Increased Osteoblast Adhesion Research Articles

In vitro comparison of titanium surface conditioning via boron-compounds and sand-blasting acid-etching

The aim of this study was to compare the effect of a boron-based titanium (Ti) surface treatment methods against the conventional sand-blasting & acid-etching method.A total of 216 machined titanium (Ti) discs were divided into four equal groups and the following surface treatments were applied; Aluminum oxide (Al2O3) sand-blasting and hydrochloric/ sulfuric acid (HCl/H2SO4) etching (SLA). Aluminum oxide (Al2O3) with boric acid (H3BO3) particle sand-blasting and tetrafluoroboric acid (HBF4) etching (SBF). Wetting of the SBF surface by boric acid-solution (SBF-B). Aluminum oxide (Al2O3) sand-blasting and tetrafluoroboric acid (HBF4) etching (SAF). Confocal laser scanning microscopy, stylus profilometry, scanning electron microscopy and X-ray photoelectron spectroscopy were used for the quantification of the surface characteristics. Adhesion and viability of Porphyromonas gingivalis and Streptococcus mutans, osteocalcin production and viability of human fetal osteoblastic cells were quantified by cell cultures and lysate analyses. Results were analyzed by non-parametric tests (p<0.05).Surface area roughness parameters were similar in all specimens with an arithmetical mean height (Sa) of 1.6 (SD: 0.6) μm. SBF-B surface yielded the highest cell viability/proliferation (187.5%, IQR: 37.5; p=0.0231), osteocalcin production (228.9 ng/ml IQR: 14.1; p<0.0001), and also the lowest adhesion rate for both bacteria (45 × 102 CFU/ml (IQR: 22.5 × 102)) and (290 × 103 CFU/ml (IQR: 45.5 × 103)) for P.gingivalis and S.mutans, respectively; p=0.0002). SLA, SBF and SAF surfaces revealed inferior outcomes as compared to the SBF-B surface.Within the limits of the in vitro investigation it can be concluded that, boric acid-wetting of the aluminum oxide-blasted, boric acid-blasted, and tetrafluoroboric acid etched Ti surface (SBF-B) increase osteoblast adhesion and reduce the bacterial adherence.

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

Incorporation of nanostructured hydroxyapatite and poly(N-isopropylacrylamide) in demineralized bone matrix enhances osteoblast and human mesenchymal stem cell activity.

Demineralized bone matrix (DBM) is currently used in many clinical applications for bone augmentation and repair. DBM is normally characterized by the presence of bone morphogenetic proteins. In this study, the authors have optimized methods to obtain DBM under good manufacturing practice, resulting in enhanced bioactivity. The processed DBM can be used alone, together with nanostructured hydroxyapatite (nanoHA), or dispersed in a physiological carrier or hydrogel. In this study, osteoblasts (MG-63) and human bone marrow derived mesenchymal stem cells (hMSCs) were cultured on DBM pastes made in phosphate buffered saline solution or poly(N-isopropylacrylamide) (PNIPAAM) hydrogels with or without nanoHA. The authors observed that the presence of PNIPAAM reduced osteoblast adhesion, while the addition of nanoHA increased osteoblast adhesion, proliferation, interleukin-6 (IL-6) production, and reduced lactate dehydrogenase (LDH) production. Increasing concentrations of PNIPAAM in combination with nanoHA further increased osteoblast proliferation, and decreased IL-6 and LDH production. Incorporation of PNIPAAM in DBM enhanced hMSCs proliferation and collagen type-I production. Furthermore, a combination of PNIPAAM and nanoHA further increased alkaline phosphatase and osteocalcin production in hMSCs, independently from the concentration of PNIPAAM. This study shows that combinations of DBM with nanoHA and PNIPAAM seem to offer a promising route to enhance cell activity and induce osteogenic differentiation.

Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions

Current titanium-based implants are often anodized in sulfuric acid (H2SO4) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications.

Increased osteoblast adhesion on physically optimized KRSR modified calcium aluminate

Calcium aluminate (CA) is a porous biocompatible material easily cast at room temperature. Through this casting process, the average surface pore size of CA was varied from an average of 100 to 290 microns. The optimal surface pore size of the hydrated CA for cell viability was determined to be 100 microns. Further, a three step-solution deposition technique was developed to covalently immobilize cell adhesion peptides, RGD, and KRSR to the CA surface. Cell adhesion for 1-, 4-, and 7-day time periods was tested with primary osteoblasts and NIH 3T3 fibroblasts. Both peptides were found to increase fibroblast adhesion to the CA surface. However, only KRSR increased osteoblast adhesion to the surface of the CA, which may aid in bone formation after implantation.

