Paper sensors for the measurement of nitric oxide release from endothelial cells

Nitric oxide (NO) is a ubiquitous and important biological mediator. However, its detection and chemical analysis are challenging due to its short lifetime in biological conditions. Paper-based NO sensors combining the ease of fabrication and affordability of paper with the quantitative capabilities of electrochemical methods are presented for the detection and quantification of NO in cultured cells. Nafion-coated and eugenol-functionalized paper devices were built and characterized using a NO donor. The electrochemical interferences from nitrite, a common interferent for NO sensing, were successfully screened out. Finally, preliminary data were obtained from 100 000 endothelial cells cultured directly, in an extracellular matrix, on the paper device. In response to vascular endothelial growth factor exposure, NO secretion was detected and quantified.