Fabrication of ternary hybrid composites of Co-MOFs/MoS₂/PEDOTs for sensitive detection of dopamine and norepinephrine in biological samples

In this study, a simple and multifunctional application for Co-based organic frameworks (Co-MOFs) with molybdenum disulfide (MoS₂) and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOTs:PSS) is presented. The Co-MOFs with MoS₂ exhibit excellent peroxidase mimicking and catalytic activities, making them suitable for colorimetric dopamine sensors. From an electrochemical standpoint, fouling-free and selective sensing of dopamine (DA) and norepinephrine (NE) is highly challenging. However, the synergistic effect of morphological tunability of Co-MOFs with hybrid composites of MoS₂ and PEDOTs:PSS offers a wide detection concentration range of 2 nM-350 µM for DA and 20 nM-1000 µM for NE, high sensitivity, excellent anti-fouling, facile kinetic rate reaction, and rapid signal response. A high selectivity rate was achieved in the presence of twenty times higher concentrations of a mixture of ascorbic acid, uric acid, and other bio-chemical co-interferents. Interestingly, ultrasensitive detection limits of 0.23 nM and 2.18 nM (S/N = 3) were achieved for DA and NE, enabling the real-time precise detection of cellular concentrations in PC12 living cells, and biological fluid samples with simple dilution pretreatments. Moreover, the sensor demonstrated satisfactory reproducibility and stability. Finally, the morphological and composite activity-based probes can detect neurotransmitter concentrations in real samples beyond the concentration limit, suggesting a potential clinical sensor tool.