Long-Term Prevention of Biofilm Formation by Polycatechol-Based Supramolecular Assemblies with Low Molecular Weight Polymers on Surfaces.

Achievement of a stable surface coating with long-term resistance to biofilm formation remains a challenge. Catechol-based polymerization chemistry and surface deposition are used as tools for surface modification of diverse materials. However, the control of surface deposition of the coating, surface coverage, coating properties, and long-term protection against biofilm formation remain to be solved. We report a new approach based on supramolecular assembly to generate long-acting antibiofilm coating. Here, we utilized catechol chemistry in combination with low molecular weight amphiphilic polymers for the generation of such coatings. Screening studies with diverse low molecular weight (LMW) polymers and different catechols are utilized to identify lead compositions, which resulted in a thick coating with high surface coverage, smoothness, and antibiofilm activity. We have identified that small supramolecular assemblies (∼10 nm) formed from a combination of polydopamine and LMW poly(N-vinyl caprolactam) (PVCL) resulted in relatively thick coating (∼300 nm) with excellent surface coverage in comparison to other polymers and catechol combinations. The coating properties, such as thickness (10-300 nm) and surface hydrophilicity (with water contact angle: 20-60°), are readily controlled. The optimal coating composition showed excellent antibiofilm properties with long-term (>28 days) antibiofilm activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains. We further utilized the combination of optimal binary coating with silver to generate a coating with sustained release of silver ions, resulting in killing both adhered and planktonic bacteria and preventing long-term surface bacterial colonization. The new coating method utilizing LMW polymers opens a new avenue for the development of a novel class of thick, long-acting antibiofilm coatings.

Physical and biological properties of alginate-based cinnamon essential oil nanoemulsions: Study of two different production strategies.

Nanoemulsions are a promising alternative for essential oil incorporation into active coatings. The influence of the preparation steps order on nanoemulsions' physical properties is still little explored. This study aimed to analyze the effect of the sequence of preparation steps and of the oil and polymer concentration on the stability, physical properties, and antifungal activity of alginate-based cinnamon essential oil nanoemulsions. The nanoemulsions were produced by two strategies: (I) preparation directly into an alginate solution (Ultra-Turrax at 10,000 rpm for 5 min + Ultrasound 150 W for 3 min); and (II) preparation in water (Ultra-Turrax at 10,000 rpm for 5 min + Ultrasound 150 W for 3 min) followed by homogenization with a sodium alginate solution (Ultra-Turrax at 10,000 rpm for 1, 3 or 5 min). The nanoemulsion prepared by the second strategy showed better stability, physical properties, and antifungal activity. In general, the presence of alginate hindered the cavitation effects of ultrasound, leading to the increase of droplets size and consequently affecting emulsions stability, turbidity, and antifungal properties.

Multifunctional surface of the nano-morphic PEEK implant with enhanced angiogenic, osteogenic and antibacterial properties.

Polyetheretherketone (PEEK) is a high-performance polymer suitable for use in biomedical coatings. The implants based on PEEK have been extensively studied in dental and orthopedic fields. However, their inherent inert surfaces and poor osteogenic properties limit their broader clinical applications. Thus, there is a pressing need to produce a multifunctional PEEK implant to address this issue. In response, we developed sulfonated PEEK (sPEEK)-Cobalt-parathyroid hormone (PTH) materials featuring multifunctional nanostructures. This involved loading cobalt (Co) ions and PTH (1-34) protein onto the PEEK implant to tackle this challenge. The findings revealed that the controlled release of Co2+ notably enhanced the vascular formation and the expression of angiogenic-related genes, and offered antimicrobial capabilities for sPEEK-Co-PTH materials. Additionally, the sPEEK-Co-PTH group exhibited improved cell compatibility and bone regeneration capacity in terms of cell activity, alkaline phosphatase (ALP) staining, matrix mineralization and osteogenic gene expression. It surpassed solely sulfonated and other functionalized sPEEK groups, demonstrating comparable efficacy even when compared to the titanium (Ti) group. Crucially, animal experiments also corroborated the significant enhancement of osteogenesis due to the dual loading of cobalt ions and PTH (1-34). This study demonstrated the potential of bioactive Co2+ and PTH (1-34) for bone replacement, optimizing the bone integration of PEEK implants in clinical applications.

