Nanophase Metals Research Articles

Temperature-related Variations of 1064 nm Surface Reflectance on Mercury: Implications for Space Weathering

It has been predicted that high equatorial temperatures on Mercury could promote thermal annealing by Ostwald ripening, where nanophase metal particles (a product of space weathering) coalesce and grow into larger, microphase particles, resulting in lower albedo. Here, we test this prediction by studying the correlation between albedo and temperature in 1° spatial bins using newly recalibrated 1064 nm reflectance data acquired by the Mercury Laser Altimeter (MLA), low incidence angle data from the Mercury Dual Imaging System (MDIS), and newly modeled maximum surface temperatures (MSTs). Accounting for local geology and latitude, we compare the reflectance values of surfaces with MSTs >675 K (where Ostwald ripening is predicted to be most effective) to surfaces with MSTs <473 K (where ripening is predicted not to be effective). Smooth plain surfaces >675 K are 10% and 12% darker than surfaces <473 K in MLA and MDIS data, respectively, and nonsmooth plain surfaces >675 K are 8% and 7% darker than surfaces <473 K. However, open questions remain regarding the causation of this darkening; statistical tests cannot distinguish whether the reflectance differences are systematic or the result of compositional variations that happen to correlate with MST. Along Mercury’s thermal longitudes, we find that reflectance is typically lower along hot poles than along the 90°E cold pole in the low-to-midlatitudes, especially in the smooth plains, consistent with previous work identifying a decrease in optical maturity along the 90°E cold pole. Longitudinal reflectance variations correlate with temperature variations, rather than variations in micrometeoroid or solar wind fluxes.

Comparative Analysis of Solution Combustion Method (Self Propagating High Temperature Synthesis) for Synthesis of Nano-phase Metal Oxides with: Mono & Mixed Fuel Approach

Comparative Analysis of Solution Combustion Method (Self Propagating High Temperature Synthesis) for Synthesis of Nano-phase Metal Oxides with: Mono & Mixed Fuel Approach

Correction to: Enhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent Applications, by Choudhary S, Haberstroh KM, and Webster TJ. Tissue Eng Part A 13, 1421, 2007.

Tissue Engineering Part AVol. 26, No. 9-10 CorrectionsFree AccessCorrection to: Enhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent Applications, by Choudhary S, Haberstroh KM, and Webster TJ. Tissue Eng Part A 13, 1421, 2007.is erratum ofEnhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent ApplicationsPublished Online:15 May 2020https://doi.org/10.1089/ten.tea.2006.0376.correxAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail In the July 2007 issue of Tissue Engineering, Part A (vol. 13, no. 7; 1421–1430) in the article titled Enhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent Applications by Saba Choudhary, Karen M. Haberstroh, and Thomas J. Webster, the authors have become aware that two images in the bottom left and bottom right panels of Figure 1 were republished without proper attribution from a previous article by third author Thomas J. Webster and Jeremiah U. Ejiorfor.The images in question originate from the bottom and top panels of Figure 5 in the following article:Webster, T.J., and Ejiorfor, J.U. Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo. Biomaterials 25, 4731, 2004.Both of the publications are from the author's research groups, and the images are their data.The authors apologize for this omission.FiguresReferencesRelatedDetailsRelated articlesEnhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent Applications15 Jul 2007Tissue Engineering Volume 26Issue 9-10May 2020 InformationCopyright 2020, Mary Ann Liebert, Inc., publishersTo cite this article:Correction to: Enhanced Functions of Vascular Cells on Nanostructured Ti for Improved Stent Applications, by Choudhary S, Haberstroh KM, and Webster TJ. Tissue Eng Part A 13, 1421, 2007..Tissue Engineering Part A.May 2020.580-581.http://doi.org/10.1089/ten.tea.2006.0376.correxPublished in Volume: 26 Issue 9-10: May 15, 2020PDF download

