Antifouling Activity Research Articles

Total synthesis and structure-antifouling activity relationship of scabrolide F.

An efficient synthetic strategy for scabrolide F (7), a norcembranolide diterpene that was isolated from the Taiwanese soft coral Sinularia scabra, has only recently been reported by our group. Herein, we report details of the first total synthesis of 7. The tetrahydrofuran domain of 7 was stereoselectively constructed via the 5-endo-tet cyclization of a hydroxy vinyl epoxide. The reaction of alkyl iodide 30 with dithiane 38, followed by the introduction of an alkene moiety, afforded allylation precursor 41. The coupling of alkyl iodide 42 and allylic stannane 43 was examined as a model experiment of allylation. Because the desired allylated product 44 was not obtained, an alternative synthetic route toward 7 was investigated instead. In the second synthetic approach, fragment-coupling between alkyl iodide 56 and aldehyde 58, macrolactonization, and transannular ring-closing metathesis were used as the key steps to achieve the first total synthesis of 7. We hope that this synthetic strategy provides access to the total synthesis of other macrocyclic norcembranolides. We also evaluated the antifouling activity and toxicity of 7 and its synthetic intermediates toward the cypris larvae of the barnacle Amphibalanus amphitrite. This study is the first to report the antifouling activity of norcembranolides as well as the biological activity of 7.

Fouling resistance investigations of seaweed products.

Any solid, unprotected, and undefended surface in the aquatic environment will be fouled. Fouling, on the other hand, can affect a wide range of species that can tolerate some epibiosis. Several others, on the other hand, aggressively keep the epibionts off their body surface (antifouling). Antifouling defenses are built into marine plants like seaweed and seagrass. They do have a distinctive surface structure with tightly packed needle-like peaks and antifouling coverings, which may hinder settling bacteria's ability to cling. Chemical antifouling resistance is most probably a biological reaction to epibiosis' ecological drawbacks, especially for organisms capable of performing photosynthesis. The goal of this study was to see how effective natural compounds derived from littoral seaweeds were in preventing fouling. The brown mussel, an important fouling organism, was evaluated in laboratory bioassays against fifty-one populations' crude organic extracts including fort-two macroalgae species. Antifouling activity, exhibited a distinct phylogenetic pattern, with red macroalgae having the largest share of active species, subsequently brown macroalgae. Antifouling action in green seaweeds has never been significant. Seven species showed some level of induced antifouling defense. Our findings appear to back up previous findings about secondary metabolite synthesis in seaweeds, indicating that in the hunt for novel antifoulants, researchers should concentrate their efforts on tropical red macroalgae.

Smart zwitterionic coatings with precise pH-responsive antibacterial functions for bone implants to combat bacterial infections.

Hydrophilic antifouling coatings based on zwitterionic polymers have been widely applied for the surface modification of bone implants to combat biofilm formation and reduce the likelihood of implant-related infections. However, their long-term effectiveness is significantly limited by the lack of effective and precise antibacterial activity. Here, a pH-responsive smart zwitterionic antibacterial coating (PSB/GS coating) was designed and robustly fabricated onto titanium-base bone implants by using a facile two-step method. First, dopamine (DA) and a poly(sulfobetaine methacrylate-co-dopamine methacrylamide) (PSBDA) copolymer were deposited on implants via mussel-inspired surface chemistry, resulting in a hydrophilic base coating with abundant catechol residues. Next, an amino-rich antibiotic, gentamicin sulfate (GS), was covalently linked to the coating through the formation of acid-sensitive Schiff base bonds between the amine groups of GS and the catechol residues present in both the zwitterionic polymer and the DA component. During the initial implantation period, the hydrophilic zwitterionic polymers demonstrated the desired anti-fouling properties that could effectively reduce protein and bacterial adhesion by over 90%. With time, the bacterial proliferation led to a decrease in the microenvironment pH value, resulting in the hydrolysis of the acid-sensitive Schiff base bonds, thereby releasing GS on demand and effectively enhancing the anti-biofilm properties of coatings. Benefiting from this synergistic antifouling and smart antibacterial activities, the PSB/GS coating exerted an excellent anti-infective activity in both in vivo preoperative and postoperative infection rat models. This proposed facile yet effective coating strategy is expected to provide a promising solution to combat bone implant-related infections.

