Fabrication and characterization of optical biosensors using polymer hydrogel microparticles and enzyme–quantum dot conjugates

As a first step in the development of a microanalysis device for the detection of phenol compounds, PHEMA hydrogel microparticles containing conjugates of enzyme (tyrosinase) and quantum dot were fabricated by dispersion photopolymerization and their feasibility as optical biosensors was investigated. The fluorescent response of the PHEMA microparticles containing tyrosinase–quantum dot conjugates decreased with the phenol concentration due to the fluorescence quenching effect caused by the enzyme reaction between tyrosinase and phenol. The results indicate that the activities of tyrosinase and quantum dot were maintained when they were conjugated and the conjugates encapsulated in PHEMA hydrogel microparticles. In conclusion, the PHEMA microparticles containing tyrosinase–quantum dot conjugates prepared in this study have the potential to be used as optical biosensors for the detection of phenol compounds.