A {P6Mo18}-type heteropolyblue modified NiO-based carbon nanofibers for bifunctional biosensors

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Non-enzymatic electrochemical biosensors have great application value in the identification and detection of organic biological small molecules, especially in biomedical detection. In this paper, a carbon-based sensing material consisting of basket-type polyoxometallates (POMs) modified with synergistic multicomponent active centers was prepared. A novel POMs with heteropolyblue properties, {Co(phen)3}3[{Co(H2O)2}{Co(H2O)3}4}{Sr ⊂ P6MoVI16MoV2O73}2]·8H2O (CoP6Mo18), was modified on NiO-loaded carbon nanofibers (NiO-CNFs) to construct novel nanocomposites CoP6Mo18@NiO-CNFs. Differential pulse voltammetry (DPV) tests show that the nanocomposite electrode had a strong response to L-tryptophan (L-Trp) and dopamine (DA) with lower detection limit of 22.2 nM and 27.8 nM (S/N = 3) in the linear range of 66.7 nM-478 μM and 83.3 nM-437 μM, respectively. The results demonstrated that the modified electrode can quickly and efficiently detect DA and L-Trp alone or together due to catalytic synergy between CoP6Mo18 and NiO-CNFs. The combination of the two materials not only enhances the current response signals of the electrodes to the analytes DA and L-Trp, but also effectively improves the selectivity and stability of the sensor. Importantly, the prepared sensor can be used for trace detection of DA and L-Trp in pre-treated human serum samples in practical applications, and the recovery rate is as high as 98.9 %, which suggests that the CoP6Mo18@NiO-CNFs/GCE sensor has potential application value in biology and medical fields.