A functional 2D MXene-DNA hybrid hydrogel for portable detection of blood disorder biomarker thrombin in human plasma

Delaminated MXenes (2D MXenes) and DNA hydrogels have created enormous opportunities due to their versatility and ability to be tailored for specific applications. 2D MXenes offer high aspect ratio morphology and electrical conductivity, while DNA provides stimuli responsiveness and specificity in binding to ligands or complementary sequences. This synergy makes DNA an ideal actuator when combined with 2D MXenes. The present work makes the first effort to integrate and exploit them for detecting the thrombin levels, a crucial proteolytic enzyme that plays a pivotal role in regulating blood clotting by cleaving fibrinogen into fibrin and plays a critical role in bleeding disorders such as haemophilia and Von Willebrand disease. This study introduces a novel hybrid DNA hydrogel by leveraging the properties of 2D MXenes with a thiol-modified thrombin-binding aptamer (TBA) as a crosslinking agent. The TBA and its complementary DNA oligos are immobilized on 2D MXene sheets, forming a packed hydrogel. Upon thrombin binding, the TBA releases its complementary DNA, resulting in a loosened hydrogel and a change in resistance, which is used as a read-out for thrombin detection. The fabricated sensor demonstrated a high sensitivity of 0.021 [MΩ (mg L^-1)]^-1 cm^-2, with a low limit of detection (LOD) of 0.1698 mg L^-1, a resolution of 6.51 mg L^-1 and also a wider linear detection range (LDR) of 10-200 mg L^-1 with a correlation coefficient (R²) of 0.98, indicating excellent linearity and reliability across the tested range. The concept was successfully demonstrated, achieving a relative standard deviation (RSD) of 8-10% for thrombin detection in artificial samples, indicating excellent performance. This robust technique holds promise for biomedical sensing devices, allowing customization for detecting various target molecules using specific aptamers.