Multifunctional curcumin-based polymer coating: A promising platform against bacteria, inflammation and coagulation.

The extensive use of polymers in the medical field has facilitated the development of various devices and implants, contributing to the restoration of organ function. However, despite their advantages such as biocompatibility and robustness, these materials often face challenges like bacterial contamination and subsequent inflammation, leading to implant-associated infections (IAI). Integrating implants effectively is crucial to prevent bacterial colonization and reduce inflammatory responses. To overcome these major issues, surface chemical modifications have been extensively explored. Indeed, click chemistry, and particularly, copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has emerged as a promising approach for surface functionalization without affecting material bulk properties. Curcumin, known for its diverse biological activities, suffers from low solubility and stability. To enhance its bioavailability, bioconjugation strategy has garnered attention in recent years. This study represents pioneering work in immobilizing curcumin derivative onto polyethylene terephthalate (PET) surfaces, aiming to combat bacterial adhesion, inflammation and coagulation. Before curcumin derivative bioconjugation, a fluorophore, dansyl derivative, was employed in order to monitor and determine the efficiency of the proposed methodology. Previous surface chemical modifications were required for the immobilization of both dansyl and curcumin derivatives. Ultraviolet-Visible (UV-Vis) demonstrated the amidation functionalization of PET surface. Other surface characterization techniques including X-ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflectance Fourier Transformed Infrared (ATR-FTIR), Scanning Electron Microscopy (SEM) and contact angle, among others, confirmed also the conjugation of both dansyl and curcumin derivatives. On the other hand, different biological assays corroborated that curcumin derivative immobilized PET surfaces do not exhibit cytotoxicity effect. Additionally, corresponding inflammation test were performed, indicating that these polymeric surfaces do not produce inflammation and, when curcumin derivative is immobilized, they decrease the inflammation marker level (IL-6). Moreover, the bacterial growth of both Gram positive and Gram negative bacteria were measured, demonstrating that the immobilization of curcumin derivative on PET provided antibacterial properties to the material. Finally, hemolysis rate analysis and whole blood clotting assay demonstrated the antithrombogenic effect of PET-Cur surfaces as well as no hemolysis concern in the fabricated functional surfaces.

Cellular Uptake of Upconversion Nanoparticles Based on Surface Polymer Coatings and Protein Corona.

Upconversion nanoparticles (UCNPs) are materials that provide unique advantages for biomedical applications. There are constantly emerging customized UCNPs with varying compositions, coatings, and upconversion mechanisms. Cellular uptake is a key parameter for the biological application of UCNPs. Uptake experiments have yielded highly varying results, and correlating trends between cellular uptake with different types of UCNP coatings remains challenging. In this report, the impact of surface polymer coatings on the formation of protein coronas and subsequent cellular uptake of UCNPs by macrophages and cancer cells was investigated. Luminescence confocal microscopy and elemental analysis techniques were used to evaluate the different coatings for internalization within cells. Pathway inhibitors were used to unravel the specific internalization mechanisms of polymer-coated UCNPs. Coatings were chosen as the most promising for colloidal stability, conjugation chemistry, and biomedical applications. PIMA-PEG (poly(isobutylene-alt-maleic) anhydride with polyethylene glycol)-coated UCNPs were found to have low cytotoxicity, low uptake by macrophages (when compared with PEI, poly(ethylenimine)), and sufficient uptake by tumor cells for surface-loaded drug delivery applications. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) studies revealed that PIMA-coated NPs were preferentially internalized by the clathrin- and caveolar-independent pathways, with a preference for clathrin-mediated uptake at longer time points. PMAO-PEG (poly(maleic anhydride-alt-1-octadecene) with polyethylene glycol)-coated UCNPs were internalized by energy-dependent pathways, while PAA- (poly(acrylic acid)) and PEI-coated NPs were internalized by multifactorial mechanisms of internalization. The results indicate that copolymers of PIMA-PEG coatings on UCNPs were well suited for the next-generation of biomedical applications.

