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Although eco-friendly amidoxime-based adsorbents own an excellent uranium (U)-adsorption capacity, their U-adsorption efficiency is commonly reduced and even damaged by the biological adhesion from bacteria/microorganisms in an aqueous environment. Herein, we present an antibiofouling ultrathin poly(amidoxime) membrane (AUPM) with highly enhanced U-adsorption performance, through dispersing the quaternized chitosan (Q-CS) and poly(amidoxime) in a cross-linked sulfonated cellulose nanocrystals (S-CNC) network. The cross-linked S-CNC not only can elevate the hydrophilicity to improve the U-adsorption efficiency of AUPM but also can enhance the mechanical strength to form a self-supporting ultrathin membrane (17.21 MPa, 10 μm thickness). More importantly, this AUPM owns a good antibiofouling property, owing to the broad-spectrum antibacterial quaternary ammonium groups of the Q-CS. As a result, within the 1.00 L of low-concentration (100 ppb) U-added pure water (pH ≈ 5) and seawater (pH ≈ 8) for 48 h, 30 mg of AUPM can recover 93.7% U and 91.4% U, respectively. Furthermore, compared with the U-absorption capacity of a blank membrane without the Q-CS, that of AUPM can significantly increase 37.4% reaching from 6.39 to 8.78 mg/g after being in natural seawater for only 25 d. Additionally, this AUPM can still maintain almost constant tensile strength during 10 cycles of adsorption-desorption, which indicates the relatively long-term usability of AUPM. This AUPM will be a promising candidate for highly efficient and large-scale U-recovery from both U-containing waste freshwater/seawater and natural seawater, which will be greatly helpful to deal with the U-pollution and enrich U for the consumption of nuclear power. More importantly, the work will provide a new convenient but universal strategy to fabricate new highly enhanced low-cost U-adsorbents, through the introduction of both an antibacterial property and a high mechanical performance, which will be a good reference for the design of new highly efficient U-adsorbents.

Uranium is the main element for nuclear energy production and is one of the most hazardous radionuclides; its effective enrichment plays a key role in energy strategy and environmental safety. Oxime-functionalized nanostructures are the most promising candidates for uranium adsorption. However, current methods for their preparation mainly focus on multistep grafting and oximation processes, and the nanostructures usually show low efficiency. Here, we report a rapid one-step process to synthesize salicylaldoxime/polydopamine modified reduced graphene oxide (RGO-PDA/oxime) via the polymerization of dopamine (DA) and simultaneous deposition of oxime with an obviously decreased total synthesis time of 2 h. The obtained maximum uranium adsorption capacity of up to 1049 mg g−1 was 3–16 times larger than those of the reported single PDA or oxime modified nanostructures. The RGO-PDA/oxime followed the pseudo-second-order kinetics model and Langmuir isotherm equation with much higher adsorption selectivity and recyclability. The outstanding sorption performance is attributed to the electrostatic repulsion between GO and salicylaldoxime and the effective combination between PDA and oxime molecules. Finally, given the adhesion capability of DA to diverse surfaces, this rapid one-step method was used to prepare five other oxime/PDA modified materials, which also showed improved uranium adsorption efficiency. These findings provide a way to obtain oxime-functionalized nanostructures with promising uranium adsorption efficiency.

