Electrochemical detection of chloride levels in sweat using silver nanoparticles: a basis for the preliminary screening for cystic fibrosis.

Cystic fibrosis is a common disease which has an associated characteristic symptom of high sweat chloride content. Thus, chloride ion quantification in sweat is important towards the screening of cystic fibrosis. Electrochemical methods, being cost effective and convenient, can be exploited for this. The electrochemical oxidation of silver nanoparticles in the absence of chloride ions gives one voltammetric signal related to the oxidation of silver to silver ions. The presence of chloride ions in the solution causes the appearance of an additional signal at a lower potential which is related to the oxidation of silver to silver chloride. This signal has a peak height which correlates linearly with the concentration of chloride ions from 2 mM to 40 mM when the electrochemical experiments are performed on silver nanoparticle modified screen printed electrodes. Thus, reliable quantification was found to be achievable. Furthermore, chloride ion levels of diluted synthetic sweat samples are measured accurately with the modified electrodes. Thus, the detection of the chloride ion concentration with a silver nanoparticle modified electrode provides a proof-of-concept for a point-of-care system for preliminary screening of cystic fibrosis.