Anti-protein and anti-bacterial behavior of amphiphilic silicones

Mucus Mimic Hydrogel Coating for Lubricous, Antibiofouling, and Anti-Inflammatory Urinary Catheters

Silicone is a common elastomer used in indwelling urinary catheters, and catheters are widely used in various medical applications due to their exceptional biocompatibility, hypoallergenic properties, and flexibility. However, silicones exhibit hydrophobic characteristics, lack inherent biolubrication, and are susceptible to nonspecific biosubstance adsorption, resulting in complications including but not limited to tissue trauma, postoperative pain, and urinary tract infections (UTIs). The development of effective surface designs for biomedical catheters to mitigate invasive damage and UITs has been a longstanding challenge. Herein, we present a novel approach to prepare a mucus mimic hydrogel coating. A thin layer of hydrogel containing xylitol is fabricated via photopolymerization. The surface modification technique and the interface-initiated hydrogel polymerization method ensure robust interfacial coherence. The resultant coating exhibits a low friction coefficient (CoF ≈ 0.1) for urinary catheter applications. Benefiting from the hydration layer and the antifouling of the xylitol unit, the xylitol hydrogel-coated surfaces (pAAAMXA) demonstrate outstanding antibiofouling properties against proteins (98.9% reduction relative to pristine polydimethylsiloxane (PDMS)). Furthermore, the pAAAMXA shows general adhesion resistance against bacteria primarily responsible for UITs (Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Methicillin-resistant strains of Staphylococcus aureus (MRSA), and Staphylococcus epidermidis (S. epidermidis)) without compromising biotoxicity (cell viability 98%). In vivo, catheters coated with the mucus mimic hydrogel displayed excellent biocompatibility, resistance to adhesion of bio substance, and anti-inflammatory characteristics. This work describes a promising alternative to conventional silicone catheters, offering potential for clinical interventional procedures with minimized complications.

Siloxane Containing Polyether Groups-Synthesis and Use as an Anti-Biocorrosion Coating

In the presented study, the effectiveness of a siloxane polyether (HOL7) coating on glass against microbiological colonization was assessed using microalgae as a key component of widespread aerial biofilms. The siloxane polyether was successfully synthesized by a hydrosilylation reaction in the presence of Karstedt's catalyst. The product structure was confirmed by NMR spectroscopy and GPC analysis. In addition, the thermal stability of HOL7 was studied by thermogravimetric measurement. Subsequently, the surfaces of glass plates were modified with the obtained organosilicon derivative. In the next step, a microalgal experiment was conducted. A mixture of four strains of algal taxa isolated from building materials was used for the experiment-Chlorodium saccharophilum PNK010, Klebsormidium flaccidum PNK013, Pseudostichococcus monallantoides PNK037, and Trebouxia aggregata PNK080. The choice of these algae followed from their wide occurrence in terrestrial environments. Application of an organofunctional siloxane compound on the glass reduced, more or less effectively, the photosynthetic activity of algal cells, depending on the concentration of the compound. Since the structure of the compound was not based on biocide-active agents, its effectiveness was associated with a reduction in water content in the cells.

Marine biofouling and the role of biocidal coatings in balancing environmental impacts

Marine biofouling is a global problem affecting various industries, particularly the shipping industry due to long-distance voyages across various ecosystems. Therein fouled hulls cause increased fuel consumption, greenhouse gas emissions, and the spread of invasive aquatic species. To counteract these issues, biofouling management plans are employed using manual cleaning protocols and protective coatings. This review provides a comprehensive overview of adhesion strategies of marine organisms, and currently available mitigation methods. Further, recent developments and open challenges of antifouling (AF) and fouling release (FR) coatings are discussed with regards to the future regulatory environment. Finally, an overview of the environmental and economic impact of fouling is provided to point out why and when the use of biocidal solutions is beneficial in the overall perspective.

