Surface Carbon Content Research Articles

Impact of monolayer WS2 surface properties on the gate dielectrics formation by atomic layer deposition

Two-dimensional transition metal dichalcogenides (2D TMDs), such as MoS2 and WS2, have emerged as promising channel materials for future generation transistors. However, carbon-based surface contaminants pose a significant challenge in the formation of high-quality metal–oxide–semiconductor gate stacks for 2D TMDs. Carbon-based surface contaminants are known to be present even on directly grown 2D TMDs that have not been in contact with polymers. These organic contaminants affect precursor adsorption during atomic layer deposition (ALD) of gate dielectrics on 2D TMDs and as such the 2D-dielectric interface. This study examines the effectiveness of predeposition annealing in mitigating carbon-based contaminants while maintaining the integrity of a directly grown WS2 monolayer on a SiO2 substrate. We show that a WS2 monolayer on a SiO2/Si substrate remains stable during vacuum annealing at temperatures up to 400 °C. Water contact angle measurements and x-ray photoelectron spectroscopy confirm that the surface concentration of carbon starts to decrease at 150 °C. Thermal anneal improves the surface coverage of Al2O3 for both conventional chemisorption-based ALD and physisorbed-precursor-assisted ALD processes by facilitating more effective Al2O3 nucleation on the WS2 monolayer. The impact of predeposition anneal on the Al2O3 growth behavior in both processes can be explained by changes in surface contaminant levels. Our results underscore the importance of surface pretreatment in dielectric deposition on 2D TMDs and demonstrate that predeposition anneal is an effective method to enhance ALD-based dielectric deposition on directly grown 2D TMDs.

Phase composition and numerical model of low-pressure pulse carburized layer in 15Cr14Co12Mo5Ni2W steel

Aerospace engine gear steel, 15Cr14Co12Mo5Ni2W steel, requires carburizing heat treatment to achieve operational performance. However, predicting the carbon concentration during the vacuum carburizing process poses significant challenges. This paper aims to design and establish a predictive model for the carbon concentration during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel. Given the complex phase transformations during the vacuum carburizing process caused by the ultra-high alloy content of 15Cr14Co12Mo5Ni2W steel, vacuum short-term intense carburization and diffusion experiments were designed. Characterization methods such as XRD, scanning electron microscopy, electron probe microanalysis, EBSD, and FIB+TEM were used to study the microstructure, phase composition, phase constituents, and distribution of element concentrations during the vacuum carburizing process. Subsequently, a carbon concentration distribution calculation model considering carbide changes during the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel was established. Boundary conditions for carbon absorption during the intense carburization process of 15Cr14Co12Mo5Ni2W steel were proposed, and the relationship between surface carbon concentration and boundary conditions was determined through experiments. Using the method of forward calculation with least squares fitting of experimental data, the diffusion coefficient of carbon in the austenite of 15Cr14Co12Mo5Ni2W steel and the rate of carbon exchange between carbides and the matrix were derived, providing a more precise predictive tool for optimizing the vacuum carburizing process of 15Cr14Co12Mo5Ni2W steel.

Food waste to hydrochar: A potential approach towards the Sustainable Development Goals, carbon neutrality, and circular economy

Food waste is a common organic solid waste generated worldwide in significant quantities, and its proper treatment and management practices are hindered by high moisture content. However, hydrothermal carbonization (HTC) technique uses food waste moisture as the reaction medium and converts it into an environmentally friendly coal-like product, i.e. hydrochar. Food waste conversion to hydrochar via HTC has many benefits but a complex mechanism because each component of food waste has its own structural and chemical properties and interacts with the other components/chemical species during the process involving heterogeneous reactions, which significantly impacts the physio-chemical properties of food waste hydrochar (FWH). Due to high surface area, stability, carbon content, and regeneration capability, FWH is an attractive choice for numerous environmental applications, helps to achieve various Sustainable Development Goals (SDGs), and supports carbon neutrality and a circular economy. Given the importance of this topic, this review provides a comprehensive analysis of the advancements in HTC technology for producing hydrochar from food waste, as well as the carbonization mechanism of each constituent of food waste. The study also highlights the significance of different modification and activation methods used to enhance the primary drawback of FWH. We primarily intend to assess the application of FWH in accomplishing several SDGs, i.e., SDG 6.3 (pollutant removal from wastewater), SDG 7 (generate clean energy), SDG 13 (combat climate change, i.e., CO2 sequestration), SDG 15.3 (land and soil restoration). Our primary focus is to evaluate the future perspective of FWH via CO2 emission assessment, life cycle assessment, and techno-economic assessment, along with challenges in commercializing FWH, and propose significant avenues for future research. These insights are essential for determining the economic viability and environmental advantages of FWH as a valuable resource to accomplish several SDGs, achieve carbon neutrality, and promote a circular economy.

