A label-free electrochemical biosensor for the detection of alpha-thalassemia 1 (SEA deletion) carriers using screen-printed carbon electrodes

A label-free electrochemical DNA biosensor based on electrochemical impedance spectroscopy (EIS) biosensor has been extensively developed for diagnosing human genetic diseases. However, its application has been limited to simulated target DNA. The aim of this study was to develop an EIS biosensor that can identify carriers of alpha (α)-thalassemia 1 with Southeast Asia (SEA) deletion. The biosensor was coupled with screen-printed carbon electrodes (SPCEs) and Hoechst 33,258 dye. To determine the optimal conditions and cutoff criteria, we evaluated forty samples with known DNA genotypes. Our findings suggested that the cutoff value for identifying α-thalassemia 1 (SEA deletion) carriers was more than 26.84 kΩ of negative imaginary impedance (-Z″) and 48.83 kΩ of charge transfer resistance (Rct). The sensitivity of the developed EIS biosensor was comparable to that of conventional gel electrophoresis, with no cross-reactivity observed in α-thalassemia 1 (THAI deletion), α-thalassemia 2 (3.7 deletion), α-thalassemia 2 (4.2 deletion), and beta (β)-thalassemia carriers. The diagnostic potential of the developed EIS biosensor was evaluated using 81 clinical blood samples, demonstrating 100% sensitivity, 88.2% specificity, 83.3% positive predictive value (PPV), 100% negative predictive value (NPV) and 92.6% accuracy for Rct measurement. The developed EIS biosensor presents an attractive screening method for the detecting α-thalassemia 1 (SEA deletion) carriers due to its simplicity, cost-effectiveness, and 45-fold reduction in turnaround time compared to conventional gel electrophoresis. Consequently, the identification of α-thalassemia 1 (SEA deletion) carrier through this approach represents the most effective strategy for the management and prevention of the most severe form of thalassemia.