Marine antifouling behavior of the surfaces modified by dopamine and antibacterial peptide

Marine biofouling causes serious harms to surfaces of marine devices in transportation,aquaculture,and offshore construction.Traditional antifouling methods pollute the environment.A novel and green antifouling strategy was developed to prevent effectively the adhe sion of bacteria and microalgae.An antifouling surface was fabricated via coating Turgencin BMox2(TB)onto dopamine-modified 304stainless steel(304 SS).The surface physical and chemical properties before and after modification were characterized by Fourier transform infrared spectrometer(FTIR),X-ray photoelectron spectrometer(XPS),contact angle measurement(CA),3D optical profilometer,ellipsometer,and atomic force microscope(AFM).Antimicrobial peptide was coated onto the surface of 304 SS successfully,and the surface morphology and wettability of the modified sample were modified.Moreover,cytocompatibility of the peptide was evaluated by co-culture of peptide and cells,indicating promising cell biocompatibility at the modified sample surface.At last,antifouling performance and electrochemical corrosion were tested.Results show that the adhesion rates of Vibrio natriegens and Phaeodactylum tricornutum on the antifouling surface were reduced by 99.85% and 67.93%,respectively from those of untreated samples.Therefore,the modified samples retained superior corrosion resistance.The study provide a simply and green way against biofouling on ship hulls and marine equipment.

Research on the Marine Antifouling Ability and Mechanism of Acrylate Copolymers and Marine Coatings Based on a Synergistic Effect

Marine biofouling is an urgent global problem in the process of ocean exploitation and utilization.In our work,a series of zinc-based acrylate copolymers(ACZn-x)were designed and synthesized using benzoic acid,zinc oxide(ZnO)and a random quaternion copolymer consisting of ethyl acrylate(EA),butyl acrylate(BA),acrylic acid(AA)and methacrylic acid(MAA)by free radical polymerization and dehydration condensation.The ACZn-x with a zinc benzoate side chain is able to hydrolyze in natural seawater under static conditions,resulting in the formation of a smooth surface.We investigated and confirmed the antifouling(AF)behavior of ACZn-x in the laboratory and revealed that they have better antibacterial(86%for S.aureus and 72%for E.coli)and anti-algal(≥60.1%for N.closterium and≥67.5%for P.subcordiformis)activities.We also assessed the marine AF properties of ACZn-x and corresponding coatings in Qingdao,China;the ACZn-x exhibited ideal AF properties with little silt and biological mucosa adhered to the ACZn-x surface after 6 months,and corresponding coatings exhibited little biofouling after 16 months in the ocean.Importantly,possible AF mechanisms were further proposed at the cellular level.These results could be helpful for the development and application of effective AF coatings.

An antifouling polydopamine-based fluorescent aptasensor for determination of arginine kinase

Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.

Towards superior permeability and antifouling performance of sulfonated polyethersulfone ultrafiltration membranes modified with sulfopropyl methacrylate functionalized SBA-15

A non-solvent induced phase separation(NIPS)process was used to fabricate a series of sulfonated polyethersulfone(SPES)membranes blending with different concentrations of SBA-15-g-PSPA with the applications in the ultrafiltration(UF)process.SBA-15 was modified with 3-methacrylate-propyltrime thoxysilane(MPS)to form SBA-15-g-MPS.It was further modified with the charge tailorable polymer chains by reacting with 3-sulfopropyl methacrylate potassium salt.The nanoparticles were uniformly dispersed and finger-like channels were developed within the membrane.The adding of surface modified SBA-15-g-PSPA nanoparticles has significantly improved membrane water permeability,hydrophilicity,and antifouling properties.The pure water fluxes of the composite SPES membranes were significantly higher than the pristine SPES membrane.For the membrane containing 5%(mass)of SBA-15-g-PSPA(MSSPA5),the pure water flux was increased dramatically to 402.15 L
m^(-2)·h^(-1),which is ~1.5 times that of MSSPA0(268.0 L
m^(-2)·h^(-1)).The high flux rate was achieved with 3%(mass)of SBA-15 nanoparticles with retained high rejection ratio 98%for natural organic matter.The results indicate that the fashioned composite membrane comprising SBA-15-g-PSPA nanoparticles have a promising future in ultrafiltration applications.

