Electrochemical–Colorimetric Dual-Mode Sensor Based on a Co-Porphyrin Covalent Organic Framework Supported on MWCNTs

Reasonable molecular design and precise synthesis are effective approaches for obtaining dual-mode sensing materials for efficient detection in complex environments. Herein, we developed an integrating colorimetric and electrochemical sensing platform based on a Co-porphyrin covalent organic framework supported on multiwalled carbon nanotubes (TP-COF-Co@MWCNT). This composite was engineered to function as an efficient active material, where the conductive MWCNT network facilitates electron transfer for electrochemical sensing, while the atomically dispersed cobalt sites within the well-ordered COF channels confer robust peroxidase-like activity for colorimetric signaling. Leveraging these properties, the sensor enabled highly sensitive detection of dopamine (DA) with a low detection limit (LOD) of 27.8 nM (electrochemical, 0.4-1000 μM) and 0.35 μM (colorimetric, 0.9-80 μM). It also displayed excellent selectivity against common interferents and achieved satisfactory recovery rates in real serum and milk samples. This work not only presents a reliable sensing platform for DA but also demonstrates a potential application prospect of rational design of metalated COF-based composites for developing robust dual-mode assays in biomedical diagnostics.