Nanoencapsulated fluorescence indicator molecules measuring pH and pO2 down to submicroscopical regions in the basis of the optode-principle.

To measure pO2 in gases or fluids and pH in solutions the fluorescence indicators pyrene butyric acid and beta-methylumbelliferone, respectively, were nanoencapsulated to obtain nano-probes for measurement in physiological structures of nano-range. For pH the fluorescence changes of beta-methylumbelliferone were monitored, for pO2 the fluoresence quenching of pyrene butyric acid by oxygen were registered. Drawing log (S1/S2) versus pH, one obtains a straight line between the pH from 6 to 8. A linear increase in pO2 between 0 and 400 torr yields a linear increase in the reciprocal fluorescence signal.