Osteoblast responses to different oxide coatings produced by the sol-gel process on titanium substrates

Advanced Antimicrobial and Anti-Infective Strategies to Manage Peri-Implant Infection: A Narrative Review

Despite reductions in bacterial infection and enhanced success rate, the widespread use of systemic antibiotic prophylaxis in implant dentistry is controversial. This use has contributed to the growing problem of antimicrobial resistance, along with creating significant health and economic burdens. The basic mechanisms that cause implant infection can be targeted by new prevention and treatment methods which can also lead to the reduction of systemic antibiotic exposure and its associated adverse effects. This review aims to summarize advanced biomaterial strategies applied to implant components based on anti-pathogenic mechanisms and immune balance mechanisms. It emphasizes that modifying the dental implant surface and regulating the early immune response are promising strategies, which may further prevent or slow the development of peri-implant infection, and subsequent failure.

Nonthermal Atmospheric Pressure Plasma Treatment of Endosteal Implants for Osseointegration and Antimicrobial Efficacy: A Comprehensive Review

The energy state of endosteal implants is dependent on the material, manufacturing technique, cleaning procedure, sterilization method, and surgical manipulation. An implant surface carrying a positive charge renders hydrophilic properties, thereby facilitating the absorption of vital plasma proteins crucial for osteogenic interactions. Techniques to control the surface charge involve processes like oxidation, chemical and topographical adjustments as well as the application of nonthermal plasma (NTP) treatment. NTP at atmospheric pressure and at room temperature can induce chemical and/or physical reactions that enhance wettability through surface energy changes. NTP has thus been used to modify the oxide layer of endosteal implants that interface with adjacent tissue cells and proteins. Results have indicated that if applied prior to implantation, NTP strengthens the interaction with surrounding hard tissue structures during the critical phases of early healing, thereby promoting rapid bone formation. Also, during this time period, NTP has been found to result in enhanced biomechanical fixation. As such, the application of NTP may serve as a practical and reliable method to improve healing outcomes. This review aims to provide an in-depth exploration of the parameters to be considered in the application of NTP on endosteal implants. In addition, the short- and long-term effects of NTP on osseointegration are addressed, as well as recent advances in the utilization of NTP in the treatment of periodontal disease.

Emerging factors affecting peri-implant bone metabolism

Implant dentistry has evolved to the point that standard implant osseointegration is predictable. This is attributed in part to the advancements in material sciences that have led toward improvements in implant surface technology and characteristics. Nonetheless, there remain several cases where implant therapy fails (specifically at early time points), most commonly attributed to factors affecting bone metabolism. Among these patients, smokers are known to have impaired bone metabolism and thus be subject to higher risks of early implant failure and/or late complications related to the stability of the peri-implant bone and mucosal tissues. Notably, however, emerging data have unveiled other critical factors affecting osseointegration, namely, those related to the metabolism of bone tissues. The aim of this review is to shed light on the effects of implant-related factors, like implant surface or titanium particle release; surgical-related factors, like osseodensification or implanted biomaterials; various drugs, like selective serotonin reuptake inhibitors, proton pump inhibitors, anti-hypertensives, nonsteroidal anti-inflammatory medication, and statins, and host-related factors, like smoking, diet, and metabolic syndrome on bone metabolism, and aseptic peri-implant bone loss. Despite the infectious nature of peri-implant biological complications, these factors must be surveyed for the effective prevention and management of peri-implantitis.

