Modification Of Topography Research Articles

Tunable superhydrophobic titanium nitride surface by ultrafast laser processing

The interaction of water droplets to the engineered hierarchical surface structures depends on the synergy between the topographical and chemical modifications. In this work, we develop an ultrafast laser processing technology to create a robust superhydrophobic nanostructured titanium nitride (TiN) surface. The process is based on the manipulation of the surface geometry and the low-pressure technique's accelerated adsorption of Volatile Organic Compounds (VOC). The laser-processed surfaces are composed of nanoscale geometry overlapped with porous, spongy structures. The metal oxides formed on the TiN surface were hydrophilic and subjected to accelerated VOC adsorption by low-pressure technique via condensation reaction with surface hydroxyl groups formed by heterolytic adsorption of water molecules from the environment. The decrease of surface energy due to the presence of adsorbed hydrocarbons and the topography of the nanostructures allow the trapping of small volumes of air. The presence of a layer of air favour the Cassie-Baxter state of wetting state. Static contact angles ranging from 155 to 180° have been reached depending on the geometry of the nanostructures. A comparative study of vacuum processed and aged (15 days) samples under atmospheric conditions were also performed. The chemical analysis by XPS demonstrates that the water molecules attached to hydroxyl groups passivate these reactive sites and hinder the adsorption of VOC, decreasing the adsorption rate drastically under aging in atmosphereic conditions. In contrast, it is enhanced under low-pressure conditions due to the reduced amount of water vapour.

Peek in dental implant- A review of literature

Polyether ether ketone (PEEK) is an important material which is used in several dental field like oral implantology, prosthodontic, orthodontic dentistry for dental implants, abutments, healing caps, orthodontic braces, and most importantly denture prosthetic framework. The best mechanical property of PEEK is that it overcomes the disadvantage of titanium implants i.e., aesthetic and allergic reaction. The aim of this article is to mainly focus on the surface modification of PEEK implant material to make it a better version of dental implant so that it overcomes the bioactivity and bone-integrity of the implant then the fabrication, structure, properties, and application, surface topographical modification and bioactive PEEK composites are described.

Understanding the Relation between Pulse Duration and Topography Evolution of Polyether Ether Ketones Textures by Ultrashort Infrared Laser Interference Patterning

Advanced polymeric materials, such as polyether ether ketones (PEEK), have been placed as direct substitutes for metals and ceramics in diverse applications, such as the machinery industry and biomedical engineering. Moreover, surface treatments allow the emergence of brand-new properties or the improvement of preexisting ones, such as friction, lubrication, wettability, cellular infiltration, or osseointegration. A paramount approach to achieving topographical modifications is by using laser micro/nanoprocessing techniques such as direct laser interference patterning (DLIP). Herein, PEEK foils are structured with DLIP method using ultrashort pulses. The influence of the pulse duration between 266 fs and 15 ps and the pulse-to-pulse overlap on the resulting surface topography and chemistry is assessed. As a result, well-defined line-like textures with a period of 5.8 μm and aspect ratios up to 0.88 are achieved. Furthermore, it is possible to explore and understand the behavior of surface phenomena such as swelling, increase/decrease of laser–material interaction onset, and laser-induced periodic surface structures formation. A comprehensive topographical and chemical characterization study demonstrates that these distinctive topographical features occur because of multiphoton absorption, incubation effects, and heat accumulation. These phenomena allow structuring polymeric substrates that are low-absorbing and challenging to pattern with conventional nanosecond infrared (IR) laser sources.

Patterning SS304 Surface at Microscale to Reduce Wettability and Corrosion in Saline Water

