Long-lasting antifouling coating from multi-armed polymer

A review of experimental Assessment Processes of material resistance to marine and freshwater biofouling

Biofouling presents hazards to a variety of freshwater and marine underwater infrastructures and is one of the direct causes of species invasion. These negative impacts provide a unified goal for both industry practitioners and researchers: the development of novel antifouling materials to prevent the adhesion of biofouling. The prohibition of tributyltin (TBT) by the International Maritime Organization (IMO) in 2001 propelled the research and development of new antifouling materials. However, the evaluation process and framework for these materials remain incomplete and unsystematic. This mini-review starts with the classification and principles of new antifouling materials, discussing and summarizing the methods for assessing their biofouling resistance. The paper also compiles the relevant regulations and environmental requirements from different countries necessary for developing new antifouling materials with commercial potential. It concludes by highlighting the current challenges in antifouling material development and future outlooks. Systematic evaluation of newly developed antifouling materials can lead to the emergence of more genuinely applicable solutions, transitioning from merely laboratory products to materials that can be effectively used in real-world applications.

Investigation of anti-adhesion ability of 8-arm PEGNHS-modified porcine pericardium

In post-adhesion surgery, there is a clinical need for anti-adhesion membranes specifically designed for the liver, given the limited efficacy of current commercial products. To address this demand, we present a membrane suitable for liver surgery applications, fabricated through the modification of decellularized porcine pericardium with 20 KDa hexaglycerol octa (succinimidyloxyglutaryl) polyoxyethylene (8-arm PEGNHS). We also developed an optimized modification procedure to produce a high-performance anti-adhesion barrier. The modified membrane significantly inhibited fibroblast cell adherence while maintaining minimal levels of inflammation. By optimizing the modification ratio, we successfully controlled post-adhesion formation. Notably, the 8-arm PEG-modified pericardium with a molar ratio of 5 exhibited the ability to effectively prevent post-adhesion formation on the liver compared to both the control and Seprafilm®, with a low adhesion score of 0.5 out of 3.0. Histological analysis further confirmed its potential for easy separation. Furthermore, the membrane demonstrated regenerative capabilities, as evidenced by the proliferation of mesothelial cells on its surface, endowing anti-adhesion properties between the abdominal wall and liver. These findings highlight the membrane's potential as a reliable barrier for repeated liver resection procedures that require the removal of the membrane multiple times.

Effect of multi arm-PEG-NHS (polyethylene glycol n-hydroxysuccinimide) branching on cell adhesion to modified decellularized bovine and porcine pericardium

Implanting physical barrier materials to separate wounds from their surroundings is a promising strategy for preventing postoperative adhesions. Herein, we develop a material that switches from an anti-adhesive surface to an adhesive surface, preventing adhesion in the early stage of transplantation and then promoting recellularization. In this study, 2-arm, 4-arm, and 8-arm poly(ethylene glycol) succinimidyl glutarate (2-, 4-, 8-arm PEG-NHS) were used to modify the surface of decellularized porcine and bovine pericardium. The number of free amines on the surface of each material significantly decreased following modification regardless of the reaction molar ratio of NH2 and NHS, the number of PEG molecule branches, and the animal species of the decellularized tissue. The structure and mechanical properties of the pericardium were maintained after modification with PEG molecules. The time taken for the PEG molecules to detach through hydrolysis of the ester bonds differed between the samples, which resulted in different cell repulsion periods. By adjusting the reaction molar ratio, the number of PEG molecule branches, and the animal species of the decellularized pericardium, the duration of cell repulsion can be controlled and is expected to provide an anti-adhesion material for a variety of surgical procedures.