Machine learning for persistent free radicals in biochar: dual prediction of contents and types using regression and classification models

Persistent free radicals (PFRs) are emerging substances with diverse impacts in biochar applications, necessitating accurate prediction of their content and types prior to their optimal use and minimal adverse effects. This prediction task is challenging due to the nonlinearity and intricate variable relationships of biochar. Herein, we employed data-driven techniques to compile a dataset from peer-reviewed publications, aiming to systematically predict the PFRs by developing supervised machine learning models. Notably, extreme gradient boosting (XGBoost) model exhibited the best predictive performance for both regression and classification tasks in predicting the PFRs, achieving a test R2 value of 0.95 for PFR content prediction, along with an Area Under the Receiver Operating Curve (AUROC) of 0.92 for PFR type prediction, respectively. Based on XGBoost model, a graphical user interface (GUI) was developed to access PFRs predictions. Analysis of feature importance revealed that the biochar properties, such as metal/non-metal doping, pyrolysis temperature, carbon content, and specific surface area were identified as the four most significant factors influencing PFRs contents. Regarding the types of PFRs in biochar, specific surface area, pyrolysis temperature, carbon content, and feedstock were top-ranked influencing factors. These findings provide valuable guidance for accurately predicting both the contents and types of PFRs in biochar, and also hold significant potential for highly efficient utilization of biochar across various applications.Graphical

Surface Texturing and Wettability Modification by Nanosecond Pulse Laser Ablation of Stainless Steels

Laser surface texturing has attracted growing interest, particularly in functional surface modification. Lasers with nanosecond pulse widths and infrared wavelengths are commonly used for metallic surface texturing because of their low cost and potential for fabricating a large range of textures. In this research, a laser with a nanosecond pulse width and infrared wavelength was used for the surface texturing of 316 stainless steels. Standard grooved and near-isotropic surface textures, as well as novel porous texture and feather-like dendrite texture, were fabricated through single-time laser texturing. Water contact angle tests were performed on the post-process surfaces, and they showed wettability changes from superhydrophilic to superhydrophobic according to different types of textures. Discussion on the relationship between water contact angle and surface roughness, groove width/depth ratio, surface carbon and oxygen contents indicated that it is the surface morphology that impacts changes in wettability. The comprehensive formation mechanism of different textures and the wettability control mechanism through different textures have been systematically discussed. For the first time, the three-level (point-line-area) laser surface ablation mechanism has been established. The proposed findings can be used for future laser texturing process designs on metals using lasers with a nanosecond pulse width and an infrared wavelength for various applications including wettability modification.

Functionalization of PTFE substrates with quaternary ammonium groups – An approach towards anion conducting properties

Hydrogen produced by electrolysis using renewable energy sources offers a zero-emission alternative to fossil-based sources providing high efficiencies in all energy sectors. Anion Exchange Membrane Water Electrolysis (AEM-WE) combines the advantages of the established technologies, alkaline (AEL) and proton exchange membrane (PEM) water electrolysis. However, AEM-WE still requires optimization, especially with regard to the membrane, catalysts and electrode structure. In this contribution we focus on the improvement of PTFE-based binders for AEM-WE membranes, which provide high chemical stability but lack the required ion conductivity. Thus, the functionalization of PTFE towards quaternary ammonium moieties (QAS) was investigated employing two approaches: (i) NH3-plasma treatment and (ii) O2-plasma with subsequent coupling of aminosilanes. Finally, the surface coupled amino groups were converted into QAS via alkylation with iodomethane (CH3-I), introducing ion conductivity. Successful functionalization was proved by X-ray photoelectron spectroscopy (XPS), displaying changes in the surface composition of PTFE surfaces such as the introduction of amino groups at the expense of fluorine, and the increase in surface carbon content upon alkylation. Furthermore, contact angle measurements revealed increased wettability with water due to the introduction of the polar surface functionalities, while zeta potential measurements confirmed the increase of positive surface charges along the modification processes.

