Microstructure and osteoblast response of gradient bioceramic coating on titanium alloy fabricated by laser cladding (original) (raw)
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Journal of Biomedical Optics, 1998
We have investigated the biocompatibility of calcium phosphate coatings deposited by pulsed laser ablation from hydroxyapatite (HA) targets onto polyethylene and Teflon substrates. It was found that the cell density, attachment, and morphology of primary rat calvaria osteoblasts were influenced by both the original polymer and by the nature of the apatite coatings. HA coatings on Teflon were found to have higher biocompatibility in terms of cell adhesion and spreading. In vivo studies of bone response to coatings deposited by KrF excimer and CO 2 lasers on commercial Ti6A14V alloy implants show that both deposition techniques suppress fibrous tissue formation and promote osteogenesis.
Materials Science and Engineering C, 2014
Hydroxyapatite (HAP) coatings on bioinert metals such as Ti-6Al-4V are necessary for biomedical applications. Together, HAP and Ti-6Al-4V are biocompatible and bioactive. The challenges of depositing HAP on Ti-6Al-4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti-6Al-4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive Xray spectroscopy, and Vickers hardness machine, and by immersion test in Hank’s solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic-ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implants applications.
Journal of Materials Research, 2009
Commercial-grade dense Ti-6Al-4V alloy substrate was mechanically roughened, cleaned, and treated with a globular protein [bovine serum albumin (BSA)] for 4 h. Biomimetic calcium phosphate (Ca-P) coating was applied onto the above-treated substrate by immersion into simulated body fluid (SBF) at 25 C for a period of 4 days, with periodic replacement by freshly prepared SBF at 48-h intervals. After 4 days, branched micron-sized fibers of hydroxyapatite (HAp), resembling the structure of bone, were obtained, connecting the clusters of HAp crystal plates in the coating (thickness $200 mm) on the substrate surface. Structural and compositional characterization of the coating was carried out using field emission scanning electron microscopy (FE-SEM) with energy-dispersive x-ray analysis unit (EDX) facility, x-ray diffraction (XRD), and Fourier transform infrared (FTIR) data. In vitro cytotoxicity (ISO 10993-5, 1999), cell adhesion assays, and phase contrast microscopy were performed using NIH 3T3 fibroblast cell lines to ascertain the bioactivity of the coated substrates, with and without protein treatment. Based on our study, we propose a correlation between a specific physical structure of the HAp coating and its biological properties.
International Journal of Periodontics and Restorative Dentistry, 2013
The purpose of this study was nondecalcified histologic analysis of titanium implants modified by laser with and without hydroxyapatite. Implants with three modified surfaces were inserted into rabbit tibias: group 1, machined surface; group 2, irradiated (laser); and group 3, irradiated and hydroxyapatite coated (biomimetic method). The mean surface roughness (Ra) scores of groups 2 and 3 were higher than that of group 1. Boneimplant contact measurements at 30 and 60 days for groups 2 and 3 were higher than for group 1. Bone area at 30 and 60 days for group 2 was higher than for groups 1 and 3. Titanium implants modified by laser with and without hydroxyapatite exhibit increased early osseointegration. (Int J
Human osteoblast response to pulsed laser deposited calcium phosphate coatings
Biomaterials, 2005
Octacalcium phosphate (OCP) and Mn 2+ -doped carbonate hydroxyapatite (Mn-CHA) thin films were deposited on pure, highly polished and chemically etched Ti substrates with pulsed laser deposition. The coatings exhibit different composition, crystallinity and morphology that might affect their osteoconductivity. Human osteoblasts were cultured on the surfaces of OCP and Mn-CHA thin films, and the cell attachment, proliferation and differentiation were evaluated up to 21 days. The cells showed a normal morphology and a very good rate of proliferation and viability in every experimental time. Alkaline phosphatase activity was always higher than the control and Ti groups. From days 7 to 21 collagen type I production was higher in comparison with control and Ti groups. The level of transforming growth factor beta 1 (TGF-b1) was lower at 3 and 7 days, but reached the highest values during following experimental times (14 and 21 days). Our data demonstrate that both calcium phosphate coatings favour osteoblasts proliferation, activation of their metabolism and differentiation. r
Journal of Oral and Maxillofacial Surgery, 2009
Purpose: Considering the potential of the association between laser ablation and smaller scale hydroxyapatite (HA) coatings to create a stable and bioactive surface on titanium dental implants, the aim of the present study was to determine, by the removal torque test, the effects of a surface treatment created by laser-ablation (Nd:YAG) and, later, thin deposition of HA particles by a chemical process, compared to implants with only laser-ablation and implants with machined surfaces. Materials and Methods: Forty-eight rabbits received 1 implant by tibia of the following surfaces: machined surface (MS), laser-modified surface (LMS), and biomimetic hydroxiapatite coated surface (HA). After 4, 8, and 12 weeks of healing, the removal torque was measured by a torque gauge. The surfaces studied were analyzed according to their topography, chemical composition, and roughness. Results: Average removal torque in each period was 23.28, 24.0, and 33.85 Ncm to MS, 33.0, 39.87, and 54.57 Ncm to LMS, and 55.42, 63.71 and 64.0 Ncm to HA. The difference was statistically significant (P Ͻ .05) between the LMS-MS and HA-MS surfaces in all periods of evaluation, and between LMS-HA to 4 and 8 weeks of healing. The surface characterization showed a deep, rough, and regular topography provided by the laser conditioning, that was followed by the HA coating. Conclusions: Based on these results, it was possible to conclude that the implants with laser surface modification associated with HA biomimetic coating can shorten the implant healing period by the increase of bone implant interaction during the first 2 months after implant placement.
