase,mass spectrum and UV-vis spectrum,B-I-Cl produced H~+through two mechanisms:heterocleavage hydrolysis and free radical hydrogen abstraction.The intracellular reactive oxygen species and H~+generation of B-I-Cl were proved synergistic capability of killing tumor cells.The cell survival rate was only5%at 0.25μM.In conclusion,SP and B-I-Cl can regulate tumor cell pHi and enhance the photodynamic tumor therapy.