Stainless steel 304 (SS304) experiences corrosion when it is exposed to a saline atmosphere, which attains severity due to its high surface wettability. Topographical modification of metallic surfaces is an effective route to reduce wettability and thereby mitigate liquid-mediated corrosion. In this work, topographical modification of stainless steel 304 flat surface in the form of micropillars was done (pillar width: 100 μm, inter-pillar distance: 100 μm and height: 80 μm). Micropillars were fabricated by a chemical etching process. Wetting and corrosion of the micropillars was studied over long-time duration in comparison with flat surface, before and after intermittent and continuous exposures to saline water for 168 h. Wetting was characterized by measuring the static water contact angle on the test surfaces and their corrosion by electrochemical polarization tests (electrolyte: 3.5 wt.% sodium chloride solution). The relationship between the nature of wetting of the test surfaces and their corrosion was examined. Micropillars showed predominantly composite wetting over a long time, which imparted an effective resistance against corrosion over a long time to the SS304 surface. When compared to the flat surface, the corrosion rates of the micropillars were lower by two orders of magnitude, prior to and also upon long-time contact with the NaCl solution. Micropillars lowered corrosion due to composite wetting, i.e., solid-liquid-air interface that reduced the area that was in contact with the NaCl solution. The efficiency of corrosion inhibition (η) of micropillars was 88% before long-time contact, 84% after intermittent contact, and 77% after continuous contact with NaCl solution. Topographical modification in the form of micropillars that can impart composite wetting is an effective route to induce long-term anticorrosion ability to the SS304 surface.

Antecedent Topography and Sediment Dispersal: The Influence of Geologically Instantaneous Events on Basin Fill Patterns

AbstractFavorable topographic gradients and channel bed aggradation are often cited as primers for river channel avulsion. Sylhet Basin in Bangladesh subsides relatively rapidly and presents a topographically favorable channel course for the Brahmaputra River. Holocene occupations of this region remained routed along the basin's western margin, depositing tens of meters of amalgamated channel sands but leaving the central basin under‐filled. The localized backwater effect from a seasonal lake that forms in Sylhet Basin, referred to as a “hydraulic barrier,” has been proposed as a mechanism for keeping the channel pinned to the western margin. Using a 1‐D channel profile model and a 2‐D depth‐averaged hydrodynamic model, we test the preferred flow path between two possible channel courses under a range of physical conditions. Results show that the hydraulic barrier interpretation is implausible unless water depths are increased beyond the physical dimensions of Sylhet Basin. Reducing topographic slope along the two pathways does not sufficiently enhance the local backwater to steer the channel to the basin center. Only the introduction of a scoured antecedent channel along the western margin induces a strong preference for bypass of the central basin. These results corroborate field evidence that Holocene outburst floods scoured a paleochannel that became the preferred course for the Brahmaputra within Sylhet Basin in the mid to late Holocene. We conclude that modification of basin topography by large, infrequent flood events can exert a persistent influence on channel steering that is comparable to previously documented effects of monsoon variability and tectonic deformation.

Organic/polymeric antibiofilm coatings for surface modification of medical devices

Infections arising from implanted medical devices cause considerable challenges for medicinal specialists and patients. These infections usually arise from the accumulation of biofilm on the device, which is difficult to eliminate and typically needs antibiotic treatment and removal of the device. In this regard, efforts have been made to design the devices or functional polymer coatings that have anti-fouling or antimicrobial properties to limit the formation of biofilm and following infection by preventing or killing bacteria near the device surface or by restricting the initial binding of proteins and bacteria. Herein, the extent of device-related infections, the biofilm formation mechanism, the role of biofilm construction in human pathogenesis, and the key strategies for the progress of antibiofilm coatings are discussed. The most promising antibiofilm coating approaches, comprising the surface topography modifications as well as the PEG, hydrogel, polyzwitterion, Benign bacterial biofilm, enzyme, cationic polymer, PTFE, and smart coatings, etc., were also summarized to avoid the biofilm formation and bacteria proliferation via controlling the antibiofilm mechanisms.

