Lipidome profiling with Raman microspectroscopy identifies macrophage response to surface topographies of implant materials

Biomaterial characteristics such as surface topographies have been shown to modulate macrophage phenotypes. The standard methodologies to measure macrophage response to biomaterials are marker-based and invasive. Raman microspectroscopy (RM) is a marker-independent, noninvasive technology that allows the analysis of living cells without the need for staining or processing. In the present study, we analyzed human monocyte-derived macrophages (MDMs) using RM, revealing that macrophage activation by lipopolysaccharides (LPS), interferons (IFN), or cytokines can be identified by lipid composition, which significantly differs in M0 (resting), M1 (IFN-γ/LPS), M2a (IL-4/IL-13), and M2c (IL-10) MDMs. To identify the impact of a biomaterial on MDM phenotype and polarization, we cultured macrophages on titanium disks with varying surface topographies and analyzed the adherent MDMs with RM. We detected surface topography–induced changes in MDM biochemistry and lipid composition that were not shown by less sensitive standard methods such as cytokine expression or surface antigen analysis. Our data suggest that RM may enable a more precise classification of macrophage activation and biomaterial–macrophage interaction.

Surface Metrology Principles for Snow and Ice Friction Studies

Recent advances in surface metrology science are applied to understanding friction with snow and ice. Conventional surface metrology’s measurement, analyses, and characterizations, have inherent limitations for elucidating tribological interactions. Strong functional correlations and confident discriminations with slider surface topographies, textures, or “roughness”, have largely eluded researchers using conventional methods. Building on 4 decades of research using multiscale geometric methods, two surface metrology axioms and corollaries are proposed with good potential to provide new technological insights.

A Study to Compare the Fouling Resistance and Self-cleaning Properties of Two-patterned Surfaces with an Un-patterned Control Surface

Biofouling is an unwelcomed phenomenon where unwanted biological matter adheres to surfaces with the presence of water, resulting in alteration to the properties of the surface. This affects many industries, especially the marine industry. Multiple biofouling control studies have been conducted to minimize damage and maintenance cost of these surfaces. With rising concerns on the toxicity of current control methods towards the environment, non-toxic methods shown to be effective are surface modifications such as self-cleaning or biomimetic textured surfaces. One of the biomimetic surfaces, shark’s skin has shown anti-fouling properties due to its surface riblets with low drag properties based on studies done. However, few researches are conducted to implement these biomimetic surface topographies for real anti-fouling applications. Therefore, this project explores the possibilities in implementing biomimetic surface topographies such as shark’s skin in real life applications using computational fluid dynamics (CFD) analysis and also to manufacture these surfaces using 3D printing methods. A computer-aided design (CAD) model of shark skin and un-patterned surface topographies are used to study the behavior of fluid over these surfaces in CFD fluent in ANSYS software. The hydrodynamic variable data such as wall shear stress over the surface topography is represented in a contour and vector plot, these results are then analyzed. According to the hypotheses, the biomimetic shark skin surface topography will show higher wall shear stress, indicating anti-fouling properties. In the next part of this project is the manufacturing of these surface, the goal is to provide a cheaper alternative to current micro-structured surface production methods such as photolithography. Additive manufacturing such as fused deposition modeling (FDM) 3D printing can potentially provide a manufacturing method with a much lower cost and time needed. Thus, 3D printing of the biomimetic shark skin surface topography will be carried out in this project to determine if FDM can provide a manufacturing solution to anti-fouling micro-topography surfaces.

Mirau-Based CSI with Oscillating Reference Mirror for Vibration Compensation in In-Process Applications

We present a Mirau-type coherence scanning interferometer (CSI) with an oscillating reference mirror and an integrated interferometric distance sensor (IDS) sharing the optical path with the CSI. The IDS works simultaneously with the CSI and measures the distance changes during the depth scanning process with high temporal resolution. The additional information acquired by the IDS is used to correct the CSI data disturbed by unwanted distance changes due to environmental vibrations subsequent to the measurement. Due to the fixed reference mirror in commercial Mirau objectives, a Mirau attachment (MA) comprising an oscillating reference mirror is designed and built. Compared to our previous systems based on the Michelson and the Linnik interferometer, the MA represents a novel solution that completes the range of possible applications. Due to its advantages, the Mirau setup is the preferred and most frequently used interferometer type in industry. Therefore, the industrial use is ensured by this development. We investigate the functioning of the system and the capability of the vibration compensation by several measurements on various surface topographies.

