RESUMEN
Two-dimensional Mo2C/Mo2N composites were synthesized by high temperature ball milling and used as support materials for fabricating a chlorpyrifos (CPF) aptasensor. Gold nanoparticles (Au NPs) were electrodeposited on the surface of a Mo2C/Mo2N-modified electrode to connect with the ferrocene (Fc) probe via Au-S bonds. The Fc probe can hybridize with the aptamer probe to form a double-stranded structure. The addition of CPF made the double strands melt and the Fc probe approached the surface of the electrode, thereby resulting in amplification of the electrochemical response. The current response of the aptasensor for detecting CPF in solutions linearly varied from 0 to 400 ng mL-1 (with a maximum at 0.98 V vs. Ag/AgCl). The Au NPs/Mo2C/Mo2N composites exhibited satisfactory electrochemical behavior due to their excellent electrical conductivity and large surface area. This ultrasensitive aptasensor showed a low limit of detection of 0.036 ng mL-1. It was applied to determine CPF in real samples with acceptable recoveries from 94.7 to 116.7%, and the relative standard deviation was from 2.57 to 7.08%.Graphical abstract Schematic diagram of the manufacturing process of the aptasensor. Electrochemical aptasensor based on Mo2C/Mo2N/Au NP composites show excellent performance in detecting CPF.
RESUMEN
Boron nitride (BN) was used as a support and covered with an ionic liquid (IL) and tungsten disulfide (WS2) nanoparticles to obtain an electrode for the determination of 4-aminophenol (4-AP). BN was prepared using a "solvent cutting" method, and the BN-IL-WS2 nanocomposite was obtained by an ultrasonic method. BN and its hybrids were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. When the BN-IL-WS2 composites were coated on the surface of the electrode, the response to 4-AP was strongly amplified due to the strong synergetic effect between the three materials. The voltammetric response of the modified sensor (with a maximum at 0.29 V vs. Ag/AgCl) in solutions with a pH of 6 is linear in the 0.01-50 µΜ 4-AP concentration range, and the limit of detection is 3 nM. A modified glassy carbon electrode was applied for the determination of 4-AP in seawater and dispersions containing paracetamol tablets. The results were consistent with those obtained by HPLC. Graphical abstract Schematic representation of the voltammetric determination process of 4-aminophenol (4-AP). The electrochemical sensor based on the glassy carbon electrode modified with boron nitride (BN), ionic liquid (IL) and tungsten disulfide (WS2) nanomaterials. They, exhibit an excellent performance compared with other electrodes.
RESUMEN
A selective electrochemical biosensor was developed for detecting carbendazim (CBZ) based on well-dispersed colloidal boron nitride (BN) nanocrystals and gold nanoparticles (Au NPs). BN was synthesized by "solvent cutting" to modify a glassy carbon electrode (GCE), and Au NPs were then electrodeposited. A single-stranded oligonucleotide with methylene blue (MB) was modified to the electrode surface through gold-sulfur bonds. A double-stranded DNA was formed in the presence of an aptamer. The aptamer chain can specifically bind to the target CBZ. When the aptamer binds to CBZ, the electroactive substance MB labeled at one end of the complementary chain can effectively contact the electrode surface. Detection of CBZ is realized by simultaneously monitoring the MB signal enhancement. The CBZ concentration was determined in a wide linearity range from 0.1 ng mL-1 to 100 µg mL-1, with a low detection limit of 0.019 ng mL-1. This biosensor exhibited excellent selectivity and acceptable repeatability and was applied in cucumber, kiwifruit, and water samples with good recoveries, demonstrating that the strategy has remarkable potential and offers a good platform for CBZ detection.
RESUMEN
PPy-Fe3O4/Kaolin was prepared with polypyrrole functionalized magnetic Kaolin by a simple, green, and low cost method to improve the agglomeration and low adsorption capacity of Kaolin. PPy-Fe3O4/Kaolin was employed to remove Hg2+ and the results were characterized by various methods. Relevant factors, including solution pH, dosage of adsorbent, concentration (C0), and temperature (T), were optimized by Response Surface Methodology (RSM) and Central Composite Designs (CCD). The optimal results show that the importance for adsorption factors is pH > T > C0 > dosage, and the optimal adsorption conditions of PPy-Fe3O4/Kaolin are pH = 7.2, T = 315 K, C0 = 50 mg/L, dosage of 0.05 g/L, and the capacity is 317.1 mg/g. The adsorption process conforms to the pseudo-second-order and Langmuir models. Dubinin-Radushkevich model shows that adsorption process is spontaneous and endothermic. Moreover, the adsorption of mercury by PPy-Fe3O4/Kaolin was achieved mainly through electrostatic attraction, pore diffusion, and chelation between amino functional groups and Hg2+. PPy-Fe3O4/Kaolin has excellent reproducibility, dispersity, and chemical stability, and it is easy to be separated from solution through an external magnetic field. The experiments show that PPy-Fe3O4/Kaolin is an efficient and economical adsorbent towards mercury.
RESUMEN
Hexagonal boron nitride (BN), an effective diffusion material for mass transport, was functionalized with molybdenum disulfide (MoS2) and Au nanoparticles (Au NPs). Then, the working electrodes with developed nanomaterials were applied to construct an electrochemical paraquat sensor. BN was prepared using a solid-state synthesis method combined with solvent-cutting. The electrochemical properties of the BN/MoS2/Au NP-based glassy carbon electrode (GCE) were investigated using differential pulse voltammetry and cyclic voltammetry. An excellent response signal to paraquat was found from 0.1 to 100 µM with a limit of detection of 0.074 µM, and it had acceptable reproducibility (relative standard deviation = 2.99%, n = 5) and good anti-interference ability. The modified GCE showed superior performance owing to the synergistic effects among all three given nanomaterials. With the proposed method, paraquat in grass samples from an orchard was then investigated. The results of the electrochemical analysis agreed with those of experiments and obtained a 96.28% confidence level via high-performance liquid chromatography, exhibiting relatively high stability. Therefore, the fabricated sensor can be a candidate for the determination of paraquat.