Novel metabolite madeirone and neomarinone extracted from Streptomyces aculeoletus as marine antibiofilm and antifouling agents.

Introduction: Biofouling poses a significant economic threat to various marine industries, leading to financial losses that can reach billions of euros annually. This study highlights the urgent need for effective alternatives to traditional antifouling agents, particularly following the global ban on organotin compounds. Material and methods: Streptomyces aculeolatus PTM-346 was isolated from sediment samples on the shores of the Madeira Archipelago, Portugal. The crude extract was fractionated using silica flash chromatography and preparative HPLC, resulting in two isolated marinone compounds: madeirone (1), a novel marinone derivative discovered in this study, and neomarinone (2). The antifouling activities of these compounds were tested against five marine bacterial species and the larvae of the mussel Mytilus galloprovincialis. Additionally, in silico and in vivo environmental toxicity evaluations of madeirone (1) and neomarinone (2) were conducted. Results: Madeirone (1) demonstrated significant antibiofilm efficacy, inhibiting Phaeobacter inhibens by up to 66%, Marinobacter hydrocarbonoclasticus by up to 60%, and Cobetia marina by up to 40%. Neomarinone (2) also exhibited substantial antibiofilm activity, with inhibition rates of up to 41% against P. inhibens, 40% against Pseudo-oceanicola batsensis, 56% against M. hydrocarbonoclasticus, 46% against C. marina, and 40% against Micrococcus luteus. The growth inhibition activity at the same concentrations of these compounds remained below 20% for the respective bacteria, highlighting their effectiveness as potent antibiofilm agents without significantly affecting bacterial viability. Additionally, both compounds showed potent effects against the settlement of Mytilus galloprovincialis larvae, with EC50 values of 1.76µg/mL and 0.12µg/mL for compounds (1) and (2), respectively, without impairing the viability of the targeted macrofouling species. In silico toxicity predictions and in vivo toxicity assays both support their potential for further development as antifouling agents. Conclusion: The newly discovered metabolite madeirone (1) and neomarinone (2) effectively inhibit both micro- and macrofouling. This distinct capability sets them apart from existing commercial antifouling agents and positions them as promising candidates for biofouling prevention. Consequently, these compounds represent a viable and environmentally friendly alternative for incorporation into paints, primers, varnishes, and sealants, offering significant advantages over traditional copper-based compounds.

Zooperiphyton on Anti-Fouling Coatings and Changes of Its Coenotic Structure

The features of the zooperiphyton communities' forming on experimental substrates - protective coatings with antifouling properties, based on industrial alkyd enamel PF-167 modified by cationic biocides 1-dodecylpyridine oleate and 1-dodecylpyridinium bis(2-ethylhexyl) phosphate in the bay of the Kaniv reservoir (the Dnieper river) have been studied. Some features of successional changes in the Zebra mussel and Bryozoans' (pearlwort) communities were discussed. On the contrast to the previous years, when the water temperature in August (time of high development of bryozoan colonies) was lower, the continual succession of communities with <i>Dreissena'</i>s dominance was not interrupted by the bryozoan's development. The protective coatings containing 8% of cationic biocides demonstrated high antifouling activity. In this study, no connections between the cenotic structure and nature of antifouling coatings were found.

Long-term antifouling surfaces for urinary catheters.

The presence of a variety of bacteria is an inevitable/indispensable part of human life. In particular, for patients, the existence and spreading of bacteria lead to prolonged treatment period with many more complications. The widespread use of urinary catheters is one of the main causes for the prevalence of infections. The necessity of long-term use of indwelling catheters is unavoidable in terms of the development of bacteriuria and blockage. As is known, since a permanent solution to this problem has not yet been found, research and development activities continue actively. Herein, polyethylene glycol (PEG)-like thin films were synthesized by a custom designed plasma enhanced chemical vapor deposition (PE-CVD) method and the long-term effect of antifouling properties of PEG-like coated catheters was investigated against Escherichia coli and Proteus mirabilis. The contact angle measurements have revealed the increase of wettability with the increase of plasma exposure time. The antifouling activity of surface-coated catheters was analyzed against the Gram-negative/positive bacteria over a long-term period (up to 30 days). The results revealed that PE-CVD coated PEG-like thin films are highly capable of eliminating bacterial attachment on surfaces with relatively reduced protein attachment without having any toxic effect. Previous statements were supported with SEM, XPS, FTIR spectroscopy, and contact angle analysis.