An XPS study on the covalent immobilization of adhesion peptides on a glass surface

Covalent attachment of adhesive peptides to biomaterials surfaces can result in the formation of a bioactive and biomimetic surface. We have demonstrated that titanium surfaces grafted with adhesion peptides, reproducing sequences of fibronectin and vitronectin, can increase osteoblast adhesion compared to non-treated surfaces. We now extend our investigation to peptide immobilization on glass for studying human osteoblast adhesion and spreading. Silanization was used to anchor adhesion peptides to the glass surface through a selective or a non-selective immobilization. Investigated samples were analysed by XPS spectroscopy. Comparison between the results obtained using two different peptides and applying selective and non-selective immobilization will be discussed.

Surface Electric Fields Increase Osteoblast Adhesion through Improved Wettability on Hydroxyapatite Electret

Osteoblasts are susceptible to the surface characteristics of bioceramics and stimulation from outside the cells. The purpose of this study was to evaluate the effects of electrical polarization on surface characteristics and osteoblastic adhesion. The surface characteristics revealed that electrical polarization had no effect on the surface roughness, crystallinity, and constituent elements. According to contact-angle measurements, electrically polarized hydroxyapatite (HA), which provides two kinds of surfaces, negatively charged HA (N-HA) and positively charged HA (P-HA), was even more hydrophilic than that of normal HA (O-HA). Morphological observations and quantitative analyses revealed that the typical adhered cells had a round shape on O-HA but had a spindle or fanlike spreading configuration on N-HA and P-HA 1 h after seeding. After 3 h of cultivation, the rate of the number of spread cells and the size of the focal adhesions on O-HA increased and approached that of N-HA and P-HA. However, the cell areas positively stained for actin, which indicates the degree of cell spreading, were distinctly larger on N-HA and P-HA than that on O-HA. The number of focal adhesions per cell was also less than that on N-HA and P-HA.

An understanding of enhanced osteoblast adhesion on various nanostructured polymeric and metallic materials prepared by ionic plasma deposition

The development of new materials through novel surface modification techniques to enhance orthopedic implant lifetimes (hence, decreasing the need for revision surgery) is of great interest to the medical community. The purpose of this in vitro study was to treat common metallic implant materials [such as titanium (Ti) and a titanium alloy (Ti6Al4V)] and traditional polymeric materials (like polyethylene terephthalate, polyvinyl chloride, polyurethane, polytetrafluoroethylene, ultra-high molecular weight polyethylene (UHMWPE) and nylon) with either nanoparticulate alumina or titanium using novel (i) ionic plasma deposition (IPD) and (ii) nitrogen ion immersion plasma deposition (NIIPD) techniques. The treated surfaces were characterized by scanning electron microscopy, atomic force microscopy and surface energy, demonstrating greater nanoscale roughness on the modified surfaces regardless of the underlying material or coating applied. These surface-modified substrates were also tested for cytocompatibility properties with osteoblasts (or bone-forming cells). Results showed increased osteoblast adhesion on modified compared to control (traditional or untreated) materials. Since the adhesion of osteoblasts is the first crucial step for new bone synthesis, these results are very promising and suggest that the plasma deposition processes used in this study should be further investigated to improve the longevity of orthopedic implants.

Increased osteoblast adhesion on nanophase Ti6Al4V

The objective of the present study was to prepare a novel nanostructured surface of Ti6Al4V alloy by the severe plastic deformation (SPD) and the chemical treatment process and to evaluate the adhesion of osteoblast on the nanophase titanium alloy. In the in vitro study, the primary cultured osteoblasts of neonatal rat calvaria were cultured on the nanophase and the as-received smooth Ti6Al4V substrates. Then osteoblasts adhesion behaviors on different substrates were observed by the fluorescence microscopy, scanning electron microscopy (SEM) and RT-PCR analysis. The results of our research showed increased osteoblast adhesion on the nanophase titanium alloy compared with the as-received case. On the nanophase substrate, the presence of extensive filopodia, strong cellular adhesion and early cellular confluency could be observed. In addition, the expression of the adhesion-related integrin β1 mRNA was also higher on the nanophase substrate. It suggested that the nano technology could be further considered for orthopedic implant applications.

