Performance comparison between solid phase extraction and magnetic carbon nanotubes facilitated dispersive-micro solid phase extractions (Mag-CNTs/d-µSPE) of a cyanide metabolite in biological samples using GC–MS

Dispersive-micro solid phase extraction (d-µSPE) has gained increasing attention due to its convenience, effectiveness, and flexibility for sorbent selection. Among a various selection of materials, magnetic carbon nanotubes (Mag-CNTs) is a promising d-µSPE sorbent with excellent separation efficiency in addition to its high surface area and adsorption capability. In this work, two different surface-modified Mag-CNTs, Mag-CNTs-COOH and Mag-CNTs-SO3H, were developed to facilitate d-µSPE (Mag-CNTs/d-µSPE). The cyanide metabolite, 2-aminothiazoline-4-carboxylic acid (ATCA), was selected to evaluate their extraction performance using gas chromatography–mass spectrometry (GC–MS) analysis. The Mag-CNTs-COOH enabled a one-step derivatization/desorption approach in the workflow; therefore, a better overall performance was achieved. Compared to the Mag-CNTs-SO3H/d-µSPE and SPE workflow, the one-step desorption/derivatization approach improved the overall extraction efficiency and reduced solvent consumption and waste production. Both Mag-CNTs/d-µSPE workflows were validated according to ANSI/ASB 036 guidelines and showed excellent analytical performances. The limit of detection (LOD) and limit of quantitation (LOQ) of ATCA in synthetic urine were 5 and 10 ng/mL, respectively, and that in bovine blood were achieved at 10 and 60 ng/mL. The SPE method’s LOD and LOQ were also determined at 1 and 25 ng/mL in bovine blood samples. The Mag-CNTs/d-µSPE methods demonstrated great potential to extract polar and ionic metabolites from biological matrices. The extraction processes of ATCA described in this work can provide an easier-to-adopt procedure for potential routine forensic testing of the stable biomarker in cyanide poisoning cases, particularly for those cases where the cyanide detection window has passed.

The selective adsorption performance and mechanism of multiwall magnetic carbon nanotubes for heavy metals in wastewater

The safe treatment of heavy metals in wastewater is directly related to human health and social development. In this paper, a new type of recyclable adsorbent is synthesized through the oxidation of enhancer and modification with magnetic nanoparticles. The new adsorbent not only inherits the advantages of multiwall carbon nanotubes (6O-MWCNTs), but also exhibits a new magnetic property and further improved adsorption capacity, which is conducive to the magnetic separation and recovery of heavy metals. The adsorption results indicate that multiwall magnetic carbon nanotubes (6O-MWCNTs@Fe3O4) have a good performance for Pb(II) selective adsorption, with a maximum adsorption capacity of 215.05 mg/g, much higher than the existing adsorption capacity of the same type of adsorbents. Under the action of an external magnetic field, 6O-MWCNTs@Fe3O4 that adsorbed metal ions can quickly achieve good separation from the solution. The joint characterization results of FTIR and XPS show that under the action of both coordination and electrostatic attraction, the C=O bond in the –COOH group is induced to open by the metal ions and transforms into an ionic bond, and the metal ions are stably adsorbed on the surface of 6O-MWCNTs@Fe3O4. Pb(II) has a stronger attraction than Cu(II) and Cd(II) to the lone pair of electrons in oxygen atoms to form complexes, due to the covalent index of Pb (6.41) is more larger than that of Cu (2.98) and Cd (2.71).These data provide a new type of recyclable adsorbent for the efficient treatment of heavy metal ions in wastewater and enrich relevant theoretical knowledge.

Investigation the Effect of Encapsulated Bromelain Enzyme in Magnetic Carbon Nanotubes on Colorectal Cancer Cells

Background: Bromelain (BL) is an enzyme extracted from Ananas comosus, which has been known for its therapeutic properties. Objectives: The anticarcinogenic activity of BL was examined with and without the presence of magnetic carbon nanotubes (MCNTs) against HT-29 colorectal cancer cells. Methods: The operational factors affecting BL adsorption, such as contact time (30, 60, 90, 120, and 180 min), adsorbent dosage (1 g/L and 5 g/L), initial bromelain concentration (50, 150, and 300 mg/L), and temperature (35 and 50°C) were studied in details. Then, cancer cells were exposed to various BL concentrations (0.1, 1, 10, and 100 μg/mL), and the cell viability was determined by methylthiazol tetrazolium (MTT) assay after 24, 48, and 72 h. Results: The highest adsorption of BL on nanotubes was at 41.62 mg/L and achieved at 35°C and 90 min at the initial concentration of 50 mg/L and 1 g/L of MCNTs. The adsorption followed the Freundlich model and second-order kinetics. The results indicated that MCNTs could be a potential effective adsorbent for the removal of BL. Conclusions: MTT assay indicated that BL at a concentration of 100 μg/mL alone and in combination with MCNTs efficiently inhibited the HT-29 cancerous cells. However, encapsulated BL had a considerable advantage of slow delivery, which is favorable for cancer treatment.