Characterization of aTiO2 surfaces functionalized with CAP-p15 peptide

Functionalization of Titanium implants using adequate organic molecules is a proposed method to accelerate the osteointegration process, which relates to topographical, chemical, mechanical, and physical features. This study aimed to assess the potential of a peptide derived from cementum attachment protein (CAP-p15) adsorbed onto aTiO2 surfaces to promote the deposition of calcium phosphate (CaP) minerals and its impact on the adhesion and viability of human periodontal ligament cells (hPDLCs). aTiO2 surfaces were synthesized by magnetron sputtering technique. The CAP-p15 peptide was physically attached to aTiO2 surfaces and characterized by atomic force microscopy, fluorescence microscopy, and water contact angle measurement. We performed in vitro calcium phosphate nucleation assays using an artificial saliva solution (pH 7.4) to simulate the oral environment. morphological and chemical characterization of the deposits were evaluated by scanning electronic microscopy (SEM) and spectroscopy molecular techniques (Raman Spectroscopy, ATR-FTIR). The aTiO2 surfaces biofunctionalized with CAP-p15 were also analyzed for hPDLCs attachment, proliferation, and in vitro scratch-healing assay. The results let us see that the homogeneous amorphous titanium oxide coating was 70 nanometers thick. The CAP-p15 (1 μg/mL) displayed the ability to adsorb onto the aTiO2 surface, increasing the roughness and maintaining the hydrophilicity of the aTiO2 surfaces. The physical adsorption of CAP-p15 onto the aTiO2 surfaces promoted the precipitation of a uniform layer of crystals with a flake-like morphology and a Ca/P ratio of 1.79. According to spectroscopy molecular analysis, these crystalline deposits correspond to carbonated hydroxyapatite. Regarding cell behavior, the biofunctionalized aTiO2 surfaces improved the adhesion of hPDLCs after 24 h of cell culture, achieving 3.4-fold when compared to pristine surfaces. Moreover, there was an increase in cell proliferation and cell migration processes. Physical adsorption of CAP-p15 onto aTiO2 surfaces enhanced the formation of carbonate hydroxyapatite crystals and promoted the proliferation and migration of human periodontal ligament-derived cells in in vitro studies. This experimental model using the novel bioactive peptide CAP-p15 could be used as an alternative to increasing the osseointegration process of implants.

Evaluation of the Biocompatibility and Osteogenic Properties of Metal Oxide Coatings Applied by Magnetron Sputtering as Potential Biofunctional Surface Modifications for Orthopedic Implants

Biomaterials with adequate properties to direct a biological response are essential for orthopedic and dental implants. The surface properties are responsible for the biological response; thus, coatings with biologically relevant properties such as osteoinduction are exciting options to tailor the surface of different bulk materials. Metal oxide coatings such as TiO₂, ZrO₂, Nb₂O₅ and Ta₂O₅ have been suggested as promising for orthopedic and dental implants. However, a comparative study among them is still missing to select the most promising for bone-growth-related applications. In this work, using magnetron sputtering, TiO₂, ZrO₂, Ta₂O₅, and Nb₂O₅ thin films were deposited on Si (100) substrates. The coatings were characterized by Optical Profilometry, Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, X-ray Photoelectron Spectroscopy, X-ray Diffraction, Water Contact Angle measurements, and Surface Free Energy calculations. The cell adhesion, viability, proliferation, and differentiation toward the osteoblastic phenotype of mesenchymal stem cells plated on the coatings were measured to define the biological response. Results confirmed that all coatings were biocompatible. However, a more significant number of cells and proliferative cells were observed on Nb₂O₅ and Ta₂O₅ compared to TiO₂ and ZrO_2. Nevertheless, Nb₂O₅ and Ta₂O₅ seemed to induce cell differentiation toward the osteoblastic phenotype in a longer cell culture time than TiO₂ and ZrO₂.

Reactivity and Corrosion Behaviors of Ti6Al4V Alloy Implant Biomaterial under Metabolic Perturbation Conditions in Physiological Solutions

The corrosion of implant biomaterials is a well-known critical issue when they are in contact with biological fluids. Therefore, the reactivity of Ti6Al4V implant biomaterials is monitored during immersion in a Hanks’ physiological solution without and with added metabolic compounds, such as lactic acid, hydrogen peroxide, and a mixture of the two. Electrochemical characterization is done by measuring the open circuit potential and electrochemical impedance spectroscopy performed at different intervals of time. Electrochemical results were completed by morphological and compositional analyses as well as X-ray diffraction before and after immersion in these solutions. The results indicate a strong effect from the inflammatory product and the synergistic effect of the metabolic lactic acid and hydrogen peroxide inflammatory compound on the reactivity and corrosion resistance of an implant titanium alloy.

