Silica Coatings Research Articles

Multifunctional pure and Sr-doped magnetite superparamagnetic nanoparticles: Synthesis, characterization, magnetic heating performance, and numerical simulation

Magnetic hyperthermia based on the utilization of multifunctional superparamagnetic nanoparticles (SNPs) is a promising method for non-invasive localized cancer treatment. Understanding the influence of properties and morphology of magnetic core and surface coatings on heating performance is crucial for their utilization in clinical applications.Multifunctional Pure and Sr-doped Fe3O4 SNPs were synthesized and coated with oleic acid, silica coatings, and surface amination for modification of their surfaces. Materials characterizations were performed via FTIR, XRD, TEM/EDS microscopy, and VSM measurements. Experimental studies were conducted to assess the heating performance of these nanoparticles using nanoparticle/agarose gel composite samples. Temperature changes on their top surface over time, induced by an externally applied magnetic field, were monitored.The simulation studies in conjunction with the experimental results, were successfully employed to comparatively evaluate the effects of multiple process parameters and to gain insights into the effects of relevant multiple parameters; including the types, properties, concentrations, and distributions of SNPs; the physical properties of the organic matrix and the surrounding medium; the interface between SNPs and the matrix; as well as the geometry of the sample and the strength and geometry of the magnetic field on the heating performance of the nanoparticles.

The Influence of Ag Addition and Different SiO2 Precursors on the Structure of Silica Thin Films Synthesized by the Sol-Gel Method.

In this work, the structure of silica thin films synthesized with three different SiO2 precursors and obtained by the sol-gel method and dip coating technique was studied. Additionally, the influence of Ag addition on the obtained silica sols and then gel structure was investigated. Silica coatings show antireflective properties and high thermal resistance, as well as hydrophobic or hydrophilic properties. Three different silica precursors, TEOS (tetraethylorthosilicate), DDS (dimethyldietoxysilane) and AerosilTM, were selected for the synthesis. DDS added to silica sol act as a pore size modifier, while Ag atoms are known for their antibacterial activity. Coatings were deposited on two different substrates: steel and titanium, dried and annealed at 500 °C in air (steel substrate) and in argon (titanium substrate). For all synthesized films, IR (infrared) spectroscopic studies were performed together with GID and XRD (Grazing Incidence Diffraction, X-ray Diffraction) measurements. The topography and morphology of the surface were traced by SEM and AFM microscopic methods, providing information on the samples' roughness, particle sizes and thickness of the particular layers. The wetting angle values were also measured. GID and XRD measurements pointed to the distinct contribution of an amorphous phase in the samples, allowing us to recognize the crystalline phases and calculate the silver crystallite sizes. The FTIR spectra gave information on the first coordination sphere of the studied samples.

Roll-to-Roll SiOx Synthesis on Polyethylene Terephthalate Film by Atmospheric-Pressure Plasma-Assisted Chemical Vapor Deposition

Silicon oxide (SiOx) coatings are attracting significant attention and are widely used in industrial applications. They can be prepared by plasma-assisted chemical vapor deposition (PACVD). PACVD at atmospheric pressure (AP-PACVD) is often employed to synthesize SiOx coatings, but it has generally not been scaled up to an industrially viable level. In the present work, a SiOx coating was continuously deposited onto a polyethylene terephthalate film using industrial-scale roll-to-roll type AP-PACVD. 1,1,3,3-Tetramethyldisiloxane (TMDSO) and tetraethoxysilane (TEOS) were selected as precursors. The elemental compositions and chemical structures of the SiOx coatings were characterized, and oxygen and water-vapor transmission rates were measured. The SiOx coating using TEOS exhibited better barrier properties than that using TMDSO, corresponding to the high oxygen content, high SiO2 content, and high siloxane network content in the SiOx coating.

Enhanced Corrosion Protection of Printed Circuit Board Electronics using Cold Atmospheric Plasma-Assisted SiOx Coatings.

