Search Results (781)

Marine biofouling remains a major challenge for maritime industries, affecting submerged structures and vessels worldwide. The long-standing reliance on biocidal coatings, together with their documented environmental impacts, has led to increasingly restrictive regulations and an urgent demand for environmentally compatible antifouling (AF) solutions. This study evaluates the AF potential and toxicological profile of two nucleoside analogues, hypoxanthine arabinoside (1′) and 2′-deoxyinosine (2′), selected based on the previously reported non-lethal AF activity of the naturally occurring nucleosides adenosine and 2′-deoxyadenosine from cyanobacteria. Both analogues inhibited the growth of Navicula sp. by approximately 60% without inducing mortality and significantly reduced settlement of Mytilus galloprovincialis plantigrades, with EC₅₀ values of 5.50 µM (1′) and 8.54 µM (2′), and no lethality detected (LC₅₀ > 200 µM). At near-EC₅₀ concentrations, both compounds increased acetylcholinesterase and tyrosinase activities, supported by molecular docking results, suggesting involvement of neurotransmission- and byssal formation-related pathways. Proteomic analysis revealed compound-specific molecular responses. No lethal effects were observed in non-target organisms (LC₅₀ > 32 µM for A. amphitrite and LC₅₀ > 50 µM for A. salina), and environmental fate modelling predicted low bioaccumulation and rapid degradation. Overall, substitution of the amino group by a carbonyl group preserved AF efficacy without increasing toxicity, highlighting nucleosides as promising low-toxicity AF agents. Full article

Biofouling is an issue of global significance that impairs marine infrastructure, causes increased fuel consumption and greenhouse gas emissions, and threatens biodiversity. Since the year 2000, self-polishing copolymer (SPC) coatings and fouling release coatings (FRCs) dominate the fouling protection coatings market. SPC technology is based on the controlled release of biocides using a mixture of acrylic and natural binders as a delivery system. FRC technology is based on PDMS providing surface properties that resist attachment of fouling organisms. FRCs often contain surface modifying agents, such as free silicone oils, to tune the physicochemical properties of the surface. However, the long-term efficacy of these agents and their migration and distribution in PDMS-based coatings have not been well studied. In this study, we employed time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with multivariate analysis to examine the distribution of silicone oils as a function of exposure to artificial seawater (ASW). The results show that pure PDMS-based coatings allow uniform distribution of silicone oils with robust behavior upon ASW exposure. In contrast, epoxy–PDMS-based coatings displayed phase separation of the oils, which strongly altered their surface chemistry. Our findings suggest that the modification of mobile oils is critical to the performance of marine antifouling coatings. Furthermore, the presence of other ingredients of commercial coating formulations strongly affected the distribution of mobile oils. This study lays the foundation for future systematic research aimed at developing predictive models to optimize fouling protection coatings for the marine industry. Full article

The complex surface architecture of natural oyster reefs is widely considered to promote biological attachment, yet the underlying mechanisms and the relevance to the design of artificial reefs are not fully understood. Here, we combined field experiments, 3D surface characterization, and numerical modelling to quantify how reef-like roughness regulates biofouling development and near-wall flow around artificial substrates. Surface morphological characteristics of natural oyster reefs were first obtained by 3D scanning and used to fabricate concrete panels with simulated rough textures, while traditional smooth concrete panels served as controls. The two types of panels were simultaneously deployed in the target sea area for a hanging-panel experiment. Samples were collected after 3, 6, 9, and 12 months to track changes in biofouling communities. At each sampling time, the panel surfaces were quantified by canopy roughness ($R_C$), surface heterogeneity ($\sigma$), and fractal dimension ($D$), and these metrics were integrated into numerical simulations combined to resolve the flow field, turbulence kinetic, and near-wall shear stress around the colonized panels. The research results show that, after 12-month immersion, the mean thickness of the biofouling layer on rough and control panels reached 6.39 mm and 5.91 mm, respectively. Rough panels exhibited consistently higher $R_C$ and $\mathsf{\sigma }$ than controls, and these two parameters are strongly linearly correlated ($R^2=0.891)$. Numerical simulations reveal that increased $R_C$ enlarges the oyster settlement shear-stress window (OSSW), indicating more favorable hydrodynamic conditions for oyster settlement and growth on rough panels. Nevertheless, the hydrodynamic differences between the initial rough panels and control panels gradually diminish over time, suggesting that biological growth can progressively naturalize initially smooth substrates. These findings advance the mechanistic understanding of how small-scale roughness and biofouling co-evolve to shape oyster habitat quality and provide a quantitative basis for the eco-engineering design of artificial oyster reefs. Full article

