Development of Minimally Invasive Biosensor for Continuous Glucose Monitoring

Good control of blood glucose degree is quite important for the prevention of serious diabetes complications onset and progression. Accurate recognition of the blood glucose degree helps the patient to provide appropriate treatments, such as insulin therapy. Recently, implantable glucose sensors for continuous glucose monitoring (CGM) are of significant importance on diabetic health care, since it not only lower the physical and mental load on glucose measurement, but also present continuous glucose trend, which is useful for treatment evaluation. However, since the length of sensor device inserted in skin is about 1 cm, development of lower invasive CGM system is expected for the improvement of diabetic patients quality of life.

   In this study, a low invasive patch type glucose sensor, which has sensing region at the tip inside of a tube, was proposed. The schematic illustration of the tip of such glucose sensor is shown in Figure 1. Since the sensing region is at the inside of a fine needle tube, it requires only the sensor tip to be implanted in the tissue for glucose monitoring.  In other words, it can be possible to perform as a patch type sensor, which impresses the user as a sticking sensor instead of implanting sensor.  Glucose oxidase was immobilized inside the tube using the combination of electrodeposition and electropolymerization technique, which was similar to the procedure proposed by Wilson’s group [1,2].  That is, phosphate buffer solution (pH 7.0) containing GOx and Triton X-100 was first poured inside the tube electrode and applied a potential of 1.3 V (vs Ag/AgCl) for 1 h to form GOx layer on the surface. Phosphate buffer solution containing o-phenylenediamine (o-PD) was next poured inside the tube and a potential of 0.7 V (vs Ag/AgCl) was applied for 15 min to induce the electropolymerization of o-PD.  Properties of the obtained sensor were evaluated both by in vitro and in vivo measurements.

Acknowledgment

This study was supported in part by a Grant-in-Aid for Scientific Research (C) No. 24500510 from Japan Society for the Promotion of Sciences (JSPS).

References

[1]   N. Matsumoto, X. Chen, G. S. Wilson, Anal Chem, 74, 362 (2002).

[2]  X. Chen, N. Matsumoto, Y. Hu, G. S. Wilson, Anal Chem, 74, 368 (2002).