The miniaturization and widespread deployment of electronic devices across diverse environments have heightened their vulnerability to corrosion, particularly affecting copper traces within printed circuit boards (PCBs). Conventional protective methods, such as conformal coatings, face challenges including the necessity for a critical thickness to ensure effective barrier properties and the requirement for multiple steps of drying and curing to eliminate solvent entrapment within polymer coatings. This study investigates cold atmospheric plasma (CAP) as an innovative technique for directly depositing ultrathin silicon oxide (SiOx) coatings onto copper surfaces to enhance corrosion protection in PCBs. A systematic investigation was undertaken to examine how the scanning speed of the CAP deposition head impacts the film quality and corrosion resistance. The research aims to determine the optimal scanning speed of the CAP deposition head that achieves complete surface coverage while promoting effective cross-linking and minimizing unreacted precursor entrapment, resulting in superior electrical barrier and mechanical properties. The CAP coating process demonstrated the capability of depositing SiOx onto copper surfaces at various thicknesses ranging from 70 to 1110 nm through a single deposition process by simply adjusting the scanning speed of the plasma head (5-75 mm/s). Evaluation of material corrosion barrier characteristics revealed that scanning speeds of 45 mm/s of the plasma deposition head provided an effective coating thickness of 140 nm, exhibiting superior corrosion resistance (30-fold) compared to that of uncoated copper. As a proof of concept, the efficacy of CAP-deposited SiOx coatings was demonstrated by protecting an LED circuit in saltwater and by coating printed circuits for potential agricultural sensor applications. These CAP-deposited coatings offer performance comparable to or superior to traditional conformal polymeric coatings. This research presents CAP-deposited SiOx coatings as a promising approach for effective and scalable corrosion protection in miniaturized electronics.

Methyl Red-loaded halloysite nanotubes-based silica coatings for durable dyeing of polyester fabrics

Since unmodified polyester fibres have no reactive groups like those in cellulose and protein fibres, they do not show an affinity for water-soluble acid, basic and direct dyestuffs. Only disperse dyestuff, a non-ionic dyestuff class with low molar mass molecules, proved to be useful for dyeing this man-made fibre following a solid–solid interaction; disperse dyestuffs do not form primary chemical bonds with polymer chains rather the dye colour is retained by H-bonds and Van der Waals forces. Herein, a new strategy for dyeing polyester fabrics with a direct dyestuff in a two-step strategy was designed and realized, using an organic–inorganic composite coating based on methyl red-loaded sol-gel modified halloysite nanotubes. In the first step two distinct reaction methods were compared to functionalize halloysite nanotubes with (3-Glycidyloxypropyl)trimethoxysilane, as a covalent crosslinker between the halloysite nanotubes and fibres, (i) in water and (ii) in ethanol, using BF3O(C2H5) and chloridric acid (HCl) as catalysts, respectively.In the second step, methyl red loaded GPTMS modified halloysite sols were applied onto polyester fabrics by impregnation. The amount of methyl red dyestuff was evaluated to be superior for the complex realized in ethanol than in water, thus promoting homogeneous nanocomposite coatings on treated polyester samples. Methyl red loaded sol-gel modified halloysite complex, as well as treated and untreated samples, were investigated to characterize their properties and morphology. NMR investigation confirmed the structure of the new complex, validating the successful dyestuff coordination reaction at GPTMS.The influence of treatments on the morphology of fibres surfaces was demonstrated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), and Atomic Force Microscopy (AFM) analyses, highlighting the influence of GPTMS-based composites on the microstructure of functionalized polyester fibres. To further confirm if the suggested approach offers a stable dyestuff loading on PE, diffuse reflectance spectroscopic studies, X-ray Photoelectron Spectroscopy (XPS) and colour fastness to rubbing and washing tests were carried out on the coated polyester.All findings make sol-gel based modification of halloysite a reliable and promising method for eco-friendly dyeing processes of polyester fabrics.