Bioinspired Nanostructured Rechargeable Batteries

Biogenic oxidation of water-soluble metal ions into insoluble oxides has been taking place for millions of years leaving its signature all around us. Nature’s evident success in producing nanophase metal oxides is inspiring scientists to understand and learn from these processes. The creation of nanostructured electrode materials for energy storage may represent one of the most attractive strategies and a path forward to dramatically improving the performance of both Li-ion and beyond Li-ion systems. Short diffusion length associated with the nanoscale dimensions effectively reduces the distance that ions and electrons must travel during cycling relative to the equivalent bulk material. Enhanced kinetics significantly improves capacity and rate capability, suppression of phase transformations improves electrochemical reversibility, and the use of defects and high surface area produces high capacity for intercalation. Furthermore, nanomaterials can offer a possible solution to excellent electronic and/or ionic conductivity required for unhindered charge flow with their ability to connect materials and build up structures from the molecular level. Electrochemical synthesis is a facile way for preparation of nanoscale architectures. Utilization of electrochemical deposition brings a high level of control to the structure, morphology, and uniformity of electrodes by adjusting the crucial parameters such as applied current, potential, electric pulses, as well as the temperature and concentration of the electrolyte. Most of the known conventional bulk battery materials may start out as highly crystalline materials but upon many repeated cycles can pulverize overtime leading to non-electrochemically active, and electrically disconnected particles. Our previous work has shown that by starting from amorphous, low-crystalline materials by electrochemical cycling we can create nanostructured electrodes with self-optimized crystalline phases (cycling of TiO2 amorphous nanotubes in Li batteries converted them into cubic titania1). Self-organization of materials during electrochemical cycling could be an easy general approach for synthesis of new, optimized crystalline forms of materials for energy applications. Manganese oxide-based materials are an ideal platform for understanding the underlying properties that determine capacity for a broad spectrum of energy storage chemistries due to the availability of multiple valence states for charge storage and the relative ease and low cost with which they can be synthesized. MnO2 exists in various crystallographic polymorphs, namely α-, ß-, γ, δ-, λ-, and ε-type. These highly crystalline, structurally disordered or amorphous phases show unique electrochemical activity as a result of complex factors such as: structural intergrowths, lattice defects, cation vacancies, random octahedral-unit (MnO6) distribution, proton diffusion, conductivity within the oxide particles. In order to accelerate the implementation of nanostructured systems in beyond Li-ion batteries functional links must be developed between nanoscale materials structure and the resulting performance characteristics. My recent results showed that it is possible to extend reversible ion-insertion chemistry of MnO2 from monovalent Li to ions with higher charge: Zn 2+. Starting from low-crystalline layered manganese oxide upon electrochemical cycling new phase was formed at the nanoscale2. One of the most important prerequisites to understanding this process is the knowledge of the atomic-scale structure of its product. Furthermore, combined with a metal anode, understanding the underlying intercalation mechanism of these systems in a multivalent metal cell and the underlying principles behind reversible intercalation of multivalent ions into a cathode (e.g., intercalation vs conversion and possible structural transformation compared to an aqueous system) is a valuable asset for multivalent cell design. Developing new synthetic electrochemical techniques to better control the nature and structure of nanostructured oxide materials and modify environment of layered oxide materials to tune ability to host various ions will ultimately enable the design of optimal structures that can operate with multiple transporting ions with higher capacity and dramatically improved cycle life. Acknowledgement This work was supported by the U. S. Department of Energy, US DOE-BES, under Contract No. DE-AC02-06CH11357.

Formation of a Nanophase Wetting Layer and Metal Growth on a Semiconductor

Based on the data on the atomic density of a film and degree of its homogeneity during the formation of the interface between 3d transition metals (Cr, Co, Fe, or Cu) and silicon, a new concept of forming a contact between a reactive metal and a semiconductor has been justified. According to this concept, the low-temperature vapor-phase deposition of a metal onto a semiconductor is accompanied by the formation of a two-dimensional nanophase wetting layer of a metal or its mixture with silicon with a thickness of several monolayers, which significantly affects the interface formation and structure. This concept changes a perspective of forming a contact between a metal and a semiconductor substrate: it is necessary to take into account not only the formation of surface phases and clusters and/or the mixing process, but also the effect of elastic wetting of a substrate by the forming phases.