Diffusely Charged Polymeric Zwitterions as Loosely Hydrated Marine Antifouling Coatings.

Polymeric zwitterions exhibit exceptional fouling resistance through the formation of a strongly hydrated surface of immobilized water molecules. While being extensively tested for their performance in biomedical, membrane, and, to a lesser extent, marine environments, few studies have investigated how the molecular design of the zwitterion may enhance its performance. Furthermore, while theories of zwitterion antifouling mechanisms exist for molecular-scale foulant species (e.g., proteins and small molecules), it remains unclear how molecular-scale mechanisms influence the micro- and macroscopic interactions of relevance for marine applications. The present study addresses these gaps through the use of a modular zwitterion chemistry platform, which is characterized by a combination of surface-sensitive sum frequency generation (SFG) vibrational spectroscopy and marine assays. Zwitterions with increasingly delocalized cations demonstrate improved fouling resistance against the green alga Ulva linza. SFG spectra correlate well with the assay results, suggesting that the more diffuse charges exhibit greater surface hydration with more bound water molecules. Hence, the number of bound interfacial water molecules appears to be more influential in determining the marine antifouling activities of zwitterionic polymers than the binding strength of individual water molecules at the interface.

A multilayered antifouling coating constructed using the synthesized capsaicin-mimicking N-(4-hydroxy-3-methoxy-benzyl) acrylamide

Biofouling is a stepwise accumulation process involving participation of various molecules and marine organisms. To tackle this complex threat, development of efficient long-term antifouling coatings yet keeps elusive. Here we report a newly constructed coating with both antifouling activity and low surface energy. The special surface structure formed by silica spheres and fluorosilanes offers the coating superhydrophobicity. Capsaicin-mimicking N-(4-hydroxy-3-methoxy-benzyl)-acrylamide (HMBA) powder is synthesized via the Friedel-Crafts reaction and is used as the antifoulant additives in the coating. By the synergistic effect of surface superhydrophobicity and the dispersed antifoulant, the multilayered HMBA-silica coating effectively inhibits the adhesion of alginate, bovine serum albumin and Chlorella, their adhesion rate on the HS-3 coating is 11.9 %, 8.7 % and 3.3 % respectively. The HS-3 coating kills 96.6 % gram-negative bacteria E. coli and 99.9 % gram-positive bacteria S. aureus. Furthermore, the HMBA-silica coating significantly mitigates by its superhydrophobicity the corrosion of artificial seawater, its corrosion current density has decreased by 4 orders of magnitude compared to bare 316 L plate. In a 90 days real seawater immersion experiment, the coating shows excellent anti-fouling and anti-corrosion properties. The fabrication route of the HMBA-silica coating using the synthesized broad-spectrum antifoulant HMBA and hydrophobic silica would give insight into developing new antifouling materials for marine applications.

Polyoxometalate-Guanosine Monophosphate Hydrogels with Haloperoxidase-like Activity for Antibacterial Performance.

Haloperoxidases represent an important class of enzymes that nature adopts as a defense mechanism to combat the colonial buildup of microorganisms on surfaces, commonly known as biofouling. Subsequently, there has been tremendous focus on the development of artificial haloperoxidase mimics that can catalyze the oxidation of X- (halide ion) in the presence of H2O2 to form HOX. The natural intermediate HOX disrupts the bacterial quorum sensing, thus preventing biofilm formation. Herein, we report a simple method for the formation of supramolecular hydrogels through the self-assembly of Keggin-structured polyoxometalates, phosphotungstic acid, and silicotungstic acid with the small biomolecule guanosine monophosphate (GMP) in an aqueous medium. The polyoxometalate-GMP hydrogels that contained highly entangled nanofibers were mechanically robust and showed thixotropic properties. The gelation of the polyoxometalates with GMP not only rendered manifold enhancement in biocompatibility but also the fibril network in the hydrogel provided high water wettability and the polyoxometalates acted as an efficient haloperoxidase mimic to trigger oxidative iodination, as demonstrated by a haloperoxidase assay. The antifouling activity of the phosphotungstic acid-GMP hydrogel was demonstrated against both Gram-positive and Gram-negative bacteria, which showed enhanced antibacterial performance of the hydrogel as compared to the polyoxometalate alone. We envision that the polyoxometalate-GMP hydrogels may facilitate mechanically robust coatings in a simple pathway that can be useful for antifouling applications.