Consideration of the effect of nanoscale porosity on mass transport phenomena in PECVD coatings

Here we show a novel approach to characterize the gas transfer behavior of silicon-oxide (SiO x ) coatings and explain the underlying dynamics. For this, we investigate the coating on a nm-scale both by measurement and simulation. Positron annihilation spectroscopy (PAS) and quantum mechanical electronic structure-based molecular dynamics simulations are combined to characterize the porous landscape of SiO x coatings. This approach analyses the influence of micropores smaller than 2 nm in diameter on gas permeation which are difficult to study with conventional methods. We lay out the main pore diameter ranges and their associated porosity estimates. An influence of layer growth on pore size and porosity was found, with an increased energy input during layer deposition leading to smaller pore sizes and a reduced porosity. The molecular dynamics simulations quantify the self-diffusion of oxygen and water vapor through those PAS deducted micropore ranges for hydrophilic and hydrophobic systems. The theoretical pore size ranges are fitting to our PAS results and complete them by giving diffusion coefficients. This approach enables detailed analysis of pore morphology on mass transport through thin film coatings and characterization of their barrier or membrane performance. This is a crucial prerequisite for the development of an exhaustive model of pore dominated mass transports in PECVD coatings.

Nanomaterials as Next-Gen Corrosion Inhibitors: A Comprehensive Review for Ceramic Wastewater Treatment

This study reviews the use of corrosion inhibitors in industrial wastewater treatment, specifically in ceramic wastewater. It discusses the main problem limits the use of treated wastewater, which is corrosion behavior. To reduce this behavior and enable safe reuse of industrial wastewater, corrosion inhibitors are used. The study aims to provide insights into the selection, use, and effectiveness of corrosion inhibitor types in the media under study. The results can help engineers, researchers, and wastewater treatment professionals to find the best corrosion inhibitors for various municipal wastewater applications, increasing the sustainability and efficiency of wastewater treatment processes. The ceramic industry faces challenges in managing complex aqueous effluents generated from mining, shaping, glazing, and manufacturing processes. Nanomaterial-based alternatives, such as titanium nanotubes, zinc oxide nanoparticles, nanoenhanced filters, and stimuli responsive polymer and silica coatings, have emerged as promising next-generation corrosion inhibitors due to their multilayer passivation and high specific surface area. The analysis focuses on the feasibility of these materials' mechanisms, such as crystal deformation, nucleation hindrance, coating barriers, and passivation improvement, in industrial settings. In conclusion, the use of corrosion inhibitors in industrial wastewater treatment can significantly improve the sustainability and efficiency of wastewater treatment processes. Understanding the mechanisms by which these nanomaterials influence crystal growth modification, deposition kinetics, and passivation performance could lead to more effective and sustainable solutions for industrial wastewater treatment.

Ordered Mesoporous Slippery Silica Coatings on Photovoltaic Cover Glasses to Enhance Photocurrent with Sustainability for Large-Scale Applications

Ordered Mesoporous Slippery Silica Coatings on Photovoltaic Cover Glasses to Enhance Photocurrent with Sustainability for Large-Scale Applications

Silica Coating of Nickel–Iron Nanocomposite by Chemical Reduction Method

The study of magnetic nanostructures is interesting because of its applications. Some of them are the development of magnetic refrigerators, ferrofluids, drug delivery systems, fabrication of devices with giant magnetoresistance effects, and high-frequency transformers. The physical and chemical properties of metal changes due to silica coating. The interaction potential can be manipulated using surface coatings and also the particle shape can be controlled. Nanoparticles with a proper surface coating are of interest for several other applications in optoelectronic devices and in the biomedical field. Thus, developing a new synthetic route for these particles and investigating the stability of magnetic materials are of great importance. Silica coating improves the chemical stability and electrical resistivity of the material. In this study, Ni3Fe (core) nanoparticles were prepared and the silica shell for this core was synthesized. The as-prepared X-ray diffraction (XRD) patterns and 300∘C annealed sample of Ni3Fe/SiO2 shows a characteristic hump in the low angle range confirming the presence of amorphous cristobalite phase of SiO2. The size of the Ni3Fe cluster in the Ni3Fe/SiO2 composite was estimated to be 8[Formula: see text]nm and 9[Formula: see text]nm, respectively, for the as-prepared and annealed samples. Vibrating sample magnetometer (VSM) measurements show the Ni3Fe to silica ratio to be 59:41. A small decrease in the coercivity value, is probably due to morphological changes associated with the coating. Scanning electron microscope (SEM) studies of the as-prepared and annealed Ni3Fe/SiO2 powder particles are of flowerlike morphology and in agglomeration. The impedance spectra were found at room temperature for the as-prepared samples.

