ABSTRACT
Microplastics (MPs) have found extensive application globally due to their low cost, flexibility and light weight. Microplastic pollution is a growing environmental concern that poses significant threats to aquatic ecosystems worldwide, including African freshwater systems. Nevertheless, although Africa houses some of the deepest and largest freshwater rivers and lakes in the world such as Lake Tanganyika and Victoria, River Congo and the Nile, there is limited information available regarding the presence of MPs in these inland waters. Selected published data on MPs in African freshwater systems, including sediments, biota, rivers, and lakes, were incorporated in this review. The study discovered that the sampling technique employed has a major impact on the morphological characteristics and abundance of MPs in African freshwater systems. Fibers and fragments were the most common shapes; black, white, and transparent were the most prevalent colors; and polyethene terephthalate, polystyrene, and polypropylene were the frequently dominant polymers. As the distance between the sampling sites increased geographically, the polymer similarities declined. MPs have been found to translocate into body cells and tissues where they are capable of causing genetic mutations, cytotoxicity, oxidative stress and neurotoxicity. In Africa, MPs are poorly managed and monitored, and there has been insufficient research done on the possibility that they could be present in drinking water. Considering the fact that humans in the continent are exposed to freshwater and aquatic organisms, the risk assessment routes are currently unvalidated, therefore it was recommended that African nations should strengthen their capacity for plastic management and environmental monitoring. This review provides up to date information on the occurrence, prevalence, ecotoxicity and management of MPs across African freshwater systems.
Subject(s)
Ecotoxicology , Environmental Monitoring , Fresh Water , Microplastics , Water Pollutants, Chemical , Microplastics/analysis , Water Pollutants, Chemical/analysis , AfricaABSTRACT
Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA.
Subject(s)
Flame Retardants , Polybrominated Biphenyls , Humans , Biological Monitoring , Flame Retardants/analysis , Polybrominated Biphenyls/toxicity , Polybrominated Biphenyls/analysisABSTRACT
Mining generates large volumes of waste, which if not regulated can release toxic metals, causing widespread environmental contamination. This study focused on heavy metal contamination in topsoil within a mining area at Nangodi in the Northern Region of Ghana. A total of 24 soil samples were collected from the study area and control samples were analyzed for Hg, Pb, Cd, As, Cr, and Fe using atomic absorption spectroscopy. Results of Pollution Index estimations and Geo-accumulation index (Igeo) classified the soil samples as moderately contaminated to heavily contaminated. Soil samples were severely enriched with As and moderately enriched with b, and Hg. Multivariate analyses such as factor analysis and cluster analysis were employed to examine the relationship between the metals and also differentiate the influence of the natural background content of metals from that due to human activities. Factor analysis identified three polluted soil factor associations. Cadmium, Fe, As, and Pb associated with factor 1, were due to anthropogenic activities. The high intercorrelation revealed by As and Pb shows similarity in their sources. Factor two dominated by Hg is considered an anthropogenic component. Factor 3 correlated with Cr and can be considered a natural component. Correlation analysis and cluster analysis supported each other. Results from the bi-plots showed that sites S1, S8, S11, and S18, have similar metal composition as the control site. Heavy metal contents in soils sampled from Zones A and B have been influenced by the mining activities as seen from the associations of these sites in the bi-plots. The results are useful for metal source identification, and can contribute to monitoring and regulatory programs.
ABSTRACT
Pharmaceuticals, heavy metals, pesticides, and dyes are the main environmental contaminants that have serious effects on both land and aquatic lives and necessitate the development of effective methods to mitigate these issues. Although some conventional methods are in use to tackle soil contamination, but biochar and biochar-based composites represent a reliable and sustainable means to deal with a spectrum of toxic organic and inorganic pollutants from contaminated environments. The capacity of biochars and derived constructs to remediate inorganic dyes, pesticides, insecticides, heavy metals, and pharmaceuticals from environmental matrices is attributed to their extensive surface area, surface functional groups, pore size distribution, and high sorption capability of these pollutants in water and soil environments. Application conditions, biochar feedstock, pyrolysis conditions and precursor materials are the factors that influence the capacity and functionality of biochar to adsorb pollutants from wastewater and soil. These factors, when improved, can benefit biochar in agrochemical and heavy metal remediation from various environments. However, the processes involved in biochar production and their influence in enhancing pollutant sequestration remain unclear. Therefore, this paper throws light on the current strategies, operational conditions, and sequestration performance of biochar and biochar-based composites for agrochemical and heavy metal in soil and water environments. The main challenges associated with biochar preparation and exploitation, toxicity evaluation, research directions and future prospects for biochar in environmental remediation are also outlined.
