Project Grant F30DK149565

DECODING TISSUE-SPECIFIC MOLECULAR KINETICS VIA MULTIPLEX MULTI-DEPTH CONTINUOUS MONITORING - PROJECT SUMMARY CONTINUOUS GLUCOSE MONITORING (CGM) HAS REVOLUTIONIZED DIABETES CARE, YET EXPANDING THIS SUCCESS TO BROADER MOLECULAR TARGETS REMAINS A CRITICAL CHALLENGE. ELECTROCHEMICAL APTAMER SENSORS PROMISE TO EXTEND CONTINUOUS MONITORING TO A VAST RANGE OF ANALYTES (E.G. PEPTIDES, HORMONES, AND SMALL MOLECULES), BUT CURRENT APPROACHES LARGELY ASSUME THAT THE HYPODERMAL PLACEMENT USED FOR GLUCOSE GENERALIZES TO OTHER BIOMARKERS. THIS ASSUMPTION IGNORES FUNDAMENTAL PHYSIOLOGICAL DIFFERENCES BETWEEN THE DERMIS AND HYPODERMIS: CAPILLARY DENSITY, ADIPOSITY, AND RECEPTOR-MEDIATED UPTAKE. EACH OF THESE FACTORS CAN DRASTICALLY ALTER SENSOR ACCURACY AND LAG TIME RELATIVE TO BLOOD. THE OVERALL GOAL OF THIS PROJECT IS TO DECODE THESE TISSUE-SPECIFIC KINETICS BY DEVELOPING THE FIRST MULTIPLEX, MULTI-DEPTH APTAMER BIOSENSOR CAPABLE OF SIMULTANEOUS MEASUREMENT IN THE DERMIS, HYPODERMIS, AND BLOOD. USING A CLINICALLY RELEVANT PORCINE MODEL, WE WILL DEPLOY A NOVEL 5-ELECTRODE SENSOR STRIP THAT UTILIZES HIGH-FREQUENCY IMPEDANCE TO CLASSIFY TISSUE DEPTH, MEASURING GLUCOSE PAIRED WITH RECEPTOR-ACTIVE HORMONES (INSULIN OR CORTISOL). WE WILL THEN QUANTIFY HOW TISSUE-SPECIFIC FACTORS INFLUENCE SENSOR PERFORMANCE. THE RESULTING ADVANCES WILL BE DISSEMINATED AS A FOUNDATIONAL FRAMEWORK FOR DEPTH-AWARE SENSING, OPTIMIZING SENSOR PLACEMENT FOR ANALYTES WHERE HYPODERMAL DIFFUSION IS RATE-LIMITING. SPECIFIC AIMS: AIM 1 - ENGINEERING TISSUE-RESOLVED MULTIPLEXING: ESTABLISH IN-VITRO MULTIPLEX FUNCTIONALIZATION AND EX-VIVO ELECTROCHEMICAL DEPTH CLASSIFICATION TO RELIABLY DISTINGUISH DERMIS FROM HYPODERMIS AND ENABLE SIMULTANEOUS GLUCOSE-HORMONE SENSING. AIM 2 - IN-VIVO TISSUE-SPECIFIC KINETICS: DEPLOY THE MULTIPLEX ARRAY IN A PORCINE MODEL TO QUANTIFY THE IMPACT OF TISSUE DEPTH ON SENSOR ACCURACY AND LAG TIME. WE WILL DETERMINE THE OPTIMAL SENSING LAYER FOR GLUCOSE, INSULIN, AND CORTISOL BY COMPUTING THE MEAN ABSOLUTE RELATIVE DIFFERENCE (MARD) AND KINETIC DELAY FOR EACH LAYER VERSUS BLOOD REFERENCES. SUCCESSFUL COMPLETION OF THIS PROJECT WILL SET A NEW BENCHMARK FOR IN-VIVO MOLECULAR ACCURACY, TRANSFORMING DEPTH FROM AN UNCONTROLLED VARIABLE INTO A DESIGN PARAMETER FOR THE NEXT GENERATION OF WEARABLE MONITORS TARGETING COMPLEX DISEASES SUCH AS HEART FAILURE, INFLAMMATION, AND METABOLIC SYNDROME.