Cu, Fe, N‐doped Carbon Nanotubes Prepared through Silica Coating for Selective Oxygen Reduction to Water in Acidic Media

AbstractWe report Cu, Fe, N‐doped carbon nanotubes, (Cu,Fe)−N−CNT, as electrocatalysts for the oxygen reduction reaction (ORR) in acidic media. (Cu,Fe)−N−CNT was prepared using a silica coating method in pyrolysis to minimize the formation of carbon‐coated metal oxide or carbide nanoparticles, which are known to be inactive for the H2O2 reduction. (Cu,Fe)−N−CNT shows a turnover frequency of 0.66 e− site−1 s−1 at +0.8 V vs. RHE and H2O2 yields of <1 % for the ORR with a utilization factor of active sites of 82 %. Kinetic analysis reveals that 4e− transfer rates for (Cu,Fe)−N−CNT are higher than those of a monometallic counterpart of Fe−N−CNT. In situ X‐ray absorption spectroscopy enables us to determine redox potentials: E°’(FeIII/FeII)=0.65 V vs. RHE and E°’(CuII/CuI)=0.45 V for (Cu,Fe)−N−CNT, and E°’(FeIII/FeII)=0.65 V for Fe−N−CNT. These results indicate that bimetallic doping into carbon nanotubes gives the effect on kinetic parameters but not on thermodynamic ones. In other words, there is no direct electronic interactions between the Cu and Fe active sites for (Cu,Fe)‐N‐CNT because such interactions should modulate their redox potentials.

Optimizing Synergistic Silica–Zinc Oxide Coating for Enhanced Flammability Resistance in Cotton Protective Clothing

This study reports process optimization studies of silica and zinc oxide-based flame-retardant (FR) coatings on cotton fabric for protective clothing and enhanced flammability properties. The experiments were designed by central composite design (CCD) using response surface methodology (RSM) to assess the synergistic protective effects of silica and zinc oxide FR coating. These prepared sols were coated on cotton fabrics by a simple dip dry cure process. The resulting FR-finished fabrics were characterized by SEM, mechanical properties, flame retardancy, and air permeability. SEM results confirmed the homogenous spreading of particles on cotton fabrics. From TGA results, it was noticed that the incorporation of silica and ZnO in the prepared nano-sols results in improved thermal stability of the FR-finished fabrics. These sol–gel-treated FR cotton fabrics showed excellent comfort properties, which shows their suitability for fire-retardant protective clothing. RSM analysis proved that the predicted values are in good agreement with the experimental values since R2 values for time to ignite, flame spread time, and air permeability were greater than 0.90. The optimized concentration of silica and ZnO in FR-finished fabrics was found to be 0.302% and 0.353%, respectively, which was further confirmed by confirmatory experiments. The optimization analysis successfully optimized the process for synergistic coating of silica and zinc oxide nanoparticles for enhanced flammability properties of FR cotton fabric for protective clothing.

