Search Results (41)

Background: Healthcare-associated infections (HAIs) significantly increase morbidity, mortality, and healthcare costs. Among HAIs, catheter-associated infections are particularly prevalent due to the susceptibility of catheters to microbial contamination and biofilm formation, especially with prolonged use. Biofilms act as infection reservoirs, complicating treatment and often requiring catheter removal, thus extending hospital stays and increasing costs. Recent technological advances in catheter design have focused on integrating antifouling and antimicrobial coatings to mitigate or prevent biofilm formation. Methods: We developed COPESIL^®, a novel silicone rubber embedded with PEGylated copper nanoparticles designed to reduce microbial contamination on catheter surfaces. We conducted in vitro assays to evaluate the antimicrobial and antibiofilm efficacy of COPESIL^® against pathogens commonly implicated in catheter-associated urinary tract infections. Additionally, the safety profile of the material was assessed through cytotoxicity evaluations using HepG2 cells. Results: COPESIL^® demonstrated substantial antimicrobial activity, reducing contamination with Escherichia coli and Klebsiella pneumoniae by >99.9% and between 93.2% and 99.8%, respectively. Biofilm formation was reduced by 5.2- to 7.9-fold for E. coli and 2.7- to 2.8-fold for K. pneumoniae compared to controls. Cytotoxicity assays suggest the material is non-toxic, with cell viability remaining above 95% after 24 h of exposure. Conclusions: The integration of PEGylated copper nanoparticles into a silicone matrix in COPESIL^® represents a promising strategy to enhance the antimicrobial properties of catheters. Future studies should rigorously evaluate the long-term antimicrobial efficacy and clinical safety of COPESIL^®-coated catheters, with a focus on their impact on patient outcomes and infection rates in clinical settings. Full article

The increasing environmental concerns of conventional antifouling coatings have led to the exploration of novel and sustainable solutions to address the biofouling caused by Limnoperna fortunei. As a rapidly expanding invasive species, the fouling process of Limnoperna fortunei is closely associated with microbial fouling, posing significant threats to the integrity of aquatic infrastructure and biodiversity. This review discusses recent progress in the development of non-toxic, eco-friendly antifouling coatings that are designed to effectively resist biofouling without using toxic chemicals. Recent research has focused on developing novel non-toxic coatings that integrate natural bioactive components with advanced material technologies. These formulations not only meet current environmental standards and exhibit minimal ecological impact, but also possess significant potential in preventing the attachment, growth, and reproduction of Limnoperna fortunei. This review aims to provide scientific guidance by proposing effective and sustainable solutions to address the ecological challenges presented by Limnoperna fortunei. The insights gained from current research not only reveal novel antifouling methods, but also identify key areas for further investigation aimed at enhancing performance and environmental compatibility. Full article

Marine biofouling is a worldwide problem in marine systems. Nowadays, innovative non-toxic antifouling and fouling-release materials are highly desirable. In this study, a strategy for preparing antifouling and fouling-release materials via one-step dip coating is reported. Copolymers were synthesized via the polymerization of a monomer with catechol sticky functional groups and four monomers with antifouling- or fouling-release functional groups, respectively. The copolymers could assemble onto different material surfaces, such as metals and plastics, using biomimetic catechol groups via multivalent complex bonding. The catechol groups were helpful for adhesion onto the surfaces, while the other functional groups endowed the coatings with antifouling or fouling-release properties. The effects of modifying the substrates using these copolymer coatings were verified via X-ray photoelectron spectroscopy; images of Chlorella cell and Ulva zoospore settlement were taken using a microscope and scanning electron microscope. The copolymer-coated surfaces, especially the surface modified by DOPA–PSPMA, displayed the best antifouling activity, and surface modification via DOPA–PTMETH was shown to be the most effective for producing the fouling-release property in the settlement assay. Full article