Seasonal and Basinal Influences on the Formation and Transport of Dissolved Trace Metal Forms in a Mining-Impacted Riverine Environment

The release of nanophase metal particles from sulfide mineral decomposition in mining-impacted environments is a growing concern because of the potential for the transport of nanoscale particles that could increase the distribution of the metals and their environmental impact. An analysis of total (unfiltered) and dissolved (450-nm filtered) metal concentrations in the mining-impacted Coeur d’Alene River indicates the leaching of dissolved metal forms from sediments and transport to and within the river. The distribution of metals between total and dissolved forms is driven by seasonal temperatures, hydraulic gradients, and ligand availability. Cd and Zn were the least influenced by changes in gradient and biological productivity between the upper and lower basins. Cd and Zn primarily travel as dissolved forms, with the lowest ratio of dissolved-to-total concentrations in spring and the highest in summer. Fe and Pb primarily travel as suspended particles, but their dissolved forms were greater during all seasons in the lower basin. A principal components analysis of upper basin data indicates that temperature and conductivity were correlated with dissolved Cd and Zn, and total Fe and Pb were correlated with streamflow. In the lower basin, dissolved Cd and Zn, conductivity, and temperature were correlated, and suspended sediment, total metals, and dissolved Pb, but not streamflow, were correlated. The correlation of metals and sediment in the lower basin is not from erosion but the availability of organic matter and Fe that form a range of dissolved to suspended metal particles. The summer decrease in surface water levels releases sediment porewater containing nanoscale-to-microscale metal particles that are transported to open water, where they may impact human and wildlife health. Such releases are unmitigated with current remediation strategies of sediment stabilization.

A lunar dust simulant: CLDS-i

Lunar dust can make serious damage to the spacecrafts, space suits, and health of astronauts, which is one of the most important problems faced in lunar exploration. In the case of rare lunar dust sample, CLDS-i with high similarity to the real lunar dust is an important objective for studying dust protection and dust toxicity. The CLDS-i developed by the Institute of Geochemistry Chinese Academy Sciences contains ∼75vol% glass and a little nanophase metal iron (np-Fe0), and with a median particle size about 500nm. The CLDS-i particles also have complicated shape and sharp edges. These properties are similar to those of lunar dust, and make the CLDS-i can be applied to many fields such as the scientific researches, the treatment technology and toxicological study of lunar dust.

Nanotechnology for Pollution Reduction

Abstract Nanotechnology is regarded as the next great scientific/industrial revolution due to the possibility of designing nanostructured materials that possess novel electronic, optical, magnetic, and catalytic properties. Nanomaterials could potentially be applied in pollution control, catalysis, water remediation, clean energy. Nanocatalysis is a phenomenon of significant research and important practical applications in a variety of fields such as materials, environmental and atmospheric sciences. Low-temperature catalytic oxidation of carbon monoxide (CO) is one of the most important problems in pollution since even small exposures to CO (ppm) can be lethal. Nanophase metal and metal oxide catalysts, with controlled particle size, high surface area, and more densely populated unsaturated surface coordination sites, could potentially provide significantly improved catalytic performance over conventional catalysts. It is therefore, expected that nanoparticle catalysts would show high catalytic activity for the low temperature oxidation of CO than bulk materials. Noble metals are well known oxidation catalysts with high activity and stability, even in the presence of moisture and sulfur compounds, and they are usually used in gas exhaust emissions control. The high cost of precious metals and their sensitivity to sulfur poisoning motivated re-searchers to search for new catalysts. Alloying is a phenomenon that can either improve the catalytic properties of the original single-metal catalysts for CO oxidation. Recently, we reported the effect of support on the catatalytic activity of Au catalyst. We have prepared metallic and bimetallic nanocatalysts on different supports using differ-ent synthesis methods. The catalytic activity of each catalyst was carried out by using a flow tube reactor coupled to an infrared detector. Our results indicate that unsupported AuCu alloy shows higher activity than Au or Cu alone. These results attributed to the formation of CuO within the bimetallic nanoparticles, which improves the catalytic activity of Au-Cu alloy nanoparticle. On the other hand, Au nanoparticles supported on CeO2 exhibit higher catalytic activity than Cu, CuO, and AuCu alloy supported on CeO2. These results attributed to the strong interaction of Au with CeO2.

Recent Advances in Microwave, Millimeter-Wave and Plasma-Assisted Processing of Materials

We present results on microwave, millimeter-wave, and millimeter-wave-driven plasma-assisted processing of materials. The research is primarily based on two systems- a 2.45 GHz, 6 kW S-band system and an 83 GHz, 15 kW gyrotron-based quasi-optical system. The S-Band system is used to synthesize nanophase metals, metal mixtures, and metal oxides by our patented continuous microwave polyol process, which has potential for large scale and low cost production. This system is also being investigated to develop techniques for titanium melting and sintering. The 83-GHz system is used for rapid sintering of ceramic powder compacts to produce polycrystalline materials with limited grain growth. An important application is to the development of polycrystalline laser host materials for high power solid-state lasers, where the requirement is for transparency with high optical quality and good lasing efficiency. We are currently investigating solid-state reactive sintering of Nd-doped YAG (Yttrium Aluminum Garnet) from commercial oxide powders. This has thus far yielded translucent samples with good fluorescence lifetime of the lasing state. Techniques for further reducing light scattering by residual pores are being investigated. Finally, the millimeter-wave system is being used in the development of millimeter-wave plasma-assisted diamond deposition, as the quasi-optical system has significant advantages over conventional microwave plasma-assisted diamond deposition systems. The results and implications of this wide range of materials processing experiments are presented and discussed.

