Antibiotics soil-solution chemistry: A review of environmental behavior and uptake and transformation by plants.

The increased use of antibiotics by humans for various purposes has left the environment polluted. Antibiotic pollution remediation is challenging because antibiotics exist in trace amounts and only highly sensitive detection techniques could be used to quantify them. Nevertheless, their trace quantity is not a hindrance to their transfer along the food chain, causing sensitization and the development of antibiotic resistance. Despite an increase in the literature on antibiotic pollution and the development and transfer of antibiotic-resistant genes (ARGs), little attention has been given to the behavior of antibiotics at the soil-solution interface and how this affects antibiotic adsorption-desorption interactions and subsequent uptake and transformation by plants. Thus, this review critically examines the interactions and possible degradation mechanisms of antibiotics in soil and the link between antibiotic soil-solution chemistry and uptake by plants. Also, different factors influencing antibiotic mobility in soil and the transfer of ARGs from one organism to another were considered. The mechanistic and critical analyses revealed that: (a) the charge characteristics of antibiotics at the soil-root interface determine whether they are adsorbed to soil or taken up by plants; (b) antibiotics that avoid soil colloids and reach soil pore water can be absorbed by plant roots, but their translocation to the stem and leaves depends on the ionic state of the molecule; (c) few studies have explored how plants adapt to antibiotic pollution and the transformation of antibiotics in plants; and (d) the persistence of antibiotics in cropland soils can be influenced by the content of soil organic matter, coexisting ions, and fertilization practices. Future research should focus on the soil/solution-antibiotic-plant interactions to reveal detailed mechanisms of antibiotic transformation by plants and whether plant-transformed antibiotics could be of environmental risk.

Defective zirconium/titanium bimetallic metal-organic framework as a highly selective and sensitive electrochemical aptasensor for deoxynivalenol determination in foodstuffs.

An electrochemical aptsensor for deoxynivalenol determination was successfully designed and constructed based on a defective bimetallic organic framework (denoted as ZrTi-MOF). The high porosity, large specific surface area, several structural defects, mixed metal clusters, and rich functionality of ZrTi-MOF markedly enhanced its electrochemical activity and facilitated the aptamer immobilization. As a result, the ZrTi-MOF-based aptasensor shows high sensitivity to detect deoxynivalenol via specific recognition between aptamer and deoxynivalenol, as well as the formation of aptamer-deoxynivalenol complex. On this basis, the developed ZrTi-MOF-based impedimetric aptasensor showed a low detection limit of 0.24 fg mL-1 for deoxynivalenol determination in the deoxynivalenol concentration range 1 fg mL-1- 1 ng mL-1 under optimized conditions, which also exhibited satisfactory selectivity, stability, reproducibility, and regenerability. Furthermore, determination of deoxynivalenol was achieved in bread and wheat flour samples via the developed ZrTi-MOF-based deoxynivalenol aptasensor. The result from this study showed that the ZrTi-MOF-based electrochemical aptasensor could become a promising strategy for detecting deoxynivalenol in foodstuffs in the future.

Recent perspective of antibiotics remediation: A review of the principles, mechanisms, and chemistry controlling remediation from aqueous media.