Subject(s)
Environmental Pollutants , Environmental Restoration and Remediation , Metals, Heavy , Pesticides , Soil Pollutants , Charcoal , Coloring Agents , Metals, Heavy/analysis , Pharmaceutical Preparations , Soil , Soil Pollutants/analysis , Wastewater , WaterABSTRACT
Various chemical treatment techniques are involved in removing refractory organic compounds from water and wastewater using the oxidation reaction of hydroxyl radicals (â¢OH). The use of catalysts in advanced catalytic ozonation is likely to improve the decomposition of molecular ozone to generate highly active free radicals that facilitate the rapid and efficient mineralization and degradation of numerous organics. For the degradation of toxic organic pollutants in wastewater, the advanced catalytic ozonation process has been widely applied in recent years. Low utilization efficiency of ozone and ineffective mineralization of organic contaminants by ozone can be remedied with advanced catalytic ozonation. Advanced catalytic ozonation has gained popularity because of these merits. However, homogeneous catalytic ozonation has the disadvantage of producing secondary contaminants from the addition of metallic ions. Heterogeneous catalytic ozonation can overcome this drawback by utilizing metals, metallic oxides, and carbon materials as a catalyst of efficacy and stability. This review discusses various aspects of catalytic ozonation in wastewater treatment of pharmaceutical pollutants, application of catalytic ozonation process in typical wastewater, and prospects in advancing the techniques in heterogeneous catalytic ozonation.
Subject(s)
Environmental Pollutants , Ozone , Pharmaceutical Preparations , Water Pollutants, Chemical , Water Purification , Catalysis , Wastewater , Water Pollutants, Chemical/analysisABSTRACT
The systematic investigation and risk assessment of dibutyl phthalate (DBP) were performed using an ultrasensitive dual-signal immunoassay in Zhenjiang, Jiangsu Province. In this study, C-dots@H-MnO2 nanohybrid were synthesized and labelled on the secondary antibody to generate fluorometric and colorimetric signals. Attributed to the efficient catalysis of carbon dots (C-dots) and the high C-dots loading of hollow manganese (IV) oxide (H-MnO2), the excellent sensitivity and low detection limits (0.243 and 0.692 µg/L respectively) were produced. Based on the proposed method, 25 water and 119 beverage samples were investigated. DBP was found in all water samples and 65.5% of beverage samples, with the concentrations varying in 16.5-32.1 µg/L and 0-553 µg/L, respectively. In addition, the mean concentration (22.9 µg/L) in waters was decreased significantly compared with that detected in 2016 (43.5 µg/L) by our Lab. For beverages, a similar phenomenon was observed by the measured concentrations from coffee. Furthermore, the potential ecological risks of DBP were evaluated, the results indicated that human activities had caused serious pollution and high risks to the local aquatic ecosystem. On the other hand, the results of health risk assessment suggested that DBP in beverages might not cause obvious side effects to local residents.
Subject(s)
Phthalic Acids , Water Pollutants, Chemical , Dibutyl Phthalate/toxicity , Ecosystem , Humans , Immunoassay , Manganese Compounds , Oxides , Risk Assessment , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicityABSTRACT
Tetrabromobisphenol A (TBBPA) is a kind of brominated flame retardant that is usually added to products to reduce their flame retardancy. However, its extensive use has resulted in their residues being found in the environment, which is very harmful. Herein, an indirect competitive immunosensor has been established for TBBPA detection based on the signal amplification system. Pd nanospheres in situ reduced on the surface of MnO2 nanosheet hybrid (MnO2/Pd) was used as the label for the secondary antibody through the Pd-N bond, and gold-toluidine blue composite was loaded onto MWCNTs (MWCNTs/Au-TB), which functioned as the platform for the immunosensor. The spherical structure of Pd had abundant catalytic active sites, which enhanced the catalytic activity of MnO2/Pd as the label, hence amplifying the signal response. Besides, MWCNTs/Au-TB improved electron transfer and produced a strong signaling pathway for immobilizing antigens through the Au-NH2 bond, which can specifically recognize primary antibodies to improve sensitivity. The immunosensor had a linear concentration range of 0-81 ng/mL, a low detection limit of 0.17 ng/mL (S/N = 3), with good stability, selectivity, and reproducibility based on the above advantages. Additionally, the acceptable accuracy and recoveries (recoveries, 92-124%; CV, 3.3-8.8%) in the real water sample analysis indicated that this strategy is promising for emerging pollutant analysis.
