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There are a large number of fouling organisms in the ocean, which easily attach to the surface of ships, oil platforms and breeding facilities, corrode the surface of equipment, accelerate the aging of equipment, affect the stability and safety of marine facilities and cause serious economic losses. Antifouling coating is an effective method to prevent marine biological fouling. Traditional organic tin and copper oxide coatings are toxic and will contaminate seawater and destroy marine ecology and have been banned or restricted. Environmentally friendly antifouling coatings have become a research hotspot. Among them, the use of natural biological products with antifouling activity as antifouling agents is an important research direction. In addition, some fouling release coatings without antifoulants, biomimetic coatings, photocatalytic coatings and other novel antifouling coatings have also developed rapidly. On the basis of revealing the mechanism of marine biofouling, this paper reviews the latest research strategies to develop environmentally friendly marine antifouling coatings. The composition, antifouling characteristics, antifouling mechanism and effects of various coatings were analyzed emphatically. Finally, the development prospects and future development directions of marine antifouling coatings are forecasted.

Engineering surface chemistry to precisely control interfacial interactions is crucial for fabricating superior antifouling coatings and separation membranes. Here, we present a hydrophobic chain engineering strategy to regulate membrane surface at a molecular scale. Hydrophilic phytic acid and hydrophobic perfluorocarboxylic acids are sequentially assembled on a graphene oxide membrane to form an amphiphilic surface. The surface energy is reduced by the introduction of the perfluoroalkyl chains while the surface hydration can be tuned by changing the hydrophobic chain length, thus synergistically optimizing both fouling-resistance and fouling-release properties. It is found that the surface hydration capacity changes nonlinearly as the perfluoroalkyl chain length increases from C 4 to C 10 , reaching the highest at C 6 as a result of the more uniform water orientation as demonstrated by molecular dynamics simulations. The as-prepared membrane exhibits superior antifouling efficacy (flux decline ratio <10%, flux recovery ratio ~100%) even at high permeance (~620 L m −2 h −1 bar −1 ) for oil-water separation. Fouling is a continuous challenge for the effective application of membranes in oily wastewater treatment. Here, the authors present a hydrophobic chain engineering strategy to regulate the surface of graphene oxide-based membranes at a molecular scale for increased antifouling even at high permeance.

The recent rate of emergence of pathogenic fungi that are resistant to the limited number of commonly used antifungal agents is unprecedented. The azoles, for example, are used not only for human and animal health care and crop protection but also in antifouling coatings and timber preservation. The ubiquity and multiple uses of azoles have hastened the independent evolution of resistance in many environments. One consequence is an increasing risk in human health care from naturally occurring opportunistic fungal pathogens that have acquired resistance to this broad class of chemicals. To avoid a global collapse in our ability to control fungal infections and to avoid critical failures in medicine and food security, we must improve our stewardship of extant chemicals, promote new antifungal discovery, and leverage emerging technologies for alternative solutions.

Affinity-based electrochemical detection in complex biological fluids could enable multiplexed point-of-care diagnostics for home healthcare; however, commercialization of point-of-care devices has been limited by the rapid loss of sensitivity caused by electrode surface inactivation and biofouling. Here, we describe a simple and robust antifouling coating for electrodes consisting of a three-dimensional porous matrix of cross-linked bovine serum albumin supported by a network of conductive nanomaterials composed of either gold nanowires, gold nanoparticles or carbon nanotubes. These nanocomposites prevent non-specific interactions while enhancing electron transfer to the electrode surface, preserving 88% of the original signal after 1 month of exposure to unprocessed human plasma, and functionalization with specific antibodies enables quantification of anti-interleukin 6 in plasma with high sensitivity. The easy preparation, stability and simplicity of this nanocomposite allow the generation of electrochemical biosensors that can operate in complex biological fluids such as blood plasma or serum.

