Miniaturized electrochemical sensor for real-time monitoring of oxidative stress in chronic respiratory disease cell models

Increased oxidative stress in the lung are observed in the exhaled breath of individuals affected by severe asthma and COPD. Airway epithelial cells are major contributors to the production of reactive oxygen species (ROS) within damaged and inflamed lung tissues. Among ROS, hydrogen peroxide (H2O2) has a longer half-life and can be detected in the extracellular space. New electrochemical sensors allow direct H2O2 measurement on easily accessible biological fluids from patients to monitor disease progression in a simple and non-invasive way. Here we present a miniaturized electrochemical sensor realized from the silver layer of the compact discs with a chitosan layer on the sensor which could absorb the humid component of human exhaled air containing the H2O2. The proposed sensor can be inserted in a wearable mask. Using this sensor, H2O2 was measured in an aerosol of the conditioned medium from human bronchial epithelial cell lines (16HBE) exposed for 24h to stimuli inducing oxidative stress (cigarette smoke=CSE) and/or the drugs with antioxidant properties, N-acetylcysteine and Formoterol. Sensor was able to detect CSE-induced oxidative stress and the counteracting effects of the tested antioxidants. Sensor results paralleled the results obtained by flow cytometry after staining cells with a specific probe for intracellular ROS. Results showed that the sensor is able to detect ROS in the aerosol, outperforming the sensitivity and selectivity of the traditional methods, thus representing a fast and cost-effective alternative for easy real-time monitoring of oxidative even stress directly on humans.