Glucose Sensor for Low-Cost Lifetime-Based Sensing Using a Genetically Engineered Protein
✍ Scribed by Leah Tolosa; Ignacy Gryczynski; Lisa R. Eichhorn; Jonathan D. Dattelbaum; Felix N. Castellano; Govind Rao; Joseph R. Lakowicz
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 112 KB
- Volume
- 267
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
We describe a glucose sensor based on a mutant glucose/galactose binding protein (GGBP) and phase-modulation fluorometry. The GGBP from Escherichia coli was mutated to contain a single cysteine residue at position 26. When labeled with a sulfhydryl-reactive probe 2-(4'-iodoacetamidoanilino)naphthalene-6-sulfonic acid, the labeled protein displayed a twofold decrease in intensity in response to glucose, with a dissociation constant near 1 microM glucose. The ANS-labeled protein displayed only a modest change in lifetime, precluding lifetime-based sensing of glucose. A modulation sensor was created by combining ANS26-GGBP with a long-lifetime ruthenium (Ru) metal-ligand complex on the surface of the cuvette. Binding of glucose changed the relative intensity of ANS26-GGBP and the Ru complex, resulting in a dramatic change in modulation at a low frequency of 2.1 MHz. Modulation measurements at 2.1 MHz were shown to accurately determine the glucose concentration. These results suggest an approach to glucose sensing with simple devices.