A Low-Cost Paper-Based Electrochemical Aptasensor for HER-2 Detection Using Ti ₃ C ₂ T _<i>x</i> MXene

Breast cancer remains a leading cause of mortality among women worldwide, emphasizing the need for early, rapid, and cost-effective diagnostic tools. In this study, we report a low-cost, paper-based electrochemical aptasensor for the specific detection of human epidermal growth factor receptor 2 (HER-2), a critical biomarker associated with breast cancer progression. The sensor was fabricated on a carbon screen-printed paper electrode (CSPPE) modified with Ti₃C₂T_<i>x</i> MXene, a two-dimensional transition metal carbide providing excellent conductivity and abundant surface sites for aptamer immobilization. The HER-2-specific aptamer was covalently attached onto the MXene surface via EDC-NHS coupling, and methylene blue (MB) served as a redox mediator to monitor binding events. The developed biosensor exhibited excellent analytical performance, achieving a wide linear detection range from 10 fg/mL to 100 μg/mL, a limit of detection (LOD) of 9.3 fg/mL, a limit of quantification (LOQ) of 28.4 fg/mL and a sensitivity of 10.05 μA/fg/mL/mm². Furthermore, the aptasensor demonstrated high selectivity, reproducibility, and operational stability, maintaining its sensing performance for up to one month under ambient storage conditions. The integration of MXene's superior electrical conductivity with a disposable paper-based platform presents a highly promising approach for point-of-care HER-2 detection, contributing toward accessible, rapid, and cost-effective breast cancer diagnostics.