Extraction of Protease Produced by Sea Mud Bacteria and Evaluation of Antifouling Performance

Enzyme-based antifouling coatings are potential alternative to traditional tributyltin-based coatings in the marine biofouling control depended on its environmental friendliness.Proteases are usually the key antifouling active components in enzyme based antifouling coatings.In this work,based on biological antagonism effect,a marine proteolytic bacterial strain of Bacillus velezensis was isolated from the sea mud,and denoted as SM-1.The scanning electron microscope(SEM)revealed that the bacteria are rod-shaped with length 1-1.3μm.The protease-producing conditions of SM-1 were investigated,and it was found that the culture solution displays higher proteolytic activity under the culture conditions of 35℃,10‰-20‰salinity,pH 6-9 and more than 7 d culture time.Moreover,the 25 kDa protein was confirmed to be the main active component in the crude protease,which was revealed via the experiment of SDS-PAGE.The antifouling assay indicated that the protease SM-1 has remarkable effect on the decomposition of barnacle cement and diatom secretion,and also can effectively inhibit the attachment of barnacle cyprids,diatom and mussel byssus.Therefore,this protease potentially can be used as environmental-friendly antifoulant of enzyme-based marine antifouling coatings,and this work also provides a new approach to obtain antifouling protease via isolating proteolytic bacteria from the sea mud surrounding representative fouling organisms.

Study on Marine Corrosion and Antifouling Behavior of Copper Alloys Exposed to Sea Areas in China

The relationship of corrosion resistance and antifouling behavior of 19 Cu alloys exposed to seawater of Qingdao ,Xiamen,Yulin sea areas in China for 1,2,4,8 year intervals was studied .The experiments were carried on by analyzing the composition of corrosion films formed on the surface of alloy specimens during the immersion time and by using OM,SEM,EDXA and AES experiment methods.The results verify the view point that it is the cuprous oxide film which played an important role in antifouling property of Cu alloys in seawater and throw a light on the view point in details further.The influence of different sea areas on the antifouling property of Cu alloys is also discussed.

Synthesis and Bacteriostatic Activity and Antifouling Capability of Benzamide Derivatives Containing Capsaicin

Five benzamide deriatives containing capsaicin were synthesized which have similar structures to capsaicin. Their yield was high. The monomers synthesized were characterized by IR, 1H NMR and MS spectroscopy. Cha-racterization data are in agreement with the proposed structures of the products. These five compounds exhibit bacterial inhibition and N-[4-hydroxy-2-methyl-5-（methylthio）benzyl]benzamide（HMMBBA）, for instance, shows that the minimal inhibitory concentrations（MIC） of HMMBBA are 0.125 and 0.25 mg/mL on Staphyloccocus aureus and Escherichia coli, respectively. A static test site was set up in the eighth harbor to investigate the antifouling effectiveness of the five new antifoulants. Five-month exposure experiments were performed on sets of panels coated with each of antifouling coatings, and the results were compared to that of the test panel without antifouling coating. Test boards with antifouling coating were covered with just a macroscopic fouling organism such as Balanus. The results of the present paper demonstrate that new antifoulants represent an alternative to the biocidal antifouling paint.

Antifouling evaluation of extracts from Red Sea soft corals against primary biofilm and biofouling