Friction, Scuffing and Transfer Layer Formation in Lubricated Sliding of EN31 Steel and Tungsten Carbide (WC): Surface Topography Effects

Surface topographies play a critical role in controlling friction, surface damage and transfer layer formation in engineering applications; hence understanding this is of great importance. In this work, experimental studies were carried out to understand the influence of surface topography on friction, scuffing and transfer layer formation in completely immersed lubricated sliding interactions. For this, sliding experiments were carried out in sphere on flat configuration using EN31 steel flats and Tungsten Carbide pin countersurface. Perpendicular and parallel surface topographies were induced onto the steel flats. Experiments were conducted at high normal loads of 1000N, 2000N and 3000N. The results show that Surface topography has a significant influence on the frictional response. When the topography directionality was perpendicular to the sliding direction, scuffing was observed only at a high load of 3000N. A ‘peak friction’ was also observed during the occurrence of scuffing. When the directionality in topography was parallel to sliding direction, scuffing and surface damage occurred from 2000N itself, accompanied by a high amount of transfer layer formation. This can be attributed to the directionality of parallel topography, which displaces away the lubricant during sliding interaction, creating metal-to-metal contact and hence leading to scuffing and higher transfer layer formation.

Spatial Controls of Ligamentous Tissue Orientations Using the Additively Manufactured Platforms in an In Vivo Model: A Pilot Study

The periodontal ligaments (PDLs) with specific orientations to tooth-root surfaces play a key role in generating biomechanical responses between the alveolar bone and cementum as a tooth-supporting tissue. However, control of angulations and regeneration of the ligamentous tissues within micron-scaled interfaces remains challenging. To overcome this limitation, this study investigated surface fabrications with microgroove patterns to control orientations of rat PDL cells in vitro and fibrous tissues in vivo. After being harvested, rat PDL cells were cultured and three different microgroove patterns (∠PDL groove = 0°, ∠PDL groove = 45°, and ∠PDL groove = 90°) were created by the digital slicing step in 3D printing. Cell-seeded scaffolds were subcutaneously transplanted at 3 and 6 weeks. In histology images, rat PDL cells were spatially controlled to angularly organize following the microgroove patterns and fibrous tissues were formed in scaffolds with specific angulations, which were reflected by additively manufactured microgroove topographies. Based on the results, specifically characterized surface topographies were significant to directly/indirectly organizing rat PDL cell alignments and fibrous tissue orientations. Therefore, interactions between surface topographies and tissue organizations could be one of the key moderators for the multiple tissue complex (bone-ligament-cementum) neogenesis in periodontal tissue engineering.

Comparative Evaluation of Marking Methods on Cast Parts of Al–Si Alloy with Image Processing

Quality issues caused by casting defects are commonly complicated to solve, because the part-specific process parameters are not traced to the individual cast part. This problem can be mitigated by the traceability of each cast part with an identifier code. Therefore, a study of the influence of marked surface topography and post-treatments on code symbol quality is desirable for a well-designed traceability system. In this work, the code symbol quality of laser, dot peen, and electrolytic marking methods on three as-cast surfaces of Al–Si alloy, after sandblasting and heat treatment, is evaluated comparatively with a customized image processing software. The result shows that the laser marking method produces the highest performance for different as-cast surfaces; electrolytic marking provides acceptable results only on the smooth surfaces of high-pressure die casting; dot peen marking produces the codes of high symbol contrasts, which are similar to those of laser marking, especially for rough as-cast surfaces of sand casting. However, for all marking methods, the code qualities of all surface topographies decrease substantially after post-treatments. Considering that dot peen marking has satisfying performances as well as low equipment and maintenance costs, this method is more suitable for small- and medium-size foundries to start to trace each cast part in an economical manner.

The Influence of the Surface Topographical Cues of Biomaterials on Nerve Cells in Peripheral Nerve Regeneration: A Review

The surface topographies of artificial implants including surface roughness, surface groove size and orientation, and surface pore size and distribution have a great influence on the adhesion, migration, proliferation, and differentiation of nerve cells in the nerve regeneration process. Optimizing the surface topographies of biomaterials can be a key strategy for achieving excellent cell performance in various applications such as nerve tissue engineering. In this review, we offer a comprehensive summary of the surface topographies of nerve implants and their effects on nerve cell behavior. This review also emphasizes the latest work progress of the layered structure of the natural extracellular matrix that can be imitated by the material surface topology. Finally, the future development of surface topographies on nerve regeneration was prospectively remarked.

Biocompatibility of Lithium Disilicate and Zirconium Oxide Ceramics with Different Surface Topographies for Dental Implant Abutments

Gingivafibroblasts were cultured on lithium disilicate, on zirconia dioxide, and on titanium with two different surface roughnesses (0.2 µm and 0.07 µm); Proliferation (MTT), Living/Dead staining, cytotoxicity (LDH), proliferation (FGF2), and inflammation (TNFα) were analyzed after 1 day and 21 days. Furthermore, alteration in cell morphology (SEM) was analyzed. The statistical analysis was performed by a Kruskal–Wallis test. The level of significance was set at p < 0.05. There were no distinct differences in cellular behavior between the tested roughness. There were slight differences between tested materials. Cells grown on zirconia dioxide showed higher cytotoxic effects. Cells grown on lithium disilicate showed less expression of TNFα compared to those grown on zirconia dioxide or titanium. These effects persisted only during the first time span. The results indicate that the two tested high-strength ceramics and surface properties are biologically suitable for transmucosal implant components. The findings may help clinicians to choose the most appropriate biomaterial as well as the most appropriate surface treatment to use in accordance with specific clinical dental applications.