Ferrocene-mediated needle-type glucose sensor covered with newly designed biocompatible membrane

A ferrocene-mediated needle-type glucose sensor covered with a newly designed biocompatible membrane of 2-methacryloyloxyethyl phosphorylcholine (MPC) has been developed and its characteristics examined in vitro and in vivo. Application of ferrocene derivatives to the glucose sensor could solve the oxygen-limitation problems, and also compensate the sensor decay due to an insufficient microconvection and diffusion of oxygen resulting from protein fixation on the sensor surface during continuous subcutaneous tissue glucose monitoring. The MPC membrane, a hydrophobic polymer surface covered with a grafted hydrophilic phosphorylcholine chain, has the potential for suppressing adsorption of biochemical molecules due to the mobility of the grafted polymer chain. With this glucose sensor covered with an MPC membrane, subcutaneous tissue glucose concentrations can be monitored for up to seven days without any in situ calibrations, followed by 14 days with one-point in situ calibrations. Therefore, we conclude that a ferrocene-mediated needle-type glucose sensor covered with an MPC membrane is stable and reliable, as compared to any other glucose sensors already developed, and can thus be applied for continuous glucose monitoring and for glycaemic control with a wearable artificial endocrine pancreas.