Bio-corrosion behavior, antibacterial property and interaction with osteoblast of laserin-situfabricated Ti-Si-Cu coatings on Ti-6Al-4V alloy

Ti-Si-xCu coatings (TS-xC,x= 5, 10 and 15 wt.%) with advanced bio-corrosion resistance, excellent antibacterial property and biocompatibility were laser cladded on Ti-6Al-4V (TAV) substrate which is widely used as endosseous implants. The bio-corrosion resistance of the TAV substrate was improved due to the presence of Ti₅Si₃and TiCu phases in the coatings. The addition of Cu in the precursor contributes to the improvement of the antibacterial property of TAV substrate. Meanwhile, induced normal cytoskeleton, well-developed focal adhesion contacts, significant higher cell attachment and proliferation rate were observed for the TS-xC coated samples due to the formation of micro-textured morphology and presence of new phases. The bio-corrosion resistance and antibacterial property depend on Cu content addition in the TS-xC precursor. The results provide a way to fabricate such multiple functional biocoating that would improve the bio-corrosion resistance, antibacterial performance and biocompatibility of TAV.

Sputtered crystalline TiO2 film drives improved surface properties of titanium-based biomedical implants

Different crystalline phases in sputtered TiO₂ films were tailored to determine their surface and electrochemical properties, protein adsorption and apatite layer formation on titanium-based implant material. Deposition conditions of two TiO₂ crystalline phases (anatase and rutile) were established and then grown on commercially pure titanium (cpTi) by magnetron sputtering to obtain the following groups: A-TiO₂ (anatase), M-TiO₂ (anatase and rutile mixture), R-TiO₂ (rutile). Non-treated commercially pure titanium (cpTi) was used as a control. Surfaces characterization included: chemical composition, topography, crystalline phase and surface free energy (SFE). Electrochemical tests were conducted using simulated body fluid (SBF). Albumin adsorption was measured by bicinchoninic acid method. Hydroxyapatite (HA) precipitation was evaluated after 28 days of immersion in SBF. MC3T3-E1 cell adhesion, morphology and spreading onto the experimental surfaces were evaluated by scanning electron microscopy. Sputtering treatment modified cpTi topography by increasing its surface roughness. CpTi and M-TiO₂ groups presented the greatest SFE. In general, TiO₂ films displayed improved electrochemical behavior compared to cpTi, with M-TiO₂ featuring the highest polarization resistance. Rutile phase exhibited a greater influence on decreasing the current density and corrosion rate, while the presence of a bi-phasic polycrystalline condition displayed a more stable passive behavior. M-TiO₂ featured increased albumin adsorption. HA morphology was dependent on the crystalline phase, being more evident in the bi-phasic group. Furthermore, M-TiO₂ displayed normal cell adhesion and morphology. The combination of anatase and rutile structures to generate TiO₂ films is a promising strategy to improve biomedical implants properties including greater corrosion protection, higher protein adsorption, bioactivity and non-cytotoxicity effect.

Addition of Sn to TiNb alloys to improve mechanical performance and surface properties conducive to enhanced cell activity

Titanium (Ti) alloys with Niobium (Nb) and Tin (Sn) were prepared in order to conduct a systematic study on the bulk and surface properties of as-cast c.p.Ti, binary Ti-40Nb and Ti-10Sn, and ternary Ti-10Nb-5Sn (at.%) to ascertain whether Sn content can be used as an enhancer for cell activity. From a metallurgy viewpoint, a range of binary and ternary alloys displaying distinctive Ti phases (i.e. β, α', α") were achieved at room temperature. Their surface (oxide thickness and composition, roughness, contact angle) and bulk (compressive stiffness, strength, elongation, microhardness, electrical resistance) features were characterised. The same surface roughness was imparted on all the alloys, therefore substrate-cell interactions were evaluated independently from this variable. The physico-mechanical properties of the ternary alloy presented the highest strength to stiffness ratio and thereby proved the most suitable for load-bearing orthopaedic applications. From a cellular response viewpoint, their cytotoxicity, ability to adsorb proteins, to support cell growth and to promote proliferation were studied. Metabolic activity using a mouse model was monitored for a period of 12 days to elucidate the mechanism behind an enhanced proliferation rate observed in the Sn-containing alloys. It was hypothesised that the complex passivating surface oxide layer and the bulk inhomogeneity with two dominant Ti phases were responsible for this phenomenon.

Biofunctionalization of titanium surfaces with alendronate and albumin modulates osteoblast performance

BACKGROUND

Biofunctionalization of titanium surfaces can improve host responses, especially considering the time for osteointegration and patient recovery. This prompted us to modify titanium surfaces with alendronate and albumin and to investigate the behavior of osteoblasts on these surfaces.

