Both the selectivity and sensitivity of electrochemical nitric oxide (NO) sensing are current problems in practical cellular NO sensing because there are several potential sources of interference in mammalian cell cultures that may disturb electrochemical NO detection. In this paper, the authors have designed and synthesized an Fe-polymer complex sensor material. The sensor material can selectively accumulate NO, and an electrode coated with this material can sense NO with both good NO selectivity and sensitivity. The authors also add mammalian cell adhesive activity to the sensor material to perform direct cell cultures on the sensor.