Mussels are opportunistic macrofouling organisms that can attach to most immersed solid surfaces, leading to serious economic and ecological consequences for the maritime and aquaculture industries. We demonstrate that lubricant-infused coatings exhibit very low preferential mussel attachment and ultralow adhesive strengths under both controlled laboratory conditions and in marine field studies. Detailed investigations across multiple length scales—from the molecular-scale characterization of deposited adhesive proteins to nanoscale contact mechanics to macroscale live observations—suggest that lubricant infusion considerably reduces fouling by deceiving the mechanosensing ability of mussels, deterring secretion of adhesive threads, and decreasing the molecular work of adhesion. Our study demonstrates that lubricant infusion represents an effective strategy to mitigate marine biofouling and provides insights into the physical mechanisms underlying adhesion prevention.

Here, we present a proactive fouling prevention mechanism that endows superhydrophilic membranes with antifouling capability against migratory viscous crude oil fouling. By simulating the hierarchical architecture/chemical composition of a dahlia leaf, a membrane surface is decorated with wrinkled-pattern microparticles, exhibiting a unique proactive fouling prevention mechanism based on a synergistic hydration layer/steric hindrance. The density functional theory and physicochemical characterizations demonstrate that the main chains of the microparticles are bent towards Fe 3+ through coordination interactions to create nanoscale wrinkled patterns on smooth microparticle surfaces. Nanoscale wrinkled patterns reduce the surface roughness and increase the contact area between the membrane surface and water molecules, expanding the steric hindrance between the oil molecules and membrane surface. Molecular dynamic simulations reveal that the water-molecule densities and strengths of the hydrogen bonds are higher near the resultant membrane surface. With this concept, we can successfully inhibit the initial adhesion, migration, and deposition of oil, regardless of the viscosity, on the membrane surface and achieve migratory viscous crude oil antifouling. This research on the PFP mechanism opens pathways to realize superwettable materials for diverse applications in fields related to the environment, energy, health, and beyond. Minimizing membrane fouling is critical for their continuous and efficient operation. Here, authors demonstrate a wrinkled-pattern microparticles-decorated membrane surface can increase contact area with water molecules, expand steric hindrance, and inhibit adhesion and deposition of oil, achieving efficient migratory viscous crude oil antifouling.

The adhesion of soft connective tissues (tendons, ligaments, and cartilages) on bones in many animals can maintain high toughness (∽800 J m −2 ) over millions of cycles of mechanical loads. Such fatigue-resistant adhesion has not been achieved between synthetic hydrogels and engineering materials, but is highly desirable for diverse applications such as artificial cartilages and tendons, robust antifouling coatings, and hydrogel robots. Inspired by the nanostructured interfaces between tendons/ligaments/cartilages and bones, we report that bonding ordered nanocrystalline domains of synthetic hydrogels on engineering materials can give a fatigue-resistant adhesion with an interfacial fatigue threshold of 800 J m −2 , because the fatigue-crack propagation at the interface requires a higher energy to fracture the ordered nanostructures than amorphous polymer chains. Our method enables fatigue-resistant hydrogel coatings on diverse engineering materials with complex geometries. We further demonstrate that the fatigue-resistant hydrogel coatings exhibit low friction and low wear against natural cartilages. Fatigue-resistant adhesion is of interest for a range of applications, but has been limited in synthetic hydrogels. Here, the authors report on a synthetic hydrogel with ordered nanocrystalline domains resulting in high fatigue-resistant adhesion and demonstrate the coating of different surfaces.