Osteoblast growth on titanium foils coated with hydroxyapatite by pulsed laser ablation
Biomaterials, 2001
Pulsed laser ablation is a new method for deposition of thin layers of hydroxyapatite (HA) on to biomaterial surfaces. In this paper, we report activity and morphology of osteoblasts grown on HA surfaces fabricated using di!erent laser conditions. Two sets of "lms were deposited from dense HA targets, at three di!erent laser #uences: 3, 6 and 9 J cm\. One set of the surfaces was annealed at 5753C to increase the crystallinity of the deposited "lms. Primary human osteoblasts were seeded onto the material surfaces and cytoskeletal actin organisation was examined using confocal laser scanning microscopy. The annealed surfaces supported greater cell attachment and more de"ned cytoskeletal actin organisation. Cell activity, measured using the alamar Blue assay, was also found to be signi"cantly higher on the annealed samples. In addition, our results show distinct trends that correlate with the laser #uence used for deposition. The cell activity increases with increasing #uence. This pattern was repeated for alkaline phosphatase production by the cells. Di!erences in cell spreading were apparent which were correlated with the #uence used to deposit the HA. The optimum surface for initial attachment and spreading of osteoblasts was one of the HA "lms deposited using 9 J cm\ laser #uence and subsequently annealed at 5753C
Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2010
Silicon-substituted hydroxyapatite (Si-HA) coatings have been plasma sprayed over titanium substrates aiming to improve the bioactivity of the constructs for bone tissue repair/regeneration. X-ray diffraction analysis of the coatings has shown that, previous to the thermal deposition, no secondary phases were formed due to the incorporation of 0.8 wt % Si into HA crystal lattice. Partial decomposition of hydroxyapatite, which lead to the formation of the more soluble phases of aand b-tricalcium phosphate and calcium oxide, and increase of amorphization level only occurred following plasma spraying. Human bone marrowderived osteoblastic cells were used to assess the in vitro biocompatibility of the constructs. Cells attached and grew well on the Si-HA coatings, putting in evidence an increased metabolic activity and alkaline phosphatase expression comparing to control, i.e., titanium substrates plasma sprayed with hydroxyapatite. Further, a trend for increased differentiation was also verified by the upregulation of osteogenesis-related genes, as well as by the augmented deposition of globular mineral deposits within established cell layers. Based on the present findings, plasma spraying of Si-HA coatings over titanium substrates demonstrates improved biological properties regarding cell proliferation and differentiation, comparing to HA coatings. This suggests that incorporation of Si into the HA lattice could enhance the biological behavior of the plasmasprayed coating. V C 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 94B: 337-346, 2010.
Surface and Coatings Technology, 2013
Composite coatings made of hydroxyapatite (HA) and titanium alloy (Ti-6Al-4V) have potential biomedical applications because of their biocompatibility and bioactive characteristics. In this research composite coating of HA and Ti-6Al-4V was prepared using the laser-assisted direct material deposition method. Surface morphology, chemical composition and mechanical properties of the composite coatings were investigated using optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, and Vickers microhardness tests. The results show that the microstructure, chemistry and mechanical properties of the coatings are influenced by laser power and traverse speed. The aspect ratio of the coating, the ratio of calcium and phosphorous (i.e., Ca/P) in the coating, and diffusion rate of titanium into the substrate vary with power and traverse speed. Traverse speed has more influence on surface morphology and Ca/P ratio than power. The variation in microhardness along the cross section of the heat affected zone was investigated and the diffusion coefficient of titanium into stainless steel estimated. The relationship between microstructural, chemical and mechanical parameters with the specific energy was established.
… Research Part A, 2010
Previous reports have shown the use of hydroxyapatite (HAp) and related calcium phosphate coatings on metal and nonmetal substrates for preparing tissue-engineering scaffolds, especially for osteogenic differentiation. These studies have revealed that the structural properties of coated substrates are dependent significantly on the method and conditions used for coating and also whether the substrates had been modified prior to the coating. In this article, we have done a comparative evaluation of the structural features of the HAp coatings, prepared by using simulated body fluid (SBF) at 25 C for various time periods, on a nonporous metal substrate titanium-aluminium-vanadium (Ti-6Al-4V) alloy and a bioinert ceramic substrate alpha-alumina (a-Al 2 O 3 ), with and without their prior treatment with the globular protein bovine serum albumin (BSA). Our analysis of these substrates by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectrometry showed significant and consistent differences in the quantitative and qualitative properties of the coatings. Interestingly, the bioactivity of these substrates in terms of supporting in vitro cell adhesion and spreading, and in vivo effects of implanted substrates, showed a predictable pattern, thus indicating that some coated substrates prepared under our conditions could be more suitable for biological/biomedical applications. V C 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 94A: 913-926, 2010.