Uranium (U), which is a radionuclide and heavy metal element, has been released into the environment in increasing amounts, mainly due to activities related to the booming nuclear industry1. This has resulted in persistent anthropogenic uranium contamination2, which contributes to ecotoxicological problems3, environmental degradation4 and could cause severe health problems. Inhalation, ingestion5 and skin contact are the main routes of uranium exposure6. Once entering human body, uranium tends to accumulate7 and with its radioactivity and heavy-metal toxicity8, often leads to significant adverse health effects on human bodies, including DNA damage9, reproductive toxicity10-12 and nephrotoxicity13. Therefore, wastewater containing uranium must be thoroughly treated in order to prevent the release of uranium into the environment14.
Several physical, biological and chemical methods have been developed for the removal of uranium from aqueous waste. These include physico-chemical methods such as ion-exchange, reverse osmosis, precipitation, flocculation18, phytoremediation1,15, rhizofiltration and other types of bioremediation16,17. However, these methods are often expensive, time-consuming and tedious, or inefficient for the treatment of large volumes of wastewater with low concentrations of the target contaminants19. After interviewing the Hunan Nuclear Geology 311 Brigade, a geological exploration unit with Grade A qualification in Hunan Province of China, it became apparent that the favored method of dealing with excavation sites is simply filling the ground with fresh soil and growing appropriate plants on it20,21. This minimalist approach is likely to be favored due to the high-cost of alternative methods mentioned above. Hence, efforts are needed to develop suitable alternative technologies to complement or replace the existing methods19.
To obviate such shortcomings, the Peking iGEM 2016 team developed a novel remediation method, Uranium Reaper, which could remove uranyl ions (the predominant form of aqueous uranium) 15,22,23, with high efficiency at an affordable cost, thus offering great convenience. Uranium Reaper utilizes a smart covalent crosslinking polymer network which is able to self-assemble in aqueous solution (BBa_K1989000, BBa_K1989001 and BBa_K1989002). The addition of biotin-coated magnetic particles to the solution enables the clearance of the complex self-assembled uranium-containing polymer network by a simple magnet. In this way, uranium pollution is alleviated and the uranyl ions could be cleared and enriched for further use.
Materials modeled on Uranyl Reaper are not limited to uranium remediation, and could obtain endless functions and applications by attaching different modules of interest to the automatically covalently cross-linking protein network. For example, by replacing SUP with Cadmium-Binding Protein (CBP) or Lead-Binding Protein (LBP) 24,25, this bio-functional polymer network is capable of adsorbing a variety of heavy metals26 as confirmed by our experiments. By complementing the leaching and elution circuit in mining, this polymer network would simplify the mining procedures and reduce the amount of contaminated wastewater produced27,28. What’s more, by optimizing the number of crosslinking modules, it may be possible to use similar biomaterials for 3D printing. We also aimed to develop a Uranium Reaper Kit, in order to facillitate the use of the material worldwide.
References:
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