METHODS

The biofunctionalization of titanium surfaces was characterized using classical physicochemical approaches and later used to challenge pre-osteoblast cells up to 24 h. Then their viability and molecular behavior were investigated using mitochondrial dehydrogenase activity and RTq-PCR technologies, respectively. Potential stimulus of extracellular remodeling was also investigated by zymography.

RESULTS

Our data indicates a differential behavior of cells responding to the surfaces, considering the activity of mitochondrial dehydrogenases. Molecularly, the differential expression of genes related with cell adhesion highlighted the importance of Integrin-β1, Fak, and Src. These 3 genes were significantly decreased in response to titanium surfaces modified with alendronate, but this behavior was reverted when alendronate was associated with albumin. Alendronate-modified surfaces promoted a significant increase on ECM remodeling, as well as culminating with greater gene activity related to the osteogenic phenotype (Runx2, Alp, Bsp).

CONCLUSION

Altogether, our study found interesting osteogenic behavior of cells in response to alendronate and albumin surfaces, which indicates the need for in vivo analyses to better consider these surfaces before clinical trials within the biomedical field.

A novel BSA immobilizing manner on modified titanium surface ameliorates osteoblast performance

Surface modification of medical and dental devices, to improve their biocorrosion resistance and biocompatibility, can be achieved with the multidisciplinary field of biomaterials. Nanostructured titanium dioxide (TiO₂) has been employed as surface modifier of titanium-based biomaterials because it can prevent the failure of the devices due to wear mechanisms. Moreover, this oxide surface is mostly terminated by hydroxyl groups (-OH) that can be directly functionalized with biomolecules to improve the biocompatibility of these devices. We explored the influence of 3-aminopropyltrimethoxysilane (APTMS) molecules as spacers in bovine serum albumin (BSA) protein immobilization on the physically hydroxylated surfaces of rutile phase TiO₂ films grown by reactive Radio Frequency (RF) magnetron sputtering. X-ray Photoelectron Spectroscopy (XPS) was used to examine the adsorption of BSA and APTMS on the hydroxylated surface of TiO₂ thin films. For biological tests, BSA was directly immobilized on the film surface and on the APTMS monolayer. Biological analysis found better osteoblast performance considering gene markers related to cell adhesion after interacting directly with the surface modified by the immobilization of BSA, especially on the surface where this protein was immobilized by APTMS. Additionally, we addressed the relevance of this biointerfaces on extracellular matrix remodeling by zymography analysis. Altogether, our data provides new insights about the cellular and molecular mechanisms covering the improved osteoblastic response of the proposed surface modification.

Study on microstructure, microhardness, bioactivity, and biocompatibility of La2 O3 -containing bioceramic coating doping SiO2 fabricated by laser cladding

To solve the lack of strength of calcium phosphate ceramic coatings in load-bearing applications, gradient Ca-P bioceramic coatings doped with La₂ O₃ and SiO₂ are fabricated by laser cladding on Ti-6Al-4 V. The effect of SiO₂ on microstructure, microhardness, bioactivity, and biocompatibility of coatings was investigated. The experimental results illustrate that the coating doped with La₂ O₃ and SiO₂ has excellent metallurgical bonding. The XRD analysis confirms that the amount of hydroxyapatite and tricalcium phosphate in the coating reached maximum when doping amount of SiO₂ is 10 wt %. SiO₂ -doped coatings show a significantly higher bone-like apatite precipitation after immersion in SBF than that of other coatings. in vitro experiment also shows that coating with 10 wt % SiO₂ is more suitable for the attachment and proliferation of MG63 cells, indicating that coating with 10 wt % SiO₂ exhibits best bioactivity and biocompatibility. These results suggest that the addition of SiO₂ improves the bonding strength, bioactivity, and biocompatibility of coatings.

Role of protein adsorption in the bio corrosion of metallic implants - A review

Implants are exposed to a complex physiological environment that contains various organic compounds, especially proteins. The adsorption of proteins has an immense influence on the corrosion, biocompatibility and wear properties of implantable metals. Proteins engage in multiple processes that could potentially inhibit or promote metal degradation, depending on the type of proteins, their concentration and the properties of the implant material. In the bio corrosion process, proteins are denatured and transform into a film on the metal surface, inhibiting corrosion. This film is found on many retrieved artificial joints, especially on worn areas, and can protect the passive film from scrapping due to its lubricating effect, thus decreasing tribocorroion. On the other hand, the interactions of metal ions with proteins (and amino acids) create colloidal organometallic complexes. Transport of the complex compounds away from the interface increases dissolution rates; thus, it accelerates the corrosion of metallic implants. The influence of protein adsorption on the corrosion behaviour of metallic biomaterials is presented in this review. Biocompatible metals that are favourably used as implants such as stainless steel, Co-Cr alloys, Ti alloys and biodegradable Mg and Fe alloys are specifically addressed. We have highlighted the adsorption phenomenon of protein on metallic implants, the interaction of proteins with metallic implants and the role of protein adsorption on implant biocorrosion behaviour as well as their wear resistance.

