Surface Coatings Research Articles

An analytical review of the therapeutic application of recent trends in MIL-based delivery systems in cancer therapy.

MILs (Materials Institute Lavoisier), as nanocarriers based on metal-organic frameworks (MOFs), are one of the most advanced drug delivery vehicles that are now a major part of cancer treatment research. This review article highlights the key features and components of MIL nanocarriers for the development and improvement of these nanocarriers for drug delivery. Surface coatings are one of the key components of MIL nanocarriers, which play the role of stabilizing the nanocarrier, pH-dependent drug release, increasing the half-life of the drug, and targeting the carrier. MIL nanocarriers have been synthesized mainly by thermal and hydrothermal methods due to their single-step nature and the ability to produce individual crystals with tunable sizes. According to the data available in the literature, MIL-53 and MIL-101 are the best MILs for drug delivery. These MILs have a high ability to release drugs under acidic conditions, indicating their high efficiency compared to other MILs. In addition to drugs, these nanocarriers can also carry fluorescent, photothermal, and photodynamic agents. These agents allow the MIL nanocarriers to benefit from the therapeutic potential of photothermal and photodynamic agents in addition to the therapeutic capacity of the drug. Furthermore, the fluorescent active ingredient gives these nanocarriers a further tracking capability in addition to the inherent tracking capability of MRI. Therefore, MIL nanocarriers as theranostic carriers have the potential to revolutionize both drug delivery and imaging.

Fabrication of Versatile Antifouling Coatings Inspired by Melanogenesis Using a Tyrosine-Conjugated Carboxybetaine Derivative.

In this study, we developed zwitterionic surface coatings of carboxybetaine by mimicking natural melanogenesis. We synthesized an unnatural tyrosine-conjugated carboxybetaine (Tyr-CB) that undergoes melanin-like oxidation upon treatment with tyrosinase under various aqueous conditions. The thickness of the resulting poly(Tyr-CB) film was tuned by adjusting the pH during the coating process. The poly(Tyr-CB)-coated surfaces demonstrated excellent antifouling performance against proteins and cells and imparted (super)hydrophilicity to various substrates. Additionally, post-functionalization with external biotin-PEG-thiol was achieved by targeting the oxidized quinone groups within the poly(Tyr-CB) film network. This enabled biospecific binding to streptavidin, while non-specific interactions were suppressed due to the antifouling background. As our one-step antifouling coating method is simple, involves aqueous conditions, and could be generically used to coat various substrates, it can be a versatile and valuable tool for biosensing, high-throughput screening, and cell-surface engineering.

The in vitro assessment of resin coating materials containing calcium phosphate, bioactive glass, and polylysine for glass ionomer cement restorations

Objective: Glass ionomer cements (GICs) require protective surface coatings to enhance their clinical performance. This study developed novel protective resin coatings for GICs containing monocalcium phosphate monohydrate (MCPM), bioactive glass nanoparticles (BAGs), and poly-L-lysine (PLS) and evaluated their physical, mechanical, and biological properties when applied to GICs. Materials and methods: Experimental resin coating materials were formulated with 5–10 wt% of MCPM, BAGs, and PLS. The degree of monomer conversion was measured usingAttenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) (n = 6). GICs coated with the experimental materials were evaluated for biaxial flexural strength and modulus after 24 h water immersion using a universal testing machine (n = 8). Vickers surface microhardness up to 4 weeks of water immersion was also determined (n = 5). Fluoride and elemental release in water were analyzed using a fluoride-specific electrode and inductively coupled plasma optical emission spectrometry (n = 3). Cell viability was assessed using an MTT assay with mouse fibrosarcoma (n = 3). A commercial resin coating (EQUIA Forte Coat, EQ) served as control. Data were analyzed using one-way ANOVA and Tukey HSD test. Results: While EQ showed higher monomer conversion (87%) compared to experimental materials (72–74%) (p < 0.05), GICs coated with experimental materials demonstrated comparable strength to EQ-coated GICs. The experimental coatings exhibited similar F, Al, Na, and Si releases to EQ-coated GICs, with enhanced P release. All experimental coatings exhibited comparable cell viability (>70%) to the commercial material. Conclusion: The novel GIC protective coatings containing MCPM, BAGs, and PLS demonstrated acceptable in vitro performance comparable to commercial materials while potentially offering enhanced remineralization through increased elemental release.