Covalent surface modification of titanium oxide with different adhesive peptides: Surface characterization and osteoblast‐like cell adhesion

A fundamental goal in the field of implantology is the design of innovative devices suitable for promoting implant-to-tissue integration. This result can be achieved by means of surface modifications aimed at optimizing tissue regeneration. In the framework of oral and orthopedic implantology, surface modifications concern both the optimization of titanium/titanium alloy surface roughness and the attachment of biochemical factors able to guide cellular adhesion and/or growth. This article focuses on the covalent attachment of two different adhesive peptides to rough titanium disks. The capability of biomimetic surfaces to increase osteoblast adhesion and the specificity of their biological activity due to the presence of cell adhesion signal-motif have also been investigated. In addition, surface analyses by profilometry, X-ray photoelectron spectroscopy, and time of flight-secondary ion mass spectrometry have been carried out to investigate the effects and modifications induced by grafting procedures.

An in vitro evaluation of the Ca/P ratio for the cytocompatibility of nano-to-micron particulate calcium phosphates for bone regeneration

Calcium phosphate based bioceramics have been widely used for orthopedic applications due to their chemical similarity to natural bone. The Ca/P stoichiometry of calcium phosphates strongly influences their performance under biological conditions, which have not yet been fully elucidated to date. For this reason, the objective of this in vitro study was to understand the relationship between the Ca/P ratio of nano-to-micron particulate calcium phosphate substrates and their biological properties, such as osteoblast (bone-forming cell) viability, collagen production, alkaline phosphatase activity and nitric oxide (NO) production. A group of calcium phosphates with Ca/P ratios between 0.5 and 2.5 were obtained by intentionally adjusting the Ca/P stoichiometry of the initial reactants necessary for calcium phosphate precipitation. For samples with 0.5 and 0.75 Ca/P ratios, tricalcium phosphate (TCP) and Ca 2P 2O 7 phases were observed. In contrast, for samples with 1.0 and 1.33 Ca/P ratios, the only stable phase was TCP. For samples with a 1.5 Ca/P ratio, the TCP phase was dominant; however, small amounts of the hydroxyapatite (HA) phase started to appear. For samples with a 1.6 Ca/P ratio, the HA phase was dominant. Lastly, for samples with 2.0 and 2.5 Ca/P ratios, the CaO phase started to appear in the HA phase which was the dominant phase. Moreover, the average grain size and the average pore size decreased from micron-scale (e.g. 1370 nm for a 0.5 Ca/P ratio) to nano-scale (e.g. 262 nm for a 2.5 Ca/P ratio) with increasing Ca/P ratios. The porosity (%) of calcium phosphate substrates also decreased with increasing Ca/P ratios. Previous in vitro results demonstrated increased osteoblast adhesion on calcium phosphates with higher Ca/P ratios (up to 2.5). The present study showed that the collagen production by osteoblasts was similar between all the calcium phosphates but slightly lower with a 1.6 Ca/P ratio. Greater alkaline phosphatase activity by osteoblasts was observed in all the cultures with various calcium phosphates (0.5–2.5 Ca/P ratios) than in the control (only cells in culture). Ca/P ratios of <2 and 1 optimized osteoblast viability and promoted alkaline phosphatase activity in osteoblasts, respectively. However, the presence of the CaO phase in Ca/P ratios ⩾2.0 increased osteoblast NO production and decreased osteoblast viability. In summary, this study provided evidence that the Ca/P ratio of calcium phosphate is a very important factor that should be considered when selecting nano-to-micron particulate calcium phosphates for various orthopedic applications.

Increased osteoblast adhesion on nano structured selenium- a promising material for orthopedic applications

Metallic bone implants possess numerous problems limiting their efficacy, such as poor osseointegration, stress shielding, and corrosion under in vivo environments. In addition, these materials were not originally developed to simultaneously serve as an orthopedic implant and treat bone cancer (for which some patients require an orthopedic implant). The objective of this study was to investigate the potential of selenium as a bone implant material to prevent bone cancer from re-occurring and support new healthy bone growth. For this, selenium (spherical or semispherical shots) was pressed into compacts and then etched using NaOH to obtain various surface structures ranging from the micron, sub micron to nano scales. Elemental selenium was also coated on titanium substrates at different coverage levels using selenium salt reduction by glutathione. Through these etching and coating techniques, biologically-inspired nano surface roughness values were created on selenium compacts and selenium coated on titanium to match those of natural bone. Increased osteoblast (bone-forming cells) adhesion was observed on the more rough selenium compacts and on titanium substrates with higher levels of selenium coverage. In this manner, this study suggests a promising future for nanostructured selenium in orthopedic applications involving bone cancer treatment

Increased osteoblast adhesion on nanoparticulate calcium phosphates with higher Ca/P ratios

