ABSTRACT
Enzyme based micron sized sensing system with optical readout was fabricated by co-encapsulation of urease and dextran couple with pH sensitive dye SNARF-1 into polyelectrolyte multilayer capsules. Co-precipitation of calcium carbonate, urease and dextran followed up by multilayer film coating and Ca-extracting by EDTA resulted in formation of 3.5-4 micron capsules, what enable the calibrated fluorescence response to urea in concentration range from 10-6 to 10-1 M. Sensitivity to urea in concentration range of 10-5-10-1 M was monitored on capsule assemblies (suspension) and on single capsule measurements. Urea presence can be monitored on single capsule level as illustrated by Confocal fluorescent microscopy.
