College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun 130012, PR China.
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Qianjin Street 2699, Changchun 130012, PR China.
Anal Chem. 2022 Nov 22;94(46):16189-16195. doi: 10.1021/acs.analchem.2c03708. Epub 2022 Nov 4.
Mn(II)-based electron spin resonance (ESR) spectroscopy was used for detecting butyrylcholinesterase (BChE) and organophosphorus pesticides (OPs). MnO nanosheets were synthesized with manganese chloride and hydrogen peroxide. With the catalysis of BChE, S-butyrylthiocholine iodide (BTCh) was hydrolyzed into thiocholine which has a reducing -SH group. In the presence of thiocholine, MnO nanosheets were broken down and Mn(IV) in MnO nanosheets was reduced into Mn(II). Mn is a paramagnetic ion and gives a good ESR signal. In contrast, MnO nanosheets have no ESR signal and need not be separated from Mn. Mn can be determined directly by ESR spectroscopy, and no further sensing probe is needed. ESR spectroscopy based on directly detecting Mn is much simpler than those using other probes besides MnO. The ESR signal of Mn is proportional to the catalytic activity of BChE. OPs which inhibit the activity of BChE can also be detected by probing the ESR signal of Mn. Since there is no ESR signal of MnO nanosheets, the background signal in the absence of BChE was close to zero. The limit of detection (LOD) of BChE was as low as 0.042 U L. The standard curve for determining the OP paraoxon was established by measuring the inhibition of BChE by paraoxon, and the LOD of paraoxon was found to be 0.076 ng mL. The spiked Chinese cabbage extract samples were analyzed, and the experimental results indicated that the recoveries were from 96.5 to 102.8%. The planted Chinese cabbage was sprayed with the paraoxon solution, and the residue amount of paraoxon in the extract was estimated by the method. The result obtained by the present method was consistent with that obtained by HPLC, which proved the practicability of this new method.
Mn(II) 基电子自旋共振（ESR）光谱用于检测丁酰胆碱酯酶（BChE）和有机磷农药（OPs）。MnO 纳米片是用氯化锰和过氧化氢合成的。在 BChE 的催化下，S-丁酰硫代胆碱碘化物（BTCh）被水解成硫代胆碱，硫代胆碱具有还原的 -SH 基团。在硫代胆碱存在下，MnO 纳米片被分解，MnO 纳米片中的 Mn(IV)被还原成 Mn(II)。Mn 是顺磁离子，给出良好的 ESR 信号。相反，MnO 纳米片没有 ESR 信号，无需与 Mn 分离。Mn 可以直接通过 ESR 光谱测定，不需要其他传感探针。基于直接检测 Mn 的 ESR 光谱比使用 MnO 以外的其他探针要简单得多。Mn 的 ESR 信号与 BChE 的催化活性成正比。抑制 BChE 活性的 OPs 也可以通过探测 Mn 的 ESR 信号来检测。由于没有 MnO 纳米片的 ESR 信号，在没有 BChE 的情况下背景信号接近零。BChE 的检测限（LOD）低至 0.042 U L。通过测量对氧乐果的抑制作用，建立了测定 OP 对氧乐果的标准曲线，发现对氧乐果的 LOD 为 0.076 ng mL。对添加的白菜提取物样品进行分析，实验结果表明回收率在 96.5%至 102.8%之间。将白菜种植后喷洒氧乐果溶液，用该方法估计提取物中氧乐果的残留量。该方法得到的结果与 HPLC 得到的结果一致，证明了该新方法的实用性。