Biomedical Silicones: Leveraging Additive Strategies to Propel Modern Utility

Silicones have a long history of use in biomedical devices, with unique properties stemming from the siloxane (Si-O-Si) backbone that feature a high degree of flexibility and chemical stability. However, surface, rheological, mechanical, and electrical properties of silicones can limit their utility. Successful modification of silicones to address these limitations could lead to superior and new biomedical devices. Toward improving such properties, recent additive strategies have been leveraged to modify biomedical silicones and are highlighted herein.

Hybrid Bio-Based Silicone Coatings with Anti-adhesive Properties

Hybrid polysiloxanes and polysilsesquioxanes grafted with naturally occurring bioactive phytochemicals: eugenol and linalool, were synthesized and investigated with regard to their structure and properties. The two series of materials, differing in the type of inorganic structure and the content of active groups, were coated onto the surface of glass plates, and their antibiofilm activities against bacteria Aeromonas hydrophila were assessed by luminometry and fluorescence microscopy. Bioactivity was correlated with specific properties of the hybrid coatings (chemical structure, surface free energy and adhesiveness). The functionalized polysilsesquioxanes exhibited the most favorable anti-adhesive effects. Cell adhesion after 6 days of incubation, expressed as RLU/cm², was significantly reduced (44 and 67 for, respectively, Z-E-100 and Z-L-100, compared to 517 for the control glass carrier). The surface stickiness of polysiloxane films deteriorated their anti-adhesion properties, despite the presence of a large amount of bioactive species.

Amphiphilic silicones for the facile dispersion of carbon nanotubes and formation of soft skin electrodes

Flexible, dry skin electrodes represent a potentially superior alternative to standard Ag/AgCl metal electrodes for wearable devices used in long-term monitoring. Herein, such electrodes were formed using a facile method for dispersing carbon nanotubes (CNTs) in a silicone matrix using custom amphiphilic dispersive additives (DSPAs). Using only brief mixing and without the use of solvents or surface modification of CNTs, twelve poly(ethylene oxide)-silanes (PEO-SAs) of varying crosslinkability, architecture, siloxane tether length, and molar ratio of siloxane:PEO were combined with an addition cure silicone and CNTs. Nearly all PEO-SA modified silicone-CNT composites demonstrated improved conductivity compared to the unmodified composite. Best conductivities correlated to composites prepared with PEO-SAs that formed micelles of particular sizes (d ~ 200 - 300 nm) and coincided to PEO-SAs with a siloxane:PEO molar ratio of ~ 0.75 - 3.00. Superior dispersion of CNT by such PEO-SAs was exemplified by scanning electron microscopy (SEM). Advantageously, modified composites retained their moduli, rather than becoming more rigid. Resultant electrodes fabricated with modified composites showed skin-electrode impedance comparable to that of Ag/AgCl electrodes. Combined, these results demonstrate the potential of silicone-CNT composites prepared with PEO-SA DSPAs as flexible, dry electrodes as a superior alternative to traditional electrodes.

Combinatorial Polyacrylamide Hydrogels for Preventing Biofouling on Implantable Biosensors

Biofouling on the surface of implanted medical devices and biosensors severely hinders device functionality and drastically shortens device lifetime. Poly(ethylene glycol) and zwitterionic polymers are currently considered "gold-standard" device coatings to reduce biofouling. To discover novel anti-biofouling materials, a combinatorial library of polyacrylamide-based copolymer hydrogels is created, and their ability is screened to prevent fouling from serum and platelet-rich plasma in a high-throughput parallel assay. It is found that certain nonintuitive copolymer compositions exhibit superior anti-biofouling properties over current gold-standard materials, and machine learning is used to identify key molecular features underpinning their performance. For validation, the surfaces of electrochemical biosensors are coated with hydrogels and their anti-biofouling performance in vitro and in vivo in rodent models is evaluated. The copolymer hydrogels preserve device function and enable continuous measurements of a small-molecule drug in vivo better than gold-standard coatings. The novel methodology described enables the discovery of anti-biofouling materials that can extend the lifetime of real-time in vivo sensing devices.

