Minimum physicochemical characterisation requirements for nanomaterial regulation.

Appropriate characterisation of manufactured nanomaterials (NMs) is vital for many aspects of their synthesis, product formulation, toxicological testing and regulation. As the range and quantity of NMs in production has expanded, the interest in their potential environmental and toxicological consequences has grown. With this growth, there is increased need for clarity and rigour in characterising appropriate physicochemical parameters.

Poly(dimethyl siloxane) (PDMS) network blends of amphiphilic acrylic copolymers with poly(ethylene glycol)-fluoroalkyl side chains for fouling-release coatings. II. Laboratory assays and field immersion trials.

Amphiphilic copolymers containing different amounts of poly(ethylene glycol)-fluoroalkyl acrylate and polysiloxane methacrylate units were blended with a poly(dimethyl siloxane) (PDMS) matrix in different proportions to investigate the effect of both copolymer composition and loading on the biological performance of the coatings. Laboratory bioassays revealed optimal compositions for the release of sporelings of Ulva linza, and the settlement of cypris larvae of Balanus amphitrite. The best-performing coatings were subjected to field immersion tests.

Conditioning of surfaces by macromolecules and its implication for the settlement of zoospores of the green alga Ulva linza.

Conditioning, ie the adsorption of proteins and other macromolecules, is the first process that occurs in the natural environment once a surface is immersed in seawater, but no information is available either regarding the conditioning of surfaces by artificial seawater or whether conditioning affects data obtained from laboratory assays. A range of self-assembled monolayers (SAMs) with different chemical terminations was used to investigate the time-dependent formation of conditioning layers in commercial and self-prepared artificial seawaters. Subsequently, these results were compared with conditioning by solutions in which zoospores of the green alga Ulva linza had been swimming.

Saccharide-functionalized alkanethiols for fouling-resistant self-assembled monolayers: synthesis, monolayer properties, and antifouling behavior.

We describe the synthesis of a series of mono-, di-, and trisaccharide-functionalized alkanethiols as well as the formation of fouling-resistant self-assembled monolayers (SAMs) from these. The SAMs were characterized using ellipsometry, wetting measurements, and infrared reflection-absorption spectroscopy (IRAS). We show that the structure of the carbohydrate moiety affects the packing density and that this also alters the alkane chain organization.

Resistance of galactoside-terminated alkanethiol self-assembled monolayers to marine fouling organisms.

Self-assembled monolayers (SAMs) of galactoside-terminated alkanethiols have protein-resistance properties which can be tuned via the degree of methylation [Langmuir 2005, 21, 2971-2980]. Specifically, a partially methylated compound was more resistant to nonspecific protein adsorption than the hydroxylated or fully methylated counterparts. We investigate whether this also holds true for resistance to the attachment and adhesion of a range of marine species, in order to clarify to what extent resistance to protein adsorption correlates with the more complex adhesion of fouling organisms.

Amphiphilic block copolymer/poly(dimethylsiloxane) (PDMS) blends and nanocomposites for improved fouling-release.

Amphiphilic diblock copolymers, Sz6 and Sz12, consisting of a poly(dimethylsiloxane) block (average degree of polymerisation = 132) and a PEGylated-fluoroalkyl modified polystyrene block (Sz, average degree of polymerisation = 6, 12) were prepared by atom transfer radical polymerization (ATRP). Coatings were obtained from blends of either block copolymer (1-10 wt%) with a poly(dimethylsiloxane) (PDMS) matrix. The coating surface presented a simultaneous hydrophobic and lipophobic character, owing to the strong surface segregation of the lowest surface energy fluoroalkyl chains of the block copolymer.

Effect of contact angle hysteresis on the removal of the sporelings of the green alga Ulva from the fouling-release coatings synthesized from polyolefin polymers.

Wettability is one of the surface characteristics that is controlled by the chemical composition and roughness of a surface. A number of investigations have explored the relationship between water contact angle and surface free energy of polymeric coatings with the settlement (attachment) and adhesion strength of various marine organisms. However, the relationship between the contact angle hysteresis and fouling-release property is generally overlooked.

Marine fouling release silicone/carbon nanotube nanocomposite coatings: on the importance of the nanotube dispersion state.

The present work reports on the influence of the dispersion quality of multiwall carbon nanotubes (MWCNTs) in a silicone matrix on the marine fouling-release performance of the resulting nanocomposite coatings. A first set of coatings filled with different nanofiller contents was prepared by the dilution of a silicone/MWCNTs masterbatch within a hydrosilylation-curing polydimethylsiloxane resin. The fouling-release properties of the nanocomposite coatings were studied through laboratory assays with the marine alga (seaweed) Ulva, a common fouling species.

