Silver-enriched microdomain patterns as advanced bactericidal coatings for polymer-based medical devices.

Today, it would be difficult for us to live a full life without polymers, especially in medicine, where its applicability is constantly expanding, giving satisfactory results without any harm effects on health. This study focused on the formation of hexagonal domains doped with AgNPs using a KrF excimer laser (λ=248 nm) on the polyetheretherketone (PEEK) surface that acts as an unfailing source of the antibacterial agent - silver. The hexagonal structure was formed with a grid placed in front of the incident laser beam. Surfaces with immobilized silver nanoparticles (AgNPs) were observed by AFM and SEM. Changes in surface chemistry were studied by XPS. To determine the concentration of released Ag+ ions, ICP-MS analysis was used. The antibacterial tests proved the antibacterial efficacy of Ag-doped PEEK composites against Escherichia coli and Staphylococcus aureus as the most common pathogens. Because AgNPs are also known for their strong toxicity, we also included cytotoxicity tests in this study. The findings presented here contribute to the advancement of materials design in the biomedical field, offering a novel starting point for combating bacterial infections through the innovative integration of AgNPs into inert synthetic polymers.

Modification of AgNP-Decorated PET: A Promising Strategy for Preparation of AgNP-Filled Nuclear Pores in Polymer Membranes.

Polymer-based membranes represent an irreplaceable group of materials that can be applied in a wide range of key industrial areas, from packaging to high-end technologies. Increased selectivity to transport properties or the possibility of controlling membrane permeability by external stimuli represents a key issue in current material research. In this work, we present an unconventional approach with the introduction of silver nanoparticles (AgNPs) into membrane pores, by immobilising them onto the surface of polyethyleneterephthalate (PET) foil with subsequent physical modification by means of laser and plasma radiation prior to membrane preparation. Our results showed that the surface characteristics of AgNP-decorated PET (surface morphology, AgNP content, and depth profile) affected the distribution and concentration of AgNPs in subsequent ion-track membranes. We believe that the presented approach affecting the redistribution of AgNPs in the polymer volume may open up new possibilities for the preparation of metal nanoparticle-filled polymeric membranes. The presence of AgNPs on the pore walls can facilitate the grafting of stimuli-responsive molecules onto these active sites and may contribute to the development of intelligent membranes with controllable transport properties.

A New Promising Material for Biological Applications: Multilevel Physical Modification of AgNP-Decorated PEEK.

In the case of polymer medical devices, the surface design plays a crucial role in the contact with human tissue. The use of AgNPs as antibacterial agents is well known; however, there is still more to be investigated about their anchoring into the polymer surface. This study describes the changes in the surface morphology and behaviour in the biological environment of polyetheretherketone (PEEK) with immobilised AgNPs after different surface modifications. The initial composites were prepared by immobilising silver nanoparticles from a colloid solution in the upper surface layers of polyetheretherketone (PEEK). The prepared samples (Ag/PEEK) had a planar morphology and were further modified with a KrF laser, a GaN laser, and an Ar plasma. The samples were studied using the AFM method to visualise changes in surface morphology and obtain information on the height of the structures and other surface parameters. A comparative analysis of the nanoparticles and polymers was performed using FEG-SEM. The chemical composition of the surface of the samples and optical activity were studied using XPS and UV-Vis spectroscopy. Finally, drop plate antibacterial and cytotoxicity tests were performed to determine the role of Ag nanoparticles after modification and suitability of the surface, which are important for the use of the resulting composite in biomedical applications.

Surface Engineering of AgNPs-Decorated Polyetheretherketone.