Synthesis and functionalization of scalable and versatile 2D protein films via amyloid-like aggregation.

Two-dimensional (2D) protein films can be used to modify the properties of surfaces, and find applications predominantly in the fields of biomaterials, lithography, optics and electronics. However, it is difficult to produce scalable homogeneous and robust protein films with an easy, low-cost, green and efficient method. Further challenges include encapsulating and releasing functional building blocks in the film without inactivating them, and maintaining or improving the bioactivities of proteins used for the formation of the films. Here we detail the process to prepare large 2D protein films with user-defined features and structures via the amyloid-like aggregation of commonly synthesized proteins. These films can be synthesized at meter scales, have high interface adhesion, high functional expansibility and tunable functional properties, obtained by controlling the position of the disulfide bond breakage. For example, we can retain or even enhance the natural antibacterial, biomineralization and antifouling activity of proteins involved in film formation, and the properties can also be expanded through the physical blending or chemical grafting of additional functional blocks on the surface of the film. A 2D protein film can be prepared in ~3 h using four alternative coating techniques: immersion, transfer, hydrogel stamping and spraying. The characterization process of the film requires ~5 d. The procedure can be carried out by users with basic expertise in materials science.

4-Aminophenylboronic acid dimer sensitized carbon nanotubes for the construction of portable and disposable sulfide electrochemical sensors

Abnormal sulfide levels in serum can cause kidney failure, Alzheimer's, Parkinson's, stroke, diabetes, and even cancer. Therefore, maintaining proper sulfide balance is crucial for managing and preventing these conditions. Electrochemical approaches have emerged as potential alternatives for sulfide detection. However, the adsorption of elemental sulfur on the working electrode leads to surface fouling and passivation, posing a significant challenge in developing reliable electrochemical methods for sulfide detection. In this study, we present a portable and surface fouling-free electrochemical system that utilizes functionalized multi-walled carbon nanotubes and 4-aminophenylboronic acid dimers for accurate sulfide measurement. The sensor showed excellent electrocatalytic activity to sulfide and antifouling activity to possible interferences. The method had a linear range from 10 µM to 2 mM and a detection limit of 2.3 µM. The effectiveness and applicability of this method were evaluated by analyzing sulfide levels in different serum samples and comparing the results with their glucose levels. As both blood glucose and sulfide levels can serve as indicators of certain health conditions, such as diabetes or sulfur metabolism disorders, this comparison provides valuable insights. Importantly, no complicated sample pretreatment was involved, thus this method can be easily adopted as a point-of-care diagnostic device. Additionally, the study also revealed a higher concentration of sulfide in cancer cells than in normal cells, offering a new development direction for differentiating between cancer cells and normal cells.

Preparation and Study of Antifouling and Fouling-Release Surface Materials from Copolymers with Anchoring Functional Groups

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.

Polydopamine functionalised ceria-zirconia nanoparticles embedded water-borne epoxy nanocomposite for anti-biofouling coatings

