Colorimetric and photothermal dual-mode sensing platform for catecholamines detection based on an irregular octahedral CoFe bimetallic organic framework nanozyme.

Accurate and efficient detection of catecholamines (CAs) is of great importance for the diagnosis and treatment of neuroendocrine-related diseases. However, developing convenient sensing platforms that combine high sensitivity, high selectivity, and multi-mode validation capabilities still faces challenges. To address this issue, an irregular octahedral cobalt-iron bimetallic organic framework (io-CoFe-MIL) nanozyme with excellent peroxidase-like activity was synthesized via a solvothermal method. The nanozyme can efficiently catalyze the oxidation of substrate 3,3',5,5'-tetramethylbenzidine (TMB), generating blue oxidized TMB (TMBox). The inhibitory effect of CAs on such TMB catalytic oxidation process leads to changes in both solution color and system temperature. Thus, a colorimetric/photothermal dual-mode sensing platform was constructed for catecholamines detection, as epinephrine (EP), dopamine (DA), and norepinephrine (NE). The colorimetric sensor exhibited sensitive responses toward various CAs with limit of detection (LOD) of 0.03 µM for EP, 0.055 µM for DA, and 0.08 µM for NE. While in the photothermal mode, the LODs for EP, DA, and NE were 0.027 µM, 0.74 µM and 1.2 µM, respectively. The presented dual-mode methods can be well used for sensitive detection of EP, DA, and NE in actual porcine serum samples, that are in consistent with those obtained from the instrument of HPLC, demonstrating the reliability and practical applicability of the method. This work provides a promising strategy for highly sensitive and multi-mode detections of CAs based on the synergistic integration of colorimetric and photothermal dual-signal responses.