Poly(ethylene glycol) hydrogel microparticles containing enzyme-fluorophore conjugates for the detection of organophosphorus compounds

For the first step in the development of a microanalysis device to detect organophosphorus compounds, PEG hydrogel microparticles containing conjugates of enzyme (AChE) and pH-sensitive fluorophore (SNAFL-1) as an optical biosensor were fabricated by a dispersion photopolymerization. Using the dual emission property of pH-sensitive SNAFL-1, changes in the microenvironment pH due to enzyme-catalyzed reactions with the analyte of interest were determined fluorescently and used to detect the analyte. The activity and sensitivity of the enzyme and pH-sensitive fluorophore were maintained when they were conjugated and encapsulated within the PEG hydrogel microparticles. The fluorescent response of the PEG microparticles containing AChE-SNAFL conjugates was affected by the concentration of a model organophosphorus compound (paraoxon) in the range of 1–20 μmol. These results indicate that the PEG microparticles containing AChE-SNAFL conjugates prepared in this study have a possibility to be used as an optical biosensor to detect organophosphorus compounds.