No abstract

Fine needle amperometric glucose sensors having outer membrane of heparin in addition of polyurethane/polydimethylsiloxane film were prepared and their glucose sensor properties were evaluated in phosphate buffer solution and in vivo monitoring by the implantation of the sensor in veins of rabbit ears. The sensitivity of the sensor was 2.2 μA mM −1 cm −2 and the detection limit for glucose was 77 μM (based on S/N = 3). Glucose sensors without heparin membrane showed glucose response on the day of implantation in vein, while reliable response was not obtained on the second day. On the other hand, the sensor with heparin outer membrane provided clear glucose response also after two days of implantation. This result indicated that the introduction of heparin membrane increased the biocompatibility of the sensor and improved the stability of sensor in vein.

A fine tube type glucose sensor, which has a sensing region at the inside wall of fine tube tip, was prepared and applied for minimally invasive glucose monitoring. The enzyme glucose oxidase was immobilized on the platinum surface located in the tube by the combination of electrodeposition and electropolymerization of o-phenylenediamine. Amperometric responses of the prepared electrodes to glucose were measured at a potential of 0.60 V (vs Ag/AgCl). The tube type electrode showed good response with good linear relationship up to the glucose concentration of 22.4 mM, which was actually higher than general sensor without outer film for permeability restriction. This may be due to it unique sensor structure.

Fine needle type glucose sensors with variety of outer membrane were prepared and their glucose sensor properties were evaluated by in vitro measurement in phosphate buffer solution and horse serum, and in vivo measurement using the veins of rats and rabbits. Extra-outer membrane materials of polyglutamic acid (PGA) and heparin, which provide hydrophilic surface were introduced in addition to polyurethane/polydimethylsiloxane composite outer membrane. Glucose sensors without extra-outer film and with PGA extra-outer film showed glucose response on the day of implantation, while clear response was not obtained on the second day of implantation due to the adsorption of thrombus on the sensor surface. On the other hand, the sensor with heparin outer membrane provided satisfactory glucose response also on the second day.

not Available.