Metal organic frameworks derived Fe-N-C catalysts boosting dual-readout biosensing platform for vascular endothelial...

Thermal transformation of metal organic frameworks (MOFs) yields carbon-based catalysts with high activity and robust stability, providing an appealing strategy to enhance the performance of electrochemical sensing platform. Herein, by one-step pyrolysis of converting Fe-doped zeolitic imidazolate framework-8 into nitrogen-doped carbon-supported monodisperse Fe (Fe-N-C) catalysts, a dual-readout electrochemical biosensor was constructed for sensitive detection of vascular endothelial growth factor (VEGF). The stable FeN_X coordination structure endowed the Fe-N-C catalysts with peroxidase-like activity via Fe(II) to Fe(III) conversion. Using Fe-N-C catalysts as amplified signal labels, the chronoamperometric curve and impedance signal of the proposed biosensor could be flexibly readout by adjusting the catalytic substrate of tetramethylbenzidine-hydrogen peroxide (TMB-H₂O₂) and 3,3'-diaminobenzidine-H₂O₂ (DAB-H₂O₂). Based on the biotin-streptavidin conjugation and aptamer-target recognition, the presence of target VEGF165 induced the released of Fe-N-C catalysts and the decrease of signal readout, achieving sensitive detection of VEGF165 with the detection limits of 22.9 pg mL^-1 (current readout) and 20.5 pg mL^-1 (impedance readout), respectively, holding promising potential for disease diagnosis and therapeutic monitoring.