Nano rough micron patterned titanium for directing osteoblast morphology and adhesion

Previous studies have demonstrated greater functions ofosteoblasts (bone-forming cells) on nanophase compared with conventional metals. Nanophase metals possess a biologically inspired nanostructured surface that mimics the dimensions of constituent components in bone, including collagen and hydroxyapatite. Not only do these components possess dimensions on the nanoscale, they are aligned in a parallel manner creating a defined orientation in bone. To date, research has yet to evaluate the effect that organized nanosurface features can have on the interaction of osteoblasts with material surfaces. Therefore, to determine if surface orientation of features can mediate osteoblast adhesion and morphology, this study investigated osteoblast function on patterned titanium substrates containing alternating regions of micron rough and nano rough surfaces prepared by novel electron beam evaporation techniques. This study was also interested in determining whether or not the size of the patterned regions had an effect on osteoblast behavior and alignment. Results indicated early controlled osteoblast alignment on these patterned materials as well as greater osteoblast adhesion on the nano rough regions of these patterned substrates. Interestingly, decreasing the width of the nano rough regions (from 80 microm to 22 microm) on these patterned substrates resulted in a decreased number of osteoblasts adhering to these areas. Changes in the width of the nano rough regions also resulted in changes in osteoblast morphology, thus, suggesting there is an optimal pattern dimension that osteoblasts prefer. In summary, results of this study provided evidence that aligned nanophase metal features on the surface of titanium improved early osteoblast functions (morphology and adhesion) promising for their long term functions, criteria necessary to improve orthopedic implant efficacy.

Improved endothelial cell adhesion and proliferation on patterned titanium surfaces with rationally designed, micrometer to nanometer features

Previous in vitro studies have demonstrated increased vascular endothelial cell adhesion on random nanostructured titanium (Ti) surfaces compared with conventional (or nanometer smooth) Ti surfaces. These results indicated for the first time the potential nanophase metals have for improving vascular stent efficacy. However, considering the structural properties of the endothelium, which is composed of elongated vascular endothelial cells aligned with the direction of blood flow, it has been speculated that rationally designed, patterned nano-Ti surface features could further enhance endothelial cell functions by promoting a more native cellular morphology. To this end, patterned Ti surfaces consisting of periodic arrays of grooves with spacings ranging from 750 nm to 100 μm have been successfully fabricated in the present study by utilizing a novel plasma-based dry etching technique that enables machining of Ti with unprecedented resolution. In vitro rat aortic endothelial cell adhesion and growth assays performed on these substrates demonstrated enhanced endothelial cell coverage on nanometer-scale Ti patterns compared with larger micrometer-scale Ti patterns, as well as controls consisting of random nanostructured surface features. Furthermore, nanometer-patterned Ti surfaces induced endothelial cell alignment similar to the natural endothelium. Since the re-establishment of the endothelium on vascular stent surfaces is critical for stent success, the present study suggests that nanometer to submicrometer patterned Ti surface features should be further investigated for improving vascular stent efficacy.