Postsynthetic modification of yttria‐stabilized zirconia aerogels with silica coatings for enhanced thermal stability

AbstractMaintaining high surface area and porosity at high temperatures is important when considering aerogels for use in thermal management systems. The mesoporous structure of aerogels results in extremely low thermal conductivity, making them lightweight, high performance insulating materials. Maintaining these properties requires innovative routes to suppress sintering and pore collapse as use temperatures rise. The current work aims to improve the pore structure stability of yttria‐stabilized zirconia aerogels by the addition of a SiO2 coating. The functionalization of surface hydroxyl groups by the addition of SiO2 is hypothesized to mitigate condensation reactions, which are a driving force for shrinkage and pore structure collapse. Zirconia aerogels with 0, 10, and 30 mol% yttria (YO1.5) additions were coated in a tetraethyl orthosilicate (TEOS) solution and exposed to temperatures up to 1200°C. Crystal structure, pore structure, and aerogel morphology were investigated to understand changes in aerogel thermal stability. The SiO2 coating exhibited a greater influence on pore stability over yttria concentration, with specific surface area of the coated aerogels being twice that of the uncoated aerogels up to 1000°C. However, the presence of the SiO2 coating promoted rapid sintering and densification at 1200°C, establishing an upper use temperature for SiO2 and a need to develop other coating chemistries.

Local water management in cotton linter papers with silica-based coatings

Paper with its mechanical strength as well as due to its microfluidic properties has emerged as an interesting sustainable material for future high-tech applications. Examples include paper-based sensors and actuators, paper-based construction materials and paper-based membranes. These examples have in common that a precise control of the water distribution inside the paper sheet during fluid water imbibition, water vapor adsorption, or drying affects the fluidic properties of the paper, which are crucial for its performance. Here silica-based coatings are applied to control the water distribution in the paper sheet during imbibition, adsorption and drying. By using dense silica coatings, the fibers are shielded from water penetration which limits the water distribution into the fiber–fiber voids. Whereas with a mesoporous silica coating, mesopores can be inserted into the paper, providing an additional space for water imbibition and adsorption. Water location upon imbibition, adsorption and drying were investigated using small angle x-ray scattering and gravimetric water vapor adsorption. Thereby, water distribution upon imbibition and adsorption depends on the type of silica coating. In addition, the drying mechanism and water distribution during drying is as well determined by the silica-based coating. The obtained results allow to deduce design criteria for local water management in paper sheets.Graphical

Properties of silicon dioxide coatings obtained by nano physical vapor deposition (PVD) method on the titanium 13‐niobium 13‐zirconium alloy

AbstractSurface modification techniques play an important role in adjusting the physicochemical properties of titanium and its alloys. To reduce the penetration of alloying element ions into the body, various types of oxide coatings are used to protect it from the corrosive environment. Another important issue related to the surface layer requirement is ensuring an appropriate set of mechanical properties. Accordingly, in this study, the mechanical and electrochemical properties of the silicon dioxide layers formed by the deposition of nano physical vapor deposition on the surface of titanium and titanium 13‐niobium 13‐zirconium alloy samples were investigated. To evaluate the mechanical properties of the layers produced by this method, hardness tests were carried out, as well as tests on the adhesion of these layers to the metal substrate. On the other hand, electrochemical properties were studied using potentiodynamic measurements to assess the resistance to pitting corrosion, followed by impedance measurements to interpret the processes and phenomena occurring at the silicon dioxide layer/electrolyte interface. The data obtained showed different mechanical and electrochemical properties of the silicon dioxide layers generated with varying process parameters.

Suppression of cracking in drying colloidal suspensions with chain-like particles.

The prevention of drying-induced cracking is crucial in maintaining the mechanical integrity and functionality of colloidal deposits and coatings. Despite exploring various approaches, controlling drying-induced cracking remains a subject of great scientific interest and practical importance. By introducing chain-like particles composed of the same material and with comparable size into commonly used colloidal suspensions of spherical silica nanoparticles, we can significantly reduce the cracks formed in dried particle deposits and achieve a fivefold increase in the critical cracking thickness of colloidal silica coatings. The mechanism underlying the crack suppression is attributed to the increased porosity and pore sizes in dried particle deposits containing chain-like particle, which essentially leads to reduction in internal stresses developed during the drying process. Meanwhile, the nanoindentation measurements reveal that colloidal deposits with chain-like particles exhibit a smaller reduction in hardness compared to those reported using other cracking suppression approaches. This work demonstrates a promising technique for preparing colloidal coatings with enhanced crack resistance while maintaining desirable mechanical properties.

