(413g) High Sensitivity Dual-Analyte Biosensor for Trauma Patient Monitoring and Management

Trauma is the 5^th leading cause of death in the United States and hemorrhage alone accounts for up to 56% of deaths within the first 24 hours of trauma. Exsanguination is the most common cause of death among those found dead upon the arrival of emergency medical services personnel. There is currently a lack of diagnostic technology at the point of injury leading to a standard of care that is less than optimal until a hospital or intensive care unit can be reached [1]. Appropriate triage of patients to higher and more advanced echelons of care will require smaller, more advanced technology that can be employed by first responders and caregivers. Fully integrated, rapidly deployable, minimally invasive biosensor systems for the continual measurement of metabolic markers of trauma, such as glucose and lactate, are at the forefront of diagnostic development to bridge this technological gap. The first generation of enzyme-based amperometric biosensors utilizes microchip technology that enables multi-analyte monitoring. One such biotransducer, the Electrochemical Cell-on-a-Chip Multidisc Electrode Array (MDEA 5037), has been developed and being used for the continual measurement of glucose and lactate in a vertebrate animal hemorrhage model [2]. The oxidoreductase enzymes glucose oxidase (GOx) and lactate oxidase (LOx) were immobilized onto MDEA 5037 transducer working electrodes via electropolymerization of a poly(pyrrole-co-pyrrole butyric acid) (p(Py-co-PyBA) copolymer. Electropolymerizations were performed at 850 mV vs. Ag/AgCl (3 M KCl) for a charge density of 100 mC/cm². Biotransducers prepared with a copolymer of a 7:1 ratio of pyrrole (Py) to pyrrole butyric acid (PyBA) were shown to have a sensitivity of 4.75 (±0.93) µA/mM/cm², a K_Mapp of 7.20 (±2.59) mM, an I_max of 76.75 (±25.50) µA/cm², a response time of 16.5 (±5) s, and a detection limit of 0.05 (±0.03) mM. The foregoing use of the p(Py-co-PyBA) co-polymer in fabricating biotransducers yielded a significant fivefold increase in sensitivity (p < 0.001) and a threefold increase in maximum current (p < 0.01) compared to biotransducers fabricated with polypyrrole (PPy) only. Biosensors were implanted into the trapezius muscle of Sprague-Dawley rats to measure interstitial analytes. The sensor was implanted for a total of 4 hours. After resection of the biotransducer and subsequent testing in vitro the device was shown to decrease in sensitivity and increase in its limit of detection by 86%. Response time of resected biotransducers was 438 s, more than 10 times greater than freshly prepared biotransducers. This is likely due to biofouling and/or protease related enzyme denaturation. For long duration implantable devices [3] an electroconductive hydrogel [4] will be employed to confer better antifouling properties.

References:

[1] Kotanen CN, Guiseppi-Elie A. Monitoring systems and quantitative measurement of biomolecules for the management of trauma. Biomed Microdevices. 2013;15:561-77.

[2] Guiseppi-Elie A. An implantable biochip to influence patient outcomes following trauma-induced hemorrhage. Anal Bioanal Chem. 2011;399:403-19.

[3] Karunwi O, Wilson AN, Kotanen C, Guiseppi-Elie A. Engineering the Abio-Bio Interface to Enable More than Moore in Functional Bioelectronics. Journal of The Electrochemical Society. 2013;160:B60-B5.

[4] Kotanen CN, Tlili C, Guiseppi-Elie A. Bioactive electroconductive hydrogels: The effects of electropolymerization charge density on the storage stability of an enzyme-based biosensor. Appl Biochem Biotechnol. 2012;166:878-88.