Subject(s)
Cetrimonium/chemistry , Electrochemical Techniques/methods , Manganese Compounds/chemistry , Oxides/chemistry , Polybrominated Biphenyls/analysis , Water Pollutants, Chemical/analysis , Antibodies, Immobilized/chemistry , Biosensing Techniques/methods , Immunoassay/methods , Limit of Detection , Nanostructures/chemistryABSTRACT
A facile immunosensor was constructed based on a barometer indicator using a double-antibody- sandwich method for rapid and sensitive detection of Escherichia coli (E. coli) from water samples. At the present study, Anti- E. coli DH-5 polyclonal antibody was modified through enriching carboxylated magnetic beads and catalase functionalized gold nanoparticles (AuNPs)- loaded nanospheres. The functionalized AuNPs-loaded nanospheres exhibited an excellent catalysis towards decomposition of hydrogen peroxide (H2O2), generating a large volume of oxygen (O2) into waters, increasing the pressure inside the glass vial, which in turn raised the water level in barometer. Under the optimized experimental conditions, the proposed method showed wide linear ranges (102- 107 cfu mL-1), good accuracy and precision (recoveries, 86.7- 107%; CV, 3.2- 8.1%) with a limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) were 80 cfu mL-1and 267 cfu mL-1, respectively. Furthermore, the fabricated portable immunosensor device showed some distinct features in low cost and visibility, suggesting great potential for rapid and on-site analysis of this bacteria from waters in less developed areas of developing countries.
Subject(s)
Biosensing Techniques , Electrochemical Techniques , Escherichia coli/isolation & purification , Immunoassay , Environmental Monitoring , Particle Size , Surface Properties , Water MicrobiologyABSTRACT
A simple indirectly competitive ratiometric fluorescent immunoassay was designed based on fluorescein amidite (FAM)-DNA-functionalized CdSe/ZnS quantum dots (QDs) for the sensitive determination of tetrabromobisphenol A (TBBPA). At the detection system, catalase (CAT) was labeled on the secondary antibody (Ab2), which served as a controller of the H2O2 concentration. After the competitive binding step, the emitted red fluorescence (excitation at 490 nm) from FAM-DNA-functionalized CdSe/ZnS QDs could be effectively quenched by the H2O2 added. Under the optimized conditions, the limit of detection (LOD) reached 0.118 µg/L with a linear range of 0.34-45.34 µg/L, which was approximately 1 order of magnitude lower than that by HRP-based traditional ELISA. Furthermore, the combination of the dual-output ratiometric fluorescence assays with ELISA improved the inherent built-in rectification to the environment, which brought about satisfactory accuracy and precision (recoveries, 83.16-112.4%; CV, 2.42-7.28%), indicating great potential for the determination of trace TBBPA from food and environmental samples. Graphical abstract.
Subject(s)
Environmental Monitoring/methods , Food Analysis/methods , Polybrominated Biphenyls/analysis , Quantum Dots/chemistry , Water Pollutants, Chemical/analysis , Animals , Cadmium Compounds/chemistry , Fluorescein/chemistry , Fluorescence , Fluorescent Dyes/chemistry , Food Contamination/analysis , Fresh Water/analysis , Immobilized Nucleic Acids/chemistry , Immunoassay/methods , Limit of Detection , Meat/analysis , Milk/chemistry , Selenium Compounds/chemistry , Sulfides/chemistry , Zinc Compounds/chemistryABSTRACT
Here, a novel chemiluminescence (CL) immunoassay was fabricated for sensitive determination of tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE), one of typical tetrabromobisphenol A derivatives. At the indirectly competitive method, the synthesized PS@hemin@Co2+ was labelled by secondary antibody (Ab2) instead of common natural enzymes, which showed excellent catalysis towards the decomposition of luminol-H2O2 for producing CL signal. Furthermore, the CL signal was greatly amplified owing to the synergistic catalysis of hemin and Co2+ in the detection system. Under the optimized conditions, the established method offered (i) low detection limit (LOD, 0.9 µg/L), which was almost 5 times lower than that using a conventional ELISA with the same antibody; (ii) a good linearity (1.6-14.3 µg/L); (iii) satisfactory accuracy and precision (recoveries, 89.67-125.33%; CV, 2.75-8.37%). The proposed CL immunoassay was applied for analysis of environmental samples from various sources collected from Jiangsu and Zhejiang province, China. And the detected concentrations were ranged in 2.4-3.7 µg/L in environmental waters and 1.8-2.4 ng/g (dry weight, dw) in soil samples, indicating great potential for trace TBBPA-DHEE detection from environmental samples.