Antibiotic pollution is an ever-growing concern that affects the growth of plants and the well-being of animals and humans. Research on antibiotics remediation from aqueous media has grown over the years and previous reviews have highlighted recent advances in antibiotics remediation technologies, perspectives on antibiotics ecotoxicity, and the development of antibiotic-resistant genes. Nevertheless, the relationship between antibiotics solution chemistry, remediation technology, and the interactions between antibiotics and adsorbents at the molecular level is still elusive. Thus, this review summarizes recent literature on antibiotics remediation from aqueous media and the adsorption perspective. The review discusses the principles, mechanisms, and solution chemistry of antibiotics and how they affect remediation and the type of adsorbents used for antibiotic adsorption processes. The literature analysis revealed that: (i) Although antibiotics extraction and detection techniques have evolved from single-substrate-oriented to multi-substrates-oriented detection technologies, antibiotics pollution remains a great danger to the environment due to its trace level; (ii) Some of the most effective antibiotic remediation technologies are still at the laboratory scale. Thus, upscaling these technologies to field level will require funding, which brings in more constraints and doubts patterning to whether the technology will achieve the same performance as in the laboratory; and (iii) Adsorption technologies remain the most affordable for antibiotic remediation. However, the recent trends show more focus on developing high-end adsorbents which are expensive and sometimes less efficient compared to existing adsorbents. Thus, more research needs to focus on developing cheaper and less complex adsorbents from readily available raw materials. This review will be beneficial to stakeholders, researchers, and public health professionals for the efficient management of antibiotics for a refined decision.

High efficient electrochemical biosensor based on exonuclease-â ¢-assisted dual-recycling amplification for ultrasensitive detection of kanamycin.

A target-triggered and exonuclease-Ⅲ-assisted strand displacement, dual-recycling amplification reaction-based biosensor was developed for the rapid, ultrasensitive and accurate detection of kanamycin. The robust profiling platform was constructed using high conductive MXene/VS2 for the electrode surface modification and high active CeCu2O4 bimetallic nanoparticles as nanozyme to improve the sensitivity as well as the catalytic signal amplification of the biosensor. Using the dual supplementary recycling of primer DNA and hairpin DNA, the electrochemical platform could accurately detect kanamycin to as low as 0.6 pM from the range of 5 pM to 5 µM. By profiling five other antibiotics, this platform exhibited high specificity, enhanced repeatability and reproducibility. Based on these intrinsic characteristics and by utilizing milk and water samples, the as-designed biosensor offers a remarkable strategy for antibiotic detection due to its favorable analytical accuracy and reliability, thereby demonstrating potential application prospect for various antibiotic biosensing in food quality control, water contamination detection and biological safety analysis.

Bipedal DNAzyme walker triggered dual-amplification electrochemical platform for ultrasensitive ratiometric biosensing of microRNA-21.

Circulating microRNAs (miRNAs) can be regarded as reliable noninvasive biomarkers in body fluids for the early diagnosis, prognosis, and monitoring of cancers. By combining target triggered bipedal DNAzyme walker cleavage cycling amplification and planar intercalated methylene blue (MB) molecules amplification, a versatile ratiometric electrochemical biosensing system is constructed for miRNAs detection. Using the microRNA-21 (miRNA-21) as a triggered model target from breast cancer cells (MCF-7) and cervical cancer cells (HeLa), the sensitivity and feasibility of the ratiometric biosensing strategy were verified on the basis of decreased streptavidin-conjugated cupric sulfide@platinum (CuS@Pt-SA) nanozyme signal with cleaved Zn2+-dependent DNAzyme walkers as well as enhanced duplex section of MB signal, which were assisted by the modification of high electronic conductivity and specific surface area of metallic WSe2 nanoflowers on the electrode. Hence, the introduced sensing strategy of higher cleavage activity of the bipedal DNAzyme walker cyclic amplification resulted into the remarkable sensitive measurement which had a detection limit of 0.16 fM from 1 fM to 1 nM for miRNA-21. Benefiting from the precise design of the capture Hairpin DNA, this proposed method showed excellent specificity to distinguish miRNA-21 from other miRNAs sequences, in addition to possessing good stability and reproducibility. Thus, this versatility platform can be utilized to sense various miRNAs biomarkers by simple of the redesigning the capture Hairpin DNA, hence presents a great promise in clinical application towards early cancer diagnosis, biological analysis and prognosis.

Macro problems from microplastics: Toward a sustainable policy framework for managing microplastic waste in Africa.