Combinatorial Polyacrylamide Hydrogels for Preventing Biofouling on Implantable Biosensors

Biofouling on the surface of implanted medical devices and biosensors severely hinders device functionality and drastically shortens device lifetime. Poly(ethylene glycol) and zwitterionic polymers are currently considered "gold-standard" device coatings to reduce biofouling. To discover novel anti-biofouling materials, a combinatorial library of polyacrylamide-based copolymer hydrogels is created, and their ability is screened to prevent fouling from serum and platelet-rich plasma in a high-throughput parallel assay. It is found that certain nonintuitive copolymer compositions exhibit superior anti-biofouling properties over current gold-standard materials, and machine learning is used to identify key molecular features underpinning their performance. For validation, the surfaces of electrochemical biosensors are coated with hydrogels and their anti-biofouling performance in vitro and in vivo in rodent models is evaluated. The copolymer hydrogels preserve device function and enable continuous measurements of a small-molecule drug in vivo better than gold-standard coatings. The novel methodology described enables the discovery of anti-biofouling materials that can extend the lifetime of real-time in vivo sensing devices.

Amphiphilic silicones to mitigate lens epithelial cell growth on intraocular lenses

Silicone intraocular lenses (IOLs) that resist lens epithelial cell (LEC) growth would greatly improve patient outcomes. Herein, amphiphilic surface modifying additives (SMAs) were incorporated into an IOL-type diphenyl silicone to reduce LEC growth without compromising opto-mechanical properties. The SMAs were poly(ethylene oxide)-silane amphiphiles (PEO-SAs) [H-Si-ODMS_m-block-PEO₈-OCH₃], comprised of a PEO segment and siloxane tether of varying lengths (m = 0, 13, and 30). These three SMAs were each blended into the addition cure diphenyl silicone at varying concentrations (5, 10, 15, 20, and 25 μmol g^-1) wherein the wt% of PEO was maintained for all SMAs at a given molar concentration. The chemical crosslinking and subsequent retention of SMAs in modified silicones was confirmed. Key material properties were assessed following equilibration in both air and aqueous environments. Silicones modified with SMAs having longer tethers (m = 13 and 30) underwent rapid and substantial water-driven restructuring of PEO to the surface to form highly hydrophilic surfaces, especially as SMA concentration increased. The % transmittance was also maintained for silicones modified with these particular SMAs. The moduli of the modified silicones were largely unchanged by the SMA and remained in the typical range for silicone IOLs. When the three SMAs were introduced at the highest concentration, modified silicones remained non-cytotoxic and LEC count and associated alpha-smooth muscle actin (α-SMA) expression decreased with increasing tether length. These results demonstrate the potential of silicones modified with PEO-SA SMAs to produce LEC-resistant IOLs.

The Microbial Mechanisms of a Novel Photosensitive Material (Treated Rape Pollen) in Anti-Biofilm Process under Marine Environment

Marine biofouling is a worldwide problem in coastal areas and affects the maritime industry primarily by attachment of fouling organisms to solid immersed surfaces. Biofilm formation by microbes is the main cause of biofouling. Currently, application of antibacterial materials is an important strategy for preventing bacterial colonization and biofilm formation. A natural three-dimensional carbon skeleton material, TRP (treated rape pollen), attracted our attention owing to its visible-light-driven photocatalytic disinfection property. Based on this, we hypothesized that TRP, which is eco-friendly, would show antifouling performance and could be used for marine antifouling. We then assessed its physiochemical characteristics, oxidant potential, and antifouling ability. The results showed that TRP had excellent photosensitivity and oxidant ability, as well as strong anti-bacterial colonization capability under light-driven conditions. Confocal laser scanning microscopy showed that TRP could disperse pre-established biofilms on stainless steel surfaces in natural seawater. The biodiversity and taxonomic composition of biofilms were significantly altered by TRP (p < 0.05). Moreover, metagenomics analysis showed that functional classes involved in the antioxidant system, environmental stress, glucose−lipid metabolism, and membrane-associated functions were changed after TRP exposure. Co-occurrence model analysis further revealed that TRP markedly increased the complexity of the biofilm microbial network under light irradiation. Taken together, these results demonstrate that TRP with light irradiation can inhibit bacterial colonization and prevent initial biofilm formation. Thus, TRP is a potential nature-based green material for marine antifouling.

