title: Co-encapsulation of enzyme and sensitive dye as a tool for fabrication of microcapsule based sensor for urea measuring.
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 the 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. The presence of urea can be monitored on a single capsule level as illustrated by confocal fluorescent microscopy. Variations in urease:dye ratio in capsules, applicability and limits of use of that type multi-component microencapsulated sensors are discussed.
authors.affiliation: Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia. lubov_kazakova@mail.ru
authors.forename: Lyubov I
authors.initials: LI
authors.lastname: Kazakova
authors.forename: Lyudmila I
authors.initials: LI
authors.lastname: Shabarchina
authors.forename: Gleb B
authors.initials: GB
authors.lastname: Sukhorukov
mesh_terms: D001578:Benzopyrans / Q000737:chemistry; D002119:Calcium Carbonate / Q000737:chemistry; D002214:Capsules / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D009284:Naphthols / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014508:Urea / Q000032:analysis*; D014510:Urease / Q000378:metabolism*
chemical_list: D001578:Benzopyrans; D002214:Capsules; D003911:Dextrans; D004573:Electrolytes; D005456:Fluorescent Dyes; D009284:Naphthols; D012235:Rhodamines; C091666:seminaphthorhodaminefluoride; D014508:Urea; D004492:Edetic Acid; D014510:Urease; D002119:Calcium Carbonate