Microcontact-Printed Flexible Electrodes for Label-Free Electrochemical Detection of Lung Cancer Biomarker

Lung cancer remains one of the deadliest cancers worldwide, which highlights the urgent need for new diagnostic tools to detect reliable biomarkers. To enable scalable and cost-effective production, we developed reusable PDMS stamps patterned with electrodes to print flexible electrodes on PET substrates using a microcontact printing (µCP) approach. PET was chosen not only for its flexibility but also as a more sustainable alternative to conventional rigid materials. On these electrodes, three sensing platforms were tested for neuron-specific enolase (NSE) detection: APTES-based monolayers, electrospun PVA/alginate nanofibers, and electropolymerized polypyrrole (PPy) films. Voltammetric and fluorescence/AFM analyses confirmed that all three platforms could recognize the target analyte, with the PPy-CdTe configuration showing the strongest signal variation. Impedance spectroscopy further supported this finding, revealing a clear linear correlation between charge transfer resistance (RCT) and NSE concentration. The PPy-CdTe sensor demonstrated high sensitivity and consistent performance for NSE detection, achieving a detection limit (LOD) of 8.05 pg·µL−1 and a quantification limit (LOQ) of 26.84 pg·µL−1.