Sensitive Detection of Epidermal Growth Factor in Lung Cancer Patients by Electrochemical Biosensors

Lung cancer is the most common cancer worldwide, responsible for more deaths per year than any other cancer, with non-small cell lung cancer (NSCLC) being the most prevalent form. Elevated epidermal growth factor (EGF) levels have been associated with NSCLC and decreased survival, highlighting its potential as a prognostic and predictive biomarker. This study proposes developing and validating a novel impedimetric electrochemical biosensor for the sensitive and accurate detection of EGF in serum samples from patients with lung adenocarcinoma. The biosensor was constructed by electropolymerization of polypyrrole nanotubes (PPy-NTs) on screen-printed carbon electrodes, followed by the deposition of carboxylated multiwalled carbon nanotubes (MWCNT-COOH) used for the immobilization of biorecognition elements. Anti-EGF antibodies were covalently immobilized on the MWCNT-COOH-modified surface, and bovine serum albumin (BSA) was used to block nonspecific interactions. Electrochemical impedance spectroscopy (EIS) was employed to characterize each fabrication step and to detect EGF. The biosensor demonstrated a wide linear detection range from 500 fg mL^-1 to 200 pg mL^-1 with high linearity (R² = 0.9924) and a remarkably low limit of detection (LOD) of 392 fg mL^-1. The developed biosensor demonstrated excellent agreement with ELISA results, with a strong Pearson correlation (r = 0.865, p < 0.0001), and Bland-Altman analysis with 97.4% of the differences within the limits of agreement. The biosensor successfully monitored changes in EGF levels in patients undergoing chemotherapy, showing a percentage change similar to that observed with ELISA. These results indicate that the developed impedimetric biosensor is a promising, sensitive, and reliable alternative for monitoring EGF levels in lung cancer patients, potentially aiding in prognosis and treatment evaluation.