Polymer films and coatings play an increasingly critical role in extending material functionality across industrial, biomedical, and environmental applications. Recent advances in surface engineering have enabled precise control of interfacial properties, leading to enhanced durability, cleanliness, and protection. This review summarizes state-of-the-art strategies for modifying polymer surfaces, with an emphasis on plasma-based surface modification and plasma-induced polymerization as versatile, solvent-free methods for tailoring wettability, chemical functionality, and adhesion. Furthermore, it examines emerging classes of self-cleaning and self-sterilizing coatings that leverage photocatalytic, hydrophobic, or antimicrobial mechanisms to mitigate contamination, biofouling, and pathogen transmission. Additionally, developments in high-performance barrier films designed to protect food products and electronic devices through improved resistance to gases, moisture, and chemical agents are highlighted. By integrating insights from materials chemistry, surface physics, and nanostructured coating design, this review provides a comprehensive overview of current achievements and future directions in functional polymer films and coatings aimed at anti-pollution, antibacterial, and anti-corrosion performance. Full article

The correlation between fouling-driven corrosion and magnetic Barkhausen noise (MBN) in AH36 naval steel was investigated under real Mediterranean seawater conditions over a 12-month immersion period. A custom-designed MBN analyzer was used to monitor four MBN parameters at monthly intervals: RMS amplitude (MBN_RMS), peak amplitude (MBN_peak), peak field position (MBN_{peak pos.}), and full width at half maximum (MBN_FWHM). Complementary characterization included pit morphology analysis, X-ray diffraction (XRD) of corrosion products, and quantitative biofouling community profiling. Three distinct MBN evolution regimes were identified, corresponding to active pitting (T₀–T₃), transitional oxide formation (T₃–T₆), and mature corrosion equilibrium (T₆–T₁₂). Over the full exposure period, MBN_RMS decreased by 50.4% and MBN_{peak pos.} increased by 83.3%, consistent with domain wall pinning at pit stress concentrations and electromagnetic shielding by paramagnetic corrosion product layers (γ-FeOOH, β-FeOOH, α-FeOOH). Pearson correlation analysis revealed near-unity relationships between MBN_RMS and maximum pit depth (r = −0.982, p < 0.01), supporting its potential use as a quantitative non-destructive indicator of corrosion severity under comparable exposure conditions. Biofouling, particularly sulfate-reducing bacteria (SRB)-dominated communities and biogenic iron sulfides (mackinawite, greigite), was identified as a statistically significant secondary correlate of MBN signal intensity (r = −0.944 vs. SRB fraction). A composite diagnostic threshold of (MBN_RMS × MBN_peak)/MBN_FWHM ≈ 0.015 effectively discriminated active pitting from passive rusting. These findings provide a physically grounded framework for multiparametric MBN analysis as a non-destructive condition monitoring tool, with the caveat that the reported correlations are descriptive and require independent validation before deployment in regulatory inspection protocols. Full article

Biofouling remains a critical challenge in membrane bioreactors (MBR), which is primarily caused by the production of extracellular polymeric substances (EPS) as an initial step in biofilm formation. This still limits their widespread application in wastewater treatment. In the past decades, much research has been carried out to understand and consequently reduce biofouling in MBR. More recent studies have focused primarily on inhibiting the release of EPS by applying quorum quenching (QQ) to control biofouling in MBR. This study presents the first investigation of the QQ potential of Rubellimicrobium mesophilum and its effects on biofilm inhibition by EPS reduction, which is demonstrated for MBR operated with submerged flat sheet (PTFE, PS) and hollow fibre polyvinylidene fluoride (PVDF) membranes operated in parallel for 114 days. The QQ effect has a significant impact on the reduction in biofilm thickness on PTFE membranes by 45% and on PS membranes by about 47%, respectively. Additionally, the performance of PVDF was improved by 287.5%. Similarly, the total protein concentration on the PTFE membranes was reduced by 57%, while on the PS membranes, the reduction was 78%. In mixed liquor, protein reduction was 55%, indicating its effectiveness in controlling biofouling over extended operation. The biofilm formation was monitored by measuring the biofilm thickness via fluorescence microscopy and by analyzing the protein and sugar content of the developing biofilm and of the mixed liquor. All parameters indicated decreasing biofilm formation with increasing amounts of entrapped QQ bacteria, while the removal efficiency of organic compounds and ammonia remained similar between all MBRs. Full article

