Nanoengineered fluorescent sensors containing enzyme assays

Describes progress towards the fabrication, calibration and testing of polyelectrolyte microshells being used as sensors for biochemicals, which are either produced or consumed in enzyme-catalyzed reactions. They are nanoengineered using layer-by-layer (LbL) self-assembly. These shells are loaded with the analyte sensitive fluorophore, the reference fluorophore for ratiometric monitoring and the enzyme, which catalyzes the reaction. A potential use of these sensors is to study the transient local changes in both glucose and lactate caused by neuronal activity. A specific application of this project is the study of the brain's response to low glucose. This paper primarily focuses on the work done on enzyme encapsulation. A study of the effect of encapsulation on enzymes as well as the influence of sensor fabrication variables (size, layer thickness, composition) on the response characteristics of the sensors is being investigated. Preliminary work has shown that the enzymes can be encapsulated by a method of aided diffusion and that the enzyme retains its activity after encapsulation. Co-loading of the labeled enzyme and the oxygen sensitive dye has also been demonstrated.