Thiolated poly(aspartic acid)-functionalized two-dimensional MoS2, chitosan and bismuth film as a sensor platform for cadmium ion detection

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV). The performance of the TPA–MoS₂-modified sensor is systemically studied. It demonstrates that the TPA–MoS₂ nanocomposite modified sensor exhibits superior analytical performance for Cd²⁺ over a linear range from 0.5 μg L⁻¹ to 50 μg L⁻¹, with a detection limit of 0.17 μg L⁻¹. Chitosan is able to form a continuous coating film on the surface of the GC electrode. The good sensing performance of the TPA–MoS₂-modified sensor may be attributed to the following factors: the large surface area of MoS₂ (603 m² g⁻¹), and the abundant thiol groups of TPA. Thus, the TPA–MoS₂-modified sensor proves to be a reliable and environmentally friendly tool for the effective monitoring of Cd²⁺ existing in aquacultural environments.

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV).     

The detoxification mechanisms of low-accumulating and non-low-accumulating medicinal plants under Cd and Pb stress

Recently, the levels of heavy metals in medicinal plants have aroused widespread concern because these elements usually enter the food chain through plants and are gradually passed to the final consumers, greatly threatening human health. To reduce heavy metal pollution, it is necessary to solve the problem from the source to ensure environmental quality during medicinal material production. We use low-accumulating and non-low-accumulating medicinal plants to remediate soil contaminated by Cd and Pb. This experiment aims to study the amino acid levels in root exudates, to study antioxidant enzymes and malondialdehyde (MDA) in leaves, and to discuss the detoxification mechanisms of low-accumulating and non-low-accumulating medicinal plants under Cd and Pb stress. In soil contaminated with Cd or Pb, catnip, thyme and Fineleaf Schizonepeta Herb were cultivated. Enrichment factor (EF) and translocation factor (TF) levels were calculated to determine which are low-accumulating medicinal plants with respect to Cd or Pb. The relationships between the amino acid levels in root exudates, the levels of antioxidant enzymes, the present heavy metal species, heavy metal concentrations, and plant species were discussed. Under Pb and Cd stress, the total amounts of amino acids secreted by plant roots and the level of each amino acid were associated with the heavy metal concentrations and plant species. Plants alleviate Pb and Cd stress via adding malondialdehyde (MDA) and antioxidant enzymes. Thyme can be used as a low-accumulating medicinal plant with any concentration of the heavy metal Pb. These results are of great significance for understanding the chemical behaviors of heavy metals at the root/soil interface under Cd and Pb stress and the detoxification mechanisms of medicinal plants.

Recently, the levels of heavy metals in medicinal plants have aroused widespread concern because these elements usually enter the food chain through plants and are gradually passed to the final consumers, greatly threatening human health.