MoS2 nanosheets grown on bowl-shaped hollow carbon spheres as an efficient electrochemical sensor for ultrasensitive determination of nephrotoxic aristolochic acids in Chinese traditional herbs.

Aristolochic acid, a substance in herbs, is highly nephrotoxic, so it is crucial to develop an assay that can rapidly and accurately analyze its content. In this study, bowl-shaped hollow carbon spheres (BHCs) were synthesized using a complex template method, and a MoS2 layer was grown in situ on their surface using a hydrothermal method. The synthesized MoS2-BHCs were used to fabricate an electrochemical sensor for the ultrasensitive and highly selective detection of aristolochic acids (AAs). The optimal conditions for AA detection were determined by tailoring the amount of MoS2 used to modify the BHCs and the pH of the electrolyte. Under optimal conditions, the MoS2-BHC-based sensor presented excellent AA detection performance. The linear concentration ranges of the MoS2-BHC-based sensor for the detection of AA were 0.05-10 µmol L-1 and 10-80 µmol L-1, and the limit of detection of the sensor was 14.3 nmol L-1. Moreover, the MoS2-BHC-based sensor detected AA in Aristolochia and Asarum sieboldii samples. The results were consistent with high-performance liquid chromatography data, demonstrating the satisfactory recovery and accuracy of the sensor. Therefore, we believe that MoS2-BHC-based sensors can be used as effective platforms for detecting AA in traditional Chinese herbs.

Determining three isoflavones from Pueraria lobata using magnetic ZIF-8 nanoparticle-based solid-phase extraction and pressurized capillary electrochromatography.

In this study, magnetic functionalized ZIF-8 nanoparticles were prepared by electrostatic self-assembly using magnetic Fe3O4 nanoparticles as cores and ZIF-8 as shells. ZIF-8 was used as the adsorbent to efficiently extract and sensitively analyze isoflavones due to its positive charge and strong adsorption capacity. Prepared samples were investigated by SEM and TEM, BET and ζ-potential analyses, FT-IR spectroscopy, powder XRD, and vibrating sample magnetism (VSM) experiments. The synthesized ZIF-8 has a dodecahedral structure that adsorbs well. Magnetic functionalized ZIF-8/Fe3O4 @SiO2 nanoparticles were prepared as a new SPE adsorbent, and a magnetic ZIF-8-pressurized capillary electrochromatography (pCEC) method was developed to separate and detect puerarin, daidzin, and daidzein (isoflavones) from Pueraria lobata by optimizing the extraction conditions, including adsorbent dosage, salt concentration, extraction time, desorption conditions, and other parameters. The developed method exhibited good linearities in the 50-2000 µg/mL concentration range for the three isoflavones, with coefficients of determination of 0.9934-0.9962. The limits of detection (LODs) for puerarin, daidzin, and daidzein were determined to be 0.02, 0.03, and 0.03 µg/mL, respectively. All analytes showed average recoveries in the 98.5-100.3% range, with relative standard deviations (RSDs, n = 6) of less than 4.0%. The developed method is convenient, enriches effectively, and shows good applications prospects for separating and analyzing components in Chinese herbal medicines.