Innovative fouling-resistant materials for industrial heat exchangers: a review

Fouling of heat exchangers (HEs) has become a major concern across the industrial sector. Fouling is an omnipresent phenomenon but is particularly prevalent in the dairy, oil, and energy industries. Reduced energy performance that results from fouling represents significant operating loss in terms of both maintenance and impact on product quality and safety. In most industries, cleaning or replacing HEs are currently the only viable solutions for controlling fouling. This review examines the latest advances in the development of innovative materials and coatings for HEs that could mitigate the need for costly and frequent cleaning and potentially extend their operational life. To better understand the correlation between surface properties and fouling occurrence, we begin by providing an overview of the main mechanisms underlying fouling. We then present selected key strategies, which can differ considerably, for developing antifouling surfaces and conclude by discussing the current trends in the search for ideal materials for a range of applications. In our presentation of all these aspects, emphasis is given wherever possible to the potential transfer of these innovative surfaces from the laboratory to the three industries most concerned by HE fouling problems: food, petrochemicals, and energy production.

Silicone Elastomer with Self-Generating Zwitterions for Antifouling Coatings

Silicone elastomer-based fouling release coatings have been gaining increased attention in marine antibiofouling. However, the lack of fouling resistance limits their application. Introducing a zwitterionic polymer into silicone enhances its fouling resistance, but their incompatibility makes this challenging. In this work, a silicone elastomer with zwitterionic pendant chains has been prepared by grafting a telomer of tertiary carboxybetaine dodecafluoroheptyl ester ethyl acrylate (TCBF) and 3-mercaptopropyltriethoxysilane to the bis-silanol-terminated poly(dimethylsiloxane) (PDMS). The fluorocarbon groups drive the telomer onto the surface in the film formation process, while the TCBF groups hydrolyze and generate zwitterions on the surface, which is confirmed by attenuated total reflection infrared spectra analysis and water contact angle measurements. Bioassays using marine bacteria (Pseudomonas sp.) and diatoms (Navicula incerta) demonstrate that the antifouling efficacy is improved as the telomer content increases. The bacteria and diatom adhesion decreases by 95 and 81%, respectively, for the PDMS with 30 wt % telomer compared with the unmodified PDMS control. Meanwhile, the fouling release performance of PDMS is maintained with a pseudobarnacle removal strength of ∼0.1 MPa. This work provides a facile way to fabricate efficient silicone-based antifouling coatings.

A critical review on surface modifications mitigating dairy fouling

Thermal treatments performed in food processing industries generate fouling. This fouling deposit impairs heat transfer mechanism by creating a thermal resistance, thus leading to regular shutdown of the processes. Therefore, periodic and harsh cleaning-in-place (CIP) procedures are implemented. This CIP involves the use of chemicals and high amounts of water, thus increasing environmental burden. It has been estimated that 80% of production costs are owed to dairy fouling deposit. Since the 1970s, different types of surface modifications have been performed either to prevent fouling deposition (anti-fouling) or to facilitate removal (fouling-release). This review points out the impacts of surface modification on type A dairy fouling and on cleaning behaviors under batch and continuous flow conditions. Both types of anti-fouling and fouling-release coatings are reported as well as the different techniques used to modify stainless steel surface. Finally, methods for testing and characterising the effectiveness of coatings in mitigating dairy fouling are discussed.

