Antifouling properties of hydrogels

Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet ‘hydrogel’. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.     

Tuning of Calcite Crystallographic Orientation to Support Brachiopod Lophophore

Organisms exert exquisite control on mineral formation by tuning structural and material properties to meet functional requirements. Brachiopods are sessile marine organisms that filter feed via a large lophophore which is supported by a delicate calcite loop that grows from the inner surface of the shell. How does the loop support the weight of the large lophophore? Electron backscatter diffraction (EBSD) and nanoindentation analyses of the loop as it emerges from the shell of Laqueus rubellus reveal that calcite fiber crystallography generates asymmetry in the material properties of the structure. In the core of the emergent loop, the fibers are short and kernel‐like. Either side of the core, the long fibers have a different crystallographic orientation and resultant material properties. fibers on the anterior, load‐bearing side, are harder (H = 3.76 ± 0.24 GPa) and less stiff (E = 76.87 ± 4.87 GPa) than the posterior (H = 3.48 ± 0.31 GPa, E = 81.79 ± 5.33 GPa). As a consequence of the asymmetry in the material properties, the loop anterior may be more flexible under load. The brachiopod strategy of tuning crystallographic orientation to confer spatially determined material properties is attractive for additive manufacturing of synthetic materials that have complex heterogeneous material property requirements.

     

Nanofunctionalized Superhydrophobic Antifouling Coatings for Environmental Sensor Applications—Advancing Deployment with Answers from Nature

In this work, a novel preparation for superhydrophobic nanofunctionalized silver and gold, copper‐coated substrates as potential antifouling coatings for environmental monitoring devices are fabricated. The superhydrophobic coating is topographically similar to the design of the Lotus leaf (Nelumbo necifera) and was synthesized by creating an electroless galvanic reaction between copper and the metal salt. In doing so, a nano‐ and micro‐topographical structure was created on the surface of a copper substrate which can be rendered superhydrophobic through the addition of a self‐assembled monolayer (SAM) of CF₃(CF₂)7CH₂CH₂SH. The work investigates whether the hydrophobicity of such materials affects micro‐organism attachment and subsequent biofouling. The materials are deployed in a marine environment in Dublin, Ireland for a 6 week study to determine the overall antifouling capacity. The materials are analyzed for biomass, slime (glycocalyx) production and more specifically protein and carbohydrate adsorption all of which are attributed to the inherent makeup of biofilm and exopolymeric substances (EPS) which are secreted by micro‐organisms during the biofouling process. This work highlights the dominance of combinational antifouling approaches rather than single tactics for such a complex problem and one that plagues multiple research areas. This novel approach in developing a new antifouling material for sensors, and indeed, any aquatic platform has shown excellent results throughout.     

AgNPs doped TEOS sol–gel coatings to prevent the adhesion of marine fouling organisms

Biosynthesis of silver nanoparticles (AgNPs) using plants is considered to be cost effective and more eco‐friendly than conventional techniques. In the authors’ previous study, they reported the biosynthesis of AgNPs using fruit extract of Aegle marmelos which were of spherical shape and high crystallinity. In order to achieve enhanced synthesis, optimisation of process parameters influencing the yield of AgNPs has been carried out in this study. Box–Behnken design has been employed to optimise the parameters in order to enhance the synthesis of AgNPs. The antimicrofouling activity of the optimised AgNPs was determined by preparing AgNPs doped TEOS sol–gels (SNSGs) and evaluating their antibiofilm activity. In addition to this, antimacrofouling activity of the AgNPs was studied against molluscs viz. Patella sp. and Trochus sp. as model organisms. Anticrustacean assay was also performed with the larvae of brine shrimp (Artemia salina) as a model crustacean fouling organism. The results indicated that the AgNPs could completely inhibit the attachment of molluscs and significantly increased the percentage of mortality against crustacean fouling larvae. Thus, this study gives scope for the possible development of formulations containing AgNPs as effective antifouling agents that could prevent the adhesion of micro and macrofoulers thereby preventing marine biofouling.Inspec keywords: silver, nanoparticles, adhesion, nanobiotechnology, microorganisms, nanofabrication, sol‐gel processing, liquid phase deposited coatings, thin films, organic compoundsOther keywords: biosynthesis, silver nanoparticle doped TEOS sol‐gel coatings, adhesion, marine fouling organisms, Box‐Behnken design, process parameter optimisation, antimicrofouling activity, antibiofilm activity, antimacrofouling activity, molluscs, Patella sp, Trochus sp, model organisms, anticrustacean assay, brine shrimp larvae, Artemia salina, model crustacean fouling organism, crustacean fouling larvae, antifouling agents, Ag     

