Accurate and Sensitive Analytical Strategy for the Determination of Antimony: Hydrogen Assisted T-Shaped Slotted Quartz Tube-Atom Trap-Flame Atomic Absorption Spectrometry

Liquid crystal based sensor for antimony ions detection using poly-adenine oligonucleotides

Antimony is highly toxic and a key water pollutant, which needs to be monitored closely. To date, however, most analytical methods for antimony detection are quite limited because they are complicated, expensive, and not suitable for real-time monitoring of antimony. In this study, a label-free and rapid method for antimony ions (Sb3+) detection is developed based on liquid crystals and a 10-mer poly-adenine oligonucleotide as a specific recognition probe for the first time. The working principle is based on the binding of the oligonucleotide to Sb3+, which weakens the interaction between the oligonucleotide and cationic surfactants. As a result, the event induces a planar-to-homeotropic orientational change of liquid crystals and a bright-to-dark optical change under crossed polars. This liquid crystal-based optical sensor exhibits a rapid response to Sb3+ in 10 s, a detection range between 20 nM and 5 μM, and a detection limit at 6.7 nM calculated from 10-mins assay time. It also shows good selectivity against other metal ions including Ag+, Cd2+, Cu2+, Fe3+, K+, Mg2+, Mn2+, Na+, Pb2+, and Zn2+. Moreover, this system can be used to detect Sb3+ in aqueous solutions with different pH or ionic strengths. This simple, fast, and low-cost liquid crystal-based sensing approach with high sensitivity and selectivity has a high potential for detecting Sb3+ in natural environments and industrial wastewater.

Sensitive Silver-Enhanced Microplate Apta-Enzyme Assay of Sb3+ Ions in Drinking and Natural Waters

The toxic effects of antimony pose risks to human health. Therefore, simple analytical techniques for its widescale monitoring in water sources are in demand. In this study, a sensitive microplate apta-enzyme assay for Sb3+ detection was developed. The biotinylated aptamer A10 was hybridized with its complementary biotinylated oligonucleotide T10 and then immobilized on the surface of polysterene microplate wells. Streptavidin labeled with horseradish peroxidase (HRP) bound to the biotin of a complementary complex and transformed the 3,3',5,5'-tetramethylbenzidine substrate, generating an optical signal. Sb3+ presenting in the sample bounded to an A10 aptamer, thus releasing T10, preventing streptavidin-HRP binding and, as a result, reducing the optical signal. This effect allowed for the detection of Sb3+ with a working range from 0.09 to 2.3 µg/mL and detection limit of 42 ng/mL. It was established that the presence of Ag+ at the stage of A10/T10 complex formation promoted dehybridization of the aptamer A10 and the formation of the A10/Sb3+ complex. The working range of the Ag+-enhanced microplate apta-enzyme assay for Sb3+ was determined to be 8-135 ng/mL, with a detection limit of 1.9 ng/mL. The proposed enhanced approach demonstrated excellent selectivity against other cations/anions, and its practical applicability was confirmed through an analysis of drinking and spring water samples with recoveries of Sb3+ in the range of 109.0-126.2% and 99.6-106.1%, respectively.

Feasible Green Strategy for the Quantitative Bioaccumulation of Heavy Metals by Lemna minor: Application of the Self-Thinning Law

This study involved the development of mathematical linear regression models to describe the relationships between mean plant biomass (M) and population density (D), M and frond diameter (L), frond numbers (N) and L of Lemna minor under different initial population densities (3200, 4450, and 6400 plants/m²), respectively, from the perspective of the self-thinning law. Our results revealed that the value of the allometric exponents for M and D were - 3/2. Further, the concentrations of Zn, Pb, Cu, Fe, and Ni accumulated in L. minor plants were 0.86, 0.32, 0.36, 0.62, and 0.39 mg/kg, respectively. Based on these developed equations and the heavy metal accumulations by L. minor, the phytoremediation capacity of L. minor was quantified via its frond diameters. Overall, the present study provides a cost-effective green method for managing the phytoremediation of heavy metal-contaminated aquatic environments.

Colorimetric Technique for Antimony Detection Based on the Use of Gold Nanoparticles Conjugated with Poly-A Oligonucleotide

A simple and rapid positive–negative colorimetric approach to determine the presence of antimony ions based on the use of gold nanoparticles conjugated with oligonucleotide (poly-A sequence) is developed. Colorimetric measurements reveal that the aggregates of modified gold nanoparticles were afforded after adding antimony ions, thus changing the solution color from pink to blue. The results of aptamer’s interaction on the gold nanoparticle surface with the target analyte can be detected either by photometry or by the naked eye. The realized assay provides rapid (2 min), sensitive (detection limit 10 ng/mL), specific, and precise (variation coefficient less than 3.8%) detection of antimony (III) in drinking water.