MXene-integrated ZIF-7 nanohybrid platform for high-performance electrochemical creatinine sensing

Two-dimensional 2D MXenes have been explored as electrochemical sensing materials however, their output current signals often remain low. To address this limitation, we rationally designed ZIF-7/Ti₃C₂T_x heterostructure by integrating zeolitic imidazolate framework (ZIF-7) with MXene (Ti₃C₂T_x) via a one-pot solvothermal method. This nanohybrid was subsequently applied to a pencil graphite electrode (PGE) via direct dip-coating to create an advanced sensor for creatinine detection. Comprehensive characterization of the ZIF-7/Ti₃C₂T_x nanocomposite was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX), and X-ray photoelectron spectroscopy (XPS). The anchoring of ZIF-7 onto Ti₃C₂T_x nanosheets not only enhances conductivity but also prevents restacking, thereby increasing the availability of electroactive sites, defects, and functional groups. The modified electrode exhibited remarkable electrochemical performance, with a linear response to creatinine concentrations ranging from 1 to 50 μM (R² = 0.996) and a low quantitation limit of 261 nM. The sensor achieved a high sensitivity of 0.079 mAμM^-1cm^-2 and a limit of detection (LOD) of 86 nM. Furthermore, the sensor showed excellent selectivity, repeatability (RSD = 0.53 %), and reproducibility (RSD = 2.36 %), with high recovery rates (94.1-101 %) for creatinine detection in real human saliva samples, underscoring its potential for precise creatinine monitoring in clinical diagnostics. This work demonstrates the successful integration of ZIF-7 with Ti₃C₂T_x to engineer a high-performance creatinine sensor with outstanding sensitivity, stability, and real-sample validation. The approach highlights the potential of ZIF/MXene heterostructures as promising candidates for non-invasive and accurate clinical diagnostics.