Novel mint-stalks derived biochar for the adsorption of methylene blue dye: Effect of operating parameters, adsorption mechanism, kinetics, isotherms, and thermodynamics

The pyrolysis of mint stalks and lemon peels was performed to synthesize mint-stalks (MBC) and lemon-peels (LBC) derived biochars for adsorbing methylene blue (MB). The preparation, characterization, and application of MBC in adsorption have not been reported in the literature. MBC showed higher surface area and carbon content than that of LBC. The removal ratios of MB were 87.5% and 60% within 90 min for MBC and LBC, respectively at pH 7, temperature of 30oC, adsorbent dose of 0.5 g/L, and MB concentration of 5 mg/L. The optimal MBC dose was 1 g/L achieving a removal efficiency of 93.6% at pH 7, temperature of 30oC, contact time of 90 min, and initial dye concentration of 5.0 mg/L. The adsorption efficiency decreased from 98.6% to 31.33% by raising the dye concentration from 3.0 mg/L to 30 mg/L. Further, the increase of adsorbent dose to 10 g/L could achieve 94.2%, 90.3%, 87.6%, and 84.1% removal efficiencies of MB in the case of initial concentrations of 200 mg/L, 300 mg/L, 400 mg/L, and 500 mg/L, respectively. MBC showed high stability in adsorbing MB under five cycles, and the performed analyses after adsorption reaffirmed the stability of MBC. The adsorption mechanism indicated that the adsorption of MB molecules on the biochar's surface was mainly because of the electrostatic interaction, hydrogen bonding, and π-π stacking. Pseudo-second-order and Langmuir models could efficiently describe the adsorption of MB on the prepared biochar. The adsorption process is endothermic and spontaneous based on the adsorption thermodynamics. The proposed adsorption system is promising and can be implemented on a bigger scale. Moreover, the prepared biochar can be implemented in other applications such as photocatalysis, periodate, and persulfate activation-based advanced oxidation processes.

Enhanced Biochar Production via Co-Pyrolysis of Biomass Residual with Plastic Waste after Recycling Process

Biomass pyrolysis for oil production results in biochar byproduct, whose characteristics can be improved by the reuse of waste plastics. While the plastic recycling process leads to a large amount of plastic waste that cannot be reused, this underutilized feedstock holds the potential for coprocessing with biomass, thereby increasing the likelihood of producing valuable biochar products. This study sought to evaluate how the inclusion of plastic waste influences the pyrolysis of biomass residue. To this end, sawdust and hardwood biomass were chosen as materials to investigate how the presence of plastics might alter the properties of the resulting chars. Synergies were observed among the biomass components, particularly in samples with higher lignin content from hardwood biomass, which resulted in increased biochar yields. The results showed that a 20% blend of plastic waste with wood at 300°C produced a solid char with a yield of 40% by weight. Co-pyrolysis of the biochar derived from blends of 20 wt. % PP with both sawdust and hardwood resulted in significant enhancement of various properties of the resulting biochar, including surface area, carbon content, hydrophobicity, and aromaticity. This enhancement had a favorable effect on the carbon content and calorific values of the biochar. These enhanced properties significantly contributed to the biochar’s capacity for sorbing substances like various heavy metals. It can be proved that this result showed the importance of the energy content of biochar and its potential use for renewable applications. The beneficial combined effect seen in the plastic blends can be credited to the interaction between the biomass and polymer components, resulting in the production of fewer volatile products at higher temperatures. It can be suggested that biochar from biowaste and plastic waste not only reduces environmental impact but also converts it into a valuable and eco-friendly product.

Petroleum-contaminated soil bioremediation and microbial community succession induced by application of co-pyrolysis biochar amendment: An investigation of performances and mechanisms

This study aimed to remediate petroleum-contaminated soil using co-pyrolysis biochar derived from rice husk and cellulose. Rice husk and cellulose were mixed in various weight ratios (0:1, 1:0, 1:1, 1:3 and 3:1) and pyrolyzed under 500 °C. These biochar variants were labeled as R0C1, R1C0, R1C1, R1C3 and R3C1, respectively. Notably, the specific surface area and carbon content of the co- pyrolysis biochar increased, potentially promoting the growth and colonization of soil microorganisms. On the 60th day, the microbial control group achieved a 46.69% removal of pollutants, while the addition of R0C1, R1C0, R1C3, R1C1 and R3C1 resulted in removals of 70.56%, 67.01%, 67.62%, 68.74% and 67.30%, respectively. In contrast, the highest efficiency observed in the abiotic treatment group was only 24.12%. This suggested that the removal of petroleum pollutants was an outcome of the collaborative influence of co-pyrolysis biochar and soil microorganisms. Furthermore, the abundance of Proteobacteria, renowned for its petroleum degradation capability, obviously increased in the treatment group with the addition of co-pyrolysis biochar. This demonstrated that co-pyrolysis biochar could notably stimulate the growth of functionally associated microorganisms. This research confirmed the promising application of co-pyrolysis biochar in the remediation of petroleum-contaminated soil.

