Rules of Attraction (IMAGE) DOE/Pacific Northwest National Laboratory Caption A polymer, here labeled PDDA, clings to a carbon nanotube of opposite charge, and an enzyme, GOX, does the same with the polymer. The steps can be repeated to build up a biosensor's layers, enzyme count and sensitivity. Credit DOE/Pacific Northwest National Laboratory Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.