Release of nanoparticle coatings additives from common surfaces via simulated dermal contact.

Both nanoparticles (NPs) and nano-enabled products have become widely available in consumer markets in the last decade. Surface coating including paints, stains, and sealants, have seen large increases in the inclusion of nanomaterials in their formulations to increase UV resistance, hydrophobicity, and scratch resistance. Currently, most literature studying the release of NPs and byproducts from coated surfaces has focused exclusively on lumber. In this study, well characterized CeO2 NPs were dispersed in either Milli-Q water, or a commercial paint primer and applied to several test surfaces including sanded plywood, drywall, low density polyethylene, acrylonitrile butadiene styrene, polycarbonate, textured polycarbonate with pebble finish, and glass. Coated surfaces were sampled using a method previously developed by U.S. Consumer Product Safety Commission staff to track the release of NPs via simulated dermal contact. Particular attention has been paid to the total amount, and morphology of material released. The total amount of cerium released from coated surfaces was found to be dependent on both the identity of the test surface, as well as the solution used for coating. Water-based application found 22-50 % of the applied cerium removed during testing, while primer-based application showed released rates ranging between 0.1 and 3 %. Finally, the SEM micrographs presented here suggest the release of microplastic particles during simulated dermal contact with plastic surfaces.

Optical Thin Films in Space Environment: Investigation of Proton Irradiation Damage.

The present work reports a systematic study of the potential degradation of metals and dielectric thin films in different space environments. The mono- and bilayers selected are made of materials commonly used for the realization of optical components, such as reflective mirrors or building blocks of interferential filters. More than 400 samples were fabricated and irradiated with protons at different energies on ground-based facilities. The fluences were selected as a result of simulations of the doses delivered within a long-term space mission considering different orbits (Sun close, Jovian, and Geostationary orbits). In order to stress the samples at different depths and layer interfaces, experiments were carried out with a range of proton energies within 1 and 10 MeV values. An estimate of a safe maximum fluence has been provided for each type of sample at each energy. The damage mechanism, when present, has been investigated with different optical and structural techniques.

Machine Learning-Based Design of Superhard High-Entropy Nitride Coatings.

Limited by the inefficiency of the conventional trial-and-error method and the boundless compositional design space of high-entropy alloys (HEAs), accelerating the discovery of superior-performing high-entropy nitride (HEN) coatings remains a formidable challenge. Herein, the superhard HEN coatings were designed and prepared using the rapidly developing data-driven model machine learning (ML). A database containing hardness and different features of HEN coatings was established and categorized into four subsets covering the information on composition, composition-physical descriptors, composition-technique parameters, and composition-physical descriptors-technique parameters. Feature engineering was employed to reduce dimensionality and interpret the impact of features on the evolution of hardness. Both root mean squared error (RMSE) and decision coefficient (R2) were applied to assess the predictive accuracy of ML models with different subsets, proportions of test set, and algorithms. The model with best predicted performance was used to explore superhard HEN coatings in a predefined virtual space. Among the generated 5-/6-/7-/8-component (excluding N) systems, the coating possessing highest hardness was individually selected for further preparation. Four newly prepared coatings achieved the superhard level with an average prediction error of 7.83%. The morphology, chemical composition, structure, and hardness of the newly prepared coatings were discussed. The nanocrystal-amorphous nanocomposite structure of the novel AlCrNbSiTiN coating with the highest hardness of 45.77 GPa was revealed. The results demonstrated that ML can effectively guide the design and composition optimization of superb-performance protective HEN coatings.

Development and life cycle assessment (LCA) of super-oleophobic (under water) and super-hydrophilic (in-air) mesh membrane for oily water treatment.

