      Development of a Multianalyte Sensor on a Single ChipSarah JeffordsLouisiana Tech UniversityThis Research Experience for Undergraduates Site is Sponsored By:Air Force Office of Scientific Research, U.S. Air Force, Department of DefenseNational Science Foundation NSF Grant No. 0453578Dr. Gerard CotéRebecca Rounds      Research ObjectivesInvestigate sensing technology in hydrogel environmentDetermine analyte of interest (i.e. pH, oxygen)Measure change with specific fluorophore (i.e. BCECF, ruthenium)Determine biocompatible gel (PEG) with optimal porosityDetermine proper mesh size of gel for analyte of interestLarge enough to allow diffusion of analyteSmall enough to contain the fluorophoreCreate and test sensor array across the following physiologically relevant conditions:For oxygen: 3% - 21%For pH: 6.0 – 8.0 (normal body pH is 7.4)      BackgroundNonintrusive, automated system for NASAPrevious systems required manual measurement of sample Introduces possibility for contamination and human errorCompact system suitable for small space allotment on shuttleAutomatic system alleviates worry for time dependent analysis Monitors multiple analytes (i.e. pH and oxygen) with one sensingmechanismPoly(ethylene) glycol (PEG) hydrogelCross-linked structure, biocompatible, hydrophilicMesh size can be altered to optimally contain fluorophore while allowing diffusion of analytes      Microarray Sensor FabricationPrecursor Solution(water, PEG, fluorophore, darocur)PDMS MoldGlass slide with TPM monolayerPhotomaskUV LightMicroarray Sensor      Optical Detection Setup      Sensor Array Elements      pH Results in PBS00.20.40.60.811.21.46 6.5 7 7.5 8Measured pHRelative IntensityPBS Room TempPBS Cold      pH Results in DMEM00.20.40.60.811.21.46 6.5 7 7.5 8Measured pHRelative IntensityDMEM Room TempDMEM Cold      Oxygen Results00.20.40.60.811.20% 21%Measured OxygenRelative IntensityPBS roomPBS coldDMEM roomDMEM cold      Results and Conclusions For pH elements:Increase in intensity with more basic pHLess intensity at lower temperatures For oxygen elements:Intensity decreases as oxygen content increasesOxygen is less sensitive to temperature effects Proves to be a viable detection system for both pH and O2in PBS and DMEM Can be expanded to monitor other analytes      Future Research Determine method for analysis of further components of cell culture media (i.e. lactate, glucose)Lactate: High lactate levels indicate many medical conditionsImportant measurement for results of exerciseGlucose:Important analyte to monitor for people with diabetesA nutrition source in cell culture      This Research Experience for Undergraduates Site is Sponsored By:National Science Foundation NSF Grant No. 0453578Air Force Office of Scientific Research, U.S. Air Force, Department of DefenseNASA Cooperative Agreement No. NCC1-02038 Air Force Research Laboratory Contract No. FA8650-05-D-1912 Acknowledgments Dr. Gerard Coté Hope Beier Seungjoon Lee Becky