Design of micro and nanostructured systems for in-situ and in-vivo sensing become an interesting subject nowadays for biological and medicaloriented research [1-3]. Miniaturization of sensing elements opens a possibility for non-invasive detection and monitoring of various analytes exploiting cell and tissues residing reporters. Typical design of such sensor is nano-and microparticles loaded with sensing substances enable to report on presence of analyte by optical means [4-9]. The particles containing fluorescent dye can be use as a sensor for relevant analytes such as H+, Na+, K+, and Cl- et al. [10-13]. The fluorescent methods are most simple and handy among the possible ways of registration. They provide high sensitivity and relative simplicity of data read-out. For analysis of various metabolites it is necessary to use the enzymatic reactions to convert analyte to optically detectable compound [14, 15]. In order to proper functioning all components of sensing elements (fluorescence dyes, peptides, enzymes) are to be immobilized in close proximity of each other. That “tailoring” of several components in one sensing entity represents a challenge in developing of a generic tool for sensor construct. One approach to circumvent problem has been introduced by the PEBBLE (Photonic Explorers for Bioanalyse with Biologically Localized Embedding) system [5, 16]. PEBBLE is a generic term to describe use co-immobilization of sensitive components in inert polymers, substantially polyacrylamide, by the microemulsion polymerization technique . This technique is useful for fluorescent probe, but to our mind, is too harsh for peptides and enzymes capsulation due to organic solvents involved in particle processing. Multilayer polyelectrolyte microcapsules have not this shortcoming as they are operated fully in aqueous solution at mild condition. These capsules are fabricated using the Layer-by-Layer (LbL) technique based on the alternating adsorption of oppositely charged polyelectrolytes onto sacrificial colloidal templates [18, 19]. Immobilization of one or more enzymes within polyelectrolyte microcapsules can be accomplished by the coprecipitation of these enzymes into the calcium carbonate particles, followed by particle dissolution in mild condition leaving a set of protein retained in capsule [15, 20, 21]. A fluorescence dye can be included in polyelectrolyte capsules as well. Thus, the multilayer polyelectrolyte encapsulation technique microcapsules allows in principle combining enzyme activity for selected metabolite and registration ability of dyes in one capsule. In this work we demonstrate urea detection using capsules containing urease and pH sensitive dye.
|Title of host publication||Chemistry and Physics of Modern Materials|
|Subtitle of host publication||Processing, Production and Applications|
|Publisher||Apple Academic Press|
|Number of pages||18|
|Publication status||Published - 1 Jan 2013|
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