Intestinal retentive systems - recent advances and emerging approaches

Intestinal retentive devices (IRDs) are devices designed to anchor within the lumen of the intestines for long-term residence in the gastrointestinal tract. IRDs can enable impactful medical device technologies including sustained oral drug delivery systems, indwelling sensors, or real-time diagnostics. The design and testing of IRDs present a myriad of challenges, including precise deployment of the device at desired intestinal locations, secure anchoring within the gastrointestinal tract to allow for natural function, and safe removal of the IRD at user-defined times. Advancing the state-of-the-art of IRD is an interdisciplinary effort that requires innovations such as new materials, novel anchoring mechanisms, and medical device design with consistent input from clinical practitioners and end-users. This perspective briefly reviews the current state-of-the-art for IRDs and charts a path forward to inform the design of future concepts. Specifically, this article will highlight materials, retention mechanisms, and test beds to measure the efficacy of IRDs and their mechanisms. Finally, potential synergies between IRD and other medical device technologies are presented to identify future opportunities.

Morphology evolution of Janus dumbbell nanoparticles in seeded emulsion polymerization

Emulsion polymerization is a versatile approach to produce different polymeric nanoparticle morphologies, which can be useful in a variety of applications. However, the detailed mechanism of the morphology formation is not entirely clear. We study the kinetics of nanoparticle morphology evolution during a seeded emulsion polymerization using both experimental and computational tools. Lightly crosslinked polystyrene seeds were first synthesized using dispersion polymerization. Then the seed particles were swollen in tert-butyl acrylate and styrene monomers, and subsequently polymerized into nanoparticles of dumbbell and multilobe morphologies. It was discovered that both the seed and final particle morphology were affected by the methanol concentration during the seed synthesis. Systematically adjusting the methanol amount will not only yield spherical seed particles of different size, but also dumbbell particles even without the second monomer polymerization. In addition to methanol concentration, morphology can be controlled by crosslinking density. The kinetics studies revealed an interesting transition from multilobe to dumbbell geometries during the secondary polymerization. Based on the results, a nucleation-growth model has been proposed to describe the morphology evolution and verification was offered by computer simulation. The key discovery is that nanoparticle morphology can be kinetically controlled by diffusion of the protrusions on the seed particles. The condition of seed synthesis and crosslinking density will drastically change the seed and final nanoparticle morphology.

Adhesion Control of Branched Catecholic Polymers by Acid Stimulation

Biomimetic material design is a useful method for producing new functional materials. In recent years, catecholic polymers inspired from the adhesion mechanism of marine organisms have attracted attention. Here, we demonstrated the preparation of catecholic polymers by reversible addition-fragmentation chain transfer (RAFT) polymerization of an acetonide-protected catecholic monomer, that is, N-(2-(2,2-dimethylbenzo-1,3-dioxol-5-yl)ethyl)-acrylamide (DDEA). By selecting the specific RAFT reagents, well-defined branched PDDEA and linear PDDEA were obtained. These PDDEA samples showed stronger adhesion strength after deprotection by acid stimulation compared with that before deprotection. In addition, we demonstrated the adhesion control of synthetic polymers by photoirradiation in the presence of photoacid generators, which decompose under light and release an acid.

Electrochemical Approach for Effective Antifouling and Antimicrobial Surfaces

Biofouling, the adsorption of organisms to a surface, is a major problem today in many areas of our lives. This includes: (i) health, as biofouling on medical device leads to hospital-acquired infections, (ii) water, since the accumulation of organisms on membranes and pipes in desalination systems harms the function of the system, and (iii) energy, due to the heavy load of the organic layer that accumulates on marine vessels and causes a larger consumption of fuel. This paper presents an effective electrochemical approach for generating antifouling and antimicrobial surfaces. Distinct from previously reported antifouling or antimicrobial electrochemical studies, we demonstrate the formation of a hydrogen gas bubble layer through the application of a low-voltage square-waveform pulses to the conductive surface. This electrochemically generated gas bubble layer serves as a separation barrier between the surroundings and the target surface where the adhesion of bacteria can be deterred. Our results indicate that this barrier could effectively reduce the adsorption of bacteria to the surface by 99.5%. We propose that the antimicrobial mechanism correlates with the fundamental of hydrogen evolution reaction (HER). HER leads to an arid environment that does not allow the existence of live bacteria. In addition, we show that this drought condition kills the preadhered bacteria on the surface due to water stress. This work serves as the basis for the exploration of future self-sustainable antifouling techniques such as incorporating it with photocatalytic and photoelectrochemical reactions.

