Selection of a High-Affinity DNA Aptamer for the Recognition of Cadmium Ions

Cadmium ions as toxic metallic pollutants have been dramatically risen due to industrial production, which causes serious environmental damages and potential health risks. Thus, developing sensitive and specific probes to recognize cadmium ions is vital for human and environmental safety. In this work, the aptamer as a capture probe was selected for the identification of cadmium ions. The modified SELEX method based on immobilizing ssDNA libraries on streptavidin magnetic beads was used to the high-affinity aptamer selection for binding cadmium ions. After 9 rounds of selection, 4 ssDNA sequences with the highest enrichment were obtained, and the Cd-1 aptamer exhibited the highest affinity to cadmium ions. The dissociation constant Kd value of the Cd-1 aptamer was 81.39 μM for cadmium ions. Later, we also investigated the binding specificity of Cd-1 aptamer toward other heavy metal ions. Given the availability of immobilizing ssDNA library on matrix, we believe the strategy also applies to discover other ions in a reproducible manner.

Screening of metallic pollution in complex environmental samples through a transcriptomic fingerprint method

Characterizing waste ecotoxicity is labourious because of both the undefined nature of environmental samples and the diversity of contaminants that can be present. With regard to these limitations, traditional approaches do not provide information about the nature of the pollution encountered. To improve such assessments, a fluorescent library of 1,870 transcriptomic reporters from E. coli K12 MG1655 was used to report the ecotoxic status of environmental samples. The reliability of the approach was evaluated with 6 metallic pollutants (As, Cu, Cd, Hg, Pb, Zn) used alone and in mixture in pure and complex matrices. A total of 18 synthetic samples were used to characterize the specificity of the resulting metallic contamination fingerprints. Metallic contamination impacted 4.5 to 10.2% of the whole transcriptomic fingerprint of E. coli. The analysis revealed that a subset of 175 transcriptomic reporters is sufficient to characterize metallic contamination, regardless of the nature of the sample. A statistical model distinguished patterns due to metallic contamination and provided information about the level of toxicity with 93–98% confidence. The use of the transcriptomic assessment was validated for 17 complex matrices with various toxicities and metal contaminants, such as activated sludge, wastewater effluent, soil, wood and river water. The presence of metals and their associated toxicity, which seems linked to their bioavailabilities, were thereby determined. This method constitutes a possible tool to screen unknown complex samples for their metallic status and identify those for which a deeper characterization must be achieved by the use of traditional biosensors and analytical methods.

PERBANDINGAN EFEKTIVITAS JERAPAN Pb DALAM PARTIKULAT OLEH POHON TANJUNG (Mimusops elengi) DAN POHON BUNGUR (Lagerstroemia) (STUDI KASUS DI JALAN TIMOHO YOGYAKARTA)

The ability of plants to absorb metallic pollutants varies. The research has been conducted to compare the effectiveness of Tanjung (Mimusops elengi) and Bungur (Lagerstroemia) plants in absorbing Pb metal in particulate matter. The effect of location and leaf height on the effectiveness of pollutant uptake was also observed. Sampling was carried out in July 2020-September 2020 by taking leaves that were not too dark or light in color. Leaves taken at heights 3, 6, and 9 m on Timoho side Street. The particulate and leaf samples were digested and then analyzed their Pb levels using an Atomic Absorption Spectrophotometer (AAS). The results showed that the Tanjung plants with denser leaves captured more particulate deposits than the Bungur plants. This plant is also more effective at absorbing and accumulating Pb metal, which is indicated by the ratio of Pb metal in the leaves to Pb in particulates which is higher than the Bungur plant. These results were consistent for each sampling period, at each location and each crown height.

Effects of Mixtures of Engineered Nanoparticles and Metallic Pollutants on Aquatic Organisms

In aquatic environment, engineered nanoparticles (ENPs) are present as complex mixtures with other pollutants, such as trace metals, which could result in synergism, additivity or antagonism of their combined effects. Despite the fact that the toxicity and environmental risk of the ENPs have received extensive attention in the recent years, the interactions of ENPs with other pollutants and the consequent effects on aquatic organisms represent an important challenge in (nano)ecotoxicology. The present review provides an overview of the state-of-the-art and critically discusses the existing knowledge on combined effects of mixtures of ENPs and metallic pollutants on aquatic organisms. The specific emphasis is on the adsorption of metallic pollutants on metal-containing ENPs, transformation and bioavailability of ENPs and metallic pollutants in mixtures. Antagonistic, additive and synergistic effects observed in aquatic organisms co-exposed to ENPs and metallic pollutants are discussed in the case of “particle-proof” and “particle-ingestive” organisms. This knowledge is important in developing efficient strategies for sound environmental impact assessment of mixture exposure in complex environments.