This paper reports the fabrication, characterization, and environmental impact analysis of a super-oleophobic (under water) and super-hydrophilic mesh membrane for oily water treatment. In order to prepare mesh membrane, Titania nanoparticles (NPs) were spray coated on mesh stainless steel followed by calcination at 500 °C. After that, the Titania-coated mesh membrane was characterized using contact angle goniometry (CA), XRD, FE-SEM, EDX and elemental mapping. The FE-SEM, EDX, elemental mapping and XRD results confirmed that the Titania NPs were successfully coated on the surface of mesh membrane. CA results demonstrated that the prepared mesh membrane is super-hydrophilic and super-oleo phobic under water conditions, making it suitable for oil/water separation. Subsequently, life cycle assessment (LCA) was performed to determine the environmental impacts of Titania NPs-coated mesh membrane fabrication process. LCA results indicate that electricity and nitrogen contributed the most toward the eighteen environmental impact categories considered for this study.

Protecting TiS3 Photoanodes for Water Splitting in Alkaline Media by TiO2 Coatings.

Titanium trisulfide (TiS3) nanoribbons, when coated with titanium dioxide (TiO2), can be used for water splitting in the KOH electrolyte. TiO2 shells can be prepared through thermal annealing to regulate the response of TiS3/TiO2 heterostructures by controlling the oxidation time and growth atmosphere. The thickness and structure of the TiO2 layers significantly influence the photoelectrocatalytic properties of the TiS3/TiO2 photoanodes, with amorphous layers showing better performance than crystalline ones. The oxide layers should be thin enough to transfer photogenerated charge through the electrode-electrolyte interface while protecting TiS3 from KOH corrosion. Finally, the performance of TiS3/TiO2 heterostructures has been improved by coating them with various electrocatalysts, NiSx being the most effective. This research presents new opportunities to create efficient semiconductor heterostructures to be used as photoanodes in corrosive alkaline aqueous solutions.

Synthesis and characterization of flame retardant unsaturated polyester-allyloxysilane resin for wood coatings.

Fireproof coatings are the simplest, most efficient, and oldest method for protecting a wide range of flammable products, such as wood. Furthermore, surface ignition is the initial phase, so surface protection is essential to reduce fire propagation. Furthermore, delaying the spread of flames can help to save someone when a fire starts. This project synthesized flame-resistant resin starting from tetraallyloxysilane monomer as a halogen-free monomer, an intrinsic flame retardant co-curing agent. The following step synthesized polyester resin using terephthalic acid as a heat-resistant resin. Unsaturated polyester was used by bulk radical polymerization. FT-IR and 1H-NMR analysis showed the successful synthesis of the desired monomer and polymeric compound. The thermal degradation and flame retardancy of pure unsaturated polyester resin (UPE) and allyloxysilane-unsaturated polyester (AUPE) were investigated by thermogravimetric analysis (TGA/DTG/DSC). The burning test and the thermal stability of the coating layers were evaluated using standard UL 94. Physical properties of resins were evaluated using Heat Deflection Temp tests (HDT) ISO 75-A, ASTM 648, Hardness ASTM D2583, Volumetric shrinkage ASTM 3521, and Water absorption ASTM D570. The results of the tests show the successful synthesis and their flame retardant properties.

Optical fiber sensor for water velocity measurement in rivers and channels.

In this work, optical fiber Bragg grating sensors were used to measure water velocity and examine how it was distributed in open channels. Several types of coatings were incorporated into the design of the sensors to examine their effects on the strain that the fibers experienced as a result of the water flow. Due to their low elastic coefficient, which reduced the hysteresis, the results indicated that the aluminum- and acrylate-coated fibers had the best performance. ANSYS-CFX V2020 R2 software was used to model the strain encountered by the fibers under various flow rates to assess the performance of the FBG sensors. The calculations and actual data exhibited good convergence, demonstrating the accuracy of the FBG sensors in determining water velocity. The study illustrated the usability of the proposal in both scenarios by contrasting its application in rivers and channels.

Modification of Epoxy Coatings with Fluorocontaining Organosilicon Copolymers.