Metal nanostructure-treated polymers are widely recognized as the key material responsible for a specific antibacterial response in medical-based applications. However, the finding of an optimal bactericidal effect in combination with an acceptable level of cytotoxicity, which is typical for metal nanostructures, prevents their expansion from being more significant so far. This study explores the possibility of firmly anchoring silver nanoparticles (AgNPs) into polyetherether ketone (PEEK) with a tailored surface morphology that exhibits laser-induced periodic surface structures (LIPSS). We demonstrated that laser-induced forward transfer technology is a suitable tool, which, under specific conditions, enables uniform decoration of the PEEK surface with AgNPs, regardless of whether the surface is planar or LIPSS structured. The antibacterial test proved that AgNPs-decorated LIPSS represents a more effective bactericidal protection than their planar counterparts, even if they contain a lower concentration of immobilized particles. Nanostructured PEEK with embedded AgNPs may open up new possibilities in the production of templates for replication processes in the construction of functional bactericidal biopolymers or may be directly used in tissue engineering applications.

Decoration of Ultramicrotome-Cut Polymers with Silver Nanoparticles: Effect of Post-Deposition Laser Treatment.

Today, ultramicrotome cutting is a practical tool, which is frequently applied in the preparation of thin polymeric films. One of the advantages of such a technique is the decrease in surface roughness, which enables an effective recording of further morphological changes of polymeric surfaces during their processing. In view of this, we report on ultramicrotome-cut polymers (PET, PEEK) modified by a KrF excimer laser with simultaneous decoration by AgNPs. The samples were immersed into AgNP colloid, in which they were exposed to polarized laser light. As a result, both polymers changed their surface morphology while simultaneously being decorated with AgNPs. KrF laser irradiation of the samples resulted in the formation of ripple-like structures on the surface of PET and worm-like ones in the case of PEEK. Both polymers were homogeneously covered by AgNPs. The selected area of the samples was then irradiated by a violet semiconductor laser from the confocal laser scanning microscope with direct control of the irradiated area. Various techniques, such as AFM, FEGSEM, and CLSM were used to visualize the irradiated area. After irradiation, the reverse pyramid was formed for both types of polymers. PET samples exhibited thicker transparent reverse pyramids, whereas PEEK samples showed thinner brownish ones. We believe that his technique can be effectively used for direct polymer writing or the preparation of stimuli-responsive nanoporous membranes.

Laser-Processed PEN with Au Nanowires Array: A Biocompatibility Assessment.

Although many noble metals are known for their antibacterial properties against the most common pathogens, such as Escherichia coli and Staphylococcus epidermidis, their effect on healthy cells can be toxic. For this reason, the choice of metals that preserve the antibacterial effect while being biocompatible with health cells is very important. This work aims to validate the effect of gold on the biocompatibility of Au/Ag nanowires, as assessed in our previous study. Polyethylene naphthalate (PEN) was treated with a KrF excimer laser to provide specific laser-induced periodic structures. Then, Au was deposited onto the modified PEN via a vacuum evaporation method. Atomic force microscopy and scanning electron microscopy revealed the dependence of the surface morphology on the incidence angle of the laser beam. A resazurin assay cytotoxicity test confirmed safety against healthy human cells and even cell proliferation was observed after 72 h of incubation. We have obtained satisfactory results, demonstrating that monometallic Au nanowires can be applied in biomedical applications and provide the biocompatibility of bimetallic Au/AgNWs.

Engineered Cu-PEN Composites at the Nanoscale: Preparation and Characterisation.

As polymeric materials are already used in many industries, the range of their applications is constantly expanding. Therefore, their preparation procedures and the resulting properties require considerable attention. In this work, we designed the surface of polyethylene naphthalate (PEN) introducing copper nanowires. The surface of PEN was transformed into coherent ripple patterns by treatment with a KrF excimer laser. Then, Cu deposition onto nanostructured surfaces by a vacuum evaporation technique was accomplished, giving rise to nanowires. The morphology of the prepared structures was investigated by atomic force microscopy and scanning electron microscopy. Energy dispersive spectroscopy and X-ray photoelectron spectroscopy revealed the distribution of Cu in the nanowires and their gradual oxidation. The optical properties of the Cu nanowires were measured by UV-Vis spectroscopy. The sessile drop method revealed the hydrophobic character of the Cu/PEN surface, which is important for further studies of biological responses. Our study suggests that a combination of laser surface texturing and vacuum evaporation can be an effective and simple method for the preparation of a Cu/polymer nanocomposite with potential exploitation in bioapplications; however, it should be borne in mind that significant post-deposition oxidation of the Cu nanowire occurs, which may open up new strategies for further biological applications.