Adsorption properties of BSA and DsRed proteins deposited on thin SiO2 layers: optically non-absorbing versus absorbing proteins

Protein adsorption on solid surfaces is of interest for many industrial and biomedical applications, where it represents the conditioning step for micro-organism adhesion and biofilm formation. To understand the driving forces of such an interaction we focus in this paper on the investigation of the adsorption of bovine serum albumin (BSA) (optically non-absorbing, model protein) and DsRed (optically absorbing, naturally fluorescent protein) on silica surfaces. Specifically, we propose synthesis of thin protein layers by means of dip coating of the dielectric surface in protein solutions with different concentrations (0.01-5.0 g l^-1). We employed spectroscopic ellipsometry as the most suitable and non-destructive technique for evaluation of the protein layers' thickness and optical properties (refractive index and extinction coefficient) after dehydration, using two different optical models, Cauchy for BSA and Lorentz for DsRed. We demonstrate that the thickness, the optical properties and the wettability of the thin protein layers can be finely controlled by proper tuning of the protein concentration in the solution. These results are correlated with the thin layer morphology, investigated by AFM, FTIR and PL analyses. It is shown that the proteins do not undergo denaturation after dehydration on the silica surface. The proteins arrange themselves in a lace-like network for BSA and in a rod-like structure for DsRed to form mono- and multi-layers, due to different mechanisms driving the organization stage.

In vitro cytotoxicity evaluation of nano-carbon particles with different sp2/sp3 ratios

Graphitization occurs during the long-term service of a diamond-like carbon (DLC) modified artificial joint. Then, DLC wear debris, which are carbon particles with different sp²/sp³ ratios and sizes ranging from the nano- to micro-meter scale produced. In this paper, to promote the application of DLC coating for artificial joint modification, the cytotoxicity of DLC debris (nano-carbon particles, NCs) with different sp²/sp³ ratios was studied. The microstructure and physical characteristics of NCs with different sp²/sp³ ratios were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM) and Dynamic Light Scattering (DLS). Meanwhile, osteoblasts and macrophages were applied to characterize the cytotoxicity of the NCs. In vitro cytotoxicity assay results indicated that cells incubated with NCs of different sp²/sp³ ratios had greater osteogenic capacity, and these particles caused a weaker immune response in comparison with CoCrMo particles. Taken together, the results indicated that NCs with different sp²/sp³ ratios presented a good cytocompatibility than CoCrMo particles. But no significant differences were observed among NCs with different sp²/sp³ ratios. The better cytocompatibility of NCs is mainly attributable to their surface charge.

Bioactivity of sol-gel-derived TiO2 coating on polyetheretherketone: In vitro and in vivo studies

A polyetheretherketone (PEEK) surface was modified using a sol-gel-derived TiO2 coating in order to confer bone-bonding ability. To enhance the bonding strength of the coating layer, pretreatment with either O2 plasma or sandblasting was performed prior to sol-gel coating. Additionally, post-treatment with acid was carried out to confer apatite (calcium phosphate)-forming ability to the surface. Biomechanical and histological analyses performed using an in vivo rabbit tibia model showed that PEEK surfaces modified with sol-gel-derived TiO2 and acid post-treatment had better bone-bonding properties than uncoated PEEK surfaces. These modified surfaces also performed well in terms of their in vitro cell responses due to their modified surface chemistries and topographies. Although O2 plasma or sandblasting treatment were, for the most part, equivocal in terms of performance, we conclude that sol-gel-derived TiO2 coating followed by acid post-treatment significantly improves the bone bonding ability of PEEK surfaces, thus rendering them optimal for their use in surgical implants.