The non-albicans Candida species Candida tropicalis is an opportunistic fungal pathogen that forms a robust gel-like biofilm on polymeric prosthetic materials. These biofilms are embedded in an extracellular polymeric substance that retains large amounts of water, resulting in a hydrogel-like matrix that protects fungal cells, increases antifungal resistance, and contributes to the biofouling of these prosthetic materials. Biofouling is the unwanted colonization and accumulation of microbial communities on material surfaces, which alters their function and compromises clinical performance. Clinically, it is significant because it is linked to recurrent urinary tract infections, bloodstream infections, and persistent device-related infections, which often result in therapeutic failure and device malfunction. Polymers such as silicone elastomer, polypropylene, polystyrene, polyurethane, polyethylene, and polyvinyl chloride are widely used in catheters, surgical meshes, implants, and prostheses because of their durability, flexibility, and biocompatibility, yet their surface properties often encourage microbial adhesion and biofilm formation. This review emphasizes that the gel-like biofilm architecture of C. tropicalis underpins its persistence and resistance, while also highlighting promising antifungal strategies being developed to mitigate these infections. Notably, palmitic acid has been shown to disrupt mature biofilms by lowering ergosterol and inducing oxidative stress, whereas C-10 massoia lactone damages the extracellular matrix and suppresses hyphal growth. Drug repurposing approaches, such as combining minocycline with fluconazole, restore susceptibility in resistant isolates and demonstrate synergistic antibiofilm activity. Additionally, biomaterial-based interventions, such as chitosan coatings on silicone surfaces, significantly reduce fungal adhesion and biofilm formation. Together, these findings reflect a translational shift toward integrating natural products, repurposed drugs, and functionalized biomaterials into antifungal development. Understanding biofouling and these emerging strategies is crucial for developing effective control measures against C. tropicalis biofilms and for guiding the design of infection-resistant prosthetic devices. Full article

This study proposes an innovative spacer design for use in spiral-wound membrane filtration systems as a high-performance alternative to conventional woven spacers. By eliminating interwoven filaments, this structure fundamentally reshapes flow patterns while maintaining mechanical support. A novel aspect of this methodology is the inaugural application of coupled computational fluid dynamics (CFD) and the discrete phase model (DPM) for modeling microbial particle transport and deposition dynamics, which has been a critical gap in prior studies that focused solely on hydrodynamic analysis without addressing biocolloid dynamics. Numerical simulations demonstrated that the novel design reduces stagnant zones by a significant amount compared to standard woven spacers and achieves a greater velocity uniformity. For all eight configurations of the novel design, the DPM-derived microbial distribution maps revealed a reduction of circa 65% in particle colonization density on the spacer surface, and this reaches a 77% reduction for the optimal design. These measurements directly linking structural geometry to antifouling efficacy provide mechanistic insight unattainable through conventional velocity field analysis alone. Experimental validation using optical coherence tomography (OCT) revealed a 40% reduction in TOC deposition, while confocal laser scanning microscopy (CLSM) quantified a 54% decrease in biofilm viability through adenosine triphosphate (ATP) measurements. The incorporation of the optimal spacer in the plate-and-frame test module demonstrated that the lower degree of fouling caused both a 23% increase in permeation flux together with 76% lower energy consumption compared to the commercial design. Full article

Microplastics have become a ubiquitous environmental contaminant in natural waters, raising significant concerns regarding aquatic ecosystem health and potential human exposure. A comprehensive synthesis of current knowledge on microplastic pollution in freshwater and marine systems is presented, focusing on sources, distribution patterns, environmental behavior, and associated risks. In freshwater environments, microplastic inputs are closely linked to human activities and land use, with wastewater treatment plant effluent, urban runoff, and agricultural drainage serving as major pathways. In marine systems, microplastics undergo dynamic transport influenced by particle properties, hydrodynamic conditions, and biological interactions such as biofouling and aggregation, leading to widespread distribution from coastal zones to deep sea sediments. Importantly, the role of the freshwater–estuarine–marine continuum is emphasized, highlighting the coupled processes of transport, retention, and remobilisation that govern the spatiotemporal distribution and ultimate fate of microplastics across interconnected aquatic systems. Toxicological effects on aquatic organisms are further examined, particularly immunotoxicity and neurotoxicity, alongside potential human health risks via ingestion, inhalation, and dermal exposure. Attention is drawn to the discrepancy between experimental exposure conditions and environmentally relevant concentrations, which constrains robust risk assessment. Current mitigation strategies, including source reduction, wastewater treatment upgrades, transport interception, and degradation technologies, are critically evaluated in terms of effectiveness and limitations. A clear distinction is made between apparent removal and actual degradation, with further consideration of the environmental implications associated with sludge retention and degradation byproducts. Finally, key research priorities are identified, including the need for standardized detection methods, improved exposure assessment, development of environmentally benign alternatives, and strengthened policy-driven source control. These insights provide a basis for advancing sustainable management strategies for microplastic pollution in natural waters. Full article