Microtopography of the eye surface of the crab Carcinus maenas: an atomic force microscope study suggesting a possible antifouling potential

Marine biofouling causes problems for technologies based on the sea, including ships, power plants and marine sensors. Several antifouling techniques have been applied to marine sensors, but most of these methodologies are environmentally unfriendly or ineffective. Bioinspiration, seeking guidance from natural solutions, is a promising approach to antifouling. Here, the eye of the green crab Carcinus maenas was regarded as a marine sensor model and its surface characterized by means of atomic force microscopy. Engineered surface micro- and nanotopography is a new mechanism found to limit biofouling, promising an effective solution with much reduced environmental impact. Besides giving a new insight into the morphology of C. maenas eye and its characterization, our study indicates that the eye surface probably has antifouling/fouling-release potential. Furthermore, the topographical features of the surface may influence the wettability properties of the structure and its interaction with organic molecules. Results indicate that the eye surface micro- and nanotopography may lead to bioinspired solutions to antifouling protection.     

环境友好型防污剂及海洋防污涂料的研究进展

本文概括了海洋生物的附着过程及其影响因素,介绍了环境友好型防污剂与海洋防污涂料的发展概况,并对未来环境友好型防污涂料的发展作了展望。     

舰船防污涂料的使用需求及研究进展

海洋生物附着导致的生物污损是舰船航行过程中面临的一大难题,涂装防污涂料被认为是防止海洋生物污损舰船最经济有效的方法。根据舰船的服役特点,介绍了舰船防污涂料对于长效性、动静普适性和海域广谱性的使用需求,提出研发环保型长效防污涂料是当前防污损研究领域的一大挑战。简单综述了自抛光型防污涂料、污损释放型防污涂料、仿生型防污涂料、表面自愈型防污涂料以及其他防污新技术的发展,指出自抛光型防污涂料仍是当前稳定批量应用的主流产品,其他新型防污技术的防污期效仍需经过实际应用验证。随着环保要求的日趋严格,防污损机理研究的不断深入以及防污性能评价方法的不断完善,新型环保防污涂料的研制将逐渐加快并得到广泛推广应用。     

Settlement and growth of copper-tolerantEctocarpus siliculosus (Dillw.) Lyngbye on different copper-based antifouling surfaces under laboratory conditions

The second paper of this series reports the results of comparative studies on the marine antifouling properties of a range of six copper and copper-alloy materials, using settlement and growth of a copper-tolerant strain of the marine-fouling algaEctocarpus siliculosus as criteria. Samples of ordinary copper, arsenical copper, copper-nickel 90/10, copper-nickel 70/30, aluminium brass and aluminum bronze were preincubated in sterilized seawater medium under laboratory conditions and then used to follow the early stages of spore settlement and subsequent development of colonies of the alga in the culture system by both light and scanning electron microscopy. The results of this bio-assay are compared with other published information relating to the long-term antifouling properties of these materials in trials at sea.     

Durable self-polishing antifouling Cu-Ti coating by a micron-scale Cu/Ti laminated microstructure design

Marine biofouling is a major issue deteriorating the service performance and lifespan of marine infrastruc-tures.The development of a durable,long-term,and environment-friendly antifouling coating is therefore of significant importance but still a critical challenge in maritime engineering.Herein,we developed a Cu-Ti composite antifouling coating with micron-sized alternating laminated-structure of Cu/Ti by plasma spraying of mechanically mixed Cu/Ti powders.The coating was designed to enable controlled release of Cu ions through galvanic dissolution of Cu laminates from the Cu/Ti micro-galvanic cell in aqueous solution.Results showed that remarkable antifouling efficiency against bacterial survival and adhesion up to ～100 ％ was achieved for the Cu-Ti coating.Cu/Ti micro-galvanic cell was in-situ formed within Cu-Ti coating and responsible for its Cu ions release.The successive dissolution of Cu laminates resulted in the formation of micro-channels under Ti laminates near surface,which contributed to controlled slow Cu ions release and self-polishing effect.Thus,environment-friendly antifouling capability and ～200 ％longer antifouling lifetime than that of the conventional organic antifouling coatings can be achieved for the Cu-Ti coating.On the other hand,as compared to the conventional organic antifouling coatings,the Cu-Ti composite coating presented much higher mechanical durability due to its strong adhesion strength,excellent mechanical properties,and two orders lower wear rate.The present laminated Cu-Ti coating exhibits combination of outstanding antifouling performance and high mechanical durability,which makes this coating very potentially candidates in marine antifouling application.     