Monosaccharide coatings on nanoparticles affect protein corona formation but not the interaction with their binding receptor

Surface coatings with polyethylene glycol (PEG) polymers have often been employed to improve nanoparticles (NPs) biocompatibility and extend circulation time by reducing protein adsorption. PEGylated NPs benefit from steric hindrance and repulsion effects, which are influenced by PEG molecular weight, density, and chain conformation. However, repetitive exposure to PEG can trigger acute and chronic immunological responses as a result of the development of Immunoglobulin G anti-PEG antibodies. NPs functionalisation with glycans has become an emerging approach to increase their biocompatibility as these biomolecules are highly hydrophilic, biocompatible interact with biological receptors expressed in the body, and can be conjugated, controlling their orientation. In this study, we developed a series of gold NPs (AuNPs) coated with PEG linkers of different lengths and conjugated with mannose (Man) or sialic acid (Sia) glycans, and we carried out a detailed characterisation prior to and after exposure to biological fluids to study their behaviour and protein corona formation. Our findings show that the glycan-coated NPs exhibit stabilisation after protein interaction, with Man coatings showing the lowest protein affinity and that the glycans are biologically active and capable of binding to glycan receptors (such as Concanavalin A) despite the presence of a complex protein environment. Results indicate that glycan modification of PEGylated NPs reduces nonspecific interactions while preserving active targeting properties, underscoring their potential for therapeutic applications.

In Situ Focused Ion Beam Redeposition Surface Coatings for Site-Specific, Near-Surface Characterization by Atom Probe Tomography.

Atom probe tomography (APT) enables three-dimensional chemical mapping with near-atomic scale resolution. However, this method requires precise sample preparation, which is typically achieved using a focused ion beam (FIB) microscope. As the ion beam induces some degree of damage to the sample, it is necessary to apply a protective layer over the region of interest (ROI). Herein, the use of redeposition, a (frequently considered negative) side effect of FIB sputtering, is explored as a technique for targeted surface coatings in site-specific, near-surface APT investigations. In addition, the concept of "self-coating" is presented, which is the application of a capping layer using material from the same, or a similar, sample. It is shown to provide a pathway for high-quality coatings, as well as a method of minimizing the field evaporation threshold difference at the cap-sample interface, thus greatly reducing the likelihood of premature fractures. In situ redeposition surface coatings are shown to be versatile, with four materials used in the coating and analysis of two Si-based semiconductors and a Fe-Mn alloy. Several factors are discussed, such as the specimen yield, the capping layer quality, and the ease of ROI identification, all of which demonstrate its effectiveness in routine sample preparation workflows.

Enhancing Hemocompatibility in ECMO Systems With a Fibrinolytic Interactive Coating: in Vitro Evaluation of Blood Clot Lysis Using a 3D Microfluidic Model.

Blood-contacting medical devices, especially extracorporeal membrane oxygenators (ECMOs), are highly susceptible to surface-induced coagulation because of their extensive surface area. This can compromise device functionality and lead to life-threatening complications. High doses of anticoagulants, combined with anti-thrombogenic surface coatings, are typically employed to mitigate this risk, but such treatment can lead to hemorrhagic complications. Therefore, bioactive surface coatings that mimic endothelial blood regulation are needed. However, evaluating these coatings under realistic ECMO conditions is both expensive and challenging. This study utilizes microchannel devices to simulate ECMO fluid dynamics and assess the clot-lysis efficacy of a self-activating fibrinolytic coating system. The system uses antifouling polymer brushes combined with tissue plasminogen activator (tPA) to induce fibrinolysis at the surface. Here, tPA catalyzes the conversion of blood plasminogen into plasmin, which dissolves clots. This positive feedback loop enhances clot digestion under ECMO-like conditions. This findings demonstrate that this coating system can significantly improve the hemocompatibility of medical device surfaces.