Enhanced antibacterial efficacy of nitric oxide releasing thermoplastic polyurethanes with antifouling hydrophilic topcoats

Surface fouling is one of the leading causes of infection associated with implants, stents, catheters, and other medical devices. The surface chemistry of medical device coatings is important in controlling and/or preventing fouling. In this study, we have shown that a combination of nitric oxide releasing hydrophobic polymer with a hydrophilic polymer topcoat can significantly reduce protein attachment and subsequently reduce bacterial adhesion as a result of the synergistic effect. Nitric oxide (NO) is a well-known potent antibacterial agent due to its adverse reactions on microbial cell components. Owing to the surface chemistry of hydrophilic polymers, they are suitable as antifouling topcoats. In this study, four biomedical grade polymers were compared for protein adhesion and NO-release behavior: CarboSil 2080A, silicone rubber, SP60D60, and SG80A. SP60D60 was found to resist protein adsorption up to 80% when compared to the other polymers while CarboSil 2080A maintained a steady NO flux even after 24 hours (∼0.50 × 10-10 mol cm-2 min-1) of soaking in buffer solution with a loss of less than 3% S-nitroso-N-acetylpenicillamine (SNAP), the NO donor molecule, in the leaching analysis. Therefore, CarboSil 2080A incorporated with SNAP and top-coated with SP60D60 was tested for antibacterial efficacy after exposure to fibrinogen, an abundantly found protein in blood. The NO-releasing CarboSil 2080A with the SP60D60 top-coated polymer showed a 96% reduction in Staphylococcus aureus viable cell count compared to the control samples. Hence, the study demonstrated that a hydrophilic polymer topcoat, when applied to a polymer with sustained NO release from an underlying SNAP incorporated hydrophobic polymer, can reduce bacterial adhesion and be used as a highly efficient antifouling, antibacterial polymer for biomedical applications.

Reversible Tethering of Polymers onto Catechol-Based Titanium Platforms

In this article, we report on the reversible tethering of end-functionalized polymers onto catechol-based titanium platforms by exploiting the reversible Diels-Alder (DA) cycloaddition reaction. For this purpose, furan and maleimide end-functionalized polymers, prepared via reversible addition-fragmentation chain transfer polymerization, were covalently grafted through a DA reaction onto reactive titanium platforms elaborated from catechol-based anchors incorporating either the furan or the maleimide moiety. As a proof of concept, a hydrophilic poly(oligo(ethylene glycol)acrylate) (POEGA) and a hydrophobic poly(2,2,2-trifluoroethyl acrylate) (PTFEA) were grafted onto titanium surfaces and subsequently detached by exploiting the thermoreversible nature of the DA reaction [i.e., retro Diels-Alder (rDA)]. These polymers were interchanged by performing a second DA reaction, thereby allowing the titanium surface wettability to be switched from hydrophobic to hydrophilic on demand. The grafting of furan/maleimide end-functionalized polymers onto functionalized (maleimide/furan, respectively) catechol-based titanium platforms and the subsequent rDA/DA sequence used for switching the titanium surface were evidenced by attenuated total reflectance-Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements.

Hybrid Hairy Janus Particles as Building Blocks for Antibiofouling Surfaces

Herein, we report a new strategy for the design of antifouling surfaces by using hybrid hairy Janus particles. The amphiphilic Janus particles possess either a spherical or a plateletlike shape and have core-shell structures with an inorganic core and hydrophilic/hydrophobic polymeric shells. Subsequently, these bifunctional Janus particles enable the fabrication of surfaces with modularity in chemical composition and final surface topography, which possess antifouling properties. The antifouling and fouling-release capability of the composite Janus particle-based surfaces is investigated using the marine biofilm-forming bacteria Cobetia marina. The Janus particle-based coatings are robust and significantly reduce bacterial retention under both static and dynamic conditions independent of the particle geometry. The plateletlike (kaolinite-based) Janus particles represent a scalable system for the rational design of antifouling coatings as well as their large-scale production and application in the future.

