Ultrasensitive Diamond Microelectrode Application in the Detection of Ca Transport by AnnexinA5-Containing Nanostructured Liposomes.

This report describes the innovative application of high sensitivity Boron-doped nanocrystalline diamond microelectrodes for tracking small changes in Ca concentration due to binding to Annexin-A5 inserted into the lipid bilayer of liposomes (proteoliposomes), which could not be assessed using common Ca selective electrodes. Dispensing proteoliposomes to an electrolyte containing 1 mM Ca resulted in a potential jump that decreased with time, reaching the baseline level after ~300 s, suggesting that Ca ions were incorporated into the vesicle compartment and were no longer detected by the microelectrode. This behavior was not observed when liposomes (vesicles without AnxA5) were dispensed in the presence of Ca.