Objectives: To evaluate antifouling property of extracts from Red Sea soft corals against primary biofilm and biofouling.Methods: Seven species of soft corals Sarcophyton glaucum(a), Sinularia compressa,Sinularia cruciata(a), Heteroxenia fuscescens(a), Sarcophyton glaucum(b), Heteroxenia fuscescens(b) and Sinularia cruciata(b) were chosen to test their extracts as antibacterial and antifouling agents in Eastern Harbour of Alexandria, Mediterranean Sea.Bioactive compounds of soft corals were extracted by using methanol and concentrated under vacuum. The residues of extracts were mixed in formulation of inert paint which consisted of rosin, chlorinated rubber and ferrous oxide against micro and macro fouling organisms. The formulated paints were then applied on PVC panels twice by brush,hanged in a steel frame and immersed in Eastern Harbour of Alexandria Mediterranean Sea followed by visual inspection and photographic recordings.Results: After 185 days of immersion in seawater, the antifouling results agreed with the antibacterial results where extracts of Sinularia compressa and Heteroxenia fuscescens(b) gave the best activity against marine fouling tubeworms and barnacles. The inhibition activity was correlated with the major functional groups(hydroxyl, amino, carbonyl,aliphatic(fatty acids), C]C of alkene or aromatic rings and CeC l of aryl halides) of the extracts.Conclusions: The strong antifouling activity makes them promising candidates for new antifouling additives. After the screening and application of natural organic compounds from soft corals, marine organisms show activity against micro and macro fouling organisms.

Antifouling Activity of Bacterial Symbionts of Seagrasses against Marine Biofilm-Forming Bacteria

Marine biofouling has been regarded as a serious problem in the marine environment. The application of TBT and other heavy metal-based antifoulants has created another environmental problem. The present study explored the possible role of baterial symbionts of seagrasses Thalassia hemprichii, and Enhalus acoroides, which were successfully screened for antifouling activity against marine biofilm-forming bacteria isolated from the surrounding colonies of seagrasses. Bacterial symbionts were isolated and tested against biofilm-forming bacteria resulted in 4 bacterial symbionts capable of inhibiting the growth biofilm-forming isolates. Molecular identification based on 16S rRNA gene sequences revealed that the active bacterial symbionts belonged to the members of the genera Bacillus and Virgibacillus. Further tests of the crude extracts of the active bacterial symbionts supported the potential of these symbionts as the alternative source of environmentally friendly marine antifoulants.

Influence of microstructure and surface condition on antifouling property of 90Cu-10Ni alloy in seawater

Through the experiment of natural seawater exposure corrosion, the antifouling properties of the plate specimens of 90Cu 10Ni alloy were studied, which were processed by different deformations, annealing treatments and surface treatments. The results indicate that after exposure corrosion for half a year, the antifouling properties of the specimens are quite different. The specimens processed by suitable deformations, annealing treatment at 650?℃ and pretreatment of surface film possess both good corrosion resistance and antifouling properties. However, the specimens processed by different deformations and annealing treatment at 450?℃ possess lower corrosion resistance, although they are also treated by the pretreatment of surface film; their antifouling properties change with different deformations. The relationships among the corrosion morphology and microstructure with the antifouling property of 90Cu 10Ni alloy are observed under the scanning electron microscopy (SEM).

Synthesis and characterization of caprolactone based polyurethane with degradable and antifouling performance

In this work,a degradable polyurethane composed of caprolactone(CL)and L-Lactide(LLA)as soft segments,and 4,40-methylenebis(cyclohexyl isocyanate)(H12 MDI)and polytetramethylene ether glycol(PTMEG)as hard segments,was prepared.Hydrolytic degradation experiment revealed that the degradable polyurethane(PU)could be degraded in artificial seawater.It also showed that caprolactone-copolyurethane(CL-PU)copolymer with higher crystallinity degraded much slower in artificial seawater.However,the introduction of LLA resulted in an increase in the hydrophilicity and reduction in the crystallinity of degradable PU,as demonstrated by the contact angle analysis.The result of the scanning electron microscope showed that the surface of degradable PU renewed under static condition.Moreover,degradable PU was able to be used as a carrier,and it controlled the release rate of 4,5-dichloro-2-octyl-isothiazolone(DCOIT).The anti-diatom(Navicula incerta)test demonstrated that the(caprolactone-co-L-lactide)-co-polyurethane 4(CL/LAx-PU4)with DCOIT contents prevented the adhesion of diatom Navicula incerta(88.37%reduction)due to their self-polishing and the release of antifoulants.Therefore,the degradable PU consisted of CL,LLA,and DCOIT could be a durable resin with good antifouling activity for the application in the marine anti-biofouling field.