The biofouling of marine structures must be controlled if crippling operational and maintenance costs are to be avoided and biological invasions prevented. However, traditional methods of biofouling control typically involve the use of toxic chemicals, which have their own drawbacks, both financial and environmental. For ships, the hull is the largest surface requiring a fouling-control coating; however, there are other so-called ‘niche’ areas (up to 10% of the total wetted area) that typically cannot be, or are not routinely, treated to prevent biofouling accumulation. The use of UV light is a tried and tested sterilization method that has been shown to also work underwater. However, the speed with which UV can be applied to large-scale biofouling control will be determined by the engineering challenges involved and the lack of basic understanding of the biological mode of action. The former is essential for the effective translation of this established technology into a high-performance, industrially useful fouling-control system. The latter will be important for environmental regulation and safe use as well as performance optimisation. Here, we developed two bespoke flow-through systems to replicate ship niche areas and deployed them in Melbourne, Australia, and North East England. We demonstrated a 40–90% reduction in biofouling coverage on silicone tiles embedded with UV-emitting LEDs, even as the LED output waned (after ~8000 h). Image analysis and amplicon sequencing of 18S genes provided complementary information about the taxonomic composition of the fouling communities and highlighted some taxa, for example, ascidians and diatoms, which may have, or in the future develop, UV resistance. Interestingly, the UV treatment far exceeded performance estimates based on the predicted attenuation distance of UV in seawater. Overall, while it is clear that UV treatment works in terms of its efficacy against the vast majority of observed fouling species, technical challenges remain, as do knowledge gaps surrounding the biological and ecological effects of widespread use. Full article

Passive-cooling building materials can achieve cooling without external energy consumption, which is an energy-saving and environmentally friendly cooling method. However, the existing passive-cooling building materials have the limitations of high cost, complicated processes, and a toxic organic solvent, which hinders the passive-cooling technology applied in practical building. To overcome these limitations, we developed a facile, high-efficiency, non-toxic, and superhydrophobic passive-cooling building coating (SPCBC) with an efficient cooling capability and excellent durability that was composed of polydimethylsiloxane and SiO₂. The fabricated SPCBC demonstrated a high reflectance and a high emittance, showing a superior cooling capability with a 14 °C temperature drop compared with a bare cement surface on a hot summer day. In addition, the SPCBC could not be wetted or contaminated by muddy water, corrosive aqueous solutions, or dust, which presented an excellent anti-fouling and self-cleaning capability. Moreover, the fabricated SPCBC could work outdoors for 30 days, withstand UV irradiation for 30 days, and resist accelerated aging for 100 h without any significant changes in the superhydrophobicity and the cooling capability, meaning that the SPCBC had an outstanding durability. This work provides a new method to facilitate passive-cooling technology to apply in practical building in hot weather regions of the world. Full article

Antifouling substances play a crucial role in inhibiting fouling and adhesion due to their broad-spectrum and non-toxic advantages. Nevertheless, the excessive release of the antifouling agents shortens the service life of the antifouling coating. In this study, we investigated the antifouling performance of an ethanol extract from the root of Stellera chamaejasme (Sc) through algal adhesion experiments. The interaction between Sc and algae (Chlorella and Dunaliella tertiolecta) was further studied by using a UV spectrophotometer. Then, Sc was encapsulated with polydopamine (PDA) microcapsules to prepare Sc@SiO₂@PDA microcapsules by the template method. The release behavior of Sc@SiO₂@PDA under different pH conditions was investigated. The result demonstrates that the interaction between Sc and algae belongs to single static quenching, and the Sc@SiO₂@PDA microcapsules exhibit good antifouling performance against Chlorella and Dunaliella tertiolecta. This work will provide guiding significance for the development of eco-friendly marine antifouling coatings. Full article

Due to environmental regulations, antifouling marine coatings must be gradually replaced by biocide-free coatings. Marine organisms weakly adhere to fouling release coatings, presenting a low surface free energy and a high elasticity, so they can be readily removed by the sheer force of water. Currently, these materials are mainly composed of petrochemical polymers, such as silicone or fluoropolymers, with hydrophilic polymers as additives. However, following the ever-increasing environmental concerns, the research on new, alternative, eco-friendly coatings is oriented towards the use of biobased polymers from renewable resources. Two main families have been studied: polyhydroxyalkanoates (PHAs) and polysaccharides. PHAs are produced by bacteria in stressful conditions, while polysaccharides are extracted from plants, animals, or micro-organisms such as bacteria, in which case they are called exopolysaccharides (EPS). Since the use of these polymers is a non-toxic approach to controlling fouling colonization, this review provides an overview of these biobased polymers for their applications in new anti-adhesive marine coatings. Full article