High anti-corrosion barrier of poly (methyl methacrylate)-silica coatings explained: A thousand-days study

Poly (methyl methacrylate) (PMMA)-silica coatings form a few micrometers thick anti-corrosive barrier that blocks corrosive species when exposed to harsh environments. Their excellent anti-corrosive performance stands out for protecting metal alloys immersed in seawater for long periods (>2 years), making them compliant for applications in the marine, aeronautical, and automotive industries. A key approach to understanding the degradation of high-performance coatings over time consists of analyzing their water uptake-induced structural changes. This work examines in detail the uptake and structural modification of PMMA-silica coatings on Al alloys immersed for more than 1000 days in 3.5 wt% NaCl solution. Gravimetry, thermal analysis, infrared spectroscopy and electrochemical impedance spectroscopy (EIS) were employed to monitor the evolution of coated samples. Nuclear magnetic resonance, X-ray photoelectron spectroscopy, electron and atomic force microscopies before and after immersion indicate a slight leaching-induced surface roughening due to silica hydrolysis. These findings comply with the low uptake values (∼0.6 vol%) and a less-Fickian diffusion coefficient obtained from modelling of the EIS data. The high impedance modulus (>GΩ) is related to the highly cross-linked structure, resulting in a very low permeation rate of the electrolyte. The applied methodology is of crucial importance for establishing a standardized analysis for high-performance protective coatings.

Targeted Drug Delivery through the Synthesis of Magnetite Nanoparticle by Co-Precipitation Method and Creating a Silica Coating on it

Billions of dollars are spent annually in the world to treat and investigate problems caused by drug side effects. According to the estimation of health researchers, a huge part of people who take medicine suffer from complications caused by it. In this way, the necessity of using a targeted system in order to deliver medicine to the targeted place without damaging healthy tissues is felt more than before. In recent years, targeted drug delivery systems based on nanoparticles have received much attention. In the same direction, in this research, co-precipitation method was used to prepare magnetic nanoparticles using iron(|) and iron(||) oxides, and further, according to the synthesis steps of magnetite nanoparticles (MNPs) and the mechanism of formation and identification of magnetite nanoparticles ( Fe3O4) by examining the infrared pattern (FT-IR) obtained from Fe3O4 nanoparticles, the results of the magnetometric test (VSM) of Fe3O4 nanoparticles, X-ray diffraction pattern (XRD) of Fe3O4 nanoparticles, Field Emission Scanning Electron Microscope (FE-SEM) images obtained from Fe3O4 nanoparticles was discussed. After this stage, silica- coated iron nanoparticles (Fe3O4@SiO2) were prepared, and the infrared (FT-IR) pattern of Fe3O4@SiO2) was also investigated. It is worth mentioning that the mechanism of formation and identification of magnetic silica-coated iron nanoparticles (Fe3O4@SiO2) has been described in detail. Therefore, the obtained results indicate that the drug can be guided in a controlled and targeted manner by the magnetic field, and the results of the FE-SEM images show that the obtained product has a spherical morphology and the particle size distribution was less than 100 nm. Therefore, spherical shape and the symmetry of these particles can be helpful for their movement in the liquid mediu.

Structure-Property Relationships for Fluorinated and Fluorine-Free Superhydrophobic Crack-Free Coatings.