Ports and recreational marinas are established hotspots for the introduction and secondary spread of non-indigenous species (NIS), mainly via vessel transport and biofouling on artificial substrates. In the AlienPorts project, we surveyed fouling and associated macrobenthic assemblages in four major Greek marinas across distinct marine regions—Rhodes (Levantine), Heraklion and Piraeus–Zea (Aegean), and Patra (Ionian)—from 2021 to 2022, applying two complementary protocols: (i) photoquadrat surveys and (ii) scraped assemblage sampling. The photoquadrats recorded twelve NIS and seven cryptogenic species, which were dominated by sessile fouling taxa, especially ascidians. The scraped samples revealed 106 polychaete and amphipod species, including 25 taxa (23 NIS, two cryptogenic). Six of the polychaetes are new NIS for the Mediterranean, and thirteen of the taxa are newly recorded as NIS in Greek waters. Heraklion had the highest NIS richness (18 NIS + two cryptogenic), while the other marinas hosted approximately ten NIS/cryptogenic taxa. In contrast, NIS often dominated the population densities, with Zea being the most impacted based on the NIS to native species ratios for both diversity and abundance. The two methods detected largely distinct biodiversity components and shared only one NIS, underscoring a strong complementarity. The multivariate analyses confirmed significant differences among marinas (ANOSIM, p < 0.01). These results support integrated, multi-method monitoring to enhance the early detection and impact assessment under MSFD Descriptor 2. Full article

The present study investigated the community composition and dynamics of freshwater biofouling on fiberglass inland waterway vessel (IWV) models coated with two commercial antifouling paints deployed in the Danube River (Serbia) for a total of five months. Biofouling was characterized using visual observations, in situ optical microscopy, the rapid ATP bioluminescence method, dry biomass measurements, and analyses of phototrophic and fungal communities. Based on the results, Hard Racing TecCel demonstrated the highest suppression of biofouling, with the lowest biomass accumulation and reduced algal diversity. At all stages of biofouling, diatoms dominated the phototrophic community, comprising 123 taxa. Achnanthidium minutissimum and Gomphonella olivacea were shown to be persistent hull colonizers, while Cyanobacteriophyta and Chlorophyta had reduced presence. Overall, the results highlight a slower progression of freshwater biofouling compared to marine systems and emphasize the need for the development of tailored antifouling strategies for IWVs to reduce environmental impact and operational costs. Full article

Biofouling has a detrimental effect on marine infrastructure and poses a severe challenge to the global marine industry. Therefore, developing efficient and environmentally friendly anti-fouling coatings to protect those facilities has become extremely necessary nowadays. To address marine biofouling, a series of photocurable degradable waterborne boron-containing polyurethane acrylate (WPU-PTPBx) anti-fouling coatings were prepared by grafting pyridine-triphenylborane (PTPB) onto polyurethane side chains and UV curing. FTIR and ¹H NMR confirmed the successful grafting of PTPB. The WPU-PTPBx aqueous dispersions had a particle size of 30~75 nm with excellent thermal storage stability. DSC and XRD characterizations revealed the amorphous structure of the coatings, which favored biodegradation. All coatings exhibited adhesion strength over 2 MPa, meeting marine application requirements. Antibacterial and anti-algal tests showed that PTPB content positively correlated with anti-fouling performance: the coating achieved a 99.66% inhibition rate against Escherichia coli and reduced the adhesion density of Nitzschia closterium to only 36.9 cells/mm². With favorable degradability and outstanding anti-fouling performance, WPU-PTPBx coatings are promising green anti-fouling materials for marine applications. Full article

