A three-enzyme microelectrode sensor for detecting purine release from central nervous system

As the purities, in particular adenosine, are important signaling agents in the nervous system we have devised a new biosensor for directly measuring their production in real time during physiological activity. Our amperometric adenosine biosensor is made by entrapping 3 enzymes (xanthine oxidase, purine nucleoside phosphorylase and adenosine deaminase) in a composite lactobionamide and amphiphillic polypyrrole matrix around a Pt microelectrode. The resulting sensors are small (25-100 pm diameter), fast responding (10-90% rise time, 2+/-0.23 s), sensitive (100-222 mA M(-1.)cm(-2)) and stable (100% activity after 5 days). The sensor was used in vivo to demonstrate the spatial localization of release of adenosine from Xenopus embryo spinal cord during fictive swimming. (C) 2002 Elsevier Science B.V. All rights reserved.