Antifouling paints incorporate biocides in their composition seeking to avoid or minimize the settlement and growing of undesirable fouling organisms. Therefore, biocides are released into the aquatic environments also affecting several nontarget organisms and, thus, compromising ecosystems. Despite global efforts to investigate the environmental occurrence and toxicity of biocides currently used in antifouling paints, the specific active ingredients that have been used in commercial products are poorly known. Thus, the present study assessed the frequencies of occurrence and relative concentrations of biocides in antifouling paint formulations registered for marketing worldwide. The main data were obtained from databases of governmental agencies, business associations, and safety data sheets from paint manufacturers around the world. The results pointed out for 25 active ingredients currently used as biocides, where up to six biocides have been simultaneously used in the examined formulations. Cuprous oxide, copper pyrithione, zinc pyrithione, zineb, DCOIT, and cuprous thiocyanate were the most frequent ones, with mean relative concentrations of 35.9 ± 12.8%, 2.9 ± 1.6%, 4.0 ± 5.3%, 5.4 ± 2.0%, 1.9 ± 1.9%, and 18.1 ± 8.0% (w/w) of respective biocide present in the antifouling paint formulations. Surprisingly, antifouling paints containing TBT as an active ingredient are still being registered for commercialization nowadays. These results can be applied as a proxy of biocides that are possibly being used by antifouling systems and, consequently, released into the aquatic environment, which can help to prioritize the active ingredients that should be addressed in future studies.

Thin-film composite membranes formed by conventional interfacial polymerization generally suffer from the depth heterogeneity of the polyamide layer, i.e., nonuniformly distributed free volume pores, leading to the inefficient permselectivity. Here, we demonstrate a facile and versatile approach to tune the nanoscale homogeneity of polyamide-based thin-film composite membranes via inorganic salt-mediated interfacial polymerization process. Molecular dynamics simulations and various characterization techniques elucidate in detail the underlying molecular mechanism by which the salt addition confines and regulates the diffusion of amine monomers to the water-oil interface and thus tunes the nanoscale homogeneity of the polyamide layer. The resulting thin-film composite membranes with thin, smooth, dense, and structurally homogeneous polyamide layers demonstrate a permeance increment of ~20–435% and/or solute rejection enhancement of ~10–170% as well as improved antifouling property for efficient reverse/forward osmosis and nanofiltration separations. This work sheds light on the tunability of the polyamide layer homogeneity via salt-regulated interfacial polymerization process. Thin-film composite membranes formed by conventional interfacial polymerization generally suffer from depth heterogeneity of the polyamide layer. Here, authors investigate salt-mediated polymerization approaches to achieve membranes with tuneable structural homogeneity.

The ability of superhydrophobic surfaces to stay dry, self-clean and avoid biofouling is attractive for applications in biotechnology, medicine and heat transfer 1 – 10 . Water droplets that contact these surfaces must have large apparent contact angles (greater than 150 degrees) and small roll-off angles (less than 10 degrees). This can be realized for surfaces that have low-surface-energy chemistry and micro- or nanoscale surface roughness, minimizing contact between the liquid and the solid surface 11 – 17 . However, rough surfaces—for which only a small fraction of the overall area is in contact with the liquid—experience high local pressures under mechanical load, making them fragile and highly susceptible to abrasion 18 . Additionally, abrasion exposes underlying materials and may change the local nature of the surface from hydrophobic to hydrophilic 19 , resulting in the pinning of water droplets to the surface. It has therefore been assumed that mechanical robustness and water repellency are mutually exclusive surface properties. Here we show that robust superhydrophobicity can be realized by structuring surfaces at two different length scales, with a nanostructure design to provide water repellency and a microstructure design to provide durability. The microstructure is an interconnected surface frame containing ‘pockets’ that house highly water-repellent and mechanically fragile nanostructures. This surface frame acts as ‘armour’, preventing the removal of the nanostructures by abradants that are larger than the frame size. We apply this strategy to various substrates—including silicon, ceramic, metal and transparent glass—and show that the water repellency of the resulting superhydrophobic surfaces is preserved even after abrasion by sandpaper and by a sharp steel blade. We suggest that this transparent, mechanically robust, self-cleaning glass could help to negate the dust-contamination issue that leads to a loss of efficiency in solar cells. Our design strategy could also guide the development of other materials that need to retain effective self-cleaning, anti-fouling or heat-transfer abilities in harsh operating environments. Water-repellent nanostructures are housed within an interconnected microstructure frame to yield mechanically robust superhydrophobic surfaces.