Multilayer porous molecularly imprinted sensor based on MXene/amino carbon nanotubes for high sensitivity and selective detection of efflorin

Fischerin is a kind of flavonoids widely distributed in plants. It has anti-oxidation, anti-aging, anti-inflammatory, anti-bacterial and other physiological activities. Fisetin has attracted widespread attention due to its strong antioxidant properties and has been widely used in clinical chemistry and human health. Therefore, the accurate and sensitive detection of fisetin is of great significance. At present, high performance liquid chromatography (HPLC) is widely used in the detection of fisetin. The method is efficient and reliable, but the operating instrument is expensive and the procedure is complicated. In contrast, electrical analysis technology has the advantages of fast response, low cost, convenient operation, and short operation time. In addition, it is verified that the electrode material and structure play an important role in achieving high detection sensitivity. Not only are there few reports on the electrochemical detection of fisetin, but the sensitivity of these sensors still needs to be improved. Therefore, it is imperative to develop a new type of electrochemical sensing substrate.

Recently, Professor Lu Limin of Jiangxi Agricultural University published a research paper titled Hierarchical porous MXene/amino carbon nanotubes-based molecular imprinting sensor for highly sensitive and selective sensing of fisetin in the internationally renowned academic journal Sensors and Actuators B: Chemical. In this work, the process of self-assembly of negatively charged Ti3C2Tx flakes and positively charged NH2-CNTs to prepare MXene/NH2-CNTs was demonstrated and coupled with molecularly imprinted polymers (MIP) to produce A new type of electrochemical sensor for detecting flavin. The prepared MIP layer has super specificity for the fisetin sensor. MXene and NH2-CNTs have synergistic fast electron transfer ability, large electrochemical area and good catalytic activity, which helps to amplify electrochemical signals, thereby improving the sensitivity of the sensor. Using differential pulse voltammetry (DPV), the electrochemical sensor exhibits a wide linear concentration range between 0.003 μmol L-1 to 20.0 μmol L-1, and a low detection limit (LOD) of 1.0 nmol L-1. In addition, the MIP/MXene/NH2-CNTs sensor has good stability and repeatability, and has been successfully used for the detection of lacxanthin in Cotinus coggygria leaf samples.

Scheme 1. The preparation of MIP/MXene/NH2-CNTs/GCE and the schematic diagram of the adsorption mechanism in the imprinting cavity.

Figure 1. SEM images of different samples.

Figure 2. XPS analysis of different samples.

Figure 3. XRD analysis of pure MXene and MXene/NH2-CNTs.

Figure 4. Analysis of material electrochemical performance.

Figure 5. The effect of different conditions on the current response.

Figure 6. Characterization of different scan rates.

Scheme 2. The electrochemical oxidation reaction mechanism of fisetin.

Figure 7. DPV in MIP/MXene/NH2-CNTs/GCE with different concentration of fisetin.

Figure 8. Sensing stability characterization

Figure 9. Performance comparison of MIP/MXene/NH2-CNTs/GCE and HPLC.

     In summary, this paper uses MXene/NH2-CNTs as the substrate to prepare a molecularly imprinted sensor with high sensitivity and high selectivity. The cavity network of the MIP layer of the rhodoxanthin molecule can simultaneously identify and quantify the rhoseaxanthin, ensuring the high selectivity of the rhodoxanthin. Multi-layer porous MXene/NH2-CNTs composite material effectively provides a large electrochemical area and excellent electrical conductivity. The combination of MXene/NH2-CNTs and MIP has a good synergistic effect on the electrocatalytic oxidation of lutein. Based on these advantages, the obtained MIP/MXene/NH2-CNTs/GCE has a higher analytical performance for efflorescence, with an LOD of 1.0 nmol L−1. In addition, the modified electrode has also been successfully applied to the detection of lacxanthin in Cotinus coggygria leaves, with a good recovery rate. This method provides a simple, low-cost, selective and sensitive new method for the determination of flavonoids. Therefore, the sensor can be easily extended to the detection of other traditional Chinese medicines.

Literature link:

https://doi.org/10.1016/j.snb.2020.127815.

Information source: MXene Frontie

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