Anekrattanasap A.Park J.Villarini N.Fukana N.Rai A.J.Siangproh W.Baldo T.A.Henry C.S.Mahidol University2026-05-162026-05-162026-09-15Biosensors and Bioelectronics Vol.308 (2026)09565663https://repository.li.mahidol.ac.th/handle/123456789/116776Early and accurate diagnosis of breast cancer is essential for guiding less invasive and more effective treatment. The overexpression of human epidermal growth factor receptor 2 (HER2) is a key molecular biomarker for breast cancer classification and treatment selection. However, conventional HER2 detection methods, such as immunohistochemistry and ELISA, suffer from limitations including invasive sampling, high cost, and labor-intensive procedures. In this work, we present a magnetic bead-based electrochemical capillary-driven immunoassay (meCaDI). This platform combines magnetic bead-based target enrichment, sensitive electrochemical detection, and a capillary-driven microfluidic format suitable for point-of-care (POC) applications. HER2 is first captured using antibody-functionalized magnetic beads. A sandwich immunocomplex is then formed using a biotinylated detection antibody and a horseradish peroxidase (HRP)-labeled streptavidin conjugate. The complex is magnetically concentrated at the detection zone, where HRP catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). Automated reagent delivery and removal are achieved through a low-cost capillary-driven microfluidic device, eliminating the need for washing steps. The system was progressively optimized from a static assay to a semi-automated magnetophoretic slider platform and finally to the fully integrated meCaDI device. The meCaDI platform achieved a limit of detection of 5.8 ng/mL for HER2 and showed good recovery in spiked serum samples (89.36–129.20%). These results demonstrate a sensitive, specific, and portable biosensing platform for HER2 detection, highlighting its potential for on-site breast cancer diagnostics.ChemistryBiochemistry, Genetics and Molecular BiologyEngineeringArticleSCOPUS10.1016/j.bios.2026.1187472-s2.0-10503813381018734235