Microplastic pollution is a ubiquitous and emerging environmental and public health concern in Africa due to increased plastic production, product and waste importation, and usage. While studies on the environmental monitoring and characterization of microplastics demonstrated the urgent need for a drastic reduction in plastic waste generation, the effectiveness of the various regulatory and policy interventions implemented or proposed in Africa countries remains poorly understood. We critically examined policies, legislations, and regulations enacted to control microplastic pollution in Africa to develop a sustainable, harmonized framework for the coordinated reduction of plastic waste generation across Africa. Analysis of the interventions revealed most African countries employed traditional perspective (i.e., command-and-control) approaches, whereby state instruments such as plastic ban, production and importation levies, and consumer taxes were enacted. However, the continued increase in microplastic waste generation suggests traditional perspective approaches might not be effective in Africa. Although rarely used in Africa, market-oriented approaches such as private-public waste management are often effective in controlling plastic pollution. Hence, we proposed a bottom-up hybrid regulatory approach for managing microplastics pollution in Africa, involving price-based, right-base, legislation and behavioral frameworks based on best practices in microplastic waste management.

Development of oxidized hydroxyethyl cellulose-based hydrogel enabling unique mechanical, transparent and photochromic properties for contact lenses.

With the development of smart devices, higher requirements are put forward for the stimuli-responsive materials. Stimuli-hydrogels as one kind of stimuli-responsive materials with hydrophilicity, demonstrate huge potential in developing intelligent devices for biomedical application. On this basis, we herein report that a sample method was devised to develop a novel composite hydrogel mainly based on oxidized hydroxyethyl cellulose and allyl co-polymer. Subsequently, a series of tests toward this oxidized hydroxyethyl cellulose-based hydrogel due to its structure and performance was applied. Here, the oxidized hydroxyethyl cellulose molecular chains were used as biomacromolecule templates to form Schiff base, borate and hydrogen bonds to obtain unique mechanical properties (fast recovery with almost no-hysteresis and remarkable compressive capacity), while a double bond functionalized spirooxazine (allyl spirooxazine derivative) was applied to endow photo- and pH sensitivity to the oxidized hydroxyethyl cellulose-based transparent hydrogel (T% = 93%) substrate. Furthermore, the oxidized hydroxyethyl cellulose-based hydrogel did exhibit good pH environment adaptability and noncytotoxicity in vitro test. Based on the advanced characteristics, the designed oxidized hydroxyethyl cellulose-based hydrogel has potential applications prospect in the development of safe, fashionable and pH- detectable contact lenses, thereby providing a new strategy for the development of smart, stylish contact lenses.

Multifunctional metal-organic frameworks in oil spills and associated organic pollutant remediation.

The release of toxic organic compounds into the environment in an event of oil spillage is a global menace due to the potential impacts on the ecosystem. Several approaches have been employed for oil spills clean-up, with adsorption technique proven to be more promising for the total reclamation of a polluted site. Of the several adsorbents so far reported, adsorbent-based porous materials have gained attention for the reduction/total removal of different compounds in environmental remediation applications. The superior potential of mesoporous materials based on metal-organic frameworks (MOFs) against conventional adsorbents is due to their intriguing and enhanced properties. Therefore, this review presents recent development in MOF composites; methods of preparation; and their practical applications towards remediating oil spill, organic pollutants, and toxic gases in different environmental media, as well as potential materials in the possible deployment in reclaiming the polluted Niger Delta due to unabated oil spillage and gas flaring.

Chemical fixation of CO2 into cyclic carbonates catalyzed by bimetal mixed MOFs: the role of the interaction between Co and Zn.

