Synthetic Polymer Surfaces Research Articles

Antimicrobial Polymer Surfaces Containing Quaternary Ammonium Centers (QACs): Synthesis and Mechanism of Action.

Synthetic polymer surfaces provide an excellent opportunity for developing materials with inherent antimicrobial and/or biocidal activity, therefore representing an answer to the increasing demand for antimicrobial active medical devices. So far, biologists and material scientists have identified a few features of bacterial cells that can be strategically exploited to make polymers inherently antimicrobial. One of these is represented by the introduction of cationic charges that act by killing or deactivating bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). Among the possible cationic functionalities, the antimicrobial activity of polymers with quaternary ammonium centers (QACs) has been widely used for both soluble macromolecules and non-soluble materials. Unfortunately, most information is still unknown on the biological mechanism of action of QACs, a fundamental requirement for designing polymers with higher antimicrobial efficiency and possibly very low toxicity. This mini-review focuses on surfaces based on synthetic polymers with inherently antimicrobial activity due to QACs. It will discuss their synthesis, their antimicrobial activity, and studies carried out so far on their mechanism of action.

The Effect of Fibrillation, Semi-Dry Pressing, and Surface Treatment on the Barrier Properties of Water Molecules and Oxygen on Food Packaging Paper.

The characteristics of fiber morphology and paper structure are critical to the barrier properties of food packaging paper. Herein, this study aimed to use pulp fibrillation, paper semi-dry pressing and carboxymethyl starch (CMS) coating to flatten the fibers, which were formed on the paper surface with good barrier properties due to the tight bond between fibers. The results showed that the permeability of paper was reduced by 87.56%, from 81.44 μm/Pa·s to 10.13 μm/Pa·s after the pulp fibrillation treatment (60 °SR). Moreover, semi-dry pressing treatment contributed to decreasing the water vapor transmission coefficient (WVP) by 50.98% to 2.74 × 10-10 g/m·s·Pa, and the oxygen permeation coefficient (OP) decreased by 98.04% to 1.93 × 10-14 cm3·cm/cm2·s·Pa. After coating the paper surface with titanium dioxide (TiO2) and CMS, the WVP of the paper was further reduced to 1.55 × 10-10 g/m·s·Pa, and OP was reduced to 0.19 × 10-14 cm3·cm/cm2·s·Pa. These values were 72.27% and 99.8% lower than those of the original paper, respectively. Therefore, through pulp fibrillation, semi-dry pressing of paper, TiO2 filling, and surface coating with CMS, there is no need to use synthetic polymer surface film-forming agents to achieve the high barrier properties that are required for low water and oxygen molecules permeation in food packaging paper.

Preparation and Functionalization of Polymers with Antibacterial Properties-Review of the Recent Developments.

The presence of antibiotic-resistant bacteria in our environment is a matter of growing concern. Consumption of contaminated drinking water or contaminated fruit or vegetables can provoke ailments and even diseases, mainly in the digestive system. In this work, we present the latest data on the ability to remove bacteria from potable water and wastewater. The article discusses the mechanisms of the antibacterial activity of polymers, consisting of the electrostatic interaction between bacterial cells and the surface of natural and synthetic polymers functionalized with metal cations (polydopamine modified with silver nanoparticles, starch modified with quaternary ammonium or halogenated benzene). The synergistic effect of polymers (N-alkylaminated chitosan, silver doped polyoxometalate, modified poly(aspartic acid)) with antibiotics has also been described, allowing for precise targeting of drugs to infected cells as a preventive measure against the excessive spread of antibiotics, leading to drug resistance among bacteria. Cationic polymers, polymers obtained from essential oils (EOs), or natural polymers modified with organic acids are promising materials in the removal of harmful bacteria. Antimicrobial polymers are successfully used as biocides due to their acceptable toxicity, low production costs, chemical stability, and high adsorption capacity thanks to multi-point attachment to microorganisms. New achievements in the field of polymer surface modification in order to impart antimicrobial properties were summarized.

UV Irradiation of Wood Surface: Bonding Properties.

