Characterization of PEBBLEs as a Tool for Real-Time Measurement ofDictyostelium discoideumEndosomal pH

Abstract

The measurement of intracellular ion concentration change is important for understanding the cellular mechanisms for communication. Recently developed nanosensors, (Photonic Explorers for Biomedical use with Biologically Localized Embedding) PEBBLEs, have a number of advantages for measuring ions in cells over established methods using microelectrodes, unbound fluorescent dyes, or NMR. PEBBLE sensors have been shown to work in principle for measuring dynamic ion changes, but few in vivo applications have been demonstrated. We modified the protocol for the fabrication of pH sensing PEBBLEs and developed a protocol for the utilization of these sensors for the monitoring of dynamic pH changes in the endosomes of slime moldDictyostelium discoideum (D. discoideum). Oregon Green 514-CdSe Quantum Dot PEBBLEs were used to measure real-time pH insideD. discoideumendosomes during cAMP stimulation. Endosomal pH was shown to decrease during cAMP signaling, demonstrating a movement of protons into the endosomes ofD. discoideumamoebae.