Zwitterionic fibrous polypropylene assembled with amphiphatic carboxybetaine copolymers for hemocompatible blood filtration

The present study serves three main functions. First, it presents a novel random copolymer, made of octadecyl acrylate hydrophobic blocks and 2-(dimethylamino)ethyl methacrylate hydrophilic groups, and it zwitterionic form. Second, random copolymer and zwitterionic random copolymer, OmDn and Z-OmDn, are used to modify polypropylene membranes by evaporation coating. Our investigations unveil that this method leads to sufficiently stable self-assembling provided a minimum number of hydrophobic repeat units of 77, which also corresponds to a hydrophobic degree of 74%. Third, antifouling and hemocompatible properties of membranes are thoroughly investigated using all types of blood cells separately, as well as challenging membranes against whole blood in static and dynamic conditions. Membranes modified with zwitterionic copolymer containing 26% of zwitterionic groups are shown to be highly antifouling and hemocompatible, for a coating density as low as 0.2mg/cm(2). Their application in a specially designed blood filtration module enabled to almost totally inhibit blood cells interactions with membrane material, as well as to importantly reduce platelet activation in the permeate (2.5-fold reduction).

STATEMENT OF SIGNIFICANCE

The design of new zwitterionic copolymer material is proposed and demonstrated in this study. It was showed that hydrophobicoctadecyl acrylate segments can be introduced in the zwitterioniccarboxybetaine polymer chain with a well-controlled random sequence. Stable, efficient, and effective surface zwitterionization of hydrophobic polypropylene are obtained via grafting onto approach by evaporation-induced self-assembling coating. In the perspective of potential application, hemocompatible blood filtration was demonstrated with the excellent results of non-activated platelets obtained.

SUMMARY OF IMPACTS

DESIGN

New zwitterionicmaterial, amphiphatic carboxybetaine copolymers.

DEVELOPMENT

Evaporation-induced self-assembling grafting.

APPLICATION

Hemocompatible blood filtration.

A Janus Mucoadhesive and Omniphobic Device for Gastrointestinal Retention

A novel Janus device with omniphobic and mucoadhesive sides that exhibit the unique capacity for antifouling and extended gastrointestinal retention is fabricated. This system enables repulsion of the food and fluid stream by the luminal-facing omniphobic side and allows attachment to the gastrointestinal mucosa by the mucoadhesive side.

Bio-inspired antifouling approaches: the quest towards non-toxic and non-biocidal materials

Biofouling is an undesirable process in which organisms and their by-products encrust a surface. Antifouling solutions are of great importance since biofouling has negative effects on numerous species, ecosystems, and areas including water treatment facilities, health-care systems, and marine devices. Many useful solutions have been developed in the last few decades. However, with the emergence of environmental issues, the search for new promising non-toxic materials has expanded. One approach tries to mimic natural antifouling surfaces and relies on mechanisms of action derived from nature. Since these materials are based on natural systems, they are mostly biocompatible and more efficient against complex fouling. In this review, we cover the latest advances in the field of antifouling materials. We specifically focus on biomaterials that are based on the chemical and physical behavior of biological systems.

Synthesis of catechol and zwitterion-bifunctionalized poly(ethylene glycol) for the construction of antifouling surfaces

Versatile antifouling coatings from catechol and zwitterion-bifunctionalized poly(ethylene glycol).