Bimetal mixed MOFs of [CoZn][(BDC)(DABCO)0.5] (CZ-BDO), [CoNi][(BDC)(DABCO)0.5] (CN-BDO), and [NiZn][(BDC)(DABCO)0.5] (NZ-BDO) were prepared under solvothermal conditions and further employed as highly active accelerants for converting carbon dioxide into cyclic carbonates. The characteristics of the bimetal compounds were revealed via various techniques, including ICP-OES, XRD, FT-IR, Raman, XPS, SEM, EDS maps, N2 adsorption, TG-DTG, and CO2/NH3-TPD. The catalytic results revealed that CZ-BDO is superior to the other samples for obtaining a satisfactory chloropropene carbonate (CPC) yield. The excellent catalytic activity may be owing to the presence of a solid solution within the Co and Zn bimetal sample, which provides synergistic catalysis in the carbon dioxide cycloaddition. In addition, the synergistic catalysis was further confirmed by the NH3-TPD profiles, whereby the amount of CZ-BDO basic sites was obviously enhanced compared to the other samples. Furthermore, DFT calculations were also performed to reveal the synergistic catalysis between Co and Zn for the coupling reaction. Additionally, when the coupling reaction was carried out at 100 °C for 5 h in the presence of 0.5 wt% epichlorohydrin (ECH) as a catalyst at 3.0 MPa, 99.31% conversion of ECH and 97.05% yield of CPC were obtained over the optimal CZ-BDO sample. Moreover, the bimetal sample can also efficiently convert other epoxides into the corresponding cyclic carbonates.

Characterization of Xanthan gum-based hydrogel with Fe3+ ions coordination and its reversible sol-gel conversion.

Since redox-responsive hydrogels have a wide range of applications especially in biochemistry, such as drug release and biosensors, a kind of redox-responsive hydrogel was fabricated based on iron which has two stable oxidation states, while xanthan gum (XG) was selected as a matrix. In this work, characterization of XG-based hydrogel with Fe3+ ions coordination and its reversible sol-gel conversion property were studied. Xanthan gum solutions with different concentrations were coordinated in situ with constant trivalent iron ions concentration to form hydrogels under ambient temperature. The chemical features of XG-based hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible light spectrum (UV-vis), while scanning electron microscope (SEM) was used to observed the morphologies of XG-based hydrogels cross-sections. In addition, the mechanical properties, thermal stability and swelling behavior of xanthan gum hydrogels were also investigated, respectively. The results showed that xanthan gum hydrogels possessed relatively uniform layered structure, in addition to possessing enhanced mechanical strength and excellent swelling behavior. Furthermore, the sol-gel conversion of XG-based hydrogel could be realized by UV light in the presence of sodium lactate. The process of changes in viscosity was studied. The result indicated that the XG-based hydrogel could be recycled and these characteristic studies may be of reference for future use of xanthan gum hydrogels in the field of biomedical materials or sensors.

Durable superhydrophobic and superoleophilic electrospun nanofibrous membrane for oil-water emulsion separation.

Marinepollution andindustrial wastewater have caused serious environmental pollution, thereby resulting into an alarming damage to public health in the past decades, hence the high demand for, cost effective, energy-efficient oil-water separation technologies for the removal of oil contaminants from such water. Herein, we report a facile method to fabricate superhydrophobic/superoleophilic membrane by immersing a polyimide (PI)-based nanofibrous membrane into a water/ethanol/ammonia/dopamine mixture, followed by modification with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT). The PI-based membrane exhibited water contact angle (WCA) above 153°, while the oil contact angle (OCA) approached 0°, thereby promoting an outstanding chemical stability which sustained its superhydrophobicity when immersed in aqueous solutions at different pH values. Additionally, the PI-based membrane possesses ultrahigh flux, high separation efficiency and good reusability in oil-water separation. The aforementioned properties, as well as the easily scale-up preparation process ensure that this promising as-fabricated membrane can be applied for practical environmental applications including treatment of oily wastewater and oil spillage clean-up.

Planar intercalated copper (II) complex molecule as small molecule enzyme mimic combined with Fe3O4 nanozyme for bienzyme synergistic catalysis applied to the microRNA biosensor.