Effect of Carburizing Temperature and Post Carburizing Treatments on Microhardness and Microstructural Evolution of Carburized Low-Carbon Steel

This paper reports the results of an experimental investigation of the effect of carburizing temperature and post carburizing heat treatments on the structural and hardness properties of pack carburized low-carbon steel. The carburizing processes were performed at temperatures of 900°C and 1035°C for 6 hours. After that, two hardening procedures were carried out. In the first hardening procedure, the specimens were directly quenched in oil from carburizing temperatures, while in the second procedure, a double quenching method using brine as a quenching medium was applied. The resultant changes in surface hardness values, carbon content, case depth, microhardness profiles, and microstructural evolution during all processes were tracked and reported. The study showed that the hardness values and carbon content of the carburized specimens increased significantly compared to an untreated specimen, also case depth values increased by two times in some hardened specimens, the increasing in these values were correlated to the changes in microstructures. The obtained results indicated that the structure and the properties of the carburized components are strongly influenced by carburizing temperature and by post carburizing heat treatments; therefore, both variables can be used to altering or modifying surface and core characteristics of the carburized steel, which make it more suitable for engineering components that require a combination of hard surface along with ductile and tough core.

Complex material analysis of a TiC coating produced by hot pressing with optical light microscopy, EDS, XRD, GDOES and EBSD

The present study investigates the interface between carbon steel and titanium samples annealed at different temperatures (ϑ1 = ▪ and ϑ2 = ▪). In both cases, an observable layer forms at the interface, with its thickness increasing from tϑ1 = 2.75 ± ▪ at ▪ to tϑ2 = 8.86 ± ▪ at ▪. The layer's composition and thickness evolve with temperature. Analysis reveals approximately 40 at.-% carbon concentration in the exterior region, indicating likely titanium carbide creation. X-ray diffraction identifies titanium carbide peaks, while microscopy and elemental mapping confirm compositional gradients at the interface. Electron Backscatter Diffraction (EBSD) shows a gradient in grain size near the TiC surface, reflecting TiC nucleation rates. XRD data detect both titanium carbide and titanium phases, with TiC becoming more prominent at ▪. Rietveld analysis further confirms TiC formation. Notably, distinct diffraction patterns on the contact and rear sides suggest a Ti(C, O, N) presence. Depth profiles exhibit varying surface and depth carbon concentrations, attributed to temperature effects. The study successfully demonstrates TiC coating fabrication through hot pressing, wherein Ti(C, O, N) coatings arise from titanium's affinity for reacting with oxygen and nitrogen. This research contributes to the understanding of phase transformations and interfacial properties in titanium-carbon steel systems.

Drivers of Surface Ocean Acidity Extremes in an Earth System Model

AbstractOceanic uptake of anthropogenic carbon causes acidification, a process that describes the increase in hydrogen ion concentrations ([H+]) and decrease in calcium carbonate mineral saturation states (Ω). Of particular concern are ocean acidity extreme (OAX) events, which pose a significant threat to many calcifying marine organisms. However, the mechanisms driving such extreme events are not well understood. Here, we use high‐frequency output from a fully coupled Earth system model of all processes that influence the surface ocean temperature and carbon budgets and ultimately [H+] and Ω anomalies to quantify the driving mechanisms of the onset and decline of high [H+] and low Ω extreme events. We show that enhanced temperature plays a crucial role in driving [H+] extremes, with increased net ocean heat uptake being the dominant driver of the event onset in the subtropics. In the mid‐to‐high latitudes, decreased downward vertical diffusion and mixing of warm surface waters during summer, and increased vertical mixing with warm and carbon‐rich subsurface waters during winter are the main drivers of high [H+] extreme event onset. In the tropics, increases in vertical advection of carbon‐rich subsurface waters are the primary driver of the onset of high [H+] extremes. In contrast, low Ω extremes are driven in most regions by increases in surface carbon concentration due to increased vertical mixing with carbon‐rich subsurface waters. Our study highlights the complex interplay between heat and carbon anomalies driving OAX events and provides a first foundation for more accurate prediction of their future evolution.

