Objective: This is a preliminary work towards preparing a device capable to measure nitric oxide levels in a cystic fibrosis cell line model. Relevance: It has been found that exhaled NO levels remains unchanged or reduced in cystic fibrosis patients unlike other inflammatory lung diseases like asthma where it increases. However it is not clear whether the lower NO levels in cystic fibrosis correlate with lowered production of this metabolite in the bronchial epithelium. We will present preliminary results of our ruthenium oxide modified combined electrodes and how they can be applied to the study of cystic fibrosis at the cellular level. Methodology: In this work, we fabricated combined reference/working carbon fiber electrodes with 7 micron diameter tips. The exposed surface of the fiber tip was electrochemically modified with ruthenium oxide and Poly(3,4-ethylenedioxythiophene) (PEDOT). In order to improve the selectivity of our sensors we coated the surface with an ionic liquid composite and lowered the applied to 0.6 V vs. Ag/AgCl and measured the response to NO using Differential Pulse Amperometry to differentiate NO response from common interferents present in biological samples especially nitrite and ascorbic acid. Validation: With the incorporation of a layer by layer method of electrodeposition we attained a normalized sensitivity of 8.38E-4 pA/nM/mM2 and 1.16E-2 pA/nM/mM2 towards NO in the linear range of 0.2-1.6 mM and 2-16 nM respectively, at an applied potential of 0.8 V vs Ag/AgCl and a detection limit in the vicinity of 500 pM Conclusion: In this work, we explore the performance of combined reference/working electrodes modified with ruthenium oxide and Poly(3,4-ethylenedioxythiophene) (PEDOT) in the detection of nitric oxide with the goal to measure nitric oxide at the level of single or collective cultured cells. The synergistic effect of the electrocatalytic activity of ruthenium oxide and the enhanced surface area for catalytic activity provided by the polymer greatly enhanced the analytical performance of our sensors in terms of sensitivity, selectivity and stability. Also our sensors are able to detect very low concentration of the NO metabolite and show very good linearity and response in the physiologically relevant range as well as provide selectivity towards Its detection in absence and presence of interferents.

Ruthenium-modified sensitive NO sensors: Quantifying nitric oxide in the pathobiology of cystic fibrosis

253rd National Meeting (2017)

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