Optimization of laser process parameters and improved corrosion behaviour of LZ/YSZ thermal barrier coating

Abstract Laser processing the surfaces of plasma-sprayed thermal barrier coatings is one of the methods used to improve the corrosion resistance of the coatings. However, laser glazing alone is not sufficient to fully protect coatings from corrosion. In this study, optimum laser surface modification parameters were determined for plasma-sprayed LZ/YSZ double-layer thermal barrier coatings. The coating surface, whose entire surface was scanned with optimum parameters, was modified with nano YSZ using the electrophoretic deposition technique. Thus, the network cracks formed during laser glazing were filled with nano YSZ. The coating modified by laser and electrophoretic deposition processes was subjected to corrosion tests. As a result of the characterizations, it was determined that the optimum laser surface modification parameters for LZ/YSZ thermal barrier coatings were 200 mm laser distance, 120 scan speed, and 28w laser power. With these parameters, discontinuities on the as-sprayed coating surface were eliminated. A dense layer was successfully created on the LZ layer. As a result of the corrosion tests, it was determined that modifying the laser-glazed surface with nano YSZ reduced the penetration depth of corrosive contaminants. Thus, the glassy melt and hot corrosion resistance of LZ/YSZ thermal barrier coatings was increased.

Facile Synthesis of Monodisperse Gold Nanorods, Gold Nanobipyramids and Gold Nanocups with Different Coatings and Evaluation of Their Cellular Cytotoxicity.

Assessing the cytotoxicity of gold nanoparticles (GNPs) has gained importance due to their development in the biomedical field. In this study, we systematically synthesized gold nanorods (GNRs), gold nanobipyramids (GNBPs), and gold nanocups (GNCs) using a seed-mediated method, with an average length of 32.53 ± 4.67 nm, 72.90 ± 7.54 nm and 118.01 ± 11.02 nm, respectively. Furthermore, using the cell counting kit-8 (CCK-8) assay, we assessed the cellular cytotoxicity of three different types of GNPs with various different surface coatings, such as organic cetyltrimethylammonium bromide (CTAB) and polyethylene glycol (PEG). The results showed that the cytotoxic behavior of GNPs was shape-dependent in the concentration range of 3.125 -100 μg/mL. The types of GNPs and their surface coating had a significant impact on how the GNPs behaved in cells. Compared to PEG-coated GNPs, which do not induce cell injury, CTAB-coated GNPs show more noticeable cytotoxicity. Furthermore, compared to GNCs, the toxicity of GNRs and GNBPs against GES-1 cells, RAW 264.7 cells and LX-2 cells was greater. Our research provides an important new understanding of the effects of surface modification on the biocompatibility and the shape of GNPs in the biomedical field.

Incidence of neutrophil extracellular traps (NETs) in different membrane oxygenators: pilot in vitro experiments in commercially available coated membranes.

Neutrophil extracellular traps (NETs) were detected in blood samples and in cellular deposits of oxygenator membranes during extracorporeal membrane oxygenation (ECMO) therapy and may be responsible for thrombogenesis. The aim was to evaluate the effect of the base material of gas fiber (GF, polymethylpentene) and heat exchange (HE) membranes and different antithrombogenic coatings on isolated granulocytes from healthy volunteers under static culture conditions. Contact of granulocytes with membranes from different ECMO oxygenators (with different surface coatings) and uncoated-GFs allowed detection of adherent cells and NETotic nuclear structures (normal, swollen, ruptured) using nuclear staining. Flow cytometry was used to identify cell activation (CD11b/CD62L, oxidative burst) of non-adherent cells. Uncoated-GFs were used as a reference. Within 3h, granulocytes adhered to the same extent on all surfaces. In contrast, the ratio of normal to NETotic cells was significantly higher for uncoated-GFs (56-83%) compared to all coated GFs (34-72%) (p < 0.001) with no difference between the coatings. After material contact, non-adherent cells remained vital with unchanged oxidative burst function and the proportion of activated cells remained low. The expression of activation markers was independent of the origin of the GF material. In conclusion, the polymethylpentene surfaces of the GFs already induce NET formation. Antithrombogenic coatings can already reduce the proportion of NETotic nuclei. However, it cannot be ruled out that NET formation can induce thrombotic events. Therefore, new surfaces or coatings are required for future ECMO systems and long-term implantable artificial lungs.