Physical representation of hillslope leaky barriers in 2D hydraulic models: A case study from the Calder Valley

AbstractThe resources of small‐scale community‐based flood risk action groups are often limited, hence studies to model and predict the effects of Natural Flood Management are often restrained by time and lack of empirical data to validate results. As a result, representations of hillslope leaky barriers are largely modelled as several equifinal approaches, often without survey data. The geometrical characteristics of hillslope leaky barriers were surveyed for the first time at Hardcastle Crags, Calder Valley. This data informed six 2D hydraulic model representation scenarios with varying combinations of topography modification and roughness increase, allowing the sensitivity of their results to be tested. Results from Scenario 3 (topography modification and roughness increase) estimated total hillslope runoff peak flow to reduce by 16.6% in a 1:1‐year design return period; however, this reduction diminished as rainfall intensity increased. Return periods of over 1:30 year estimated peak flow reductions of <5%. Only 14.3%–21.7% (98–148 m3) of the total additional storage provided by the barriers is mobilised during simulated events. A multi‐peaked rainfall event from December 2015 was also simulated. Although the initial peak flow was reduced by 22.7%, as storage became mobilised, effectiveness reduced significantly for subsequent peaks within the same event.

A systematic review on neutrophils interactions with titanium and zirconia surfaces: Evidence from in vitro studies.

ObjectivesThis systematic review aimed to assess in vitro studies that evaluated neutrophil interactions with different roughness levels in titanium and zirconia implant surfaces.Material and MethodsAn electronic search for literature was conducted on PubMed, Embase, Scopus, and Web of Science and a total of 14 studies were included. Neutrophil responses were assessed based on adhesion, cell number, surface coverage, cell structure, cytokine secretion, reactive oxygen species (ROS) production, neutrophil activation, receptor expression, and neutrophil extracellular traps (NETs) release. The method of assessing the risk of bias was done using the toxicological data reliability assessment tool (TOXRTOOL).ResultsTen studies have identified a significant increase in neutrophil functions, such as surface coverage, cell adhesion, ROS production, and NETs released when interacting with rough titanium surfaces. Moreover, neutrophil interaction with rough–hydrophilic surfaces seems to produce less proinflammatory cytokines and ROS when compared to naive smooth and rough titanium surfaces. Regarding membrane receptor expression, two studies have reported that the FcγIII receptor (CD16) is responsible for initial neutrophil adhesion to hydrophilic titanium surfaces. Only one study compared neutrophil interaction with titanium alloy and zirconia toughened alumina surfaces and reported no significant differences in neutrophil cell count, activation, receptor expression, and death.ConclusionsThere are not enough studies to conclude neutrophil interactions with titanium and zirconia surfaces. However, different topographic modifications such as roughness and hydrophilicity might influence neutrophil interactions with titanium implant surfaces.

Effects of surface topography at different scales on the dispersion of the wetting data for sessile water droplets on nitrided austenitic stainless steels

Plasma nitriding is used to increase the durability of steels. The wettability of nitrided surfaces is poorly studied. The ability of nitriding in modifying the wetting and evaporation of sessile droplets on austenitic stainless steel is studied. Transferred plasma for nitriding provides independent substrate biasing giving the opportunity to tailor the surface before and during the nitriding treatments. It was shown that a cleaning treatment (ArH2 plasma) produces topographical modifications of the surface by selective sputtering of the grains giving contact angles between 80 and 90°. Similar results are obtained when the nitriding treatments are carried out with a rather high bias voltage. It is explained using the skewness (Ssk) topographical roughness parameter which reveals the asymmetry of the profile. The more the Ssk is, the higher the contact angle is. During nitriding treatments, the very high internal stresses leads to the formation of spikes at the grain boundaries. Pinning of the three-phase contact line on peaks localized at grain boundaries are responsible for high contact angles. For nitriding treatments carried out with lower bias, surface contamination occurs and a discontinuous oxynitride layer is formed. The nanostructure formed by these oxides gives contact angles up to 120°.

Bioinspired Topographic Surface Modification of Biomaterials.

Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials. Many techniques have been reported to modify surfaces, including the use of natural sources as inspiration to fabricate topographies on artificial surfaces. Biomimetics is a tool to take advantage of nature to solve human problems. Physical surface modification using animal and vegetal topographies as inspiration to reduce bacterial adhesion and improve cell attachment has been investigated in the last years, and the results have been very promising. However, just a few animal and plant surfaces have been used to modify the surface of biomaterials with these objectives, and only a small number of bacterial species and cell types have been tested. The purpose of this review is to present the most current results on topographic surface modification using animal and plant surfaces as inspiration to modify the surface of biomedical materials with the objective of reducing bacterial adhesion and improving cell behavior.