Subject(s)
Immunoassay , Catalysis , China , Ethers , Hemin , Hydrogen Peroxide , Limit of Detection , Luminescence , Luminescent Measurements , Polybrominated BiphenylsABSTRACT
Nanozymes with peroxidase-like activity have been widely used as signal labels in electrochemical immunosensors. However, these sensors always suffer from some shortcomings during the processes underlying nanozyme labeling, including complex reactions, nanozyme inactivation after being decorated on the antibodies. To solve these problems, a novel electrochemical immunosensor was designed for ultrasensitive detection of sulfonamides (SAs), in which the synthesized 2D Cu-TCPP(Fe) with peroxidase-like property was used as a nanozyme that was directly modified on the electrode surface. Meanwhile, the structure of 2D Cu-TCPP(Fe) could be destroyed by the polyethyleneimine (PEI) from PEI-GO@Ab2 due to the stronger affinity between PEI and Cu2+, leading to an activity change of the prepared nanozyme. When H2O2 was introduced to the system, the electrochemical current was significantly declined owing to the peroxidase activity of 2D Cu-TCPP(Fe) decreased, which led to signal amplifications. Under the optimized conditions, this strategy had a wide detection range (1.186-28.051â¯ng/mL), satisfactory accuracy and precision (recoveries, 64-118%; CV, 2.16-7.27%) with a low detection limit of 0.395â¯ng/mL. The findings of this study indicate that the electrochemical immunosensor we developed has great potential and can be used for enzyme-free detection of SAs in environmental samples.
Subject(s)
Biosensing Techniques/methods , Copper/chemistry , Nanostructures/chemistry , Polyethyleneimine/chemistry , Sulfonamides/analysis , Water Pollutants, Chemical/analysis , Antibodies, Immobilized/chemistry , Catalysis , Electrochemical Techniques/methods , Hydrogen Peroxide/chemistry , Immunoassay/methods , Limit of Detection , Porphyrins/chemistryABSTRACT
An electrochemical biosensor was proposed utilizing an improved amplification strategy for the rapid detection of sulfamethazine (as a model target) in aquatic environments. In this competitive immunoassay, cetyltrimethylammonium bromide-capped gold nanoparticles (CTAB-AuNPs) were used as a signal amplifier and electrode matrix and coated with an antigen-antibody (Cag-Ab1) specific binding system as a recognition unit for the target compound. In addition, silver nanoparticle labels were functionalized with dendritic fibrous nanosilica (DFNS@AgNPs) and decorated onto chitosan/single walled carbon nanohorn (CS/SWCNH)-modified glass carbon electrodes (GCEs), which improved the electron transfer rate and increased the surface area, enabling more coating antigens to be captured. Under acidic conditions, massive amounts of the Ag+ bound to the surface of the AuNPs dissolved, and consequently, formed Ag+@CTAB-AuNP complexes, which resulted in a distinctly improved peroxidase-like activity and enhanced current response. Furthermore, the destroyed Ab1-Ab2-DFNS conjugation greatly decreased the impedance, bringing about the amplification of the electrochemical signals. After optimization of the parameters, the proposed approach exhibited excellent performance, including good sensitivity (LOD, 0.0655â¯ng/mL) and satisfactory accuracy (recoveries, 79.02%-118.39%; CV, 3.18%-9.82%), which indicates the great potential of this strategy for the rapid detection of trace pollutants in the environments.
Subject(s)
Biosensing Techniques , Immunoassay , Metal Nanoparticles/chemistry , Sulfamethazine/isolation & purification , Antibodies, Immobilized/chemistry , Carbon/chemistry , Chitosan/chemistry , Gold/chemistry , Humans , Limit of Detection , Silver/chemistry , Sulfamethazine/chemistryABSTRACT
MicroRNAs (miRNAs) play important roles as significant biomarkers in disease diagnostics. Here, an electrochemical biosensor was developed for the quick, sensitive, and specific detection of miRNAs from human-serum samples using three-dimensional (3D) DNA tetrahedron-structured probes (TSPs) and duplex-specific nuclease (DSN). The designed TSPs were composed of a recognition sequence that corresponded to a target miRNA and a G-quadruplex sequence that was combined with hemin to mimic the biocatalytic functions for H2O2 reduction and l-cysteine oxidation. After hybridization with miRNA, the TSPs were immobilized on the Au electrode to shape the DNA-RNA double strands, which could be discriminated by DSN for hydrolysis of the DNA in the heteroduplexes to generate significant change in the reduction currents. Under optimal conditions, the biosensor showed a wide linear response ranging from 0.1 fM to 0.1 pM, with a low detection limit of 0.04 fM. Meanwhile, the method showed acceptable accuracy and precision for the determination of miRNAs in serum after a series of assessments.