Biofouling, the accumulation of microorganisms, plants, algae on wet surfaces is one of the major issues adversely affecting the overall hydrodynamic performance of the marine vessels. Ceria (CeO2) nanoparticles (NPs) are effectively used as anti-biofouling agent to prevent the deterioration of steel structures, due to their excellent redox capacity. Various approaches are being investigated to enhance the antifouling activity of ceria NPs. Here, we report the development of novel polydopamine (PDA) functionalised ceria-zirconia nanoparticles filled water-borne epoxy nanocomposite coating to prevent the microbial-induced corrosion of mild steel. Ceria NPs were functionalised with PDA to enhance the dispersibility and improve their ability to resist biofouling in water-borne epoxy resin coatings against microbial species. As the anti-biofouling activity of ceria depends on their oxygen storage capacity, zirconium was incorporated to create a defective crystal structure with more active oxygen storage and release sites. Ceria and ceria-zirconia NPs were synthesised by precipitation method and functionalised with PDA. The functionalisation of ceria-zirconia (CZ) NPs was confirmed by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Confocal Raman spectroscopy and X-ray Photon spectroscopy (XPS). Thermogravimetric analysis (TGA) shows that incorporation of zirconium increases the amount of oxygen vacancies in the crystal lattice there by enhancing ceria's redox potential. Anti-biofouling and anti-biocorrosion properties of the coatings were explored against different microbial strains. The antibacterial tests show that colony-forming units (CFU) of PDA functionalized ceria-zirconia epoxy (EPCZ) nanocomposites were suppressed by 93 % and 87 % in the case of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria, respectively. Biofilm inhibition studies show that EPCZ nanocomposite coatings have higher biofilm inhibition efficiency against gram-negative bacteria (96.37 %) than gram-positive bacteria (62.67 %) due to the differences in their morphology. The practical applicability of the nanocomposite coatings was studied using cultured seawater consortia, and the results reveal that PCZ nanoparticles provide superior biofilm inhibition. Electrochemical impedance spectroscopy (EIS) reveals that the EPCZ coatings exhibit significant enhancement in charge transfer resistance and coating resistance. The synergistic effect of PDA functionalisation and zirconium incorporation in ceria leads to the exceptional biocorrosion resistance in corrosive bacterial environments.

Fabrication and characterization of electrospun porous cellulose acetate ultrathin fiber coatings incorporating essential oil

Bacterial adhesion has become a significant problem in industry and in the domestic domains due to causes loss of capital, labor, and energy worldwide. Microbial resistance to biocides and antimicrobials is a major concern, and several applications have been designed to prevent and inhibit bacterial adhesion. Therefore, there has recently been a demand for materials having antibacterial properties that contain active components which do not cause antibiotic resistance. Among them, integration of essential oils with micro/nano fibers as green and safe antimicrobial compounds was considered to have potential. For this reason, in this study, coatings containing St. John’s wort oil (SJWO) onto porous cellulose acetate ultrathin fiber (pCA_UF) were produced and the antibacterial and antifouling activities were evaluated. The average fiber diameter of 1356.37 ± 496.89 µm and the pore diameters of 413.91 ± 173.52 µm analyzed by scanning electron microscopy (SEM). In addition, the thickness of the coatings was found as 226 ± 35 µm. Attenuated Fourier-transform infrared (ATR-FTIR) indicated a physical type of interaction between SJWO and pCA_UF. Contact angle (CA) results confirmed the presence of SJWO on the pCA_UF decreased the hydrophobicity from 160 ± 16° to 74 ± 2°. pCA_UF-SJWO coatings showed a reduction in adherent bacteria such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, compared to the glass substrate and pCA_UF coatings. Overall, the data supports the use of ultrathin fiber with essential oil coatings for bacterial adhesion.

Bacteria-responsive hydrogel for on-demand release of antimicrobial peptides that prevent superbug infections and promote wound healing

Various skin infections present a substantial challenge in both patient care and the medical community. A primary obstacle to effective wound healing is the colonization of pathogenic bacteria, which would produce hyaluronidase (HAase). This enzyme degrades hyaluronic acid (HA) at wound sites, facilitating bacterial infection. Herein, we developed a HAase-responsive hydrogel, HA-EPL-PEG, incorporating the antimicrobial peptide ε-Poly-l-lysine (EPL) and Polyethylene glycol diacrylate (PEGDA), chemically crosslinked via a photoinitiator. Following, the in vitro antibacterial and antifouling properties of this hydrogel were evaluated, along with its cytotoxicity to mammalian cells. Subsequently, its bacteria secreted HAase responsive functionality was evaluated. In vivo antibacterial, anti-infectious and wound healing effects were further investigated in a rodent model. All these results demonstrated the multifunctional benefits of HA-EPL-PEG hydrogel, showcasing its HAase-responsive nature, antibacterial and antifouling activities. Importantly, the hydrogel significantly expedited the healing of full-thickness skin wounds, denoting a promising avenue for advancing wound care.