Laser-Promoted Immobilization of Ag Nanoparticles: Effect of Surface Morphology of Poly(ethylene terephthalate).

In the last two decades, the importance of nanomaterials in modern technologies has been unquestionable. Metal nanoparticles are frequently used in many areas of science and technology, delivering unprecedented improvements to properties of the conventional materials. This work introduces an effective tool for preparing a highly enriched poly (ethylene terephthalate) (PET) surface with silver nanoparticles, firmly immobilized in the same surface area on polymer. We showed that besides pristine polymer, this approach may be successfully applied also on laser pre-treated PET with laser-induced periodic surface structures. At the same time, its final nanostructure may be effectively controlled by laser fluence applied during the immobilization process.

Bimetallic Nanowires on Laser-Patterned PEN as Promising Biomaterials.

As inflammation frequently occurs after the implantation of a medical device, biocompatible, antibacterial materials must be used. Polymer-metal nanocomposites are promising materials. Here we prepared enhanced polyethylene naphthalate (PEN) using surface modification techniques and investigated its suitability for biomedical applications. The PEN was modified by a KrF laser forming periodic ripple patterns with specific surface characteristics. Next, Au/Ag nanowires were deposited onto the patterned PEN using vacuum evaporation. Atomic force microscopy confirmed that the surface morphology of the modified PEN changed accordingly with the incidence angle of the laser beam. Energy-dispersive X-ray spectroscopy showed that the distribution of the selected metals was dependent on the evaporation technique. Our bimetallic nanowires appear to be promising antibacterial agents due to the presence of antibacterial noble metals. The antibacterial effect of the prepared Au/Ag nanowires against E. coli and S. epidermidis was demonstrated using 24 h incubation with a drop plate test. Moreover, a WST-1 cytotoxicity test that was performed to determine the toxicity of the nanowires showed that the materials could be considered non-toxic. Collectively, these results suggest that prepared Au/Ag nanostructures are effective, biocompatible surface coatings for use in medical devices.

Surface Texturing of Polyethylene Terephthalate Induced by Excimer Laser in Silver Nanoparticle Colloids.

We report on a novel technique of surface texturing of polyethylene terephthalate (PET) foil in the presence of silver nanoparticles (AgNPs). This approach provides a variable surface morphology of PET evenly decorated with AgNPs. Surface texturing occurred in silver nanoparticle colloids of different concentrations under the action of pulse excimer laser. Surface morphology of PET immobilized with AgNPs was observed by AFM and FEGSEM. Atomic concentration of silver was determined by XPS. A presented concentration-controlled procedure of surface texturing of PET in the presence of silver colloids leads to a highly nanoparticle-enriched polymer surface with a variable morphology and uniform nanoparticle distribution.

Nanostructured Materials for Artificial Tissue Replacements.

This paper review current trends in applications of nanomaterials in tissue engineering. Nanomaterials applicable in this area can be divided into two groups: organic and inorganic. Organic nanomaterials are especially used for the preparation of highly porous scaffolds for cell cultivation and are represented by polymeric nanofibers. Inorganic nanomaterials are implemented as they stand or dispersed in matrices promoting their functional properties while preserving high level of biocompatibility. They are used in various forms (e.g., nano- particles, -tubes and -fibers)-and when forming the composites with organic matrices-are able to enhance many resulting properties (biologic, mechanical, electrical and/or antibacterial). For this reason, this contribution points especially to such type of composite nanomaterials. Basic information on classification, properties and application potential of single nanostructures, as well as complex scaffolds suitable for 3D tissues reconstruction is provided. Examples of practical usage of these structures are demonstrated on cartilage, bone, neural, cardiac and skin tissue regeneration and replacements. Nanomaterials open up new ways of treatments in almost all areas of current tissue regeneration, especially in tissue support or cell proliferation and growth. They significantly promote tissue rebuilding by direct replacement of damaged tissues.