The biological properties of calcium phosphate-derived materials are strongly influenced by changes in Ca/P stoichiometry and grain size, which have not yet been fully elucidated to date. For this reason, the objective of this in vitro study was to understand osteoblast (bone forming cells) adhesion on nanoparticulate calcium phosphates of various Ca/P ratios. A group of calcium phosphates with Ca/P ratios between 0.5 and 2.5 were obtained by adjusting the Ca/P stoichiometry of the initial reactants necessary for calcium phosphate precipitation. For samples with 0.5 and 0.75 Ca/P ratios, tricalcium phosphate (TCP) and Ca(2)P(2)O(7) phases were observed. In contrast, for samples with 1.0 and 1.33 Ca/P ratios, the only stable phase was TCP. For samples with 1.5 Ca/P ratios, the TCP phase was dominant, however, small amounts of the hydroxyapatite (HA) phase started to appear. For samples with 1.6 Ca/P ratios, the HA phase was dominant. Last, for samples with 2.0 and 2.5 Ca/P ratios, the CaO phase started to appear in the HA phase, which was the dominant phase. Moreover, the average nanometer grain size, porosity (%), and the average pore size decreased in general with increasing Ca/P ratios. Most importantly, results demonstrated increased osteoblast adhesion on calcium phosphates with higher Ca/P ratios (up to 2.5). In this manner, this study provided evidence that Ca/P ratios should be maximized (up to 2.5) in nanoparticulate calcium phosphate formulations to increase osteoblast adhesion, a necessary step for subsequent osteoblast functions such as new bone deposition.

TiO2 nanotubes functionalized with regions of bone morphogenetic protein‐2 increases osteoblast adhesion

Titanium (Ti) and its alloys are widely used in orthopedic and dental applications. However, the native TiO2 layer is not bioactive enough to form a direct bond with bone, which sometimes translates into a lack of osseointegration into juxtaposed bone that might lead to long term implant failure. In this study, the 20 amino acid peptide sequence (the so-called "knuckle epitope") of bone morphogenetic protein-2 (BMP-2) was immobilized onto Ti nanotubes created by electrochemical anodization. Further, human osteoblast (bone-forming cell) responses to such anodic Ti oxides functionalized with the BMP-2 knuckle epitope was examined in vitro. Materials were characterized by scanning electron and atomic force microscopy. Results of this in vitro study continued to provide evidence of increased osteoblast adhesion on Ti anodized to possess nanotubes compared to unanodized Ti. However, for the first time, results also showed that the immobilization of the BMP-2 knuckle epitope onto Ti anodized to possess nanotubes increased osteoblast adhesion compared to non-functionalized anodized Ti, anodized Ti functionalized with amine (NH2) groups, and unanodized Ti after 4 h. Results also showed increased osteoblast adhesion on amine terminated anodized Ti compared to respective non-functionalized anodized Ti and unanodized Ti. In summary, results of this in vitro study provided evidence that Ti anodized to possess nanotubes and then further functionalized with the BMP-2 knuckle epitope should be further studied for improved orthopedic applications.

Increased osteoblast adhesion on nanograined hydroxyapatite and tricalcium phosphate containing calcium titanate

Increased osteoblast adhesion on nanograined hydroxyapatite and tricalcium phosphate containing calcium titanate

Increased osteoblast adhesion on nanograined Ti modified with KRSR

Peptide sequences such as lysine-arginine-serine-arginine (KRSR) selectively bind transmembrane proteoglycans (e.g. heparin sulfate) of osteoblasts (bone-forming cells) and are, therefore, actively being investigated for orthopedic applications. Further, nanophase materials (or materials with grain or particle sizes less than 100 nm) are promising new materials that promote new bone growth more than compared to conventional (that is, micron grain or particle size) materials. To combine the above two promising approaches for improving orthopedic implants, the objective of this in vitro study was to functionalize titanium (Ti) surfaces (both nanophase and conventional) with KRSR peptides and study their osteoblast cell adhesive properties. Materials were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. Results of this in vitro study provided evidence of increased osteoblast adhesion on nanophase compared to conventional Ti whether functionalized with KRSR or not. Results further showed that the immobilization of KRSR onto Ti (both nanophase and conventional) increased osteoblast adhesion compared to respective nonfunctionalized Ti and those functionalized with the negative control peptide KSRR. Most importantly, osteoblast adhesion on nonfunctionalized nanophase Ti increased compared to conventional Ti functionalized with KRSR. Further, select initial osteoblast adhesion was observed to occur at particle boundaries for any type of nanophase and conventional Ti formulated in this study. In summary, results provided evidence that not only should nonfunctionalized nanophase Ti be further studied for improved orthopedic applications but so should nanophase Ti functionalized with KRSR.