Physicochemical properties of (ethylene glycol)-containing self-assembled monolayers relevant for protein and algal cell resistance.

The influence of the number of repeating units in self-assembled monolayers (SAMs) of ethylene glycol and of their end-group termination on the settlement and adhesion of two types of algal cells, viz., zoospores of the macroalga Ulva and cells of the diatom Navicula , was studied. The findings are related to the resistance of these surfaces against fibrinogen adsorption.

Antifouling potential of Subtilisin A immobilized onto maleic anhydride copolymer thin films.

The proteinaceous nature of the adhesives used by most fouling organisms to attach to surfaces suggests that coatings incorporating proteolytic enzymes may provide a technology for the control of biofouling. In the present article, the antifouling (AF) and fouling release potential of model coatings incorporating the surface-immobilized protease, Subtilisin A, have been investigated. The enzyme was covalently attached to maleic anhydride copolymer thin films; the characteristics of the bioactive coatings obtained were adjusted through variation of the type of copolymer and the concentration of the enzyme solution used for immobilization.

Fluorinated/siloxane copolymer blends for fouling release: chemical characterisation and biological evaluation with algae and barnacles.

Fouling-release coatings were prepared from blends of a fluorinated/siloxane copolymer with a poly(dimethyl siloxane) (PDMS) matrix in order to couple the low modulus character of PDMS with the low surface tension typical for fluorinated polymers. The content of the surface-active copolymer was varied in the blend over a broad range (0.15-10 wt % with respect to PDMS).

Nanostructured films of amphiphilic fluorinated block copolymers for fouling release application.

New amphiphilic block copolymers S nSz m consisting of blocks with varied degrees of polymerization, n and m, of polystyrene, S, and polystyrene carrying an amphiphilic polyoxyethylene-polytetrafluoroethylene chain side-group, Sz, were prepared by controlled atom transfer radical polymerization (ATRP). The block copolymers, either alone or in a blend with commercial SEBS (10 wt% SEBS), were spin-coated in thinner films (200-400 nm) on glass and spray-coated in thicker films ( approximately 500 nm) on a SEBS underlayer (150-200 microm). Angle-resolved X-ray photoelectron spectroscopy (XPS) measurements proved that at any photoemission angle, varphi, the atomic ratio F/C was larger than that expected from the known stoichiometry.

The potential of nano-structured silicon oxide type coatings deposited by PACVD for control of aquatic biofouling.

SiO(x)-like coatings were deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD (PACVD). Surface energies (23.1-45.

Poly(ethylene glycol)-containing hydrogel surfaces for antifouling applications in marine and freshwater environments.

This work describes the fabrication, characterization, and biological evaluation of a thin protein-resistant poly(ethylene glycol) (PEG)-based hydrogel coating for antifouling applications. The coating was fabricated by free-radical polymerization on silanized glass and silicon and on polystyrene-covered silicon and gold. The physicochemical properties of the coating were characterized by infrared spectroscopy, ellipsometry, and contact angle measurements.

Preparation and characterisation of silicone-based coatings filled with carbon nanotubes and natural sepiolite and their application as marine fouling-release coatings.

This article reports on the preparation and partial characterisation of silicone-based coatings filled with low levels of either synthetic multiwall carbon nanotubes (MWCNTs) or natural sepiolite (NS). The antifouling and fouling-release properties of these coatings were explored through laboratory assays involving representative soft-fouling (Ulva) and hard-fouling (Balanus) organisms. The bulk mechanical properties of the coatings appeared unchanged by the addition of low amounts of filler, in contrast to the surface properties, which were modified on exposure to water.

Advanced nanostructures for the control of biofouling: The FP6 EU Integrated Project AMBIO.

The colonization of man made structures by marine or freshwater organisms or "biofouling" is a problem for maritime and aquaculture industries. Increasing restrictions on the use of toxic coatings that prevent biofouling, create a gap in the market that requires new approaches to produce novel nonbiocidal alternatives. This review details the systematic strategy adopted by an FP6 EU Integrated Project "AMBIO" to develop fundamental understanding of key surface properties that influence settlement and adhesion of fouling organisms.

Settlement and adhesion of algal cells to hexa(ethylene glycol)-containing self-assembled monolayers with systematically changed wetting properties.

Protein resistance of self-assembled monolayers (SAMs) of hexa(ethylene glycols) (EG(6)) has previously been shown to be dependent on the alkoxyl end-group termination of the SAM, which determines wettability [S. Herrwerth, W. Eck, S.