ZnO/porous carbon composite from a mixed-ligand MOF for ultrasensitive electrochemical immunosensing of C-reactive protein

Carbon-based nano-composite materials obtained via simple thermolysis of metal-organic framework (MOF) have competitive virtues in accordance of layered porosity, controllable morphologies, and easily functionalizing with other metal/metallic oxides or hetero atoms. These make them directly as high activity catalysts or supports for various electrochemical sensor. Herein, we developed a novel ZnO/porous carbon matrix (ZnO/MPC)-based electrochemical immunosensing through thermolysis of a mixed-ligand MOF (Zn-BDC-TED) for real sample analysis of C-reactive protein. The ZnO/MPC and ionic liquid (IL) composite membrane modified electrode displayed prominent conductivity and biocompatibility for ultrasensitive detection of C-reactive protein (CRP). Subsequently, the step-by-step assembly process of the CRP immunosensor was monitored by electrochemical measurements including cyclic voltammogram (CV) and electrochemical impedance spectra (EIS). After the parameter optimization, the differential pulse voltammetry (DPV) response decreased linearly with the logarithm of CRP levels in an extensive range of 0.01–1000 ng·mL−1, and the detection limit was as low as 5.0 pg·mL−1. Meanwhile, the lable-free immunosensor also showed excellent selectivity, reproducibility and stability. We believe that ZnO/MPC composite and many carbon-based nano-composite materials obtained via simple thermolysis of MOF will be a prospective platform for sensitive detecting other biomarkers.