Exogenous control over intracellular acidification: Enhancement via proton caged compounds coupled to gold nanoparticles

•Proton caged compounds can be used for intracellular acidification.•The acidification effect is largely enhanced by gold coupled nanoparticles.•Fluorescence images of marked compounds show a distribution in the intracellular cytoplasm.

The pH regulation has a fundamental role in several intracellular processes and its variation via exogenous compounds is a potential tool for intervening in the intracellular processes. Proton caged compounds (PPCs) release protons upon UV irradiation and may efficiently provoke intracellular on-command acidification. Here, we explore the intracellular pH variation, when purposely synthesized PCCs are coupled to gold nanoparticles (AuNPs) and dosed to HEK-293 cells. We detected the acidification process caused by the UV irradiation by monitoring the intensity of the asymmetric stretching mode of the CO2 molecule at 2343 cm− 1.The comparison between free and AuNPs functionalized proton caged compound demonstrates a highly enhanced CO2 yield, hence pH variation, in the latter case. Finally, PCC functionalized AuNPs were marked with a purposely synthesized fluorescent marker and dosed to HEK-293 cells. The corresponding fluorescence optical images show green grains throughout the whole cytoplasm.

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