Antibiofouling activity of 1-hexadecyl-3-methylimidazolium chloride against Amphora sp. BARC 104, a fouling diatom isolated from back waters of Kalpakkam

1-Hexadecyl-3-methylimidazolium chloride (C16MimCl), an alkylimidazolium ionic liquid (IL) with a long alkyl side chain (-hexadecyl group) is attractive for antimicrobial applications. However, there are limited studies on the antifouling efficacy of ILs using biofouling organisms especially diatoms. In this study, the antifouling activity of C16MimCl was determined against Amphora sp. BARC 104, a dominant fouling diatom isolated from Kalpakkam coastal waters. Growth of the diatom was inhibited in the presence of IL at varied concentrations starting from 0.15 μM C16MimCl. A complete inhibition in the growth was observed in the presence of 2.5 μM C16MimCl. Adhesion and biofilm formation by Amphora sp. was strongly inhibited at sub-micromolar concentrations of IL. Exposure of diatom cells to IL in acute toxicity assays induced oxidative stress (increased reactive oxygen species generation) and reduced metabolic activity (decreased esterase activity) as revealed by 2,7 -Dichlorodihydrofluorescein diacetate (DCH2FDA) and fluorescein diacetate (FDA) staining, respectively. SYTOX® Green staining and extracellular chlorophyll a measurement revealed a severe membrane damage and leakage of chlorophyll a, respectively, in IL treated diatom cells. These measurements during recovery experiments indicated a permanent damage to cell and thylakoid membranes in the diatom cells. Damage to multiple cellular targets coupled with strong antibiofilm activity suggest potential application of C16MimCl in preparation of antifouling formulations and coatings.

Antibacterial adsorptive membrane decorated via silver nanolayer for ammonia removal

The presence of ammonia pollution in surface water warrants a rigorous examination due to its tendency to surpass established regulatory thresholds, particularly in several global river systems. Numerous traditional techniques have been extensively used for the elimination of ammonia; nevertheless, their efficacy in ammonia removal is not deemed remarkable. The use of membrane technology is increasingly being employed to eliminate nitrogen compounds from water and wastewater. Nevertheless, it is crucial to acknowledge the limited body of literature pertaining to the use of nanomaterials to eradicate multiple pollutants. Specifically, there is a notable scarcity of studies investigating the simultaneous eradication of both bacteria and ammonium. This work included the fabrication of a PES-PVP flat sheet membrane that featured an adsorbent material, namely a silver (Ag) nanolayer. The objective was to investigate the effectiveness of this membrane in removing ammonia as well as its potential antifouling and antibacterial properties. The PES-PVP/Ag nanocomposite membrane underwent characterization by several spectroscopic and microscopic analytical techniques. We not only showed that the PES-PVP/Ag nanocomposite membrane has a superior 96% ammonia removal efficiency but also discussed the antibacterial mechanism against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli in order to better understand the interaction of PES-PVP/Ag nanocomposite membrane with bacteria. Moreover, as compared to the PES-PVP membrane, the PES-PVP/Ag nanocomposite membrane exhibited enhanced antifouling capabilities. The PES-PVP/Ag nanocomposite membrane appears as a very promising method for the treatment of advanced antimicrobial or ammonia-contaminated water due to the ease of separation, plentiful availability, as well as the extremely strong antifouling and antibacterial activity displayed by the membrane.

Selective Adsorption of Ionic Species Using Macroporous Monodispersed Polyethylene Glycol Diacrylate/Acrylic Acid Microgels with Tunable Negative Charge.

Monodispersed polyethylene glycol diacrylate (PEGDA)/acrylic acid (AA) microgels with a tuneable negative charge and macroporous internal structure have been produced using a Lego-inspired droplet microfluidic device. The surface charge of microgels was controlled by changing the content of AA in the monomer mixture from zero (for noncharged PEGDA beads) to 4 wt%. The macroporosity of the polymer matrix was introduced by adding 20 wt% of 600-MW polyethylene glycol (PEG) as a porogen material into the monomer mixture. The porogen was successfully leached out with acetone after UV-crosslinking, which resulted in micron-sized cylindrical pores with crater-like morphology, uniformly arranged on the microgel surface. Negatively charged PEGDA/AA beads showed improved adsorption capacity towards positively charged organic dyes (methylene blue and rhodamine B) compared to neutral PEGDA beads and high repulsion of negatively charged dye molecules (methyl orange and congo red). Macroporous microgels showed better adsorption properties than nonporous beads, with a maximum adsorption capacity towards methylene blue of 45 mg/g for macroporous PEGDA/AA microgels at pH 8.6, as compared to 23 mg/g for nonporous PEGDA/AA microgels at the same pH. More than 98% of Cu(II) ions were removed from 50 ppm solution at pH 6.7 using 2.7 mg/mL of macroporous PEGDA/AA microgel. The adsorption of cationic species was significantly improved when pH was increased from 3 to 9 due to a higher degree of ionization of AA monomeric units in the polymer network. The synthesized copolymer beads can be used in drug delivery to achieve improved loading capacity of positively charged therapeutic agents and in tissue engineering, where a negative charge of scaffolds coupled with porous structure can help to achieve improved permeability of high-molecular-weight metabolites and nutrients, and anti-fouling activity against negatively charged species.