Amphiphilic, thixotropic additives for extrusion-based 3D printing of silica-reinforced silicone

The ability to utilize extrusion-based, direct ink write (DIW) 3D printing to create silica-reinforced silicones with complex structures could expand their utility in industrial and biomedical applications. Sylgard 184, a common Pt-cure silicone, lacks the thixotropic behavior necessary for effective printing and its hydrophobicity renders cured structures susceptible to biofouling. Herein, we evaluated the efficacy of various PEO-silane amphiphiles (PEO-SAs) as thixotropic and surface modifying additives in Sylgard 184. Eight amphiphilic PEO-SAs of varying architecture (e.g. linear, star, and graft), crosslinkability, and PEO content were evaluated. Modified formulations were also prepared with additional amounts of silica filler, both hexamethyldisilazane (HMDS)-treated and dimethyldichlorosilane (DiMeDi)-treated types. Numerous PEO-SA modified silicone formulations demonstrated effective water-driven surface hydrophilicity that was generally diminished with the addition of HMDS-treated silica filler. While increased yield stress was observed for PEO-SA modified silicones with added HMDS-treated filler, none achieved the initial target for 3D printing (>1000 Pa). Only the formulations containing the DiMeDi-treated filler (17.3 wt%) were able to surpass this value. These formulations were then tested for their thixotropic properties and all surpassed the targets for recovered storage modulus (G') (>1000 Pa) and loss factor (<0.8). In particular, the triblock linear PEO-SA produced exceptionally high recovered G', low loss factor, and substantial water-driven restructuring to form a hydrophilic surface. Combined, these results demonstrate the potential of silicones modified with PEO-SA surface-modifying additives (SMAs) for extrusion-based, DIW 3D printing applications.

Hemocompatible, biocompatible and antifouling Acylated dextran-g-polytetrahydrofuran graft copolymer with silver nanoparticles: Synthesis, characterization and properties

The novel amphiphilic acylated dextran-g-polytetrahydrofuran (AcyDex-g-PTHF) graft copolymers have been successfully synthesized via combination of living cationic ring-opening polymerization of tetrahydrofuran (THF) to prepare living PTHF chains with different molecular weights (M_{n, PTHF}) of 800-2800 g/mol with nucleophile substitution to mediate grafting numbers (G_N) of 4-25 per 1000 Dex monosaccharide. The microphase separation in the graft copolymer exists for the incompatibility of hard dextran backbone and soft PTHF branches and the confined crystallization of backbone. This copolymer behaves excellent hemocompatibility with red blood cells, good biocompatibility with HeLa cells and strong resistance to bovine serum albumin adsorption. The microspheres (~1 μm) of graft copolymers loaded with drug ibuprofen exhibit pH sensitive controlled drug release behavior. Moreover, the AcyDex-g-PTHF/Ag nanocomposites show good antibacterial property against E. coli and S. aureus. This novel hemocompatible, biocompatible and antifouling AcyDex-g-PTHF graft copolymer will have potential application in biological and medical fields.

New Antiadhesive Hydrophobic Polysiloxanes

Intrinsic hydrophobicity is the reason for efficient bacterial settlement and biofilm growth on silicone materials. Those unwelcomed phenomena may play an important role in pathogen transmission. We have proposed an approach towards the development of new anti-biofilm strategies that resulted in novel antimicrobial hydrophobic silicones. Those functionalized polysiloxanes grafted with side 2-(carboxymethylthioethyl)-, 2-(n-propylamidomethylthioethyl)- and 2-(mercaptoethylamidomethylthioethyl)- groups showed a wide range of antimicrobial properties towards selected strains of bacteria (reference strains Staphylococcus aureus, Escherichia coli and water-borne isolates Agrobacterium tumefaciens, Aeromonas hydrophila), fungi (Aureobasidium pullulans) and algae (Chlorella vulgaris), which makes them valuable antibacterial and antibiofilm agents. Tested microorganisms showed various levels of biofilm formation, but particularly effective antibiofilm activity was demonstrated for bacterial isolate A. hydrophila with high adhesion abilities. In the case of modified surfaces, the relative coefficient of adhesion for this strain was 18 times lower in comparison to the control glass sample.