Massive uranium recovery from seawater is a key project to provide the long-time consumption of global nuclear power, while it is still greatly difficult to achieve high-efficient adsorbents with high mechanical property. In this work, a new nanoclay-poly(amidoxime) (NC-PAO) high-strength double-network (DN) composite hydrogel adsorbent with high-efficient and fast uranium extraction capacity has been explored. The uranium adsorbing performance can be significantly enhanced by the small content of added super-hydrophilic NC (Laponite RDS sheets), because of the largely improved hydrophilicity of the hydrogel. Compared with the blank PAO DN hydrogel without nanoclay, the uranium adsorbing capacity of this NC-PAO DN hydrogel can largely increase 73.4% from 4.97 mg/g to 8.62 mg/g, after in seawater only 25 days. The uranium adsorption rate of this hydrogel from natural seawater, can reached 0.345 mg/(g∙day), which is excellent among existing uranium adsorbents. Furthermore, this hydrogel has high mechanical performance with 2.42 MPa of tensile strength and 16.13 MPa of compressive strength, which can be used in seawater for relatively longer time than traditional low-strength single-network hydrogel, owing to its double network (DN) structure (the weakly crosslinked gelatin soft network and the strongly crosslinked cellulose nanofiber (CNF) hard network). This NC-PAO DN hydrogel adsorbent will be an excellent candidate for fast uranium recovery from seawater in largescale. Most importantly, this work will inspire the development of new hydrogel-based adsorbents and even other type of adsorbents for high-efficient uranium extraction, through compositing various low-cost and super-hydrophilic nanomaterials to significantly improve the hydrophilicity of the adsorbent and designing double-network structure to largely enhance the mechanical property.

To withstand the complex natural environment and ecological system in the ocean, adsorbents with high strength, rapid rate, and antifouling ability are urgently needed for uranium extraction. Herein, instead of the traditional poly(amidoxime) structures, we design an anti-adhesive adsorbent (Anti-LS/SA) by conjugating functional ligands of salicylaldoxime (SA) and hyaluronic acid (HA) on the porous biomass via a facile one-step process. The interconnected microchannels in the porous biomass can accelerate seawater transport, along with the micromolecular uranium-adsorbing ligand, endowing the Anti-LS/SA with a very fast uranium adsorption ability; the average adsorption rates reach up to 131 ± 1.8 mg g−1 hour−1 (in uranium spiked seawater with concentration of 8 ppm) and 0.1176 mg g−1 day−1 (in natural seawater) in the main adsorption stages, exceeding the currently used oxime-based adsorbents. Owing to the high hydration of HA, the adsorbents exhibit excellent hydrophilicity and anti-bacterial adhesion properties, as demonstrated by the bacteria adhesion testing and extraction experiments in bacteria-spiked seawater. Furthermore, the Anti-LS/SA displays a long service life and a very high tensile strength (62.63 MPa) to withstand strong ocean waves. Kinetics models and XPS data are used to analyze the extraction mechanisms. Considering its high efficiencies, structural advantages, as well as the facile and massive construction, we believe that the Anti-LS/SA will be a promising candidate for the large-scale uranium extraction from seawater.

This study presents a facile, rapid and effective method for the fabrication of optical fiber surface plasmon resonance (SPR) sensors via polydopamine (PDA)-accelerated electroless plating (ELP). The bioinspired PDA coating formed through the facile self-polymerization of dopamine (DA) was utilized as a versatile material for optic-fiber functionalization. Gold seeds were then rapidly and firmly adsorbed onto the PDA functional layer by amino and imino intermediates generated during the polymerization, and a gold film sensor was fabricated after metal deposition. The fabrication time of the sensor was decreased by 6–12 times, and the fabricated sensor exhibited higher sensitivity, better reproducibility and adhesion stability compared with those fabricated by the traditional ELP. Some key experimental parameters, including DA polymerization temperature, DA polymerization time, and plating time, were investigated in detail. The optimized sample exhibited high sensitivity ranging from 1391 nm per RIU to 5346 nm per RIU in the refractive index range of 1.328 to 1.386. Scanning electron microscopy images indicated that the sensor surface consisted of gold nanoparticles with a uniform particle size and an orderly arrangement, and the film thickness was approximately 60 nm. Another PDA layer was formed on the gold film for facile immobilization of antibodies. The sensor exhibited effective antibody immobilization ability and high sensitivity for human IgG detection over a wide range of concentrations from 0.5 to 40 μg mL−1, which indicate the potential applications of the fabricated sensor in immunoassays.