Various surface modification techniques have been developed to improve synthetic polymer surfaces' wetting, adhesion, and printing by adding various functional (polar) groups. UV irradiation has been proposed as a suitable procedure to achieve adequate surface modifications of such polymers, which can be of further use to bond many compounds of interest. The activation of the surface, the favourable wetting properties, and the increased micro tensile strength of the substrate after short-term UV irradiation suggest that such pretreatment can also improve the bonding of the wood-glue system. Thus, this study aims to determine the feasibility of UV irradiation for pretreatment of wood surfaces before gluing and to determine the properties of wooden glued joints prepared in this way. UV irradiation was used to modify variously machined pieces of beech wood (Fagus sylvatica L.) before gluing. Six sets of samples were prepared for each machining process. Samples prepared in this manner were exposed to irradiation on a UV line. Each radiation level had a certain number of passes through the UV line, the more passes, the stronger the irradiation. Thus, the radiation levels were as follows: 1, 5, 10, 20, and 50 passes. The dose (energy delivered on the wood surface) in one pass was 2.36 J/cm2. A wetting angle test with glue, a compressive shear strength test of lap joints, and designation of main failure patterns were used to evaluate the properties of wooden glued joints. Wetting angle test was performed according to EN 828, while the compressive shear strength test samples were prepared and tested following the ISO 6238 standard. The tests were conducted using a polyvinyl acetate adhesive. The study found that UV irradiation before gluing improved the bonding properties of variously machined wood.

Xeno-free culture and proliferation of hPSCs on 2D biomaterials.

Human pluripotent stem cells (human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs)) have unlimited proliferative potential, whereas adult stem cells such as bone marrow-derived stem cells and adipose-derived stem cells have problems with aging. When hPSCs are intended to be cultured on feeder-free or xeno-free conditions without utilizing mouse embryonic fibroblasts or human fibroblasts, they cannot be cultured on conventional tissue culture polystyrene dishes, as adult stem cells can be cultured but should be cultivated on material surfaces grafted or coated with (a) natural or recombinant extracellular matrix (ECM) proteins, (b) ECM protein-derived peptides and specific synthetic polymer surfaces in xeno-free and/or chemically defined conditions. This review describes current developing cell culture biomaterials for the proliferation of hPSCs while maintaining the pluripotency and differentiation potential of the cells into 3 germ layers. Biomaterials for the cultivation of hPSCs without utilizing a feeder layer are essential to decrease the risk of xenogenic molecules, which contributes to the potential clinical usage of hPSCs. ECM proteins such as human recombinant vitronectin, laminin-511 and laminin-521 have been utilized instead of Matrigel for the feeder-free cultivation of hPSCs. The following biomaterials are also discussed for hPSC cultivation: (a) decellularized ECM, (b) peptide-grafted biomaterials derived from ECM proteins, (c) recombinant E-cadherin-coated surface, (d) polysaccharide-immobilized surface, (e) synthetic polymer surfaces with and without bioactive sites, (f) thermoresponsive polymer surfaces with and without bioactive sites, and (g) synthetic microfibrous scaffolds.

Formation of Nanostructure during Replication of a Hierarchical Plant Surface.

Plant and animal surfaces have become a model for preparing special synthetic surfaces with low wettability, reflectivity, or antibacterial properties. Processes that lead to the creation of replicas of natural character use two-step imprinting methods. This article describes a technique of synthetic polymer surface preparation by the process of two-stage imprinting. The laboratory-prepared structure copies the original natural pattern at the micrometer and sub-micrometer levels, supplemented by a new substructure. The new substructure identified by the scanning electron microscope is created at the nanometer level during the technological process. The nanostructure is formed only under the conditions that a hierarchical structure forms the surface of the natural replicated pattern, the replication mold is from a soft elastomeric material, and the material for producing the synthetic surface is a polymer capable of crystallizing. A new nanometer substructure formation occurs when the polymer cools to standard laboratory temperature and atmospheric pressure.

Comparative ecological and physiological characteristics of <i>Penicillium chrysogenum</i> Thom 1910 strains found on the territory of Surgut

The paper deals with ecological and physiological properties of four strains of the species Penicillium chrysogenum Thom 1910, taken on the territory of Surgut from soil, water and the surface of synthetic polymers, depending on the source of carbon nutrition and temperature. The author also considers phytotoxic properties of these strains in relation to several test objects. The cultural and morphological characteristics of the strains are similar to each other in places with sucrose, lactose, mannitol, starch and cellulose, and are variable in places with sorbitol and glycerol. The highest average values of the radial growth rate were recorded in places with alcohols sorbitol and glycerine. General cultural and morphological characteristics are typical for strains when cultivated in the same temperature regime; a low temperature of +5C contributes more to the growth of colonies than a high temperature of +37C, the optimal one is +25C; the obtained data confirm that P. chrysogenum belongs to mesophilic (psychrotolerant) species. All strains are toxic to radish seedlings; variably toxic to wheat seedlings, Canada water weed and duckweed and non-toxic to wheat and radish seeds. The obtained results can be used for studying the ecology of P. chrysogenum strains, as well as for identifying this species.

