Tissue-like Conductive Ti3C2/Sodium Alginate Hybrid Hydrogel for Electrochemical Sensing

Endowed with a soft and conductive feature, hydrogels have been widely used as interface materials in bioelectronics to fulfill mechanical matching and bidirectional exchange between electronic platforms and living samples. Despite their ionic conductivity, the lack of electron mobility has limited their further applications in biosensing, especially in the field of electrochemical sensing. Here, we propose a Ti3C2/sodium alginate (SA) hybrid hydrogel with not only a tissue-like mechanical strength (down to 80 kPa) but also a combined exchange interface for ions and electrons, realizing both mechanical and electrical coupling toward biological tissues. Due to the shared gelation tendency with cations, the Ti3C2 sheets and SA chains can be easily in situ coassembled through a one-step electrogelation method, making the hybrid hydrogel a well-suited interface layer for device functionalization. In addition, the typical two-dimensional (2D) structure and the abundant active terminals of Ti3C2 have endowed the Ti3C2/SA with a massive loading capacity toward catalytic nanoparticles. For example, the Prussian Blue (PB)-loaded Ti3C2/SA hybrid hydrogel exhibited an excellent electrochemical performance (sensitivity: 600 nA μM-1 cm-2; LOD: 12 nM) toward hydrogen peroxide sensing in tissue fluids, illustrating a promising application potentiality of the hybrid hydrogel in biochemical detection at tissue interfaces.