Preparation of hydrophobic coatings is still a challenge for researchers in various fields of science. One of the easiest ways consists of the use of special modifiers. However, usually such modifiers are poorly compatible with organic polymeric matrixes, which leads to segregation of modifiers and deterioration of coating properties. In this work, we have synthesized a number of organosilicon copolymers and studied their compatibility with epoxy matrix and hydrophobic efficiency. It was shown that the increase of phenyl-containing units leads to increase of compatibility but decreases hydrophobic efficiency. Addition of small amounts of such modifiers into commercial epoxy paint material can lead to an increase of contact angle of the final coating from 63 to 87° without deterioration of other physico-mechanical properties. These results open new perspectives in preparation of organosilicon hydrophobic modifiers with directed properties for fields of application such as paints and coating materials.

Gallium-doped zirconia coatings modulate microbiological outcomes in dental implant surfaces.

Despite the significant recent advances in manufacturing materials supporting advanced dental therapies, peri-implantitis still represents a severe complication in dental implantology. Herein, a sol-gel process is proposed to easily deposit antibacterial zirconia coatings onto bulk zirconia, material, which is becoming very popular for the manufacturing of abutments. The coatings' physicochemical properties were analyzed through x-ray diffraction and scanning electron microscopy-energy-dispersive x-ray spectroscopy investigations, while their stability and wettability were assessed by microscratch testing and static contact angle measurements. Uniform gallium-doped tetragonal zirconia coatings were obtained, featuring optimal mechanical stability and a hydrophilic behavior. The biological investigations pointed out that gallium-doped zirconia coatings: (i) displayed full cytocompatibility toward human gingival fibroblasts; (ii) exhibited significant antimicrobial activity against the Aggregatibacter actinomycetemcomitans pathogen; (iii) were able to preserve the commensal Streptococcus salivarius. Furthermore, the proteomic analyses revealed that the presence of Ga did not impair the normal oral microbiota. Still, interestingly, it decreased by 17% the presence of Fusobacterium nucleatum, a gram-negative, strictly anaerobic bacteria that is naturally present in the gastrointestinal tract. Therefore, this work can provide a valuable starting point for the development of coatings aimed at easily improving zirconia dental implants' performance.

Long-Lasting Antibacterial PDMS Surfaces Constructed from Photocuring of End-Functionalized Polymers.

A challenge remains in the development of anti-infectious coatings for the inert surfaces of biomedical devices that are prone to bacterial colonization and biofilm formation. Here, a facile photocuring method to construct functionalized polymeric coatings on inert polydimethylsiloxane (PDMS) surfaces, is developed. Using atom transfer radical polymerization (ATRP) initiator bearing thymol group, hydrophilic DMAEMA and benzophenone (BP)-containing monomers are copolymerized to form polymers with end functional groups. An end-functionalized biocidal coating is then constructed on the inert PDMS surface in one step using a photocuring reaction. The functionalized PDMS surfaces show excellent antibacterial and antifouling properties, are capable of completely eradiating MRSA within ≈6 h, and effectively inhibit the growth of biofilms. In addition, they have good stability and long-lasting antibacterial activity in body fluid environments such as 0.9% saline and urine. According to bladder model experiments, the catheter's lifespan can be extended from ≈7 to 35 days by inhibiting the growth and migration of bacteria along its inner surface. The photocuring technique is therefore very promising in terms of surface functionalization of inert biomedical devices in order to minimize the spread of infection.

Encapsulation of Probiotics within Double/Multiple Layer Beads/Carriers: A Concise Review.

An increased demand for natural products nowadays most specifically probiotics (PROs) is evident since it comes in conjunction with beneficial health effects for consumers. In this regard, it is well known that encapsulation could positively affect the PROs' viability throughout food manufacturing and long-term storage. This paper aims to analyze and review various double/multilayer strategies for encapsulation of PROs. Double-layer encapsulation of PROs by electrohydrodynamic atomization or electrospraying technology has been reported along with layer-by-layer assembly and water-in-oil-in-water (W1/O/W2) double emulsions to produce multilayer PROs-loaded carriers. Finally, their applications in food products are presented. The resistance and viability of loaded PROs to mechanical damage, during gastrointestinal transit and shelf life of these trapping systems, are also described. The PROs encapsulation in double- and multiple-layer coatings combined with other technologies can be examined to increase the opportunities for new functional products with amended functionalities opening a novel horizon in food technology.