Polydopamine and Its Derivative Surface Chemistry in Material Science: A Focused Review for Studies at KAIST.

Polydopamine coating, the first material-independent surface chemistry, and its related methods significantly influence virtually all areas of material science and engineering. Functionalized surfaces of metal oxides, synthetic polymers, noble metals, and carbon materials by polydopamine and its related derivatives exhibit a variety of properties for cell culture, microfluidics, energy storage devices, superwettability, artificial photosynthesis, encapsulation, drug delivery, and numerous others. Unlike other articles, this review particularly focuses on the development of material science utilizing polydopamine and its derivatives coatings at the Korea Advanced Institute of Science and Technology for a decade. Herein, it is demonstrated how material-independent coating methods provide solutions for challenging problems existed in many interdisciplinary areas in bio-, energy-, and nanomaterial science by collaborations and independent research.

Mature biofilm communities on synthetic polymers in seawater - Specific or general?

To understand the ecological impacts of the “Plastisphere”, those microbes need to be identified that preferentially colonize and interact with synthetic polymer surfaces, as opposed to general surface colonizers. It was hypothesized that the microbial biofilm composition varies distinctly between different substrates. A long-term incubation experiment was conducted (15month) with nine different synthetic polymer films as substrate as well as glass using a natural seawater flow-through system. To identify colonizing microorganisms, 16S and 18SrRNA gene tag sequencing was performed. The microbial biofilms of these diverse artificial surfaces were visualized via scanning electron microscopy. Biofilm communities attached to synthetic polymers are distinct from glass associated biofilms; apparently a more general marine biofilm core community serves as shared core among all synthetic polymers rather than a specific synthetic polymer community. Nevertheless, characteristic and discriminatory taxa of significantly different biofilm communities were identified, indicating their specificity to a given substrate.

Engineered natural and synthetic polymer surfaces induce nuclear deformation in osteosarcoma cells.

Cell-substrate interactions involve constant probing of microenvironment by cells. One of the responses of cells to environmental cues is to change the conformation of their cytoplasm and nucleus. We hypothesized that surface chemistry and topography could be engineered to make these differences significant enough. When designing the substrates that would accentuate these differences, we prepared surfaces carrying cell adhesive biological cues arranged in specific patterns. Collagen type I and poly(lactic acid-co-glycolic acid) (PLGA) were used to represent substrates with biological cues and those without, and these materials were decorated with four square prism micropillars with different dimensions. The nuclear deformations were analyzed using some descriptors. Nucleus area and solidity were the best descriptors in distinguishing the substrates in terms of biological cues, while nucleus area, solidity, and circularity were more sensitive to the interpillar distances. Another distinguishing factor tested was the duration of contact. Nucleus area was the only descriptor sensitive to nuclear deformation change with time. PLGA was more suitable in nuclear conformation analysis while collagen was better in cell adhesion and proliferation. These deformations lead to changes in the molecular processes and further studies are needed to better understand cell mechanobiology. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 366-376, 2019.

Biobased, Internally pH-Sensitive Materials: Immobilized Yellow Fluorescent Protein as an Optical Sensor for Spatiotemporal Mapping of pH Inside Porous Matrices.

The pH is fundamental to biological function and its measurement therefore crucial across all biosciences. Unlike homogenous bulk solution, solids often feature internal pH gradients due to partition effects and confined biochemical reactions. Thus, a full spatiotemporal mapping for pH characterization in solid materials with biological systems embedded in them is essential. In here, therefore, a fully biocompatible methodology for real-time optical sensing of pH within porous materials is presented. A genetically encoded ratiometric pH sensor, the enhanced superfolder yellow fluorescent protein (sYFP), is used to functionalize the internal surface of different materials, including natural and synthetic organic polymers as well as silica frameworks. By using controlled, tailor-made immobilization, sYFP is homogenously distributed within these materials and so enables, via self-referenced imaging analysis, pH measurements in high accuracy and with useful spatiotemporal resolution. Evolution of internal pH is monitored in consequence of a proton-releasing enzymatic reaction, the hydrolysis of penicillin by a penicillin acylase, taking place in solution or confined to the solid surface of the porous matrix. Unlike optochemical pH sensors, which often interfere with biological function, labeling with sYFP enables pH sensing without altering the immobilized enzyme's properties in any of the materials used. Fast response of sYFP to pH change permits evaluation of biochemical kinetics within the solid materials. Thus, pH sensing based on immobilized sYFP represents a broadly applicable technique to the study of biology confined to the internally heterogeneous environment of solid matrices.

