Solution-processed graphene films for electrochemical monitoring of extracellular nitric oxide released by breast cancer cells

Nitric oxide plays an important role in cardiovascular function, immune response, and intercellular signaling. However, due to its short lifetime, real-time detection of nitric oxide is challenging. Herein, an electrochemical sensor based on fibronectin-modified, solution-processed graphene ink for nitric oxide detection is developed using a facile fabrication method involving spin-coating and hot-plate annealing. The sensor is first electrochemically characterized with a nitric oxide donor, spermine NONOate, exhibiting a dynamic range of 10 – 1000 μM. The fibronectin-functionalized graphene supports the attachment and growth of MDA-MB-231 breast cancer cells, as confirmed by optical microscopy. Extracellular nitric oxide production is stimulated using the amino acid L-arginine. Nitric oxide production results in morphological changes to the adhered cells, which are reversible upon the addition of the nitric oxide synthase antagonist Nω-nitro-L-arginine methyl ester (L-NAME). The production of nitric oxide is also confirmed using real-time amperometric measurements with the fibronectin-functionalized graphene sensors. While this work focuses on nitric oxide detection, this potentially scalable platform could be extended to other cell types with envisioned applications including the high-throughput evaluation of therapeutics and biocompatible coatings.