(472c) Zwitterionic Poly(carboxybetaine) Hydrogels for Glucose Biosensors in Complex Media

Amperometric enzyme glucose sensors, based on glucose oxidase (GOx), have played a leading role in the move towards continuous blood glucose monitoring and tight glycemic control. However, undesirable interactions between the surface of the implanted probe and biological media have been shown to be the major barrier to the development of reliable in vivo glucose sensors. As a result, tremendous effort in designing more biocompatible in vivo glucose sensors focuses on preparing interfaces that resist biofouling in complex media. However, most of these approaches suffer disadvantages one way or another such as lacking of long-term stability in blood media and/or use of additional carriers for GOx loading.  Ideally, a surface coating capable of immobilizing enzymes with high loads while protecting glucose sensors from complex media is highly desirable.

In this work, we report the successful development of an amperometric glucose biosensor based on zwitterionic poly(carboxybetaine) (polyCB) hydrogels with covalently immobilized GOx for long-term applications in complex media. With one single zwitterionic polyCB coating, the excellent performance of glucose sensors coated with polyCB hydrogels was demonstrated. All the polyCB hydrogel-coated sensors displayed a fast and ~100-fold response increase compared to previous work over a period of 40 days. Moreover, the sensors coated with 0.1% polyCB hydrogels retained excellent sensitivity and linearity after exposure to undiluted blood samples over 20 days, making it a promising candidate to detect the glucose level. The surface hydrogel coating based on one simple nonfouling and functionalizable polyCB is a powerful step towards realizing noninvasive or minimally invasive sensing with fast, linear, sensitive, specific, and long-term stability in blood, and provides a generic surface coating strategy for other medical devices.