Amphiphilic silicones to reduce the absorption of small hydrophobic molecules

Silicones (i.e. crosslinked poly(dimethylsiloxane), PDMS) are commonly used material for microfluidic device fabrication. Nonetheless, due to the uncontrollable absorption of small hydrophobic molecules (<1 kDa) into the bulk, its applicability to cell-based drug assays and sensing applications has been limited. Here, we demonstrate the use of substrates made of silicones bulk modified with a poly(ethylene oxide) silane amphiphile (PEO-SA) to reduce hydrophobic small molecule sequestration for cell-based assays. Modified silicone substrates were generated with concentrations of 2 wt.%, 9 wt.% and, 14 wt.% PEO-SA. Incorporation of PEO-SA into the silicone bulk was assessed by FTIR analysis in addition to water contact angle analysis to evaluate surface hydrophobicity. Cell toxicity, absorption of small hydrophobic drugs, and cell response to hydrophobic molecules were also evaluated. Results showed that the incorporation of the PEO-SA into the silicone led to a reduction in water contact angle from 114° to as low as 16° that was stable for at least three months. The modified silicones showed viability values above 85% for NIH-3T3, MCF7, MDA-MB-468, and MDA-MB-231 cell lines. A drug response assay using tamoxifen and the MCF7 cell line showed full recovery of cell toxicity response when exposed to PDMS modified with 9 wt.% or 14 wt.% PEO-SA compared to tissue culture plastic. Therefore, our study supports the use of PEO-SA at concentrations of 9 wt.% or higher for enhanced surface wettability and reduced absorption of small hydrophobic molecules in PDMS-based platforms.

Thromboresistance of Polyurethanes Modified with PEO-Silane Amphiphiles

Surface-induced thrombosis is problematic in blood-contacting devices composed of silicones or polyurethanes (PUs). Poly(ethylene oxide)-silane amphiphiles (PEO-SA) are previously shown effective as surface modifying additives (SMAs) in silicones for enhanced thromboresistance. This study investigates PEO-SAs as SMAs in a PU at various concentrations: 5, 10, 25, 50, and 100 µmol g^-1 PU. PEO-SA modified PUs are evaluated for their mechanical properties, water-driven surface restructuring, and adhesion resistance against a human fibrinogen (HF) solution as well as whole human blood. Stability is assessed by monitoring hydrophilicity, water uptake, and mass loss following air- or aqueous-conditioning. PEO-SA modified PUs do not demonstrate plasticization, as evidenced by minimal changes in glass transition temperature, modulus, tensile strength, and percent strain at break. These also show a concentration-dependent increase in hydrophilicity that is sustained following air- and aqueous-conditioning for concentrations ≥25 µmol g^-1 . Additionally, water uptake and mass loss are minimal at all concentrations. Although protein resistance is not enhanced versus an HF solution, PEO-SA modified PUs have significantly reduced protein adsorption and platelet adhesion from human blood at concentrations ≥10 µmol g^-1 . Overall, this study demonstrates the versatility of PEO-SAs as SMAs in PU, which leads to enhanced and sustained hydrophilicity as well as thromboresistance.

Amphiphilic hydrolyzable polydimethylsiloxane-b-poly(ethyleneglycol methacrylate-co-trialkylsilyl methacrylate) block copolymers for marine coatings. II. Antifouling laboratory tests and field trials

Poly(dimethylsiloxane) (PDMS) elastomer coatings containing an amphiphilic hydrolyzable diblock copolymer additive were prepared and their potential as marine antifouling and antiadhesion materials was tested. The block copolymer additive consisted of a PDMS first block and a random poly(trialkylsilyl methacrylate (TRSiMA, R = butyl, isopropyl)-co-poly(ethyleneglycol) methacrylate (PEGMA) copolymer second block. PDMS-b-TRSiMA block copolymer additives without PEGMA units were also used as additives. The amphiphilic character of the coating surface was assessed in water using the captive air bubble technique for measurements of static and dynamic contact angles. The attachment of macro- and microorganisms on the coatings was evaluated by field tests and by performing adhesion tests to the barnacle Amphibalanus amphitrite and the green alga Ulva rigida. All the additive-based PDMS coatings showed better antiadhesion properties to A. amphitrite larvae than to U. rigida spores. Field tests provided meaningful information on the antifouling and fouling release activity of coatings over an immersion period of 23 months.