Preparation of antifouling ultrafiltration membranes from copolymers of polysulfone and zwitterionic poly(arylene ether sulfone)s

The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the antifouling performance and the hemocompatibility of the membranes.In this study,a series of copolymers(PSF-PESSB)containing polysulfone(PSF)and poly(arylene ether sulfone)bearing pendant zwitterionic sulfobetaine groups(PESSB)were prepared via one-pot polycondensation.Subsequently,the ultrafiltration(UF)membranes were prepared from different zwitterion-containing copolymers.The prepared membranes showed high thermal stability and mechanical properties.Besides,it also displayed attractive antifouling performance and blood compatibility.Compared with the original PSF membrane,the amount of protein absorption on the modified membrane was reduced;the flux recovery ratio and the resistance to blood cells were significantly improved.The results of this work suggest that PSF-PESSB membranes are expected to be applied in blood purification.The introduction of zwitterion-containing polymers to membranes paves ways for developing advanced hemodialysis technologies for crucial process.

Numerical Study on the Hydrodynamic Performance of Antifouling Paints

This study presents a simple numerical method that can be used to evaluate the hydrodynamic performances of antifouling paints.Steady Reynolds-averaged Navier-Stokes equations were solved through a finite volume technique,whereas roughness was modeled with experimentally determined roughness functions.First,the methodology was validated with previous experimental studies with a flat plate.Second,flow around the Kriso Container Ship was examined.Lastly,full-scale results were predicted using Granville’s similarity law.Results indicated that roughness has a similar effect on the viscous pressure resistance and frictional resistance around a Reynolds number of 10^7.Moreover,the increase in frictional resistance due to roughness was calculated to be approximately 3%-5%at the ship scale depending on the paint.

Antifouling Potential of Bacteria Isolated from a Marine Biofilm

Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.

Characterization and antifouling activity analysis of extracellular polymeric substances produced by an epibiotic bacterial strain Kocuria flava associated with the green macroalga Ulva lactuca

Extracellular polymeric substances(EPS)are present externally to the microorganisms and play an important role in attachment and biofilm formation.These polymers possess antibacterial and antifouling activities.In this study,the antifouling activity of EPS produced by an epibiotic bacterium associated with macroalga Ulva lactuca was assessed against fouling bacteria and barnacle larvae.Results indicate that the EPS isolated from the epibiotic bacterium inhibits the biofilm formation of the bacteria without much antibacterial activity.Also,the EPS reduced the settlement of barnacle larvae on the hard substrate under laboratory conditions.The epibiotic bacterium was identified as Kocuria flava based on 16 S rRNA gene sequencing.The EPS was further analysed using Fourier transform infrared(FT-IR),nuclear magnetic resonance(NMR)and X-ray diffraction(XRD)to understand the biochemical composition.NMR analysis revealed the presence of polysaccharides,proteins,acetyl amine and succinyl groups.Scanning electron microscope analysis indicated that the EPS consisted of aggregated and irregular sphere-shaped particles.

A strong adhesive block polymer coating for antifouling of large molecular weight protein

Some proteins secreted by microorganisms have large molecular weights. We report here an approach to prepare coating by multilayer polymers for antifouling of proteins, especially the proteins with a large molecular weight.Stainless steel was used as the model substrate. The substrate was first coated with a hybrid polymer film, which was formed by simultaneous hydrolytic polycondensation of 3-aminopropyltriethoxysilane and polymerization of dopamine(HPAPD). After grafting the macroinitiator 2-bromoisobutyryl bromide, the block polymer brushes PMMA-b-PHEMA were grafted. Three proteins were used to test protein adsorption and antifouling behavior of the coating, including recombinant green fluorescent(54 k Da), recombinant R-transaminase(2 × 90 k Da), and recombinant catalase(4 × 98 k Da). It is demonstrated that the block polymer brushes not only can prevent the adsorption of small molecular weight proteins, but also can significantly reduce the adsorption of the large molecular weight proteins.

