Abstract
Detection of salivary pepsin has been given attention as a new diagnostic tool for laryngopharyngeal reflux (LPR) disease, because saliva collection is non-invasive and relatively comfortable. In this study, we prepared polypyrrole nanocorals (PPNCs) on a screen-printed carbon electrode (SPCE) by a soft template synthesis method, using β-naphthalenesulfonic acid (NSA) (for short, PPNCs/SPCE). Gold nanoparticles (GNPs) were then decorated on PPNCs/SPCE by electrodeposition (for short, GNP/PPNCs/SPCE). To construct the immunosensor, pepsin antibody was immobilized on GNP/PPNCs/SPCE. Next, citric acid was applied to prevent non-specific binding and change the electrode surface charge before pepsin incubation. Electrochemical stepwise characterization was performed using cyclic voltammetry, and immunosensor response toward different pepsin concentrations was measured by differential pulsed voltammetry. As a result, our electrochemical immunosensor showed a sensitive detection performance toward pepsin with a linear range from 6.25 to 100 ng/mL and high specificity toward pepsin, as well as a low limit of detection of 2.2 ng/mL. Finally, we quantified the pepsin levels in saliva samples of LPR patients (n = 2), showing that the results were concordant with those of a conventional ELISA method. Therefore, we expect that this electrochemical immunosensor could be helpful for preliminarily diagnosing LPR through the detection of pepsin in saliva.
Highlights
Laryngopharyngeal reflux (LPR) disease refers to the backflow of gastric juice containing acid and pepsin into the laryngopharynx, causing irritation of the vocal folds and the surrounding mucous membrane [1]
Electrodeposition of Gold nanoparticles (GNPs) on polypyrrole nanocorals (PPNCs)/screen-printed carbon electrode (SPCE) was carried out using cyclic voltammetry (CV) over ten cycles at a potential range from −1.0 to 0.2 V and at a scan rate of 50 mV·s−1 in a 0.1
We compared the sensitivity of the GNP/PPNCs/SPCE-based immunosensor with that of an SPGE-based immunosensor, which was prepared by the same fabrication process
Summary
Laryngopharyngeal reflux (LPR) disease refers to the backflow of gastric juice containing acid and pepsin into the laryngopharynx, causing irritation of the vocal folds and the surrounding mucous membrane [1]. Conducting polymer-based electrochemical biosensors have received great attention, because they are easy and cost-effective to fabricate, and show superior sensing performances, including high sensitivity, selectivity, and rapid response time [17]. GNPs possess unique properties, such as rich surface chemistry, low toxicity, high electron density, and strong optical absorption [24] Because this biologically inert material does not affect molecular structure or activity, GNPs can be functionalized with biological macromolecules to allow for detection using a variety of optical and electrochemical transduction mechanisms [7].
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