Biofouling control on human-made structures and seagoing technologies that minimize environmental impacts is a major focus of research in marine industries. However, the most widely used antifouling (AF) method is still copper-based coatings. Some “eco-friendly” approaches are commercially available but have been scarcely tested in natural conditions, especially high-energy environments. We conducted a replicated long-term field experiment in a highly wave-exposed, high productivity coastal environment to test three untreated materials used in maritime industries, two traditional copper-based AF coatings, and two materials offered as “eco-friendly” AF in the market (i.e., a slow-copper release and a self-adhesive, fiber-covered, skin-like coating). We showed that biofouling cover and biomass increased at similar rates over time among all untreated materials, including the skin-like AF. The two traditional copper-based AF coatings and the slow-release AF paint both showed similarly low biofouling biomass and richness, demonstrating their efficacy after 12 months in the field. Although the “eco-friendly” slow-release technologies are not completely innocuous to the environment, we suggest this approach over the more environmentally aggressive traditional copper paints, which are the most widely used in aquaculture and shipping industries today. However, further research is needed to test whether their environmental impact is significantly lower in the long-term than traditional AF paints, and therefore the search for non-toxic coating must continue. The fortuitous settlement and growth of sea urchins in our experiments also suggest that a combination of “eco-friendly” AF and biological control would be possible and should be further investigated. The skin-like coatings must be tested under different environmental conditions, and they are not recommended in wave-exposed coastal habitats. Full article

Biofilms are known to be difficult to eradicate and control, complicating human infections and marine biofouling. In this study, self-polishing and anti-fouling waterborne polyurethane coatings synthesized from gemini quaternary ammonium salts (GQAS), polyethylene glycol (PEG), and polycaprolactone diol (PCL) demonstrate excellent antibiofilm efficacy. Their anti-fouling and anti-biofilm performance was confirmed by a culture-based method in broth media, with the biofilm formation factor against Gram-positive (S. aureus) and Gram-negative bacterial strains (E. coli) for 2 days. The results indicate that polyurethane coatings have excellent anti-biofilm activity when the content of GQAS reached 8.5 wt% against S. aureus, and 15.8 wt% against E. coli. The resulting waterborne polyurethane coatings demonstrate both hydrolytic and enzymatic degradation, and the surface erosion enzymatic degradation mechanism enables them with good self-polishing capability. The extracts cyto-toxicity of these polyurethane coatings and degradation liquids was also systematically studied; they could be degraded to non-toxic or low toxic compositions. This study shows the possibility to achieve potent self-polishing and anti-biofilm efficacy by integrating antibacterial GQAS, PEG, and PCL into waterborne polyurethane coatings. Full article

Marine biofouling is a natural process often associated with biofilm formation on submerged surfaces, creating a massive economic and ecological burden. Although several antifouling paints have been used to prevent biofouling, growing ecological concerns emphasize the need to develop new and environmentally friendly antifouling approaches such as bio-based coatings. Chitosan (CS) is a natural polymer that has been widely used due to its outstanding biological properties, including non-toxicity and antimicrobial activity. This work aims to produce and characterize poly (lactic acid) (PLA)-CS surfaces with CS of different molecular weight (Mw) at different concentrations for application in marine paints. Loligo opalescens pens, a waste from the fishery industry, were used as a CS source. The antimicrobial activity of the CS and CS-functionalized surfaces was assessed against Cobetia marina, a model proteobacterium for marine biofouling. Results demonstrate that CS targets the bacterial cell membrane, and PLA-CS surfaces were able to reduce the number of culturable cells up to 68% compared to control, with this activity dependent on CS Mw. The antifouling performance was corroborated by Optical Coherence Tomography since PLA-CS surfaces reduced the biofilm thickness by up to 36%, as well as the percentage and size of biofilm empty spaces. Overall, CS coatings showed to be a promising approach to reducing biofouling in marine environments mimicked in this work, contributing to the valorization of fishing waste and encouraging further research on this topic. Full article

Biofouling has destructive effects on shipping and leisure vessels, thus producing severe problems for marine and naval sectors due to corrosion with consequent elevated fuel consumption and higher maintenance costs. The development of anti-fouling or fouling release coatings creates deterrent surfaces that prevent the initial settlement of microorganisms. In this regard, new silica-based materials were prepared using two alkoxysilane cross-linkers containing epoxy and amine groups (i.e., 3-Glycidyloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively), in combination with two functional fluoro-silane (i.e., 3,3,3-trifluoropropyl-trimethoxysilane and glycidyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononylether) featuring well-known hydro repellent and anti-corrosion properties. As a matter of fact, the co-condensation of alkoxysilane featuring epoxide and amine ends, also mixed with two opportune long chain and short chain perfluorosilane precursors, allows getting stable amphiphilic, non-toxic, fouling release coatings. The sol–gel mixtures on coated glass slides were fully characterized by FT-IR spectroscopy, while the morphology was studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). The fouling release properties were evaluated through tests on treated glass slides in different microbial suspensions in seawater-based mediums and in seawater natural microcosms. The developed fluorinated coatings show suitable antimicrobial activities and low adhesive properties; no biocidal effects were observed for the microorganisms (bacteria). Full article