Development of Coatings Marine Antifouling Based on Perfluorinated Surfactants Synthesis and Physicochemical Study

The fight against dirt settling on the hulls of ships and more generally on all underwater structures is more than 2000 years. The need for effective antifouling paints, which prevents the establishment and growth of marine organisms on submerged structures, is universally recognized. In this work, we synthesize two perfluorinated surfactants from simple monomers. After describing the reactions, we discuss the different analyzes of the proton nuclear magnetic resonance (1H NMR), the fluorine nuclear magnetic resonance (NMR I9F), gel permeation chromatography (GPC) and the light scattering (LS) at a fixed angle 90. The glass transition temperature of the two surfactants diethylallylphosphonate and allylamine are obtained by Differential Scanning Calorimetry (DSC). Antifouling paint properties were followed by exposure of the plates to the marine environment by visual observation.

Comparative Toxicity of “Tin Free” Self-Polishing Copolymer Antifouling Paints and Their Inhibitory Effects on Larval Development of a Non-Target Organism

Toxic substances released as a result of leaching from painted surfaces to the aquatic environment affect both fouling organisms and “non-target” biota. Artemia fransiscana nauplii have been considered a useful test system for the examination of toxicity for antifouling paints. In this study, we examined the effect of four “tin free” self-polishing copolymer (SPC) antifouling paints on the larval development of Artemia nauplii. Based on the L(S/V)50 values the order of toxicity of the antifouling paints was: ANTI F > SHARKSKIN > OCEAN T/F > MICRON. Furthermore, the body size of Artemia nauplii was significantly affected at lethal and above lethal L(S/V)5024h values. The body size of 48 h-aged nauplii exposed for the last 24 hours to each of the four SPC antifouling paints was significantly lower than that of the 48 h-aged controls (0.88 ± 0.030 mm). In addition, the body size of 72 h-aged nauplii maintained for the last 24 hours to pure synthetic seawater after exposure for 24 hours to each of the four SPC antifouling paints was significantly lower than that of the 72 h-aged controls (0.96 ±0.027 mm). Overall, the SPCs examined here were substantially toxic to Artemia nauplii, but with different toxicities and modes of action, as a result of the synergistic action of distinct components of the antifouling paints.

Bienzyme system immobilized in biomimetic silica for application in antifouling coatings

Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to non-target organisms, imposex in gastropods and increased multiresistance among bacteria. Therefore,enzyme-based coatings could be a new alternative solution. A H2O2-producing bienzyme system was developed in this study. H2O2 can be produced from starch by the cooperation of α-amylase and glucose oxidase, which promotes the hydrolysis of polymeric chain and oxidizes the glucose to produce H2O2, respectively. The encapsulated bienzyme(A-G@BS) exhibits enhanced stabilities of thermal, pH, recycling and tolerance of xylene. The A-G@BScontaining coating releases H2O2 at rates exceeding a target of 36 nmol·cm-2·d-1for 90 days in a laboratory assay. The results demonstrate that the method is a promising coating technology for entrapping active enzymes,presenting an interesting avenue for enzyme-based antifouling solutions.

Metabolic Response of the Two Marine Unicellular Algae <i>Chlorella salina</i>and <i>Dunaliella bardawil</i>to Toxicity of the Antifouling Agent Irgarol 1051

Toxic pollutants are metabolic poisons that can seriously injure or destroy the photosynthetic organisms upon which the food chain depends. Since microalgae play a key role in marine ecosystems, marine microalgae are proposed as excellent bio-indicators of pollution due to their high sensitivity, which can give warning of the toxic effects of chemicals sooner than any other species. The aim of this work concentrated on the effect of different concentrations of the antifouling biocide (Irgarol 1051) on growth and chlorophylls content (as an essential metabolite) of the two marine unicellular green algae Chlorella salina and Dunaliella bardawil that usually used in fish feeding. The growth of the wall-less Dunaliella bardawil was more sensitive to Irgarol 1051 than the walled cells Chlorella salina, although the concentrations used were greatly different. The product of photosynthesis in the two algal species greatly affected since in the presence of Irgarol 1051, a serious destructive effect was observed. The cell wall appeared to play a significant role in protecting the organism against toxicity of the antifouling agent either by adsorption or degradation. The strength of toxicity depends mainly on the concentration of the antifouling agent, the length of culturing period and the type of organism tested.