UC Irvine

Continuous measurements of physiological biomarkers enables patients to assess their levels in real-time and can help healthcare professionals determine if treatment is improving patient outcome. To monitor these biomarkers, an invasive blood draw is often required. Unfortunately, frequent blood draws increase the likelihood of anemia, blood infection, and nerve damage, which in many situations, may worsen the patient’s condition. My thesis works addresses the need to alleviate frequent blood draws by replacing such laboratory assays with continuous and implantable optical sensors.

My first project was in collaboration with Dr. Gregory Weiss in the Department of Chemistry at UCI. I have engineered an implantable Förster Resonance Energy Transfer (FRET)-based calcium (Ca2+) sensor that provides continuous, physiologically relevant Ca2+ measurements. The FRET sensor addresses the foreign body response by incorporating a molecular filter and takes advantage of the conformational changes observed when Ca2+ binds to Troponin-C (within FRET complexes) to optically monitor Ca2+. My findings suggest that FRET-based sensing of target analytes using an implantable optical fiber sensor is effective and, in conjunction with protein engineering, is a new option for continuously monitoring physiologically relevant electrolytes.

For my second project, I spectroscopically monitor pH and lactate on an implantable flexible sensor. Together, pH and lactate values and trends can help healthcare professionals discriminate between metabolic and respiratory dysfunctions, helping to guide patient therapy. When implanted in a rabbit, the pH and lactate multi-analyte sensor shows accurate pathophysiological trends with respect to a handheld blood analyzer.

Collectively, these efforts show the feasibility of implantable optical sensors to continuously monitor multiple physiological biomarkers, simultaneously. With libraries of new and selective luminescence dyes and FRET probes, there is potential for implantable optical sensors to displace blood draws for improved patient care.