Investigation of the Effect of Surface Coating Resin Application on Salt Crystallization Resistance in Ignimbrites with Different Welding Degrees

Investigation of the Effect of Surface Coating Resin Application on Salt Crystallization Resistance in Ignimbrites with Different Welding Degrees

Gold Nanoparticles and Chitosan as Innovative Compounds in Medicine and Cosmetology:A Review of Current Applications.

The medical and cosmetic industries have developed in recent years, there has been a growing demand for new materials. Gold nanoparticles (Au NPs) and chitosan (CS) have been known and used for many years. Unfortunately, despite their numerous advantages and possible applications, such materials may possess certain disadvantages and limitations that constitute a problem in medical or cosmetic applications. Au NPs may have potential toxicity depending on their size, shape, charge, surface coatings, and tendency to agglomerate into larger clusters. On the other hand, the CS production process requires strict control due to the possibility of uncontrolled hydrolysis or chemical modifications during polymer isolation. The combination of Au NPs and CS that differ in chemical and phase in one composite (Au/CS) allows for acquiring of new material with many advantages. The obtained composite has good mechanical properties and is biocompatible due to the presence of CS and the antibacterial properties of Au NPs. Therefore, it can be successfully used in many branches of medicine, including gene delivery, cell encapsulation, wound healing process, or as a preservative ingredient of cosmetics. Moreover, Au/CS nanocomposites are used in the food industry and environmental protection. This review highlights the preparation routes, properties, and applications of Au NPs and CS as separate materials. Moreover, the last part presents the advantages of combining these two materials into one nanocomposite. Specifically, we described the role of CS in the synthesis of Au NPs and possible subsequent applications of such nanomaterials as an element of biosensors, scaffolds, and an intelligent drug release system or tissue engineering.

Oxygen, light, and mechanical force mediated radical polymerization toward precision polymer synthesis.

The synthesis of polymers with well-defined composition, architecture, and functionality has long been a focal area of research in the field of polymer chemistry. The advancement of controlled radical polymerization (CRP) has facilitated the synthesis of precise polymers, which are endowed with new properties and functionalities, thereby exhibiting a wide range of applications. However, radical polymerization faces several challenges, such as oxygen intolerance, and common thermal initiation methods may lead to side reactions and depolymerization. Therefore, we have developed some oxygen-tolerant systems that directly utilize oxygen for initiating and regulating polymerization. We utilize oxygen/alkylborane as an effective radical initiator system in the polymerization, and also as a reductant for the removal of polymer chain ends. Moreover, we employ the gentler photoinduced CRP to circumvent side reactions caused by high temperatures and achieve temporal and spatial control over the polymerization. To enhance the penetration of the light source for polymerization, we have developed near-infrared light-induced atom transfer radical polymerization. Additionally, we have extended photochemistry to reversible addition-fragmentation chain transfer polymerization involving ion-pair inner-sphere electron transfer mechanism, metal-free radical hydrosilylation polymerization, as well as carbene-mediated polymer modification through C-H activation and insertion mechanisms. Furthermore, we propose a new method for polymerization initiation synergistically triggered by oxygen and mechanical energy. This review not only showcases the current advancements in CRP but also outlines future directions, such as the potential for 3D printing and surface coatings, and the exploration of new heteroatom radical polymerizations. By expanding the boundaries of polymer synthesis, these innovations could lead to the creation of new materials with enhanced functionality and applications.

Innovations in isocyanate synthesis for a sustainable future.

Isocyanates play a crucial role as key building blocks in the production of thermoplastic foams, elastomers, adhesives, agrochemicals, and pharmaceuticals. These compounds are essential in the manufacture of various polymeric products, such as polyurethane foams, synthetic rubbers, and surface coatings. Given their significance, and the fact that many isocyanates are highly reactive and toxic, there is an increasing demand for innovative and sustainable methods for their synthesis and detection that emphasize safety, efficiency, and selectivity. Developing processes for isocyanate production that avoid hazardous reagents like phosgene is particularly critical. While several methods exist for the in situ generation of isocyanates, the search for an eco-friendly and sustainable approach for their direct synthesis and isolation continues. Recent advances in isocyanate synthesis promise innovative and efficient strategies with broad industrial and environmental benefits. This review highlights various methods for synthesizing di- and monoisocyanates, emphasizing their isolation and conversion into ureas and carbamates in line with the principles of sustainable and green chemistry.