Silicone-Based Fouling-Release Coatings for Marine Antifouling

Marine biofouling profoundly influences marine industries and activities. It slows the speed and increases the fuel consumption of ships, corrodes offshore platforms, and blocks seawater pipelines. The most effective and economical antifouling approach uses coatings. Fouling-release coatings (FRCs) with low surface free energy and high elasticity weakly adhere to marine organisms, so they can be readily removed by the water shear force. FRCs have attracted increasing interest because they are biocide-free and hence ecofriendly. However, traditional silicone-based FRCs have weak adhesion to substrates, low mechanical strength, and low fouling resistance, limiting their applications. In recent years, many attempts have been made to improve their mechanical properties and fouling resistance. This review deals with the progress in the construction of high-performance silicone-based fouling-release surfaces.

Polymer-Based Marine Antifouling and Fouling Release Surfaces: Strategies for Synthesis and Modification

In marine industries, the accumulation of organic matter and marine organisms on ship hulls and instruments limits performance, requiring frequent maintenance and increasing fuel costs. Current coatings technology to combat this biofouling relies heavily on the use of toxic, biocide-containing paints. These pose a serious threat to marine ecosystems, affecting both target and nontarget organisms. Innovation in the design of polymers offers an excellent platform for the development of alternatives, but the creation of a broad-spectrum, nontoxic material still poses quite a hurdle for researchers. Surface chemistry, physical properties, durability, and attachment scheme have been shown to play a vital role in the construction of a successful coating. This review explores why these characteristics are important and how recent research accounts for them in the design and synthesis of new environmentally benign antifouling and fouling release materials.

Dynamic surface antifouling: mechanism and systems

Marine biofouling is a global problem today. High efficiency and eco-friendly antifouling systems are in pressing need. In recent years, we have proposed the concept of dynamic surface antifouling (DSA). That is, a continuously changing surface can effectively prevent marine fouling organisms from landing and adhesion. Based on this strategy, we developed coatings with dynamic surfaces by using degradable polymers including polyester-polyurethane, modified polyester and poly(ester-co-acrylate). They exhibit tunable renewability, and excellent antifouling and mechanical performance. Moreover, the polymers can serve as carrier and controlled release systems of antifoulants so that they have long service life. This paper reviews the progress and trends in marine anti-biofouling, and presents the mechanism and systems of DSA.

Antifouling amphiphilic silicone coatings for dairy fouling mitigation on stainless steel

Pasteurization of dairy products is plagued by fouling, which induces significant economic, environmental and microbiological safety concerns. Herein, an amphiphilic silicone coating was evaluated for its efficacy against fouling by a model dairy fluid in a pilot pasteurizer and against foodborne bacterial adhesion. The coating was formed by modifying an RTV silicone with a PEO-silane amphiphile comprised of a PEO segment and flexible siloxane tether ([(EtO)₃Si-(CH₂)₂-oligodimethylsiloxane_m-block-(OCH₂CH₂)_n-OCH₃]). Contact angle analysis of the coating revealed that the PEO segments were able to migrate to the aqueous interface. The PEO-modified silicone coating applied to pretreated stainless steel was exceptionally resistant to fouling. After five cycles of pasteurization, these coated substrata were subjected to a standard clean-in-place process and exhibited a minor reduction in fouling resistance in subsequent tests. However, the lack of fouling prior to cleaning indicates that harsh cleaning is not necessary. PEO-modified silicone coatings also showed exceptional resistance to adhesion by foodborne pathogenic bacteria.