Freedom from finger pricking: continuous glucose monitoring
  • Yun Jung Heo Ph.D
  • SLS Colloquia / Oct 31st 04:00pm / bldg.110 room N104

Diabetes is a global pandemic that affects 300 million people and is one of the leading cause of death and disability in the world. Repeated occurrence of high or low blood glucose episodes leads to disorders of the heart, kidney, retina and neural system. To prevent such diabetic complications, diabetic patients have to maintain their blood glucose concentrations in a normal level by blood glucose monitoring and insulin therapy. Diabetic patients have to prick their figure tip by a needle, drop blood sample on a sensor strip, and then insert the sensor tip into a glucose meter to measure blood glucose. Such sensing method cannot help diabetic patients understand blood glucose continuously, thereby not efficient to prevent diabetic complications. A continuous glucose monitoring system (CGMS) using implantable glucose sensors measures blood glucose continuously and then provides alarm when blood glucose is high or low. If people with diabetes use a CGMS, they can understand not only blood glucose but also trend of blood glucose change involuntary. Commercial CGMS includes a semi-implantable glucose sensor; such sensors are electrochemical sensors based on mediated electron-transfer in glucose oxidase-catalyzed reactions. Electrochemical sensors do not have long lifespan in vivo due to irreversible glucose detection. They also require reference electrodes, moreover cannot access to the deep lying of the body. Alternately, fluorescence-based implantable glucose sensors have been explored. Fluorescence-based glucose sensors are implanted under the skins and sensor signals are read optically. Fluorescent sensors are sensitive with low noise levels compared to other optical methods. Optical readouts can sense glucose through optically transparent wall, thus possible to sense glucose in which difficult to access in the body and control remotely. If a fluorescent sensor is sufficiently small to minimize inflammation, and continuously transduce optical signals to body-worn detectors, the sensor scheme can be quasi non-invasive system for CGM, so called “glowing smart tattoos.” To bring “glowing smart tattoos” technology to be an ideal CGM (i.e., reversible, reliable, biocompatible, long-lasting, patient-acceptable CGM), various glucose-sensing fluorescence and sensor combinations have been studied. Implantable glucose sensors conjugated with fluorescence recognize glucose, and then transduce to optical signals. Efforts have been conducted to find an effective combination of implantable glucose sensor form and optical detectors. This seminar describes current status of implantable sensors for CGM, and related materials with an emphasis on glucose-sensor fluorescence, and sensor schemes to realize CGM.  



Related papers:

1.          Y. J. Heo, and S.-H. Kim, Toward long-term implantable glucose biosensors for clinical use. Applied Sciences, vol. 9, no. 10, 2019: 2158.

2.          Y. J. Heo, H. Shibata, T. Okitsu, T. Kawanishi, and S. Takeuchi, Long-term in vivo glucose monitoring using fluorescent hydrogel fibers, Proc Natl Acad Sci USA, Vol. 108, pp. 13399-13403, 2011. *selected in “This week in PNAS” and 2011 Todai Research (one of the top 4 research projects at the University of Tokyo).

3.          H. Shibata*, Y. J. Heo*, T. Okitsu, Y. Matsunaga, T. Kawanishi, and S. Takeuchi, Injectable hydrogel microbeads for fluorescence-based in vivo continuous glucose monitoring, Proc Natl Acad Sci USA, Vol. 107, pp. 17894-17898, 2010. *equal contribution on this publication.