抗蛋白吸附材料及其在海洋防污领域的应用前景

综述了抗蛋白吸附材料的种类及其抗蛋白吸附机制,分析了海生物污损发生过程中蛋白吸附的作用,展望了抗蛋白吸附材料在海洋防污领域的应用前景。     

Molecular Design of Antifouling Polymer Brushes Using Sequence‐Specific Peptoids

Material systems that can be used to flexibly and precisely define the chemical nature and molecular arrangement of a surface would be invaluable for the control of complex biointerfacial interactions. For example, progress in antifouling polymer biointerfaces that prevents nonspecific protein adsorption and cell attachment, which can significantly improve the performance of an array of biomedical and industrial applications, is hampered by a lack of chemical models to identify the molecular features conferring their properties. Poly(N‐substituted glycine) “peptoids” are peptidomimetic polymers that can be conveniently synthesized with specific monomer sequences and chain lengths, and are presented as a versatile platform for investigating the molecular design of antifouling polymer brushes. Zwitterionic antifouling polymer brushes have captured significant recent attention, and a targeted library of zwitterionic peptoid brushes with different charge densities, hydration, separations between charged groups, chain lengths, and grafted chain densities, is quantitatively evaluated for their antifouling properties through a range of protein adsorption and cell attachment assays. Specific zwitterionic brush designs are found to give rise to distinct but subtle differences in properties. The results also point to the dominant roles of the grafted chain density and chain length in determining the performance of antifouling polymer brushes.     

Automatic technique for measuring interfacial properties of liquid metals

Abstract

An improved technique for calculating the interfacial characteristics of liquids in the sessile drop configuration has been developed. The procedure, based on grabbing of the observed shape of the sessile drop followed by computer analysis, has acceptable accuracy and good productivity.

MST/3017     

细菌生物膜与海洋附着生物之间的生化作用

综述了生物附着过程中细菌生物膜与海洋附着生物之间复杂的生化作用。生物膜中有些菌株对生物附着起抑制作用,有些菌株对生物附着起促进作用。防污涂料表面的细菌生物膜对涂料的防污性能和污损生物的附着有不同程度的影响。     

Development and in vitro characterization of self-emulsifying drug delivery system (SEDDS) for oral opioid peptide delivery

Aim: In this study, self-emulsifying drug delivery system (SEDDS) for oral delivery of opioid peptide dalargin were developed and characterized in vitro.

Methods: Dalargin lipophilicity was increased by O-esterification of tyrosine OH group, hydrophobic ion pairing, or a combination thereof. Distribution coefficients (log?D) of lipidized dalargin derivatives were determined. Then, dalargin was incorporated in chosen SEDDS, namely SEDDS-1, composed of 50% Capmul 907, 40% Cremophor EL, and 10% propylene glycol and comparatively more lipophilic SEDDS-2 composed of 30% Captex 8000, 30% Capmul MCM, 30% Cremophor EL, and 10% propylene glycol. Additionally, SEDDS were characterized regarding droplet size, polydispersity index (PDI), cloudy point, physical stability and stability against pancreatic lipase. Furthermore, mucus permeating properties of SEDDS and their ability to protect the incorporated dalargin against proteolysis by trypsin, α-chymotrypsin, elastase, simulated gastric fluid (SGF), and simulated intestinal fluid (SIF) were evaluated.

Results: The highest dalargin drug payload of 4.57% in SEDDS-2 was achieved when dalargin palmitate (pDAL) was ion paired with sodium dodecyl sulfate (SDS) in molar ratio 1:1. Moreover, SEDDS-1 and SEDDS-2 had a narrow droplet size distribution with average droplet sizes of 42.1 and 33.1?nm with PDI of 0.042 and 0.034, respectively. Lipolysis study showed that within 30?min 78.5% of SEDDS-1 and 92.1% of SEDDS-2 were digested. In addition, both SEDDS exhibited mucus permeating properties as well as a protective effect against enzymatic degradation by trypsin, α-chymotrypsin, elastase, SGF and SIF.