Effect of composite magnetic microspheres and curing time on the corrosion and wear properties of phosphate ceramic coatings

In order to enhance the corrosion and wear resistance of ceramic coatings in marine environment, different types of micro-nano structures were constructed on the surface of phosphate ceramic coatings by magnetic polystyrene (PS@Fe3O4) microspheres and curing time. Subsequently, the surface properties of the magnetic composite microspheres and coatings were characterized, and the corrosion and wear properties of the coatings were investigated. The results revealed that the microspheres were gradually decomposed with the increase of curing time, and the surface of the coating presented different micro-nano structure with convex, flat and concave. Compared to unstructured coating (NSC), the convex micro-nano structured coating (CXMNC) and concave micro-nano structured coating (CEMNC) possessed outstanding superhydrophobicity. Through three tests of the knife scraping, tape peeling and sandpaper abrasion, the coatings showed excellent bonding strength and mechanical durability. After a long immersion period (256h), the impedance modulus of CXMNC and CEMNC were 27 and 15 times that of NSC, respectively. Compared with the NSC, the wear rate of CXMNC and CEMNC was reduced by 31.09% and 5.42%, respectively. Compared with the uncorroded samples, the wear rate of NSC, CXMNC and CEMNC after the immersion corrosion (30 days) was increased by 127.23%, 59.18% and 65.48%, respectively. Therefore, the micro-nano structured coatings have superior corrosion resistance and wear resistance to NSC, and CXMNC so as to CEMNC, which will provide better insight into the development of new corrosion-wear resistant materials.

Modified multilayered porous titanium scaffolds with silicon-doped coating surface-loaded BMP-2 prepared by microarc oxidation for bone defect repair

As is generally known, the lack of osteoinductive properties in titanium scaffolds has been a major barrier to bone defects repair. In our previous studies, we found that silicon-doped porous coatings prepared via micro-arc oxidation (MAO) had the potential application of Si-doped coatings in dental and orthopedic fields. We are currently focused on developing more advanced surface coatings to maximize their osteoinductive efficacy. Bone morphogenetic protein-2 (BMP-2), known for its ability to induce bone and cartilage development, has also been extensively studied. Therefore, in this study, macroporous titanium alloy scaffolds were fabricated using 3D printing technology, silicon ions were introduced onto the surface of customized macroporous titanium alloy scaffolds through MAO to enhance the bioactivity of the scaffolds, and BMP-2 was loaded onto the Si-doped coating to further improve the osseointegration of the titanium alloy scaffolds post-implantation. Results demonstrated that silicon-doped coating-loaded BMP2-modified multi-level porous titanium scaffolds exhibited improved hydrophilicity and biocompatibility. In-vivo and vitro studies further confirmed the superior bone regeneration capabilities of these scaffolds. This study demonstrates an optional strategy to combine two surface modification treatments, offering substantial potential as an advanced bone defect repair material with improved and accelerated bone regeneration.

A New Approach to Automatic Detection of Tactile Coating Surfaces with Deep Learning

In this study, tactile coating surfaces of visually impaired individuals were detected using the deep learning method. For this detection, 4 of the You Only Look Once (YOLO) architectures, one of the best deep learning methods, were used. No ready data set was used in the study. A unique and new data set was prepared for the study. For the data set, 6278 images were taken from tactile coating surfaces. Images for real-time applications were obtained from many different environments. The tactile coating surfaces in the pictures were labelled separately. A total of 9184 tags were made. The dataset was implemented in YOLOv5, YOLOv6, YOLOv7, and YOLOv8 architectures. The highest accuracy was achieved in the YOLOv8 architecture with an accuracy rate of 97%, F1-Score of 0.940, and mAP@.5 of 0.977. The model was applied with k-fold cross-validation to evaluate performance measurements. In order for the study to be used in real-time, the frame per second (FPS) was increased to 150.