Enzyme mimics have been developed for bioassay of nucleic acids, with some of them involving complicated labeling. Herein, we report a label-free bioassay for ultrasensitive electronic determination of microRNA at an ultralow concentration based on target-triggered long-range self-assembly DNA-based hybridization chain reaction (HCR) protocol coupled with bienzyme mimics synergistic catalysis strategy. In this work, a planar intercalation molecule, copper (II) complex, is applied for the first time as a small molecule enzyme mimic as well as intercalation molecule in microRNA biosensor for signal amplification. Fe3O4 nanozyme were used as a separate and enriched target under magnetic field, and also in combination with HCR protocol detected in 3,3',5,5'-tetramethylbenzidine+hydrogen peroxide (TMB+H2O2) system to improve the sensitivity of the biosensor. Under optimal conditions, these strategies present good electrochemical behaviors for the detection of microRNA with a wide range from 100 aM to 100 nM and at relatively low detection limit of 33 aM This remarkable sensitivity can make this proposed approach a promising scheme for development of next-generation microRNA sensors without the need of enzyme labeling or fluorophore labeling.

Glycogen-based self-healing hydrogels with ultra-stretchable, flexible, and enhanced mechanical properties via sacrificial bond interactions.

The development of hydrogel materials with enhanced mechanical properties is the primary focus in designing autonomous self-healable hydrogel materials. Here, we present a facile and cost-effective method for the autonomous self-healing hydrogel based on Glycogen (Gly/PAA-Fe3+) with enhanced mechanical properties by simple insertion of ferric ions in the physically cross-linked network via metal-ligand interactions. This dual physically cross-linked hydrogel has an excellent elongation at break and self-healing properties due to the dynamic ionic cross-linking point. This work will encourage researchers to focus on this facile technique for the synthesis of self-healing hydrogel materials with enhanced mechanical properties.

A Conductive Self-Healing Double Network Hydrogel with Toughness and Force Sensitivity.

Mechanically tough and electrically conductive self-healing hydrogels may have broad applications in wearable electronics, health-monitoring systems, and smart robotics in the following years. Herein, a new design strategy is proposed to synthesize a dual physical cross-linked polyethylene glycol/poly(acrylic acid) (PEG/PAA) double network hydrogel, consisting of ferric ion cross-linked linear chain extensions of PEG (2,6-pyridinedicarbonyl moieties incorporated into the PEG backbone, PEG-H2 pdca) as the first physical network and a PAA-Fe3+ gel as the second physical network. Metal-ion coordination and the double network structure enable the double network hydrogel to withstand up to 0.4 MPa tensile stress and 1560 % elongation at breakage; the healing efficiency reaches 96.8 % in 12 h. In addition, due to dynamic ion transfer in the network, the resulting hydrogels exhibit controllable conductivity (0.0026-0.0061 S cm-1 ) and stretching sensitivity. These functional self-healing hydrogels have potential applications in electronic skin. It is envisioned that this strategy can also be employed to prepare other high-performance, multifunctional polymers.

Green synthesis of oriented xanthan gum-graphene oxide hybrid aerogels for water purification.

Three-dimensional xanthan gum (XG)/graphene oxide (GO) hybrid aerogels were fabricated by ice crystal templating without using chemical modifiers. The hybrid aerogels were prepared by the stirring of xanthan gum-graphene oxide hybrid solution, followed by freezing at low temperature and finally by freeze-drying. The whole preparation could be completed within 12h without producing any contamination and thus considered a fast, simple, economical, and green method for aerogel fabrication. XG/GO hybrid aerogels possessed different hierarchical pore structures because of various freezing temperatures. A network composed of co-aligned pore channels was obtained at a freezing temperature of -40°C. The as-prepared hybrid aerogels exhibited stability and excellent adsorption capacity for organic dyes and heavy metal ions. Therefore, these aerogels could be used as efficient adsorbents in water purification. This study provided a basis for the cost-effective and large-scale commercial production of high-performance graphene oxide-based aerogels for water purification.