A RATIOMETRIC IMPLANTABLE SENSOR FOR CONTINUOUS pH MONITORING IN VIVO - Micah M. Lawrence Logo

A RATIOMETRIC IMPLANTABLE SENSOR FOR CONTINUOUS pH MONITORING IN VIVO - Micah M. Lawrence

Micah M. Lawrence

University of California - Irvine, Newport Beach, CA

Type I Diabetes is an autoimmune disease where T cells attack Beta cells of the pancreas, resulting in an inhibition of insulin secretion. This can cause the pH levels of blood to be lower than the normal range of 7.35-7.45 through Diabetic Ketoacidosis (DKA). DKA occurs when blood sugar levels are high, because without adequate levels of insulin the body cannot sequester glucose. Therefore, the body starts breaking down fats yielding ketones which provide energy to the body in a form that does not require insulin. Unfortunately, ketones cause the blood to rapidly become acidic, which can cause fatigue, dehydration, frequent urination, and lead to death. To help address this occurrence, we are developing a Ratiometric Implantable Sensor (RIS) for continuous pH monitoring in vivo. By utilizing polytetrafluoroethylene (PTFE), Polyethylene glycol di-methacrylate (PEGDMA), and anion-exchange resin beads we can immobilize HPTS, a fluorescent pH-sensitive dye, into a sensing matrix to sense pH. HPTS shows great sensitivity when analyzed using a plate reader and a spectrophotometer. Both systems utilize an excitation light source with a small bandpass which cannot be imitated in vivo. However, with the RIS, we can maintain the pH sensitivity of HPTS while using LEDs as an excitation source and a photodiode to collect the spectra. With LEDs, the dye can potentially be excited and analyzed in vivo, providing health care professionals a reliable way to continuously monitor pH levels.