Development of a Lactate Biosensor for Monitoring of the Physical Fitness of Astronauts
- Paper number
IAC-11,B3,7,7,x11355
- Author
Ms. Miraida Pagan, NASA Harriet Jenkins Pre-Doctoral Fellowship, University of Puerto Rico, United States
- Author
Dr. Kai Griebenow, University of Puerto Rico, Puerto Rico
- Coauthor
Ms. Andrea Delgado, Puerto Rico
- Coauthor
Ms. Mariam Vila, Puerto Rico
- Year
2011
- Abstract
The development of robust biosensors that exhibit superior sensitive response and long-term stability has drawn significant attention to monitor human health and physical conditions. Since lactate levels in blood are an established indicator for physical fitness in humans, our long-term goal is to develop a stable enzyme-based biosensor for monitoring lactic acid concentration in blood. The model protein for this sensor is lactate oxidase (LOx) that has been widely used as a component of electrochemical sensor systems for monitoring lactate concentration. Nanomaterials like carbon nanofibers and carbon nanotubes (CNTs), by virtue of their nano size, possess unique physical and chemical properties (e.g. excellent electronic and thermal properties) that make them useful in biosensor construction. The use of CNT electrodes will help not only to warranty proper immobilization of the biomolecule to the sensor but also to provide highest sensitivity. On the other hand, the stability of the sensor depends also on the life-time of the protein. One methodology used to improve the stability and the life of the protein is chemical glycosylation, in which glycans are attached to the surface of the protein. They provide a cage effect and help protecting and stabilizing the protein. The central hypothesis of the research is that covalent chemical modification of the enzyme with glycans will reduce conformational motions (dynamics) and increase its thermodynamic stability thus affecting positively the long-term stability of the biosensor. To address this aim the different LOx glycoconjugates will be covalently attached to the CNT electrode as we already did with the non-modified enzyme. The electrode consists of a group of CNTs, embedded on a self- assembling monolayer of 4-aminothiophenol onto a platinum substrate. The enzyme was covalently attached to the CNT via EDC-carbodiimine coupling to improve the biosensor signal and sensitivity. Cyclic voltammetry and amperometric experiments were used to establish the sensitivity and the linear response of the biosensor. FTIR and XPS were used to demonstrate the covalent attachment of LOx onto the electrode. These experiments will now be performed with glycosylated LOx. We expect that the use of the glycoconjugates in combination with the covalent immobilization of the protein onto the new CNT-platform will increase the stability and the response of the biosensor.
- Abstract document
- Manuscript document
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