The levels of essential nutrients and nonessential metals in different varieties of teff produced in Hidabu Abote Woreda, Oromia, Ethiopia.

Ethiopia is the world's largest producer of teff (Eragrostis tef Zucc). This research was intended to determine the levels of mineral nutrients (metals and nonmetals) and nonessential metals in the grains of teff. Following the optimization of the method, the samples were wet-digested using reagents (5-mL HNO3 and 1-mL HClO4) at a temperature of 230°C for two and a half hours and analyzed using inductively coupled plasma-optical emission spectrometry. Under the optimum procedure, the coefficients of determination (R 2) ranged between .9980 and .9999. The limits of detection and limits of quantification were in the range of 0.036-14.49 and 0.111-43.93 mg/kg, respectively. The recovery ranged from 80.72% to 107.79%, indicating that the method was accurate. The optimized and validated method was applied to quantify the levels of analytes in the teff samples. The overall mean concentrations of the analytes in the three varieties of teff samples were determined (mg/kg) to be in the order P (3890-4853) > K (3040-3784) > Ca (1906-1959) > Mg (1402-1698) > Fe (128-305) > Mn (64-127.8) > Na (50-136.5) > Zn (19.8-27.3) > B (1.8-21.9) > Cu (4.17-6.9) > Ni (2.6-4.05) > Hg (1.8-4.0) > Pb (0.048-3.7) > Cd (0.012-2.09) > As (0.02-0.24), with a % RSD ranging between 0.017 and 11.1. The results revealed that teff grains are a good source of minerals and contain a significant amount of toxic elements, such as Cd, Hg, Pb, and As.

Two-Dimensional Layered Nanomaterial-Based Electrochemical Biosensors for Detecting Microbial Toxins.

Toxin detection is an important issue in numerous fields, such as agriculture/food safety, environmental monitoring, and homeland security. During the past two decades, nanotechnology has been extensively used to develop various biosensors for achieving fast, sensitive, selective and on-site analysis of toxins. In particular, the two dimensional layered (2D) nanomaterials (such as graphene and transition metal dichalcogenides (TMDs)) and their nanocomposites have been employed as label and/or biosensing transducers to construct electrochemical biosensors for cost-effective detection of toxins with high sensitivity and specificity. This is because the 2D nanomaterials have good electrical conductivity and a large surface area with plenty of active groups for conjugating 2D nanomaterials with the antibodies and/or aptamers of the targeted toxins. Herein, we summarize recent developments in the application of 2D nanomaterial-based electrochemical biosensors for detecting toxins with a particular focus on microbial toxins including bacterial toxins, fungal toxins and algal toxins. The integration of 2D nanomaterials with some existing antibody/aptamer technologies into electrochemical biosensors has led to an unprecedented impact on improving the assaying performance of microbial toxins, and has shown great promise in public health and environmental protection.

A novel reduced graphene oxide/molybdenum disulfide/polyaniline nanocomposite-based electrochemical aptasensor for detection of aflatoxin B1.

In this study, we developed a novel reduced graphene oxide/molybdenum disulfide/polyaniline@gold nanoparticles-based electrochemical aptasensor (termed as RGO/MoS2/PANI@AuNPs/Apt) for detection of aflatoxin B1 (AFB1). The RGO/MoS2/PANI nanocomposites were synthesized and characterized by multiple techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (FTIR), UV-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). A glassy carbon electrode (GCE) was then modified by the RGO/MoS2/PANI nanocomposites, coated with a chitosan (Cs) film, and followed by AuNPs attachment for immobilizing the AFB1 aptamers. In the presence of AFB1, the AFB1 binding-induced conformation change of the immobilized aptamer on the electrode surface results in the reduction of the electron transfer from a [Fe(CN)6]3-/4- redox couple in the solution to the GCE surface. Therefore, the aptamer-AFB1 binding event can be easily monitored by the peak current change of the RGO/MoS2/PANI@AuNPs/Apt through differential pulse voltammetry (DPV) measurement. Under the optimized conditions, the as-developed RGO/MoS2/PANI@AuNPs/Apt exhibits a wide linear range from 0.01 fg mL-1 to 1.0 fg mL-1 and a remarkably low detection limit (3σ) of 0.002 fg mL-1. The aptasensor also has good reproducibility as well as shows high selectivity against other fungal toxins, such as OTA and FB1. Moreover, the practicability of the RGO/MoS2/PANI@AuNPs/Apt was demonstrated by the analysis of AFB1 in the spiked wine samples.

Polyacrylamide-Phytic Acid-Polydopamine Conducting Porous Hydrogel for Efficient Removal of Water-Soluble Dyes.

Removal of toxic dyes from wastewater has become a hot topic in both academic and industrial fields since there is growing concern about the threat of sewage to human health. Herein, we demonstrate that the three-dimensional porous polyacrylamide-phytic acid-polydopamine (termed as PAAM/PA/PDA) hydrogel can be served as reusable adsorbent with high efficiency for either anionic or cationic dyes. Using methyl blue (MB), methylene blue (YMB), methyl violet (MV) and neutral red (NR) as model dyes, we investigate the effect of pH, temperature, dye concentration, and PAAM/PA/PDA hydrogel mass on the adsorption. The experimental maximum adsorption capacities are more than 350.67 mg g-1 for four selected dyes. Adsorption kinetic and thermodynamic analysis suggests that the dyes are adsorbed on the PAAM/PA/PDA hydrogel through the strong π-π stacking and anion-cation interaction, and the adsorption process satisfies a pseudo-second-order model. Furthermore, the free-standing PAAM/PA/PDA hydrogel can be easily removed from water after adsorption process, and regenerated by adjusting solution pH values.