STATEMENT OF SIGNIFICANCE

The role of polyetheretherketone (PEEK) as an alternative biomaterial to conventional metallic implant materials has become increasingly important. However, its low bone bonding ability is yet to be resolved. This in vivo and in vitro investigation on the functionalization of PEEK surfaces highlights the utility of this material in clinical interventions that require implants, and may extend range of applications of PEEK.

Contribution of fibronectin and vitronectin to the adhesion and morphology of MC3T3-E1 osteoblastic cells to poly(NaSS) grafted Ti6Al4V

This study is focused on understanding the underlying mechanisms involved in the improved in vitro and in vivo responses of osteoblasts on poly(sodium styrene sulfonate) (poly(NaSS)) functionalized Ti6Al4V surfaces. We probed the contribution of cell-adhesive glycoproteins fibronectin (Fn) and vitronectin (Vn) in the initial adhesion of MC3T3-E1 osteoblastic cells to poly(NaSS) functionalized and control Ti6Al4V surfaces. Firstly, culture media containing serum depleted of Fn and Vn (DD) were used to establish the contribution of Fn and Vn in the adhesion and spreading of cells on poly(NaSS) grafted and control surfaces. Compared to ungrafted surfaces, poly(NaSS) grafted surfaces enhanced the levels of cell adhesion, cell spreading and the formation of intracellular actin cytoskeleton and focal contacts in serum treatments where Fn or Vn were present (FBS, DD+Fn, DD+Vn). Cell responses to Fn were more significant than to Vn. Secondly, blocking Fn and Vn integrin receptors using antibodies to α5β1 (Fn) and αvβ1 (Vn) showed that adhesion of cells to poly(NaSS) grafted surfaces principally involved the Fn integrin receptor α5β1. Thirdly, blocking of the heparin and cell-binding regions of Fn molecule (RGD, C-HB, N-HB) showed that grafting with poly(NaSS) altered the conformation of Fn. Together these outcomes explained why the presence of sulfonate (SO3(-)) groups grafted on the Ti6Al4V surface enhanced the early cell adhesion and spreading processes which determine clinical success for applications that require osseointegration.

STATEMENT OF SIGNIFICANCE

This study is devoted to the basic analysis of the mechanism at the origin of the improved in vitro and in vivo osteoblast cell responses exhibited by poly(sodium styrene sulfonate) (poly(NaSS)) functionalized Ti6Al4V surfaces. The aim was to probe the contribution of cell adhesive glycoproteins fibronectin and vitronectin in the initial adhesion of MC3T3-E1 osteoblastic cells to poly(NaSS) functionalized Ti6Al4V surfaces. The outcomes of this research explained why the presence of SO3(-) (sulfonate) groups grafted on the Ti6Al4V surface enhanced the early cell adhesion and spreading processes which determine clinical success for applications that require osseointegration. This work is a step further in the research of poly(NaSS), a very promising bioactive polymer with potential to the orthopedic and dental fields.

A Zr-based bulk metallic glass for future stent applications: Materials properties, finite element modeling, and in vitro human vascular cell response

Despite the prevalent use of crystalline alloys in current vascular stent technology, new biomaterials are being actively sought after to improve stent performance. In this study, we demonstrated the potential of a Zr-Al-Fe-Cu bulk metallic glass (BMG) to serve as a candidate stent material. The mechanical properties of the Zr-based BMG, determined under both static and cyclic loadings, were characterized by high strength, which would allow for the design of thinner stent struts to improve stent biocompatibility. Finite element analysis further complemented the experimental results and revealed that a stent made of the Zr-based BMG was more compliant with the beats of a blood vessel, compared with medical 316L stainless steel. The Zr-based BMG was found to be corrosion resistant in a simulated body environment, owing to the presence of a highly stable ZrO2-rich surface passive film. Application-specific biocompatibility studies were conducted using human aortic endothelial cells and smooth muscle cells. The Zr-Al-Fe-Cu BMG was found to support stronger adhesion and faster coverage of endothelial cells and slower growth of smooth muscle cells than 316L stainless steel. These results suggest that the Zr-based BMG could promote re-endothelialization and potentially lower the risk of restenosis, which are critical to improve vascular stent implantation integration. In general, findings in this study raised the curtain for the potential application of BMGs as future candidates for stent applications.