In this study, particle loading, polyfluorinated alkyl silanes (PFAS or FAS) content, superhydrophobicity, and crack formation for nanocomposite coatings created by the spray coating process were investigated. The formulations comprised hydrophobic silica, epoxy resin, and fluorine-free or FAS constituents. The effect of FAS content and FAS-free compositions on the silica and epoxy coatings' chemistry, topography, and wetting properties was also studied. All higher particle loadings (~30 wt.%) showed superhydrophobicity, while lower particle loading formulations did not show superhydrophobic behavior until 13% wt. FAS content. The improved water repellency of coatings with increased FAS (low particle loadings) was attributed to a combination of chemistry and topography as described by the Cassie state. X-ray photoelectron spectroscopy (XPS) spectra showed fluorine enrichment on the coating surface, which increases the intrinsic contact angle. However, increasing the wt.% of FAS in the final coating resulted in severe crack formation for higher particle loadings (~30 wt.%). The results show that fluorine-free and crack-free coatings exhibiting superhydrophobicity can be created.

Damage-Free Silica Coating for Colloidal Nanocrystals Through a Proactively Water-Generating Amidation Reaction at High Temperature.

Silica is a promising shell coating material for colloidal nanoparticles due to its excellent chemical inertness and optical transparency. To encapsulate high-quality colloidal nanocrystals with silica shells, the silane coupling hydrolysis is currently the most effective approach. However, this reaction requires water, which often adversely affects the intrinsic physicochemical properties of nanocrystals. Achieving a damage-free silica encapsulation process to nanocrystals by hydrolysis is a huge challenge. Here, a novel strategy is developed to coat colloidal nanocrystals with a denser silica shell via a proactively water-generating reaction at high temperature. In this work, water molecules are continuously and proactively released into the reaction system through the amidation reaction, followed by in situ hydrolysis of silane, completely avoiding the impacts of water on nanocrystals during the silica coating process. In this work, water sensitive perovskite nanocrystals (CsPbBr3) are selected as the typical colloidal nanocrystals for silica coating. Notably, this high-temperature in situ encapsulation technology greatly improves the optical properties of nanocrystals, and the silica shells exhibit a denser structure, providing nanocrystals with better protection. This method overcomes the challenge of the influence of water on nanocrystals during the hydrolysis process, and provides an important reference for the non-destructive encapsulation of colloidal nanocrystals.

Novel Antifouling Coatings by Zwitterionic Silica Grafting on Glass Substrates.

Zwitterionic silica coatings for surface functionalization are greatly prominent because of their simple and fast preparation, high availability, and effective antifouling properties. In this work, two zwitterionic sulfobetaine silane coatings, i.e., mono-SBSi and tris-SBSi, were deposited on glass surfaces and tested for antifouling of biological material and biofilm using human cancer cell and seawater, respectively. The used zwitterionic precursors mono-SBSi and tris-SBSi differ by the number of hydrolyzable silane groups: mono-SBSi contains one trimethoxysilane group, whereas tris-SBSi contains three of these functions. First, X-ray photoelectron spectroscopy indicates the successful grafting of zwitterionic coatings onto a glass surface. Characterization using atomic force microscopy shows the different morphologies and roughness of the two coatings. The glass surface became more hydrophilic after the grafting of zwitterionic coatings than the bare glass substrate. The antifouling properties of two coatings were evaluated via human cancer cell adsorption. Interestingly, the tris-SBSi coating displays a significantly lower level of cell adsorption compared to that of both mono-SBSi coating and the non-modified control surface. The same trend was observed for biofilm formation in seawater. Finally, the toxicity of mono-SBSi and tris-SBSi coatings was evaluated on zebrafish embryos, indicating the good biocompatibility of both coatings. Our results indicate interesting antifouling properties of zwitterionic coatings. The chemical constitution of the used precursor has an impact on the antifouling properties of the formed coating: the tris-SBSi-based zwitterionic silica coatings display improved antifouling properties compared to those of the mono-SBSi-based coating. Besides, the use of trisilylated precursors should result in the formation of more resistant and robust coatings due to the higher number of grafting functions. For all these reasons, we anticipate that tris-SBSi coatings will open new perspectives for antifouling applications for biological environments and implants.