Submicron topography design for controlling staphylococcal bacterial adhesion and biofilm formation.

Surface topography modification with nano- or micro-textured structures has been an efficient approach to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection without modification of surface chemistry/bulk properties of materials and without causing antibiotic resistance. This manuscript focuses on submicron-textured patterns with ordered arrays of pillars on polyurethane (PU) biomaterial surfaces in an effort to understand the effects of surface pillar features and surface properties on adhesion and colonization responses of two staphylococcal strains. Five submicron patterns with a variety of pillar dimensions were designed and fabricated on PU film surfaces and bacterial adhesion and biofilm formation of Staphylococcal strains (Staphylococcus epidermidis RP62A and Staphylococcus aureus Newman D2C) were characterized. Results show that all submicron textured surface significantly reduced bacterial adhesion and inhibited biofilm formation, and bacterial adhesion linearly decreased with the reduction in top surface area fraction. Surface wettability did not show a linear correlation with bacterial adhesion, suggesting that surface contact area dominates bacterial adhesion. From this, it appears that the design of textured patterns should minimize surface area fraction to reduce the bacterial interaction with surfaces but in a way that ensures the mechanical strength of pillars in order to avoid collapse. These findings may provide a rationale for design of polymer surfaces for antifouling medical devices.

Micro-textured silicone-based implant fabrication using electrospun fibers as a sacrificial template to suppress fibrous capsule formation

Conventionally, macro-textured surfaces comprising several hundred micrometer-sized patterns are used to minimize silicone-based breast implant complications, including capsular contracture. However, because of the recent cases of breast implant-associated anaplastic large cell lymphoma from macro-textured implants, there is a strong demand for nano- or micro-textured silicone implants with dimensions smaller than sub-micrometers. Herein, we propose a simple and cost-effective topographical surface modification strategy for silicone-based implants. Several hundred nanometer to sub-micrometer wide groove-type micro-textures were fabricated on a polydimethylsiloxane surface using electrospun polyvinylpyrrolidone fibers as a sacrificial template. The aligned and randomly oriented micro-textures were prepared by controlling the electrospun fiber orientation. In vitro experiments demonstrated that the micro-textured polydimethylsiloxane was cytocompatible and suppressed differentiation of fibroblasts into myofibroblasts. Importantly, the aligned micro-texture promoted the polarization of macrophages into the anti-inflammatory M2 phenotype. Long-term in vivo studies established that the micro-textures potently suppressed various factors affecting foreign body reactions by downregulating profibrotic cytokine gene expression and reducing the fibroblast and myofibroblast counts, the cells playing important roles in the immune response. Thus, the thickness and collagen density of fibrous capsules were decreased, demonstrating that the micro-textured surface effectively inhibited capsular contracture. Although the aligned micro-textures contributed to the polarization of macrophages to the M2 phenotype both in vitro and in vivo, foreign body reaction by both the aligned and randomly oriented micro-textures are similar.

Mapping Bone Marrow Cell Response from Senile Female Rats on Ca-P-Doped Titanium Coating.

Chemical and topographical surface modifications on dental implants aim to increase the bone surface contact area of the implant and improve osseointegration. This study analyzed the cellular response of undifferentiated mesenchymal stem cells (MSC), derived from senile rats’ femoral bone marrow, when cultured on a bioactive coating (by plasma electrolytic oxidation, PEO, with Ca2+ and P5+ ions), a sandblasting followed by acid-etching (SLA) surface, and a machined surface (MSU). A total of 102 Ti-6Al-4V discs were divided into three groups (n = 34). The surface chemistry was analyzed by energy dispersive spectroscopy (EDS). Cell viability assay, gene expression of osteoblastic markers, and mineralized matrix formation were investigated. The cell growth and viability results were higher for PEO vs. MSU surface (p = 0.001). An increase in cell proliferation from 3 to 7 days (p < 0.05) and from 7 to 10 days (p < 0.05) was noted for PEO and SLA surfaces. Gene expression for OSX, ALP, BSP, and OPN showed a statistical significance (p = 0.001) among groups. In addition, the PEO surface showed a higher mineralized matrix bone formation (p = 0.003). In conclusion, MSC from senile female rats cultured on SLA and PEO surfaces showed similar cellular responses and should be considered for future clinical investigations.