Adsorption is a promising solution to the presence of contaminants in water resources that involves the use of adsorbent materials, such as granular activated carbon (GAC) and nanoparticles like silver (Ag) and copper (Cu). However, the practical challenge of using pure GAC lies in its susceptibility to biofouling. This study aimed to develop a multifunctional GAC/AgCu nanocomposite to address the dual challenge of pharmaceutical contamination and bacterial activity of Escherichia coli. Characterization by SEM, XRF, XRD and FTIR confirmed the successful impregnation of nanoparticles. Kinetic studies showed that the pseudo-first-order model was more suitable for both caffeine and paracetamol contaminants. The Langmuir model provided the best fit for isotherms, achieving maximum adsorption capacities of 138.35 $\mathrm{m}\mathrm{g} {\mathrm{g}}^{-1}$ for caffeine and 92.21 $\mathrm{m}\mathrm{g} {\mathrm{g}}^{-1}$ for paracetamol. In antibacterial tests, GAC/AgCu achieved a bacterial reduction of over 97%, whereas pure GAC showed no inhibitory effect, confirming that the antimicrobial properties are derived from the Ag and Cu nanoparticles. These results highlight GAC/AgCu as a promising multifunctional material for the simultaneous removal of emerging pharmaceutical pollutants and biological contaminants, offering a solution to mitigate biofouling and enhance water treatment efficiency. Full article

Patients receiving dialysis treatments suffer from a high rate of systemic comorbid conditions, including cardiovascular disease, mineral and bone disorders, chronic inflammation, amyloidosis, and recurring infections, leading to increased morbidity and mortality rates despite the progress made in the field of renal replacement therapies. The aforementioned conditions result from the continued dysregulation and overproduction of molecular biomarkers, which cannot be adequately monitored by traditional, intermittent laboratory tests. This review critically assesses the newly developed biosensor technologies for the detection of major dialysis biomarkers, including potassium, phosphorus, parathyroid hormone (PTH), β₂-microglobulin, creatinine, and cystatin C, with special emphasis on biosensors based on electrochemistry, optics, impedimetry, nanophotonics, and biological engineering techniques. These recent biosensors have been evaluated based on their analytical performance, the biofluids used in the studies, and their suitability for measuring relevant concentrations of these biomarkers. Special attention is given to biosensors capable of continuous operation or minimally invasive sampling, as well as to newly developed biofluid sampling techniques, including microneedle-, microtube-, and micropillar-based systems, for the long-term monitoring of the biomarkers in the serum of patients receiving dialysis treatments. The biosensing techniques for measuring infection biomarkers have also been discussed, given the high risk of bloodstream and access infections among patients receiving dialysis. The limitations of these biosensors include biofouling, calibration drift, and their integration into the dialysis treatment workflow. Finally, the future prospects of the recent biosensors offer the possibility of the proactive management of the high rate of comorbid conditions in this high-risk population of patients receiving dialysis treatments. Full article

Quorum quenching (QQ) is a promising biological approach that has the potential to control membrane biofouling. However, the implementation of the QQ membrane bioreactor still requires a more systematic and comprehensive understanding, including the selection of membrane materials, the determination of the optimal QQ bacterial dosage, and the use of appropriate media for the immobilization of QQ bacteria, all of which are important to ensure long-term operation. The present study investigated the impact of QQ bacteria on biofilm formation across different polymeric membranes. These include flat sheet membranes, Polytetrafluoroethylene (PTFE), Polysulfones (PSs), and hollow-fibre polyvinylidene difluoride (PVDF) membranes. It also evaluated biofilm development, membrane filtration performance, extracellular polymeric substance (EPS) production, and sludge floc properties, which were characterized using fluorescence microscopy. The results revealed that QQ intervention markedly suppressed quorum sensing (QS), leading to a pronounced, dose-dependent reduction in biofilm thickness, membrane fouling, EPS production and sludge floc size. Biofilm thickness was reduced by 63.5% on PTFE and 55.4% on PS membranes, accompanied by a notable reduction in EPS protein and polysaccharides, thereby weakening the biofilm formation and enhancing membrane filterability. Therefore, the permeability performance of the PVDF membrane improved by 338.2%. Furthermore, sludge settleability was enhanced, and floc size was reduced, resulting in the mitigation of biofilm formation without impacting pollutant degradation. These findings elucidate the material-dependent and dose-responsive mechanism by which QQ regulates EPS synthesis and biofilm formation in MBR. Full article