Conclusion: The results of this study suggest that the developed SEDDS could be considered for oral opioid peptide delivery.     

Preparation of an optimized ciprofloxacin-loaded chitosan nanomicelle with enhanced antibacterial activity

Objective: The objective of this study was to evaluate the effect of lipid structure on physicochemical properties of chitosan-fatty acid nanomicelles and prepare an optimum ciprofloxacin-loaded formulation from these conjugates which could enhance the antibacterial effects of drug against some important pathogens like P. aeruginosa.

Significance: Nowadays, resistance in infectious diseases is a growing worldwide concern. Nanocarriers can increase the therapeutic index and consequently reduce the antibiotic resistance. By site-specific delivery of drug, the adverse effects of broad-spectrum antibiotics such as ciprofloxacin would be reduced.

Methods: Fatty acid grafted chitosan conjugates were synthetized in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The effects of fatty acid type (stearic acid, palmitic acid, and linoleic acid) on physicochemical properties of conjugates were investigated. Ciprofloxacin was encapsulated in nanomicelles by thin film hydration method. Also, the preparation process was optimized with a central composite design. The antibacterial effect of optimum formulation against P. aeruginosa, K. pneumoniae, and S. pneumoniae species was determined.

Results: All conjugates were synthetized with high yield values and the substitution degrees ranged between 2.13 and 35.46%. Ciprofloxacin was successfully encapsulated in nanomicelles. The optimum formulation showed high drug loading (≈?19%), with particle size of about 260?nm and a sustained release profile of ciprofloxacin. The minimum inhibitory concentrations of ciprofloxacin in optimum formulation against P. aeruginosa and K. pneumoniae species were 4 and 2 times lower in comparison with the free drug, respectively.

Conclusions: The antibacterial effect of ciprofloxacin was improved by encapsulation of drug in chitosan nanomicelles.     

基于嵌段聚醚酯多元醇的聚氨酯控释机理研究

针对海洋工程设备中弹性基材的防污特殊需求,合成聚乙二醇（PEG）/聚己内酯（PCL）嵌段共聚物PEG/CL_X,并与HDI三聚体固化形成可降解聚氨酯,研究其亲水性能及降解性能,再将PEG/CL_X与氧化亚铜等结合,制备成一系列的海洋防污涂层,研究其控释机理。      

海洋天然产物防污研究进展

多种海洋天然产物都具有防污活性 ,将其开发为高效无毒的防污涂料已成为防污技术发展方向之一。本文综述了海洋植物、海洋动物及海洋微生物中天然产物的防污活性 ,并对海洋天然产物防污研究进行了展望     

海洋防污剂的研究进展

概述了海洋防污剂的研究现状,简要介绍了主要商业防污剂的特点,重点介绍了新型环保防污剂的研究进展,包括天然产物基防污剂、酶基防污剂、纳米防污剂以及硅酸盐防污剂。最后,对海洋防污剂的研究和发展方向进行了展望。      

Synthesis and pharmaceutical properties of N-acyloxymethyl prodrugs of Allop with potential anti-trypanosomal activity

Abstract

We report herein the synthesis, and the physicochemical and pharmacokinetic properties of N-acyloxymethyl prodrugs of allopurinol (Allop) (2a–f). Allop is a compound with activity against Trypanosoma cruzi, a causative agent of Chagas disease. Its pathology leads to a huge number of infections and deaths per year, because in addition to many sufferers only having limited access to health services only an inefficient chemotherapy is available. Relevant pharmaceutical properties (pK_a, stability, solubility, lipophilicity, in vitro permeability, binding protein, xanthine oxidase binding) were also determined. The results obtained showed that derivatives behave as prodrugs of Allop, since they exhibit improved physicochemical and pharmacokinetic properties relative to their precursor. This behavior turns these compounds into active reservoirs of Allop, and reduces its unfavorable characteristics, so 2a–f compounds are excellent candidates for the treatment of Chagas disease. This work is therefore an important contribution leading to the suppression of Chagas disease.     

海洋防污涂料发展现状与研究趋势

本文概述了海洋防污涂料的发展情况,并重点介绍了新型环保防污涂料的发展现状及其作用机制,同时分析了其面临的问题,并提出了如何解决新型防污涂料的应用,以及海洋防污涂料未来发展的趋势。