Anisotropic response of additively manufactured 316 L stainless steel towards low-temperature gaseous carburization

In order to modify the surface properties of austenitic stainless steel fabricated by Laser Powder Bed Fusion (L-PBF), low-temperature gaseous carburization (LTGC) was employed. During LTGC, a carburized case of expanded austenite forms at the surface, which contains a high surface carbon content (∼2.5 wt%), high nano-hardness (∼12.6 GPa), large compressive residual stresses (from −2.4 GPa to −3.2 GPa), and is free of carbide precipitates. In the expanded austenite zones, different residual stresses were measured with X-ray diffractometry (XRD) for the top plane, i.e. in the plane perpendicular to the build direction, and for the side plane. This anisotropy is suggested to be caused by grain-shape anisotropy for the different specimen planes and inherent to the hierarchical microstructures resulting from L-PBF.

Influence of re-deposited nanoparticles on the surface elemental composition of femtosecond laser machined copper surfaces

Nanoparticles re-deposited during the laser machining process have been suspected to modify the intrinsic surface chemistry of machined metallic surfaces. However, only very few studies have focused on elucidating their effect. In this work, under two different machining conditions (laboratory air & controlled humid air), we fabricated laser-induced periodic surface structures, LIPSS, on polished Cu surfaces with three different amounts of re-deposited Cu nanoparticles to quantify how re-deposited Cu nanoparticles affect the surface chemistry of the machined samples. In carrying out these experiments, we demonstrate that the re-deposition of nanoparticles during laser machining is affected by the volume of the laser machining environment, which impacts the surface chemistry of laser-machined surfaces. Our results indicate that evacuation of the vacuum chamber before and after laser machining using a vacuum scroll pump did not affect the adsorption of carbonaceous molecules. Further, we present the effect of removing re-deposited nanoparticles through ultrasonic cleaning on the surface chemistry of the test surface. The cleaning exposes the LIPSS surface entirely to airborne carbonaceous species, resulting in a more significant increase in the total surface carbon content. Finally, we evaluated the quality of the nanoparticles generated during laser machining by assessing their stability to provide a first insight into the utility of those nanoparticles.

Effect of the Surface Carbon Content on Microstructure and Deformation of M50 Steel

Effect of the Surface Carbon Content on Microstructure and Deformation of M50 Steel

Implementing and Improving CBMZ-MAM3 Chemistry and Aerosol Modules in the Regional Climate Model WRF-CAM5: An Evaluation over the Western US and Eastern North Pacific

The representation of aerosols in climate–chemistry models is important for air quality and climate change research, but it can require significant computational resources. The objective of this study was to improve the representation of aerosols in climate–chemistry models, specifically in the carbon bond mechanism, version Z (CBMZ), and modal aerosol modules with three lognormal modes (MAM3) in the WRF-CAM5 model. The study aimed to enhance the model’s chemistry capabilities by incorporating biomass burning emissions, establishing a conversion mechanism between volatile organic compounds (VOCs) and secondary organic carbons (SOCs), and evaluating its performance against observational benchmarks. The results of the study demonstrated the effectiveness of the enhanced chemistry capabilities in the WRF-CAM5 model. Six simulations were conducted over the western U.S. and northeastern Pacific region, comparing the model’s performance with observational benchmarks such as reanalysis, ground-based, and satellite data. The findings revealed a significant reduction in root-mean-square errors (RMSE) for surface concentrations of black carbon (BC) and organic carbon (OC). Specifically, the model exhibited a 31% reduction in RMSE for BC concentrations and a 58% reduction in RMSE for OC concentrations. These outcomes underscored the importance of accurate aerosol representation in climate–chemistry models and emphasized the potential for improving simulation accuracy and reducing errors through the incorporation of enhanced chemistry modules in such models.

Effects of High Temperature Tempering on Microstructure and Hardness Distribution on 18Cr2Ni4WA Alloy Steel Heavy-duty Gears: Numerical Simulation and Experiments

In the present work, simulations of gas carburizing heat treatment of heavy-duty gears on a coal-cutting machine fabricated by a 18Cr2Ni4WA alloy steel were carried out by using a finite element method software. The physical property database of the 18Cr2Ni4WA alloy steel was constructed in the software. The effects of the high temperature tempering process on the microstructure and hardness distributions were simulated and studied. The hardness distribution results obtained by simulation are in good agreement with the experimental results, which verifies the accuracy of the simulation. The evolution of the volume fractions of the austenite, martensite, and bainite microstructure after high temperature tempering was simulated, while the change of the retained austenite varying with the number of high temperature tempering was studied. The results show that with the increase of the number of high-temperature tempering, the content of retained austenite in the gear decreases, and it could reduce the surface carbon concentration. The hardness variation, calculated by the Maynier equation through secondary development, is shown to be governed by the joint influence of carbon concentration and microstructure distribution. The hardness distribution from the surface layer to the core is 62HRC-32HRC after the heat treatment process with twice high tempering, which meets the needs of the practical application of the gears.

