Defect and Additional Active Sites on the Basal Plane of Manganese-Doped Molybdenum Diselenide for Effective Enzyme Immobilization: In Vitro and in Vivo Real-Time Analyses of Hydrogen Peroxide Sensing

The defect engineering makes the new concepts and designs to further enhance the electrocatalytic activity of layered structures. In this work, we demonstrated the synthesis of Mn-doped MoSe ₂ and reported the resultant defective sites. Subsequently, the MnMoSe ₂ was developed as a new type of electrocatalyst for electrochemical biosensors. The formation of defect/distortion and effective immobilization of myoglobin (Mb) were evidently confirmed by using the transmission electron microscopy and UV-vis spectroscopy analyses, respectively. The result of electrochemical impedance spectroscopy analysis reveals that the Mn doping not only helps to enzyme immobilization but also enhances the electronic conductivity of layered material. Owing to the multiple signal amplification strategies, the proposed Mb-immobilized MnMoSe ₂ (Mb@MnMoSe ₂ ) exhibited an ultralow detection limit (0.004 μM) and a higher sensitivity (222.78 μA μM ^-1 cm ^-2 ) of H ₂ O ₂ . In real-sample analysis, the Mb@MnMoSe ₂ showed a feasible recovery range of H ₂ O ₂ detection in human serum (95.6-102.1%), urine (101.2-102.3%), and rain water (100.7-102.1%) samples. On the other hand, an in vivo study using HaCaT (7.1 × 10 ⁵ /mL) and RAW 264.7 (1 × 10 ⁶ /mL) living cells showed the feasible current responses of 0.096 and 0.085 μA, respectively. Finally, the Mn doping gives a new opportunity to fabricate a promising electrocatalyst for H ₂ O ₂ biosensing.