Characterization of Lactate Sensors Based on Lactate Oxidase and Palladium Benzoporphyrin Immobilized in Hydrogels
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An optical biosensor for lactate detection is described. By encapsulating enzymes and phosphorescent oxygen sensing molecules within permeable hydrogel materials, a lactate-sensitive change in emission lifetimes was achieved. The relative amount of monomer was varied to compare the response of the enzyme-phosphor system in three homo- and co-polymer materials: poly(2-hydroxyethyl methacrylate) (pHEMA) and two copolymers of pHEMA and poly(acrylamide) (pAam). Diffusion analysis demonstrated the ability to control lactate transport by varying the hydrogel composition, while having a minimal effect on oxygen diffusion. Sensors displayed the desired dose-variable response to lactate challenges, highlighting the tunable, diffusion-controlled nature of the sensing platform. Short-term repeated exposure tests revealed enhanced stability for sensors comprising hydrogels with acrylamide additives; after an initial “break-in” period, signal retention was 100% for 15 repeated cycles. Evaluation of long-term sensor performance revealed significant reduction in lactate sensitivity for all materials investigated. Sensor response was quickly saturated in a low oxygen testing environment, indicating further work is needed to enhance viability of platform for implantation. Finally, because this study describes the modification of a previously developed glucose sensor for lactate analysis, it demonstrates the potential for mix-and-match enzyme-phosphor-hydrogel sensing for use in future multi-analyte sensors.
Andrus, Liam P (2015). Characterization of Lactate Sensors Based on Lactate Oxidase and Palladium Benzoporphyrin Immobilized in Hydrogels. Master's thesis, Texas A & M University. Available electronically from