
Polyelectrolyte Microsensors as a New Tool for Metabolites’ Detection 127
log (C
urea
, µM)
012345
pH calculated
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
FIGURE 7 Calibration curve for detecting urea using the SNARF-1 dextran/urease capsules
in water solutions.
It is worth to notice, that this calibration curve is obtained for SNARF-1 dextran/
urease capsule in pure water without substantial contamination of any salt which could
buffer the systems and spoil truly picture for urea detection. We carried out experi-
ments to build a similar calibration curve in the presence of the 0.001 M TRIS-maleate
buffer (were used solutions with the pH 6.5 and 7.5) but it resulted ...