Recent Advances in Corrosion Inhibition of Bonded NdFeB Magnets.

Bonded permanent NdFeB magnets are useful in numerous applications, including electric vehicles, and the demand is steadily increasing. A major drawback is corrosion due to inadequate wetting of the magnetic particles by liquid polymers such as polyphenylene sulfide or polyamide. Recently reported methods for corrosion inhibition are summarized, and their applicability is critically evaluated. The phosphorylation of magnetic particles inhibits corrosion but does not enable appropriate properties in harsh environments. The same applies to metallic coatings, which usually contain aluminum and zinc. Advanced epoxy adhesives are a promising solution, although some authors have reported inadequate corrosion resistance. The application of composite coatings seems like an appropriate solution, but the exact mechanisms are yet to be studied.

Processability and Separability of Commercial Anti-Corrosion Coatings Produced by In Situ Hydrogen-Processing of Magnetic Scrap (HPMS) Recycling of NdFeB.

The recycling of NdFeB magnets is necessary to ensure a reliable and ethical supply of rare earth elements as critical raw materials. This has been recognized internationally, prompting the implementation of large-scale legislative measured aimed at its resolution; for example, an ambitious recycling quote has been established in the Critical Raw Materials Act Successful recycling in sufficient quantities is challenged by product designs that do not allow the extraction and recycling of these high-performance permanent magnets without excessive effort and cost. This is particularly true for smaller motors using NdFeB magnets. Therefore, methods of recycling such arrangements with little or no dismantling are being researched. They are tested for the hydrogen-processing of magnetic scrap (HPMS) method, a short-loop mechanical recycling process. As contamination of the recycled material with residues of anti-corrosion coatings, adhesives, etc., may lead to downcycling, the separability of such residues from bulk magnets and magnet powder is explored. It is found that the hydrogen permeability, expansion volume, and the chosen coating affect the viable preparation and separation methods as recyclability-relevant design features.

The Influence of nc-AlCrTiN/α-BN Coatings on Increasing the Durability of WC/Co Cutting Inserts in the Inconel Alloy Machining Process.

Anti-wear coatings obtained through PVD methods may significantly increase the durability of cutting tools by impacting their wear mechanisms. This study presents and discusses the results of studies on the impact of the thermal conductivity of PVD coatings on the intensity of the built-up edge (BUE) and built-up layer (BUL) formation in Inconel 600 alloy machining processes. The authors determine the microstructure, phase structure, mechanical properties (hardness, Young's modulus, and adhesion), and thermal conductivity of different PVD coatings selected for the purpose of the study and varying in terms of conductivity-i.e., AlCrTiN and AlCrTiN/BN. Machining processes were carried out under controlled conditions using VBGT160404-M3 cutting inserts with AlCrTiN and AlCrTiN/BN coatings deposited on their surface. The authors prove that the adjustment of the thermal conductivity of PVD coatings to the thermal conductivity of the tool and machined materials can help change the direction of heat flow to cool the cutting zone more effectively. The study results presented in this article show that the deposition of the AlCrTiN/BN coating reduces the friction wear on the tool flank by over 70% and lowers the intensity of BUE and BUL formation processes on the face by 10%, compared to the AlCrTiN coating.

The Development of Novel Cu/GO Nano-Composite Coatings by Brush Plating with High Wear Resistance for Potential Brass Sliding Bearing Application.

Low friction and high wear resistance are critical properties for sliding bearings. In this research, advanced Cu/GO nanocomposite coatings have been developed by a brush plating method to improve the tribological performance of brass-based sliding bearings. A series of brush plating studies under voltages from 2 to 6 V with different GO concentrations (0.2-0.8 g/L) was conducted, and the coating microstructures were characterised by SEM, EDX, GDOES and XRD and the tribological behaviour of the Cu/GO composite coatings were evaluated using dry ball-on-plane tribological tests The experimental results have demonstrated that GO can be successfully introduced into the whole composite coating layer; the Cu/GO composite coatings can reduce the friction of brass and increase its wear resistance by two orders of magnitude, mainly due to the self-lubricating GO added into the coatings.