Mechanisms for recirculation cells in granular flows in rotating cylindrical rough tumblers.

Friction at the endwalls of partially filled horizontal rotating tumblers induces curvature and axial drift of particle trajectories in the surface flowing layer. Here we describe the results of a detailed discrete element method study of the dry granular flow of monodisperse particles in three-dimensional cylindrical tumblers with endwalls and cylindrical wall that can be either smooth or rough. Endwall roughness induces more curved particle trajectories, while a smooth cylindrical wall enhances drift near the endwall. This drift induces recirculation cells near the endwall. The use of mixed roughness (cylindrical wall and endwalls having different roughness) shows the influence of each wall on the drift and curvature of particle trajectories as well as the modification of the free surface topography. The effects act in opposite directions and have variable magnitude along the length of the tumbler such that their sum determines both direction of net drift and the recirculation cells. Near the endwalls, the dominant effect is always the endwall effect, and the axial drift for surface particles is toward the endwalls. For long enough tumblers, a counter-rotating cell occurs adjacent to each of the endwall cells having a surface drift toward the center because the cylindrical wall effect is dominant there. These cells are not dynamically coupled with the two endwall cells. The competition between the drifts induced by the endwalls and the cylindrical wall determines the width and drift amplitude for both types of cells.

Lysyl-Oxidase Dependent Extracellular Matrix Stiffness in Hodgkin Lymphomas: Mechanical and Topographical Evidence.

Simple SummaryAlterations of the composition and architecture of the extracellular matrix (ECM), leading to increased stiffness, is known to condition development, invasiveness and severity of neoplasms. In this study, we report increased lymph node (LN) stiffness in human lymphomas, measured by LN elastometry or by computerized imaging of bioptic specimens. Stiffness matched to lymphoma histotype and grading. The enzyme lysyl oxidase (LOX) is involved in the rise of collagen cross-linking in Hodgkin lymphomas, while altered architecture, shown by scanning electron microscopy and polarized light microscopy is involved in advanced follicular lymphomas. Based on these data, digital pathology may help in the staging of lymphomas, and lysyl oxidase may represent a target for therapy in Hodgkin lymphomas.Purpose: The biochemical composition and architecture of the extracellular matrix (ECM) is known to condition development and invasiveness of neoplasms. To clarify this point, we analyzed ECM stiffness, collagen cross-linking and anisotropy in lymph nodes (LN) of Hodgkin lymphomas (HL), follicular lymphomas (FL) and diffuse large B-cell lymphomas (DLBCL), compared with non-neoplastic LN (LDN). Methods and Results: We found increased elastic (Young’s) modulus in HL and advanced FL (grade 3A) over LDN, FL grade 1–2 and DLBCL. Digital imaging evidenced larger stromal areas in HL, where increased collagen cross-linking was found; in turn, architectural modifications were documented in FL3A by scanning electron microscopy and enhanced anisotropy by polarized light microscopy. Interestingly, HL expressed high levels of lysyl oxidase (LOX), an enzyme responsible for collagen cross-linking. Using gelatin scaffolds fabricated with a low elastic modulus, comparable to that of non-neoplastic tissues, we demonstrated that HL LN-derived mesenchymal stromal cells and HL cells increased the Young’s modulus of the extracellular microenvironment through the expression of LOX. Indeed, LOX inhibition by β-aminopropionitrile prevented the gelatin stiffness increase. Conclusions: These data indicate that different mechanical, topographical and/or architectural modifications of ECM are detectable in human lymphomas and are related to their histotype and grading.

Implant Materials: Topography and Their Influence in Osseointegration

With advancements in science and technology, edentulousness has been provided with a permanent solution in the form of dental implants. Implant materials have been evolving in various aspects to enhance their property of Osseointegration since their discovery. With research revealing the intense process of bone formation and biology around osseointegration, scientists have been experimenting with various compositions of alloys, allotropic forms, and commercially pure (cp) forms of titanium. Topographical modifications and their effect on new bone formations will be dealt with in this article.

