Competitive electrochemical assay of CA19-9 on gold nanoparticles/porous carbons nanohybrid amplified by polyoxometalate/aptamer/graphene quantum dot-decorated gold nanotags

Abstract

Although recent breakthroughs have brought hope for a complete cure for cancer, early and rapid diagnosis remains crucial for effective treatment. Carbohydrate antigen 19-9 (CA19-9) is a clinically established biomarker widely used in the diagnosis and management of gastric and pancreatic cancers. Accurate detection of CA19-9 is crucial for early diagnosis, treatment monitoring, and predicting recurrence. This study presents a novel competitive electrochemical aptasensor for CA19-9 detection, utilizing a composite of highly porous carbons (carboHIPEs) derived from the pyrolysis of polyHIPEs and polyethylenimine-capped gold nanoparticles (PEI-AuNPs) on a modified screen-printed electrode (SPE). The high porosity of carboHIPEs and the functionalized AuNPs enhance protein immobilization, boosting assay sensitivity and specificity. In this indirectly competitive assay, the CA19-9 is immobilized on the electrode surface, followed by binding with CA19-9-specific aptamer/polyoxometalate (POM)/graphene quantum dots (GQDs)@citrate-capped gold nanoparticles (CT-AuNPs) for signal amplification. The redox-active POM signal is measured via differential pulse voltammetry (DPV) in 0.20 M acetate buffer, with the electrochemical signal inversely correlating to CA19-9 concentration. The linear detection range of the sensor is observed from 0.10 to 200 U mL⁻¹ with a limit of detection (LOD) of 0.039 U mL⁻¹, making it suitable for the clinical diagnosis of both cancers. Integrating nanomaterials such as carboHIPEs, GQDs, and CT-/PEI-AuNPs yields high overall conductivity, increased electroactive surface area, and excellent biocompatibility, resulting in a high electrochemical response. This sensing platform offers broad detection capabilities and high selectivity, positioning it as a promising tool for detecting cancer biomarkers.