Recent Advances in Microwave and Millimeter-Wave Processing of Materials

We are using 2.45 GHz (S-Band) microwave systems and an 83-GHz, gytrotron-based, millimeter-wave beam system in material processing and other areas. We use one 2.45 GHz system in preparation of nanophase metals, metal mixtures and metal oxides, via the patented continuous microwave polyol process, with potential for large scale, low cost production. Of interest are precious metals, mixtures of magnetic and nonmagnetic metals, and mixed metal oxides for ceramic precursors. The other S-Band systems are used to develop repair techniques for ceramic matrix composites where the repairs are heated to 200-1000°C. A portable, battery-powered system is being developed for field repairs, and promises to be much more practical than alternative approaches (e.g., heating blankets). The 83-GHz system is being used in rapid sintering of polycrystalline ceramic materials intended for use in high power solid state lasers, where the requirement if for sintering to transparency with high optical quality and good lasing efficiency. Transparent Yb-doped yttria has been produced with hybrid conventional/millimeter-wave sintering of nanophase powders, as well as theoretically dense YAG. Another application for the millimeterwave beam system is in consolidation and bonding of hard coatings to light alloys, such as SiC on titanium, where the beam system allows heating of the coating to very high temperatures without overheating the metallic substrate. Finally, the millimeter-wave system is being used in the development of millimeter-wave plasma-assisted diamond deposition, where the quasi-optical system has significant advantages over conventional microwave plasma-assisted diamond deposition. Results for these various areas will be presented and discussed.

System for continuous production of nanophase materials using a microwave-driven polyol process

A prototype system is described for the large scale, continuous production of nanophase metals, metal oxides, and other nanophase materials using the polyol process. The polyol process employs an organic solvent such as ethylene glycol to reduce a metal oxide/metal salt at high temperature to the metal oxide or metal. The system employs a 6 kW, 2.45 GHz microwave source to rapidly heat the continuously flowing solution to a desired process temperature as it flows through a silica tube placed along the center line of a section of waveguide.

Hope for The Short-Term Use of Nanorough Metallic Implant Formulations in The Clinical Arena

Evaluation of: Webster TJ, Ejiofor JU: Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo. Biomaterials 25, 4731–4739 (2004) [1] . This article reviews a recent paper published in the field of nanotechnology as related to orthopedic implant formulations. Webster and Ejiofor have developed and characterized metals with nanoroughness and have evaluated their efficacy in an in vitro (cellular) setting. The bone-adhesive properties of these materials were found to surpass material formulations that are used currently in the design of orthopedic implants, including hip replacements. Follow-up experiments should focus on other bone and competitive cell lines, examination of subsequent cell functions, such as bone deposition, and testing in the complex in vivo environment of the human body. If successful, this foundation set of experiments will undoubtedly revolutionize the field of bone tissue engineering and replacement.

Pressure effects on grain boundary plasticity in nanophase metals

Grain boundary sliding is often the picture that explains computer simulation results and experiments on plasticity of nanophase materials. Using atomistic computer simulations we perform a detailed study of the effects of high hydrostatic pressure on nanophase Cu plasticity and find that it can be understood in terms of pressure dependent grain boundary sliding controlled by a Mohr-Coulomb law. This result explains recent findings on pressure-induced ultrahigh strength observed in computer simulations of shocks in nanophase Cu reported by Bringa et al. [Science 309, 1838 (2005)].

Increased functions of osteoblasts on nanophase metals

In a recent study, researchers demonstrated that metal surfaces utilizing low-micron to nanophase topography fostered increased adhesion of osteoblasts, the cells that create the matrix of bone. In this study, Ti, Ti6Al4V, and CoCrMo alloys were investigated, and these alloys were identical to current orthopedic implant alloys except for surface topography. The objective of this in vitro research was to determine whether these same nanophase metal surfaces not only foster osteoblast adhesion but also increase osteoblast metabolic activities leading to calcium deposition. Light microscopy and Energy Dispersion Spectroscopy (EDS) were used to verify the presence of calcium and phosphorous deposition by osteoblasts cultured on the metal substrates. Results indicated that both calcium and phosphorous were deposited on several of the metal substrates. More importantly, compared to conventional metals, results provided the first evidence that more calcium and phosphorous was deposited by osteoblasts cultured on respective nanophase metals (Ti, Ti6Al4V, and CoCrMo). Nanophase CoCrMo had the most calcium and phosphorous minerals deposited by osteoblasts compared to any other metal substrate. Thus, the results of this study continue to provide evidence for the use of nanophase metals for the design of the next generation of more successful orthopedic implants.

Microwave–polyol process for metal nanophases

The microwave-assisted polyol process was investigated for the synthesis of severalnanophase metals under different conditions in the temperature range of 100 to200 °C. Nanophase Ag metal particle synthesis using ethylene glycol (EG) was carried out at 100 and150 °C in the presence of polyvinyl pyrrolidone (PVP), dodecyl amine (DDA), oleic acid (OA) ortrioctylphosphine (TOP) to determine whether particle size and shape can be controlled.The Ag particle size was changed with different capping agents. The use of PVP led to welldefined Ag nanoparticles in the range of about 30–50 nm. Morphologically well definednanophase metals of Fe, Co and Ni were produced in the presence of both PVP and DDA,while the use of just PVP or PVP and TOP did not yield such particles. Theresults presented here show that a variety of well defined nanophase metals can beproduced by using the microwave–polyol process and optimizing the metal cappingagents.