Cationic proteins for enhancing biosludge dewaterability: A comparative assessment of surface and conditioning characteristics of synthetic polymers, surfactants and proteins

Abstract Synthetic organic polymers are commonly used to facilitate challenging solid-liquid separations such as biosludge dewatering. However, there is interest in reducing the use of polymers due to their toxicity and synthetic sourcing. Surfactants and proteins have shown potential to enhance sludge dewaterability but little is known about the properties and/or mechanism(s) that promote this enhancement. In this study, synthetic polymers, surfactants and proteins were investigated to evaluate whether surface properties such as charge, surfactant activity and hydrophobicity, play a role in how these conditioners affect biosludge dewatering. Capillary suction time (CST), dry solids content, filtrate rate and filtrate solids content were used to assess dewaterability. Results show that surface charge determines the potential of conditioners. The effect of charge was greater for surfactants and proteins than for polymers. In contrast with previous reports, surfactant activity negatively affected the dewaterability of biosludge. Cationic conditioners, regardless of the group improved biosludge dewaterability. However, the dose of cationic proteins is still high compared to currently used synthetic polymers (e.g. protamine is 0.1 g/g TSS vs. synthetic polymer 0.03 g/g TSS). Our results suggest that there is potential for using proteins to improve biosludge dewaterability but a further reduction in protein dose and/or an increase in the protein’s efficiency as a conditioner is needed.

Synthesis and antibacterial activity of surface‐coated catechol‐conjugated polymer with silver nanoparticles on versatile substrate

In the present study, 2‐chloro‐3′,4′‐dihydroxyacetophenone (CCDP), a catechol derivative, was quaternized with poly(propylene oxide)‐g‐poly(dimethylaminoethyl methacrylate) (PPO‐g‐PDMA, PgP) to prepare surface coatings for various substrates. The surfaces of noble metals, oxides, and synthetic polymers were coated by immersion in an aqueous solution of CCDP quaternized with PgP (C‐PgP). The catechol functional groups that remained on the surface were used for deposition of Ag nanoparticles (AgNPs) on the coated surface, to provide a water‐resistant antibacterial polymer with long‐term antimicrobial activity. X‐ray photoelectron spectroscopy confirmed deposition of C‐PgP and AgNPs on the surface coated with the antibacterial polymer. Surface‐immobilized C‐PgP/AgNPs showed outstanding antibacterial activities against Staphylococcus aureus, a Gram‐positive bacterium, and Escherichia coli, a Gram‐negative bacterium. C‐PgP/AgNPs can be applied to a variety of substrates and can therefore be used as antibacterial materials in various fields. Copyright © 2016 John Wiley & Sons, Ltd.

Correlating cell transfectability and motility on materials with different physico-chemical properties

Gene delivery into cells can be facilitated by adding plasmid DNA/transfection reagent complexes in culture medium or pre-adsorbing the complexes on the substrate before cell seeding. Using transfection reagents, however, often causes cytotoxicity. Effective delivery of naked plasmid without any transfection reagent remains a challenge. In this study, we cultured human umbilical cord derived mesenchymal stem cells (hMSCs) on different biomaterial substrates with different physico-chemical properties and examined the transfectability of naked plasmid. Specifically, we synthesized a negatively charged polyurethane (PU) to mimic the hyaluronan-modified chitosan (CS-HA) membranes previously found to promote the transfection of naked plasmid. We observed that the PU membranes were as effective as CS-HA membranes in substrate-mediated delivery of naked plasmid into hMSCs. PU membranes with surface microgrooves further increased the gene delivery efficiency to a similar level as the commercial transfection reagent but without the harmful effect. The gene delivery efficiency was associated with the extent of activation of cellular integrins β1 and α5 on different substrates. Moreover, the delivery efficiency was positively correlated with the cell migration rate on various substrates. The substrate-mediated gene delivery by synthetic polymeric substrates supports that integrin activation and cell behavior (e.g. migration and transfectability) changes can be modulated by synthetic polymer surface with microfeatures. The transfection by PU microgrooves is easy, nontoxic, and as effective as the commercial transfection reagent.

Polyurethane: Stable Cell Phenotype Requires Plasticity: Polymer Supported Directed Differentiation Reveals a Unique Gene Signature Predicting Stable Hepatocyte Performance (Adv. Healthcare Mater. 12/2015).

One major obstacle to the routine deployment of stem cell-derived cells is their instability in culture. On page 1820 David C. Hay and co-workers describe the use of a synthetic polymer surface. The image shows stem cell-derived hepatocytes replated on this polyurethane surface. Importantly the cells express Zonal Occludin (green stain) at the cell surface, which indicates that the cells display elements of polarization. The blue stain is DAPI, which demarks the nucleus.