STATEMENT OF SIGNIFICANCE

Vascular stents are medical devices typically used to restore the lumen of narrowed or clogged blood vessel. Despite the clinical success of metallic materials in stent-assisted angioplasty, post-surgery complications persist due to the mechanical failures, corrosion, and in-stent restenosis of current stents. To overcome these hurdles, strategies including new designs and surface functionalization have been exercised. In addition, the development of new materials with higher performance and biocompatibility can intrinsically reduce stent failure rates. The present study demonstrates the advantages of a novel material, named bulk metallic glass (BMG), over the benchmarked 316L stainless steel through experimental methods and computational simulations. It raises the curtain of new research endeavors on BMGs as competitive alternatives for stent applications.

Surface Modifications and Their Effects on Titanium Dental Implants

This review covers several basic methodologies of surface treatment and their effects on titanium (Ti) implants. The importance of each treatment and its effects will be discussed in detail in order to compare their effectiveness in promoting osseointegration. Published literature for the last 18 years was selected with the use of keywords like titanium dental implant, surface roughness, coating, and osseointegration. Significant surface roughness played an important role in providing effective surface for bone implant contact, cell proliferation, and removal torque, despite having good mechanical properties. Overall, published studies indicated that an acid etched surface-modified and a coating application on commercial pure titanium implant was most preferable in producing the good surface roughness. Thus, a combination of a good surface roughness and mechanical properties of titanium could lead to successful dental implants.

Osseointegration improvement by plasma electrolytic oxidation of modified titanium alloys surfaces

Titanium (Ti) is a material frequently used in orthopedic applications, due to its good mechanical properties and high corrosion resistance. However, formation of a non-adherent fibrous tissue between material and bone drastically could affect the osseointegration process and, therefore, the mechanical stability of the implant. Modifications of topography and configuration of the tissue/material interface is one of the mechanisms to improve that process by manipulating parameters such as morphology and roughness. There are different techniques that can be used to modify the titanium surface; plasma electrolytic oxidation (PEO) is one of those alternatives, which consists of obtaining porous anodic coatings by controlling parameters such as voltage, current, anodizing solution and time of the reaction. From all of the above factors, and based on previous studies that demonstrated that bone cells sense substrates features to grow new tissue, in this work commercially pure Ti (c.p Ti) and Ti6Al4V alloy samples were modified at their surface by PEO in different anodizing solutions composed of H2SO4 and H3PO4 mixtures. Treated surfaces were characterized and used as platforms to grow osteoblasts; subsequently, cell behavior parameters like adhesion, proliferation and differentiation were also studied. Although the results showed no significant differences in proliferation, differentiation and cell biological activity, overall results showed an important influence of topography of the modified surfaces compared with polished untreated surfaces. Finally, this study offers an alternative protocol to modify surfaces of Ti and their alloys in a controlled and reproducible way in which biocompatibility of the material is not compromised and osseointegration would be improved.

Surface characteristics, corrosion resistance and MG63 osteoblast-like cells attachment behaviour of nano SiO2–ZrO2 coated 316L stainless steel

Nano ceramic coatings were produced on to 316L SS. MG-63 osteoblast like cells attachments were good for silica containing coatings.

Poly(NaSS) functionalization modulates the conformation of fibronectin and collagen type I to enhance osteoblastic cell attachment onto Ti6Al4V

Functionalization of surfaces with poly(sodium styrenesulfonate) (poly(NaSS)) has recently been found to enhance osteointegration of implantable materials. Radical polymerization of poly(NaSS) on titanium (Ti)-based substrates has been used to improve their long-term performance by preventing fibrosis and consequently implant loosening. However, the influence of the sulfonate groups on the early cell behavior and the associated molecular phenomena remains to be understood. In this work, we used quartz crystal microbalance with dissipation (QCM-D) to elucidate the role of poly(NaSS) in enhancing osteoblastic cell attachment. This was measured by following the cell attachment using the MC3T3-E1 cell line, on fetal bovine serum (FBS) preadsorbed surfaces and on substrates adsorbed with a series of relevant proteins, bovine serum albumin (BSA), fibronectin (Fn), and collagen type I (Col I). Comparison of the performance of poly(NaSS) with other clinically important substrates such as Ti alloy Ti6Al4V, gold, and poly(desamino-tyrosyl-tyrosine ethyl ester carbonate) (poly(DTEc)) indicates poly(NaSS) to be a superior substrate for MC3T3-E1 cells attachment. This attachment was found to be integrin mediated in the presence of Fn and Col I. Antibodies specific to the RGD peptide and the N- and C-terminal HB-binding domains reacted more intensively with Fn adsorbed on poly(NaSS). Fn adapts a conformation favorable to RGD mediated cell attachment when adsorbed onto poly(NaSS).