Convenient Fabrication of Electrospun Prolamin Protein Delivery System with Three-Dimensional Shapeability and Resistance to Fouling

It has been newly discovered that by simply altering the applied voltage, the resultant electrospun prolamin protein fabrics can rapidly (within 30 s) form either flat sheets or self-rolled tubes when immersed in water. This phenomenon opens up many potential biomedical applications for drug delivery. The morphology and structure of both dry and wet fibers were characterized in detail. The hordein/zein fibers fabricated at relatively lower voltage were stabilized by the preaggregated nanoscale hydrophobic domains and exhibited restricted swelling while maintaining a flat sheet shape with minimal changes to secondary structure when immersed in water. By applying a higher voltage, we triggered a greater bending instability during the electrospinning process, and the hordein/zein network structure generated could rapidly relax in an aqueous environment. This increased mobility of molecular chains allowed the uneven aggregation of hydrophobic dopants, which catalyzed the self-rolling of the aligned fibers. Sessile drop measurements even showed a reduction in the contact angle from 106 to 39° for the fibers with 50% zein prepared at raised voltage, indicating the conversion of surface properties caused by the relaxation. All the fibers demonstrated low toxicity in human primary dermal fibroblast cell culture. Moreover, the electrospun fabrics exhibited a strong resistance to protein adsorption and cell attachment, and the release experiment indicated that both three-dimensional porous structures could serve as a carrier for controlled release of incorporated bioactive compounds into phosphate-buffered saline. Therefore, these electrospun prolamin protein fabrics represent an ideal and novel platform to develop nonadherent drug delivery systems for wound dressing and other biomedical applications.

Ethylene glycol-based microgels at solid surfaces: swelling behavior and control of particle number density

The adsorption of ethylene glycol (EG)-based microgel particles at silicon surfaces was investigated. Monodisperse p-MeO2MA-co-OEGMA microgel particles were synthesized by precipitation polymerization. Particle size and the volume phase transition temperature (VPTT) can be tailored by changing the amount of comonomer. The effect of geometrical confinement on the microgel particles was studied at the solid/liquid interface. Therefore, layer formation, particle number density, and swelling/deswelling at the surface were studied in dependence on the spin-coating preparation parameters and characterized by means of AFM against ambient conditions. The deswelling/swelling behavior was investigated by AFM in the water-swollen state.

State of the art, challenges and perspectives in the design of nitric oxide-releasing polymeric nanomaterials for biomedical applications

Recently, an increasing number of publications have demonstrated the importance of the small molecule nitric oxide (NO) in several physiological and pathophysiological processes. NO acts as a key modulator in cardiovascular, immunological, neurological, and respiratory systems, and deficiencies in the production of NO or its inactivation has been associated with several pathologic conditions, ranging from hypertension to sexual dysfunction. Although the clinical administration of NO is still a challenge owing to its transient chemical nature, the combination of NO and nanocarriers based on biocompatible polymeric scaffolds has emerged as an efficient approach to overcome the difficulties associated with the biomedical administration of NO. Indeed, significant progress has been achieved by designing NO-releasing polymeric nanomaterials able to promote the spatiotemporal generation of physiologically relevant amounts of NO in diverse pharmacological applications. In this review, we summarize the recent advances in the preparation of versatile NO-releasing nanocarriers based on polymeric nanoparticles, dendrimers and micelles. Despite the significant innovative progress achieved using nanomaterials to tailor NO release, certain drawbacks still need to be overcome to successfully translate these research innovations into clinical applications. In this regard, this review discusses the state of the art regarding the preparation of innovative NO-releasing polymeric nanomaterials, their impact in the biological field and the challenges that need to be overcome. We hope to inspire new research in this exciting area based on NO and nanotechnology.

Self-repairing nonfouling polyurethane coatings via 3D-grafting of PEG-b-PHEMA-b-PMPC copolymer

Long-lasting nonfouling polyurethane coatings via 3D-grafting of a triblock copolymer showed inhibition ability for the adhesion of protein and human platelets.

Fabrication of ultra-thin polyrotaxane-based films via solid-state continuous assembly of polymers

Surface-confined ultra-thin polyrotaxane (PRX)-based films with tunable composition, surface topology and swelling characteristics were prepared by solid-state continuous assembly of polymers (ssCAP).