The development of marine-inspired compounds as non-toxic antifouling (AF) agents has been pursued in the last years. Sulfur is the third most common element in seawater. Sulfur is present in oxygenated seawater as sulfate anion (SO₄²⁻), which is the most stable combination of sulfur in seawater, and several promising AF secondary metabolites with sulfate groups have been described. However, sulfated compounds proved to be an analytical challenge to quantify by HPLC. Taking these facts into consideration, this work presents the development and validation of a method for the quantification of gallic acid persulfate (GAP) in seawater and ultrapure water matrix, based on hydrophilic interaction liquid chromatography (HILIC). This method was used to evaluate GAP stability following several abiotic and biotic degradation assays, and to quantify its release in seawater from room-temperature-vulcanizing polydimethylsiloxane commercial coating. GAP was very stable in several water matrices, even at different pH values and in the presence/absence of marine microorganisms and presented a leaching value lower than 0.5%. This work discloses HILIC as an analytical method to overcome the difficulties in quantifying sulfated compounds in water matrices and highlights the potential of GAP as a promising long-lasting coating. Full article

The need to ensure adequate antifouling protection of the hull in the naval sector led to the development of real painting cycles, which involve the spreading of three layers of polymeric material on the hull surface exposed to the marine environment, specifically defined as primer, tie coat and final topcoat. It is already well known that coatings based on suitable silanes provide an efficient and non-toxic approach for the hydrophobic and antifouling/fouling release treatment of surfaces. In the present work, functional hydrophobic hybrid silica-based coatings (topcoats) were developed by using sol-gel technology and deposited on surfaces with the “doctor blade” method. In particular, those organic silanes, featuring opportune functional groups such as long (either fluorinated) alkyl chains, have a notable influence on surface wettability as showed in this study. Furthermore, the hydrophobic behavior of this functionalized coating was improved by introducing an intermediate commercial tie-coat layer between the primer and the topcoat, in order to decrease the wettability (i.e., decreasing the surface energy with a matching increase in the contact angle, CA) and to therefore make such coatings ideal for the design and development of fouling release paints. The hereby synthesized coatings were characterized by optical microscopy, contact angle analysis and a mechanical pull-off test to measure the adhesive power of the coating against a metal substrate typically used in the nautical sector. Analysis to evaluate the bacterial adhesion and the formation of microbial biofilm were related in laboratory and simulation (microcosm) scales, and assessed by SEM analysis. Full article

Semiconductor photocatalytic materials have shown potential in the field of antifouling due to their good antibacterial properties, stability, and nontoxic properties. It is an effective way to use them to improve the static antifouling performance of silicone antifouling coatings. g-C₃N₄/TNTs/CNTs (CNTC) photocatalytic composite powders were prepared and introduced into polydimethylsiloxane (PDMS) coatings to enhance their antifouling performance. Firstly, g-C₃N₄/TNTs with heterostructure were thermally polymerized by urea and TiO₂ nanotubes (TNTs), and then g-C₃N₄/TNTs and multi-walled carbon nanotubes (CNTs) were composited to obtain CNTC. Finally, CNTC was added into PDMS to prepare g-C₃N₄/TNTs/CNTs/PDMS (CNTC/P) composite antifouling coating. The results showed that CNTC successfully recombined and formed a heterostructure, and the recombination rate of photogenerated carriers decreased after recombination. The addition of CNTC to PDMS increased the hydrophobicity and roughness while reducing the surface energy (SE) of the coatings. CNTC could effectively improve the anti-attachment performance of PDMS coatings to bacteria and benthic diatom. The bacterial attachment rate (A_B) and benthic diatom attachment rate (A_D) of CNTC/P-20 were, respectively, 13.1% and 63.1%; they are much lower than that of the coating without photocatalytic composite powder. This coating design provides a new idea for developing new “efficient” and “green” photocatalytic composite antifouling coatings. Full article

Great attention has been paid to silicone-based fouling-release coatings (FRCs) in the realm of maritime antifouling due to their highly efficient and eco-friendly properties, but many challenges remain for developing a silicone-based FRC that improves its adhesion performance without reducing the antifouling property. Herein, a non-toxic silicone-based FRC has been developed by integrating acrylic resin (AR) with a silicon resin (PDMS) to spontaneously form a self-stratified AR/PDMS coating. The AR/PDMS antifouling coating still has the same fouling-release performance but improved adhesion strength (from 0.4 to 2.0 MPa) in comparison with pristine PDMS. Moreover, the antifouling coating has proven to be extremely stable in different environments (such as pH, heating, and ultraviolet exposure). The study provides a facile and convenient self-stratified strategy to develop antifouling coatings, contributing to environmentally friendly coatings in marine applications. Full article