In vivo nitric oxide sensor using non-conducting polymer-modified carbon fiber

Nitric oxide (NO) is emerging as a very important and ubiquitous gaseous me ssenger in the body. The response characteristics of NO sensors made of non -conducting polymer modified carbon fiber electrodes are investigated to de termine their selectivity, sensitivity, and stability for in vivo use. A co mposite polymer, comprising Nafion, m-phenylenediamine, and resorcinol, sho wed the best selectivity and stability to amperometric NO detection. The no n-conducting, self-limiting polymer film protects the electrode from interf erence and fouling by other biochemicals. Although the relative sensitivity to NO of the modified sensor is lower than that of the unmodified carbon f iber electrodes (less than 6%), the composite polymer electrode showed high selectivity against ascorbic acid ( > 2000:1), nitrite ( > 600:1), and dop amine ( > 200:1). The stability of the NO sensor was maintained for at leas t 1 week. The NO sensitivity after in vivo experiments (n = 8) is 88.1 +/- 5.6% of initial sensitivity data obtained before in vivo experiments. Preli minary in vivo experiments done with this electrode are shown to capture el evated NO levels in brain following an ischemic injury. (C) 1998 Elsevier S cience S.A. All rights reserved.