Glucose sensing using competitive binding assay co-encapsulated in uniform sized alginate microspheres

In the search to improve the sensitivity and stability of the existing glucose biosensors, uniform sized alginate microspheres loaded with fluorescent glucose sensing assay have been developed. The glucose sensing chemistry includes TRITC-conjugated apo-glucose oxidase and FITC-conjugated dextran. The glucose sensing is based on the principle of fluorescence resonance energy transfer from donor molecule (FITC) to acceptor molecule (TRITC). Polyelectrolyte multilayers are coated over the alginate microspheres to physically restrict the sensing molecules. Preliminary glucose sensing studies have been performed with the uniform sized alginate microspheres. Upon addition of glucose into the microsphere suspension, glucose diffuses inside the microspheres and displaces FITC-dextran from TRITC-apo-glucose oxidase. The displacement causes an increase in the distance between FITC and TRITC and subsequently results in decrease in energy transfer from the donor dye (FITC) to acceptor dye (TRITC). A linear increase in FITC-TRITC peak ratio is observed till 33.3 mM glucose and the linear range response sensitivity is calculated to be 0.529%/mM glucose. Further experiments will involve changing the ratio of the co-encapsulants to achieve higher sensitivity. Thus, the work is intended to establish the potential of uniform sized fluorescent alginate microspheres as implantable glucose biosensors ("smart tattoos").