Polymer Supported Directed Differentiation Reveals a Unique Gene Signature Predicting Stable Hepatocyte Performance.

In theory, pluripotent stem cells can give rise to all somatic cell types found in the human body. The ability to generate renewable sources of human cells has enormous potential to improve human health and wealth. One major obstacle to the routine deployment of stem cell-derived cells is their instability in culture. To tackle this issue a synthetic polymer surface is used.

Method for estimating protein binding capacity of polymeric systems

Composite biomaterials made from synthetic and protein-based polymers are extensively researched in tissue engineering. To successfully fabricate a protein-polymer composite, it is critical to understand how strongly the protein binds to the synthetic polymer, which occurs through protein adsorption. Currently, there is no cost-effective and simple method for characterizing this interfacial binding. To characterize this interfacial binding, we introduce a simple three-step method that involves: 1) synthetic polymer surface characterisation, 2) a quick, inexpensive and robust novel immuno-based assay that uses protein extraction compounds to characterize protein binding strength followed by 3) an in vitro 2D model of cell culture to confirm the results of the immuno-based assay. Fibrinogen, precursor of fibrin, was adsorbed (test protein) on three different polymeric surfaces: silicone, poly(acrylic acid)-coated silicone and poly(allylamine)-coated silicone. Polystyrene surface was used as a reference. Characterisation of the different surfaces revealed different chemistry and roughness. The novel immuno-based assay showed significantly stronger binding of fibrinogen to both poly(acrylic acid) and poly(allylamine) coated silicone. Finally, cell studies showed that the strength of the interaction between the protein and the polymer had an effect on cell growth. This novel immuno-based assay is a valuable tool in developing composite biomaterials of synthetic and protein-based polymers with the potential to be applied in other fields of research where protein adsorption onto surfaces plays an important role.

Correction: Chemical approaches to synthetic polymer surface biofunctionalization for targeted cell adhesion using small binding motifs

In the present review the principal strategies to chemically modify the surface of synthetic polymeric materials with small molecules for targeted cell adhesion are collated and critically discussed. The focus is purposely oriented on the chemistry involved in these modifications and neither the physical characterizations nor the activity evaluations resulting from these modifications are addressed in depth, although most reviewed examples demonstrate cell adhesion. Particularly, the introduction of a chemical anchor onto the polymeric substrate, the spacing via a linker between the polymer surface and the cell-binding motif, as well as the linkage generated on this cell-binding motif are discussed. Particular cases where variable substrate geometries or spatial patterning are achieved are additionally highlighted.

A cell-assembled, spatially aligned extracellular matrix to promote directed tissue development

A nanometer thick, micron scale-patterned interface on a polymeric material directs fibroblast proliferation into a highly aligned, confluent cell monolayer. These cells assemble fibronectin extracellular matrix (ECM) fibrils that are aligned with the pattern, and matrix alignment on the synthetic polymer surface is maintained throughout a decellularization process. Biologic relevance of this ECM-synthetic material composite is illustrated by directing oriented neurite outgrowth in register with the aligned matrix fibrils.

Nanowell-trapped charged ligand-bearing nanoparticle surfaces: a novel method of enhancing flow-resistant cell adhesion.

Assuring cell adhesion to an underlying biomaterial surface is vital in implant device design and tissue engineering, particularly under circumstances where cells are subjected to potential detachment from overriding fluid flow. Cell-substrate adhesion is a highly regulated process involving the interplay of mechanical properties, surface topographic features, electrostatic charge, and biochemical mechanisms. At the nanoscale level, the physical properties of the underlying substrate are of particular importance in cell adhesion. Conventionally, natural, pro-adhesive, and often thrombogenic, protein biomaterials are frequently utilized to facilitate adhesion. In the present study, nanofabrication techniques are utilized to enhance the biological functionality of a synthetic polymer surface, polymethymethacrylate, with respect to cell adhesion. Specifically we examine the effect on cell adhesion of combining: 1. optimized surface texturing, 2. electrostatic charge and 3. cell adhesive ligands, uniquely assembled on the substrata surface, as an ensemble of nanoparticles trapped in nanowells. Our results reveal that the ensemble strategy leads to enhanced, more than simply additive, endothelial cell adhesion under both static and flow conditions. This strategy may be of particular utility for enhancing flow-resistant endothelialization of blood-contacting surfaces of cardiovascular devices subjected to flow-mediated shear.