Determining the characteristics of contact interaction between structural elements with varied properties of surface layers

The object of this study is the stressed-strained state of contacting elements of close-shaped machine-building structures. The presence and flexibility of surface layers and coatings are modeled. There are cases of the matching shape of the contacting surfaces of bodies, as well as the perturbation of the shape of these surfaces. The task being solved relates to the fact that the analysis methods of such bodies contact interaction are not yet sufficiently developed. It was established that for the case of the matching shape of contacting surfaces, the contact area does not depend on the level of loads. In this case, the contact pressure distribution is proportional to the operating load. Such features of the solution do not depend on the properties of the materials of surface layers. A different case is when the shape of the contacting surfaces of bodies is disturbed. In particular, it was established that the properties of the materials of surface layers exert a strong influence on the shape and dimensions of bodies contact area, as well as on the distribution of contact pressure (the difference is 1.5–2.5 times or more). The theory of variational inequalities is used to model the stressed-strained state of contacting bodies. As a result, the problem about contact interaction of bodies with surfaces of close shape is reduced to the problem of minimizing the modified energy functionality. The minimization is carried out on a set of distributions of displacements, which describes conditions of bodies not penetrating each other. The finite element method is used to discretize the problem of determining the stressed-strained state of contacting bodies. The parametric model built makes it possible to determine the stressed-strained state of contacting bodies when the disturbance of the nominal shape of the bodies and the properties of their surface layers is varied

Gradient Surface Gallium-Doped Hematite Photoelectrode for Enhanced Photoelectrochemical Water Oxidation.

Hematite is a promising material for photoelectrochemical (PEC) water oxidation, but its photocurrent is limited by bulk charge recombination and poor oxidation kinetics. In this study, we report a high-performance Fe2O3 photoanode achieved through gradient surface gallium doping, utilizing a Ga2O3 overlayer on FeOOH precursors via atomic layer deposition (ALD) and co-annealing for Ga diffusion. The Ga-doped layer passivates surface states and modifies the band structure, creating a built-in electric field that enhances the charge separation efficiency. Following the electrodeposition of CoFeOx as a cocatalyst, the resulting CoFe-Ga:Fe2O3 photoanode exhibited a notable negative shift in onset potential by approximately 100 mV, a high photocurrent density of 2.6 mA cm-2 at 1.23 V versus RHE, and excellent long-term PEC stability over 40 h. This work presents an effective strategy for enhancing the PEC performance of photoelectrodes through advanced surface coatings.

Comparison of the Wear and Friction Properties of Titanium Nitride-Based Coatings

This paper describes the wear and friction behavior of titanium nitride (TiN)-based coatings produced via chemical vapor deposition (CVD) in detail. Coatings composed of TiN, titanium carbide (TiC) and aluminum oxide (Al2O3) layers were applied to a tungsten carbide-cobalt composite and steel substrates. The elemental and phase compositions of these coatings, manufactured with varying deposition parameters and layer thicknesses, were determined using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The mechanical properties of the coatings were evaluated through Vickers microhardness testing, lubricant-free tribological model tests and scratch testing. For the linearly alternating tribological tests, a static counterpart made of yttria-stabilized zirconium oxide was utilized. The wear, friction and adhesive properties of the coatings were studied, revealing significant differences in tribological behavior based on their hardness, crystal structure and surface roughness. The tribological tests highlighted that coatings with sharp, spherical crystal structures on their surfaces exhibited the greatest resistance to abrasive and frictional stresses. The durability of the surface coatings was found to be primarily dependent on their adhesion and surface roughness.

Pigment granule architecture varies across yellow, red, and brown chromatophores in squid Doryteuthis pealeii

Cephalopods produce dynamic colors and skin patterns for communication and camouflage via stratified networks of neuronally actuated yellow, red, and brown chromatophore organs, each filled with thousands of pigment granules. While compositional analysis of chromatophore granules in Doryteuthis pealeii reveals the pigments as ommochromes, the ultrastructural features of the granules and their effects on bulk coloration have not been explored. To investigate this, we isolated granules from specific colored chromatophores and imaged them using multiple modalities. The brown granules are largest with smooth surface coatings. Red granules are intermediate in size with irregular surface textures, and yellow granules are smallest, with rough, porous surfaces. Many of the granules contain sub-granular features that also vary in presentation with color. Correlated light and electron microscopy reveal that differences in hue of individual granules are similarly associated with size, shape, and texture, suggesting that granules may be structurally adapted to modify the dominant visible colors presented within the chromatophores. These findings suggest that granule ultrastructure, not just chemical composition, may be significant in producing the range of colors presented in cephalopod chromatophores.