α-Fe₂O₃/Ti₃C₂T_xMXene heterostructures as photo-fenton catalysts driving RAFT polymerization for ultrasensitive...

Photocatalytic processes have emerged as powerful signal amplification strategies for electrochemical biosensors by generating reactive radicals under mild conditions. However, the integration of photocatalysis with controlled radical polymerization, such as reversible addition-fragmentation chain transfer (RAFT), remains underexplored. Herein, we report a novel photo-Fenton-mediated RAFT polymerization system based on a heterostructured α-Fe₂O₃/Ti₃C₂T_xMXene, which synergistically bridges photocatalysis and polymer chemistry for biosensing applications. Within this heterostructure, Ti₃C₂T_xMXene serves as a conductive scaffold that promotes charge separation in α-Fe₂O₃ under visible light, accelerating H₂O₂ decomposition to generate abundant hydroxyl radicals (•OH). These radicals initiate and regulate RAFT polymerization, enabling controllable chain growth and amplified electrochemical signals. The developed photo-Fenton-driven RAFT coupling was successfully integrated into a biosensor for microRNA-144 detection, exhibiting a broad linear range (0.01 fM-10 pM) and an ultralow detection limit of 4.44 aM. This work demonstrates a synergistic strategy that connects photocatalysis with controlled radical polymerization, providing a rational design approach for MXene-based hybrid materials toward ultrasensitive biomedical sensing.