Increased osteoblast adhesion on nanophase metals: Ti, Ti6Al4V, and CoCrMo

Previous studies have demonstrated increased functions of osteoblasts (bone-forming cells) on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly lactic-glycolic acid and polyurethane), carbon nanofibers/nanotubes, and composites thereof. Nanophase materials are unique materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to synthesize, characterize, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti, Ti6Al4V, and CoCrMo alloys). Such metals in conventional form are widely used in orthopedic applications. Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional metals. Interestingly, osteoblast adhesion occurred preferentially at surface particle boundaries for both nanophase and conventional metals. Since more particle boundaries are present on the surface of nanophase compared to conventional metals, this may be an explanation for the measured increased osteoblast adhesion. Lastly, material characterization studies revealed that nanometal surfaces possessed similar chemistry and only altered in degree of nanometer surface roughness when compared to their respective conventional counterparts. Because osteoblast adhesion is a necessary prerequisite for subsequent functions (such as deposition of calcium-containing mineral), the present study suggests that nanophase metals should be further considered for orthopedic implant applications.

Directed Osteoblast Adhesion at Particle Boundaries: Promises for Nanophase Metals

AbstractIn spite of under performance, metals and metal alloys are currently being used in orthopedic implantable devices. Poor osseointegration, severe stress shielding, bone cell death and eventual necrotic bone resulting from the generation of wear debris are known to be some of the reasons responsible for their under performance. In addition, metallic corrosion products may also initiate cancer. Steady growth in the use of metals in orthopedic applications inspired researchers to deal with these problems in an integrated way. When conventional Ti, Ti6Al4V, and CoCrMo surfaces were modified to the nano-range, this study showed increased percentages of osteoblast (bone forming cell) adhesion on nanophase metals. Moreover, larger amounts of osteoblast adhesion was related to quantitative increases in the total length of particle boundaries per unit area and the total number of pores between surface particles per unit area, and the surface particle boundary index (SPBI) of nanophase metals. Additionally, we have developed a novel anticarcinogenic orthopedic metalloid, selenium (Se). When micron range surface particles of Se compacts were modified to the nano-range by chemical etching, we found positive relationships between directed osteoblast adhesion and various particle boundary parameters mentioned above under in vitro conditions. These results provided the first evidence to utilize nanosurface Se as an anticarcinogenic and bio-inspiring material for future applications in orthopedic metallic devices.

Effect of Metal Substrate Nanometer Topography on Osteoblast Metabolic Activities

AbstractSurgeons and bioengineers have continuously been challenged by implant failure. Many of these engineers and surgeons trace implant failure to poor osseointegration (the bonding of an orthopedic implant to juxtaposed bone) and to the inability of implants to match the physical properties of surrounding bone. Researchers have recently shown that nanostructured materials (or materials with fundamental length scales less than 100 nm) enhance cell functions pertinent to effectively regenerating the tissue of numerous organs. Specifically, in a recent study, researchers demonstrated that metal surfaces utilizing low-micron to nanophase topography fostered increased adhesion of osteoblasts, the cells that create the matrix of bone. In this study, Ti, Ti6Al4V, and CoCrMo alloys were investigated, and these alloys were identical to current orthopedic implant alloys except for surface topography. The objective of this in vitro research was to determine whether these same nanophase metal surfaces not only foster osteoblast adhesion but also increase osteoblast metabolic activities leading to bone regeneration. Light microscopy and Energy Dispersion Spectroscopy (EDS) were used to verify the presence of calcium and phosphorous deposition by osteoblasts cultured on the metal substrates. Results indicated that both calcium and phosphorous are being deposited on several of the metal substrates. More importantly, compared to conventional metals, results provided the first evidence that more calcium and phosphorous was deposited by osteoblasts cultured on respective nanophase metals (Ti, Ti6Al4V, and CoCrMo). Nanophase CoCrMo had the most calcium and phosphorous minerals deposited by osteoblasts compared to any other metal substrate. Thus, the results of this study continue to provide evidence for the use of nanophase metals for the design of the next generation of more successful orthopedic implants.