Increased osteoblast adhesion on nanograined hydroxyapatite and tricalcium phosphate containing calcium titanate

Depending on the coating method utilized and subsequent heat treatments (such as through the use of plasma-spray deposition), inter-diffusion of atomic species across titanium (Ti) and hydroxyapatite (HA) coatings may result. These events may lead to structural and compositional changes that consequently cause unanticipated HA phase transformations which may clearly influence the performance of an orthopedic implant. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), HA doped with Ti, and those containing calcium titanate (CaTiO(3)). In doing so, results of this study showed that osteoblast (bone-forming cells) adhesion increased with greater CaTiO(3) substitutions in either HA or TCP. Specifically, osteoblast adhesion on HA and TCP composites with CaTiO(3) was almost 4.5 times higher than that over pure HA. Material characterization studies revealed that enhanced osteoblast adhesion on these compacts may be due to increasing shrinkage in the unit lattice parameters and decreasing grain size. Although all CaTiO(3) composites exhibited excellent osteoblast adhesion results, Ca(9)HPO(4)(PO(4))(5)OH phase transformation into TCP/CaTiO(3) increased osteoblast adhesion the most; because of these reasons, these materials should be further studied for orthopedic applications.

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.

Increased osteoblast and decreased Staphylococcus epidermidis functions on nanophase ZnO and TiO2

Many engineers and surgeons trace implant failure to poor osseointegration (or the bonding of an orthopedic implant to juxtaposed bone) and/or bacteria infection. By using novel nanotopographies, researchers have shown that nanostructured ceramics, carbon fibers, polymers, metals, and composites enhance osteoblast adhesion and calcium/phosphate mineral deposition. However, the function of bacteria on materials with nanostructured surfaces remains largely uninvestigated. This is despite the fact that during normal surgical insertion of an orthopedic implant, bacteria from the patient's own skin and/or mucosa enters the wound site. These bacteria (namely, Staphylococcus epidermidis) irreversibly adhere to an implant surface while various physiological stresses induce alterations in the bacterial growth rate leading to biofilm formation. Because of their integral role in determining the success of orthopedic implants, the objective of this in vitro study was to examine the functions of (i) S. epidermidis and (ii) osteoblasts (or bone-forming cells) on ZnO and titania (TiO(2)), which possess nanostructured compared to microstructured surface features. ZnO is a well-known antimicrobial agent and TiO(2) readily forms on titanium once implanted. Results of this study provided the first evidence of decreased S. epidermidis adhesion on ZnO and TiO(2) with nanostructured when compared with microstructured surface features. Moreover, compared with microphase formulations, results of this study showed increased osteoblast adhesion, alkaline phosphatase activity, and calcium mineral deposition on nanophase ZnO and TiO(2). In this manner, this study suggests that nanophase ZnO and TiO(2) may reduce S. epidermidis adhesion and increase osteoblast functions necessary to promote the efficacy of orthopedic implants.

Increased osteoblast adhesion on nanograined hydroxyapatite and partially stabilized zirconia composites

To improve the mechanical properties of hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) for orthopedic applications, numerous investigators have proposed combining HA with high strength materials, specifically zirconia. Despite the fact that, compared to pure HA, it is now well-established that zirconia and HA composites have improved mechanical properties, the cytocompatibility properties of this composite remain largely uninvestigated. For these reasons, the objective of the present in vitro study was to synthesize HA and partially stabilized zirconia composites for osteoblast (bone-forming cell) adhesion assays. Various sintering temperatures and amounts of zirconia in HA composites were used in order to ascertain their influence on osteoblast adhesion. Results demonstrated increased interactions between HA and partially stabilized zirconia, when either higher sintering temperatures (between 900 and 1,300 degrees C for 1 h) or higher zirconia contents (between 10 and 40 wt %) were used during material synthesis. More importantly, greater osteoblast adhesion was measured on HA-zirconia composites sintered either at lower temperatures (specifically, 900 degrees C) or with lower amounts of zirconia added to HA composites (specifically, 10 wt %). Results further indicated that when sintered at lower temperatures the composites possessed smaller nanometer grain sizes with increased surface roughness and a more stable HA phase. For these reasons, this study suggests that to optimize osteoblast adhesion on HA and partially stabilized zirconia composites for orthopedic applications, low sintering temperatures and low amounts of zirconia should be used. This suggests that a delicate balance must be reached between increasing mechanical properties of HA without decreasing osteoblast cytocompatibility properties through zirconia addition.