Atomistic Insights into Early-Stage Oxidation of χ-Fe5C2 and the Dependence on the Surface Structure

Iron carbides play a crucial role in many industrial fields, such as the steel industry, catalysis, carbon material production, and so on. One of the main challenges is that iron carbides are highly susceptible to being oxidized under service conditions, which can significantly reduce the performance and retard their industrial applications. However, the complex chemical structure of iron carbide materials and the dynamic nature of the Fe–C–O system under reactive conditions, such as the Fischer–Tropsch synthesis condition, hindered the understanding of the oxidation process. In this paper, structure evolution of the early-stage oxidation of χ-Fe5C2 was investigated through reactive force field molecular dynamics simulations. The impacts of surface structure, oxygen coverage, temperature, and particle size were systemically explored. It was found that the oxidation rate was not only related to the surface carbon content but also to the homogeneity of the subsurface. Meanwhile, the dynamic structure transformation during oxidation was analyzed by various correlation functions. The mechanism of counter-direction migration of surface atoms during the oxidation process was illustrated, where carbon atoms migrate to the bulk region and iron atoms migrate to the surface. Our study reveals the atomistic dynamic mechanism of χ-Fe5C2 oxidation, which offers crucial insights for catalyst oxidation and iron carbide materials.

CO2 capture using biochar derived from conditioned sludge via pyrolysis

To reduce pollution and simultaneously mitigate carbon emission. Biochar samples were prepared via the pyrolysis of sludge after conditioning with K2FeO4 and cationic polyacrylamide (CPAM) or chitosan (CTS), and their CO2 capture performance was compared. The optimal preparation conditions were 600 °C and 80 mg/g dry solid (DS) for K2FeO4, 20 mg/L for CPAM, and 1 mg/g DS for CTS. The results showed that the CO2 capture capacity of the biochar with K2FeO4 (K2FeO4-B) increased from 75.69 mg/g to 81.68 mg/g compared to RSB, the CO2 capture capacity of the biochar with PF + CPAM (K2FeO4-CPAM-B) was 94.81 mg/g, and the CO2 capture capacity of the biochar with PF + CTS (K2FeO4-CTS-B) was 86.56 mg/g. The CO2 capture capacity of the biochar (K2FeO4-CTS-B) was 86.56 mg/g. The main reason for this improved capacity is that the addition of K2FeO4 and CPAM enhanced chemical properties of the biochar surface (carbon content, N–H content, etc.). Additionally, the biochar conditioned with K2FeO4 and CPAM demonstrated better cyclic adsorption performance and economic efficiency than the other samples. It has the prospect of engineering application. This study provides a reference for the selection of conditioning agents for wastewater treatment plants and a new solution for sludge disposal.

In-Vitro Evaluation of Photofunctionalized Implant Surfaces in a High-Glucose Microenvironment Simulating Diabetics

The present study aimed to assess the efficacy of photofunctionalization on commercially available dental implant surfaces in a high-glucose environment. Discs of three commercially available implant surfaces were selected with various nano- and microstructural alterations (Group 1-laser-etched implant surface, Group 2-titanium-zirconium alloy surface, Group 3-air-abraded, large grit, acid-etched surface). They were subjected to photo-functionalization through UV irradiation for 60 and 90 min. X-ray photoelectron spectroscopy (XPS) was used to analyze the implant surface chemical composition before and after photo-functionalization. The growth and bioactivity of MG63 osteoblasts in the presence of photofunctionalized discs was assessed in cell culture medium containing elevated glucose concentration. The normal osteoblast morphology and spreading behavior were assessed under fluorescence and phase-contrast microscope. MTT (3-(4,5 Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and alizarin red assay were performed to assess the osteoblastic cell viability and mineralization efficiency. Following photofunctionalization, all three implant groups exhibited a reduced carbon content, conversion of Ti4+ to Ti3+, increased osteoblastic adhesion, viability, and increased mineralization. The best osteoblastic adhesion in the medium with increased glucose was seen in Group 3. Photofunctionalization altered the implant surface chemistry by reducing the surface carbon content, probably rendering the surfaces more hydrophilic and conducive for osteoblastic adherence and subsequent mineralization in high-glucose environment.