Design parameters of dental implants: A review

An ideal dental implant is a design that maximizes the anchorage strength of implants in human jawbones and minimizes peak stress values in bone-implant interfaces under given standard loads. The stress concentration at the bone-implant contact is controlled by implant design, which determines the bone biological response. Implant design has improved as a result of marketing demands. The modification of shape, size, material, and surface topography of primary designs has been the focus of dental implant design in response to marketing needs. Since the integration of bone-implant has been highlighted in dentistry investigations, improving implant design depends on the prediction of mechanical reactions and remodeling response of bony tissues around implants. There are four types of implants design including Screws, cylinders, Conical cylinders, and Blades type implants. The major difference between these designs is in implant primary stability. With the development of computational technologies, researchers can predict long term oral bone remodeling around implants by use of the finite element method. This review considers the design parameters of dental implants in which affect stress, strain in bone-implant interfaces, and bone remodeling around the implant.

Mechanical, Morphological, and Biological Compatibility in Implantology

A dental implant (DI) is a prime illustration of the integrated construct of science and technology involving several arenas, including surface science, biophysics, from macroscopic to nanoscopic manufacturing techniques, among other materials utilized in dentistry and their effective implementations. Since the exterior of DI is in close contact with tissues and is sensitive to biochemical as well as biomechanical environments, there are important criteria placed on dental implants systems, just as there are for many other materials and equipment used in dentistry. Numerous elements of biocompatibility profiling created for DI have been shown to be dependent on parameters related to the individual, the hard and soft tissue present, and the constituents; these factors are either connected to superficial or bulk qualities. Biological, mechanical, and morphological compatibility with adjacent critical tissues should at the very least be part of these standards. Because alloying elements are believed to only be capable of penetrating the surrounding biosystem around and producing harmful effects by converting to ions chemically or electrochemically, biological compatibility of metals fundamentally equals to their ability to resist corrosive forces under such hostile settings. Further, the technique through which mechanically acting loads undergo effective transfer from the implanted device to bony structure is a crucial factor determining whether an implant will succeed or fail. Also, any relative motion that could erode the osseous structure or cause the implants to gradually loosen must be avoided. An implant that has undergone osseointegration offers a direct and comparatively rigid link to the bone. Additionally, the surface characteristics of materials must not seep or emit substances that are active biologically or pose hazard. Clinical DI have been produced with an emphasis on topographic modifications to DI surfaces as opposed to modifications to chemical characteristics.

Hierarchical microgroove/nanopore topography regulated cell adhesion to enhance osseointegration around intraosseous implants in vivo.

Implant surface topography plays a crucial role in achieving successful implantation. Simple and controllable surface topographical modifications are considered a promising method to accelerate bone osseointegration for biomedical applications. Moreover, comprehension of the mechanism between surface topography and cell osteogenic differentiation is vital for the manipulation of these processes to promote bone tissue regeneration. In this study, we investigated the effects of implant surfaces with various sized hierarchical microgroove/nanopore topographies on cell adhesion, osteogenesis, and their underlying mechanism both in vitro and in vivo. Our findings reveal that a titanium surface with an appropriately sized microgroove/nanopore topography (SLM-1MAH) exhibits the more satisfactory adhesive and osteogenic efficiency than the clinically used sand-blasted, large-grit, and acid-etched (SLA) surface. The underlying molecular mechanism lies in the activation of the integrin α2-PI3K-Akt signaling pathway, where the SLM-1MAH surface increased the protein expressions of integrin α2 (Itga2), phosphatidylinositol 3-kinase (PI3K), and phosphorylated serine/threonine kinase Akt (p-Akt) to enhance osteogenesis and osseointegration. Furthermore, the SLM-1MAH surface also displays better osseointegration efficiency with stronger bonding strength than that on the SLA surface. This work provides a novel strategy for implant surface topography design to improve bone-implant osseointegration.

Fucoidan and Topography Modification Improved in Situ Endothelialization on Acellular Synthetic Vascular Grafts

Fucoidan and Topography Modification Improved in Situ Endothelialization on Acellular Synthetic Vascular Grafts