Early thalassemia screening <i>via</i> hemoglobin β-subunit detection: a portable PDA–P <i>o</i> PD-MWCNT electrochemical immunosensor

β-Thalassemia is a hereditary hemolytic anemia caused by an imbalance in hemoglobin (Hb) synthesis. Patients experience severe anemia, with severe cases requiring lifelong blood transfusions. The condition may also lead to iron overload-related organ damage and growth and developmental disorders, imposing significant health and economic burden. The β-subunit of hemoglobin (HB-β) serves as a key biomarker closely associated with the onset and progression of β-thalassemia. Testing for HB-β is crucial for the early screening, genetic counseling, and early intervention of β-thalassemia. Based on this, an electrochemical immunosensor comprising polydopamine/poly(<i>o</i>-phenylenediamine)/multi-walled carbon nanotubes (PDA-P<i>o</i>PD-MWCNTs) was developed to detect the HB-β antigen. With abundant hydrophilic functional groups and amino and hydroxyl groups on the composites, the HB-β antibody (Ab) can be directly allowed to associate with dopamine (DA) molecules on the PDA-P<i>o</i>PD-MWCNT electrode under mild conditions. It caused HB-β-Ab to be immobilized on the electrode surface to obtain HB-β-Ab/PDA-P<i>o</i>PD-MWCNTs/GCE. This method utilizes the specific binding between the HB-β antigen and HB-β antibody (HB-β-Ab) to achieve highly sensitive and specific detection of HB-β. It offers a convenient, efficient, and ultrasensitive diagnostic approach for early screening and intervention of β-thalassemia based on hemoglobin β subunit detection. Under the optimized experimental conditions, the sensor exhibits an excellent linear relationship in the concentration range of 1.0-4.0 × 10⁵ ng mL^-1, and the detection limit is 0.3 ng mL^-1. This study presents an efficient, rapid, and low-cost diagnostic approach for early β-thalassemia screening, which is crucial for precise early detection and intervention in high-prevalence regions.