For the uranium extraction from seawater in marine environments, the adsorbents need to possess sufficient mechanical strength to withstand the crashing force of the ocean waves, as well as anti-biofouling ability to prevent the blockage of the chelating sites by marine microorganisms. Herein, a facile one-step process is designed to massively construct robust and anti-biofouling poly(amidoxime) aerogels (Anti-PAO gels) for highly efficient uranium extraction. The gels display porosity, large surface area, flexibility, excellent mechanical strength to withstand the crash of the waves benefitting from the adhesive antibacterial compounds and the tight covalent bonding between the antibacterial compounds and PAO molecules, and the adsorption capacity reaches up to 1013 ± 9.7 mg-U/g-Ads in the 8 ppm uranium spiked solution. Significant inhibition zones are observed around the Anti-PAO gels, the adsorption amounts in bacteria-contained seawater reach 90.67%-94.82% of that in sterilized seawater, indicating the beneficial antifouling effects of the prepared aerogels for uranium extraction, providing an excellent extraction capacity of 9.29 ± 0.59 mg-U/g-Ads after a 30-day field test in natural seawater. More importantly, this developed strategy possesses universal applicability, and it can be used in other amidoxime molecules and other forms of uranium adsorbents to prepare the antifouling aerogels and fibers. Together with the economic analysis results, we believe that the developed amidoxime aerogels are promising in the industrialized uranium extraction from seawater.

The oceans contain 4.5 billion tons of uranium which can supply almost infinite nuclear energy. However, it is an urgent need to develop adsorbents simultaneously possessing enhanced efficiency, collect ability, durability and economy to massively extract uranium from seawater. Herein, a simple two-step process is designed to massively produce pure poly(amidoxime) porous network membranes (PAO PNMs) which exhibit high uranium uptake capacity and excellent mechanical strength. The resulting membranes display high hydrophilicity, flexibility, strength (16.98 MPa tensile strength), stiffness (0.55 GPa Young's modulus), and porosity (3D porous network structure) which arise from a modified phase separation technique, providing the membranes a very high adsorption efficiency of 707 ± 5.8 mg-U/g-Ads in 8 ppm uranium spiked seawater and 9.35 ± 0.47 mg-U/g-Ads in natural seawater, respectively. Furthermore, the membranes exhibit a long service life of over 10 cycles of adsorption-desorption, and they can be massively produced via this facile phase separation technique by being simply immersed in water. Overall, coupled with the techno-economic advantages, these PAO PNMs are promising in industrial uranium extraction from seawater due to their robustness, high-efficiency and low-consumption.

Surface plasmon resonance (SPR) biosensors have many possible applications, but are limited by sensor chip surface fouling, which blocks immobilization and specific binding by the recognizer elements. Therefore, there is a pressing need for the development of antifouling surfaces. In this paper, the mechanisms of antifouling materials were firstly discussed, including both theories (hydration and steric hindrance) and factors influencing antifouling effects (molecular structures and self-assembled monolayer (SAM) architectures, surface charges, molecular hydrophilicity, and grafting thickness and density). Then, the most recent advances in antifouling materials applied on SPR biosensors were systematically reviewed, together with the grafting strategies, antifouling capacity, as well as their merits and demerits. These materials included, but not limited to, zwitterionic compounds, polyethylene glycol-based, and polysaccharide-based materials. Finally, the prospective research directions in the development of SPR antifouling materials were discussed. Statement of Significance Surface plasmon resonance (SPR) is a powerful tool in monitoring biomolecular interactions. The principle of SPR biosensors is the conversion of refractive index change caused by molecular binding into resonant spectral shifts. However, the fouling on the surface of SPR gold chips is ubiquitous and troublesome. It limits the application of SPR biosensors by blocking recognition element immobilization and specific binding. Hence, we write this paper to review the antifouling mechanisms and the recent advances of the design of antifouling materials that can improve the accuracy and sensitivity of SPR biosensors. To our knowledge, this is the first review focusing on the antifouling materials that were applied or had potential to be applied on SPR biosensors.