Marine antifouling properties of enzyme modified polyaniline coated stainless steel surface

On solid surfaces immersed in a liquid medium, a biofilm layer which is called biofouling formed over time by organic molecules and microorganisms. It is important to produce new eco-friendly ideas can prevent this undesired phenome. In this study, we focused on the antifouling performance of polyaniline (PANI), whose anticorrosive properties have been already known. The main purpose of this study was to immobilize hydrolytic enzymes that could break down biomolecules and microorganisms and how this would contribute to the antifouling performance of the PANI coating. When α-amylase, DNAse, glucose oxidase, α-chymotrypsin, lipase and pectinase enzymes immobilized into PANI that was synthesized in ammonium oxalate (PANIAO) and sodium salicylate (PANISS) electrolytes, α-amylase containing film (PANISS-A) showed the highest performance (76.5% antifouling activity). The surface properties after keeping in the Mediterranean Sea for 12 days were compared by digital photography, Scanning Electron microscope (SEM) and fluorescence microscope images, also with Energy Dispersive X-Ray (EDX) analysis and crystal violet staining. Carbohydrate and protein amounts and CFU (Colony Forming Units) values of biofilms formed on the surface for bare, PANISS and PANISS-A coupons after keeping 12 days in the Mediterranean Sea were determined. Vibrio species (V.harveyi, V.alginolyticus, V.parahaemolyticus) were detected in the biofilms by Matrix- Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) analysis.

Reverse osmosis membranes applied in seawater desalination plants as a source of bacteria with antifouling activity: Isolation, biochemical and molecular characterization

BackgroundDuring lifespan of reverse osmosis systems applied in seawater desalination plants, a common phenomenon of undesirable growth and accumulation of biological material known as biofouling occurs. Microbial cells are first settlers, attaching and enclosing themselves in extracellular polymeric substances –biomass accumulation usually referred to as microfouling or biofilms, which becomes a serious issue when having a detrimental effect on materials or hampering industrial processes. Thus, control of microfouling on reverse osmosis membranes is crucial since chemical and physical treatments are usually costly and ineffective. In this context, even though microorganisms are the source of the problem, they can also provide possible solutions due to their capacity to produce secondary metabolites, being several of these competition mediators secreted compounds (i.e., bioactive molecules) produced during the stationary phase (e.g., lipases, proteases, DNases and other enzymes with alginate lyase and xanthine oxidases). Such bioactive substances can be utilized against the development of biofilms. Considering biofouled surfaces a niche for complex microbial interactions, here we have used reverse osmosis membranes and cartridge filters applied in a seawater desalination plant as a source for the isolation of bacteria with anti-fouling potential, among other biotechnological applications. ResultsWe obtained 27 bacterial isolates able to secrete exoenzymes displaying a wide array of bioactivity such as lipases, alginases, and glucosidases, among others. Additionally, we showed two main candidates able to inhibit the growth of common microbial colonizers of ROM and cartridge filter. ConclusionsThese results highlight the potential biotechnological application of bioactive molecules against biofouling formation.How to cite: Vera-Villalobos H, Cortes-Martinez A, Gonzalez-Gutierrez Á, et al. Reverse osmosis membranes applied in seawater desalination plants as a source of bacteria with antifouling activity: Isolation, biochemical and molecular characterization. Electron J Biotechnol 2023;66. https://doi.org/10.1016/j.ejbt.2023.09.003.