Surface Modification of Gold Screen-Printed Electrodes with a Sulfonated Polymer for Improved Electrochemical Detection of Cardiac Troponin I

Cardiac troponins are fundamental biomarkers for the diagnosis and management of heart conditions. Cardiac troponin I (cTnI) plays a crucial role in muscle contraction and can be used as a specific biomarker for myocardial injury. Recent advancements in medical diagnostics include the use of electrochemical biosensors as a promising approach for rapid, sensitive, and cost-effective diagnostic tools. A promising alternative to improve electrochemical biosensor detection is electrode surface modification with conductive polymers. The incorporation of specific functional groups in conductive polymers may enhance the specificity for biomolecules. In this work, sulfonated poly-(styrene-isobutylene-styrene) (S-SIBS) is proposed as a selective polymer for cardiac troponin I detection on a gold screen-printed electrode (SPE) surface. This SPE surface modification enhances the selectivity and electrical signal, therefore allowing detection of cTnI. The experimental analysis was used to evaluate the electrochemical response of polymer-biomarker interactions. In addition, the research focused on determining the limit of detection (LOD) of cTnI using the gold SPE modified with an S-SIBS polymer electrochemical biosensor. The S-SIBS characterization was performed using Raman spectroscopy to confirm the presence of sulfonic groups and other chemical functionalities. The polymer and electrode surface analyses were obtained using Atomic Force Microscopy (AFM). The electrochemical technique used for the cTnI assay was Differential Pulse Voltammetry (DPV).