Effect of Sr on the bioactivity and corrosion resistance of nanoporous niobium oxide coating for orthopaedic applications

In this study, strontium incorporated Nb2O5 was synthesized in two different proportions by sol-gel methodology and was deposited on 316L SS by spin coating method. The synthesis conditions were optimized to obtain a nanoporous morphology. The prepared Sr-incorporated Nb2O5 coatings were uniform, smooth and well adherent on to the substrate 316L SS. The coatings were characterized by attenuated total reflectance-infrared spectroscopy (ATR-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and transmission electron microscopy (TEM) and the formation of Sr-incorporated Nb2O5 coatings with nanoporous morphology was confirmed. Static water contact angle measurements showed an enhancement in the wettability of the obtained coatings. In vitro bioactivity test of the coated substrates showed that 0.05M Sr-incorporated Nb2O5 coating had better bioactivity compared to 0.1M Sr-incorporated coating. Solution analysis studies confirmed the controlled release of Sr ions from the coating, which aid and enhance hydroxyapatite (HAp) growth. Electrochemical studies confirmed that the coatings provided excellent corrosion protection to the base material as increased charge transfer resistance and decreased double layer capacitance was observed for the coated substrates.

Refining nanotopographical features on bone implant surfaces by altering surface chemical compositions

Nb₂O₅/TiO₂ composite coatings with controllable nanostructures were achieved by adjusting the amount of Nb₂O₅ in one simple and single plasma spraying process and Nb₂O₅ doping showed its potential use in enhancing the biological properties of biomedical TiO₂ coatings.

Cytocompatibility of medical biomaterials containing nickel by osteoblasts: a systematic literature review

The present review is based on a survey of 21 studies on the cytocompatibility of medical biomaterials containing nickel, as assessed by cell culture of human and animal osteoblasts or osteoblast-like cells. Among the biomaterials evaluated were stainless steel, NiTi alloys, pure Ni, Ti, and other pure metals. The materials were either commercially available, prepared by the authors, or implanted by various techniques to generate a protective layer of oxides, nitrides, acetylides. The observation that the layers significantly reduced the initial release of metal ions and increased cytocompatibility was confirmed in cell culture experiments. Physical and chemical characterization of the materials was performed. This included, e.g., surface characterization (roughness, wettability, corrosion behavior, quantity of released ions, microhardness, and characterization of passivation layer). Cytocompatibility tests of the materials were conducted in the cultures of human or animal osteoblasts and osteoblast-like cells. The following assays were carried out: cell proliferation and viability test, adhesion test, morphology (by fluorescent microscopy or SEM). Also phenotypic and genotypic markers were investigated. In the majority of works, it was found that the most cytocompatible materials were stainless steel and NiTi alloy. Pure Ni was rendered and less cytocompatible. All the papers confirmed that the consequence of the formation of protective layers was in significant increase of cytocompatibility of the materials. This indicates the possible further modifications of the manufacturing process (formation of the passivation layer).

Responses of bone-forming cells on pre-immersed Zr-based bulk metallic glasses: Effects of composition and roughness

Bulk metallic glasses (BMGs) demonstrate attractive properties for potential biomedical applications, owing to their amorphous structure. The present work has investigated the biocompatibility of Zr-based BMGs by studying the cellular behavior of bone-forming mouse MC3T3-E1 pre-osteoblast cells. A Ti-6Al-4V alloy was used as a reference material. Pre-immersion treatment was performed on BMG samples in phosphate-buffered saline prior to cell experiments. The effects of 1at.% yttrium alloying and surface roughness on cellular behavior were examined. The general biosafety of Zr-based BMGs for MC3T3-E1 cells was revealed as normal cell responses. Pre-immersion treatment was found to effectively reduce the surface concentrations of alloying elements. Micro-alloying with 1 at.% yttrium did not significantly affect cell adhesion and proliferation, but slightly decreased alkaline phosphatase (ALP) activity on rough surfaces. Lower cell adhesion and proliferation were found on smooth surfaces of Zr-based BMGs compared to their rougher counterparts. Higher ALP activity was detected on rougher surfaces. To obtain a mechanistic understanding surface free energy was correlated with cell adhesion.