Biomimetic Calcium Phosphate Coatings for Bioactivation of Titanium Implant Surfaces: Methodological Approach and In Vitro Evaluation of Biocompatibility.
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ABSTRACT:
SUBMITTER: Kreller T
PROVIDER: S-EPMC8269522 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Innovative nanomaterials are required for the coatings of titanium (Ti) implants to ensure the activation of Ti surfaces for improved osseointegration, enhanced bone fracture healing and bone regeneration. This paper presents a systematic investigation of biomimetic composite (BC) coatings on Ti implant surfaces in a rat model of a diaphyseal femoral fracture. Methodological approaches of surface modification of the Ti implants via the usual joining methods (e.g., grit blasting and acid etching) and advanced physicochemical coating via a self-assembled dip-coating method were used. The biomimetic procedure used multi-substituted hydroxyapatite (ms-HAP) HAP-1.5 wt% Mg-0.2 wt% Zn-0.2 wt% Si nanoparticles (NPs), which were functionalized using collagen type 1 molecules (COL), resulting in ms-HAP/COL (core/shell) NPs that were embedded into a polylactic acid (PLA) matrix and finally covered with COL layers, obtaining the ms-HAP/COL@PLA/COL composite. To assess the osseointegration issue, first, the thickness, surface morphology and roughness of the BC coating on the Ti implants were determined using AFM and SEM. The BC-coated Ti implants and uncoated Ti implants were then used in Wistar albino rats with a diaphyseal femoral fracture, both in the absence and the presence of high-frequency pulsed electromagnetic shortwave (HF-PESW) stimulation. This study was performed using a bone marker serum concentration and histological and computer tomography (micro-CT) analysis at 2 and 8 weeks after surgical implantation. The implant osseointegration was evaluated through the bone-implant contact (BIC). The bone-implant interface was investigated using FE-SEM images and EDX spectra of the retrieved surgical implants at 8 weeks in the four animal groups. The obtained results showed significantly higher bone-implants contact and bone volume per tissue volume, as well as a greater amount of newly formed bone, in the BC-coated Ti implants than in the uncoated Ti implants. Direct bone-implant contact was also confirmed via histological examination. The results of this study confirmed that these biomimetic composite coatings on Ti implants were essential for a significant enhancement of osseointegration of BC-coated Ti implants and bone regeneration. This research provides a novel strategy for the treatment of bone fractures with possible orthopedic applications.
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Project description:Currently, there are more than 1.5 million knee and hip replacement procedures carried out in the United States. Implants have a 10-15-year lifespan with up to 30% of revision surgeries showing complications with osteomyelitis. Titanium and titanium alloys are the favored implant materials because they are lightweight and have high mechanical strength. However, this increased strength can be associated with decreased bone density around the implant, leading to implant loosening and failure. To avoid this, current strategies include plasma-spraying titanium surfaces and foaming titanium. Both techniques give the titanium a rough and irregular finish that improves biocompatibility. Recently, researchers have also sought to surface-conjugate proteins to titanium to induce osteointegration. Cell adhesion-promoting proteins can be conjugated to methacrylate groups and crosslinked using a variety of methods. Methacrylated proteins can be conjugated to titanium surfaces through atom transfer radical polymerization (ATRP). However, surface conjugation of proteins increases biocompatibility non-specifically to bone cells, adding to the risk of biofouling which may result in osteomyelitis that causes implant failure. In this work, we analyze the factors contributing to biofouling when coating titanium to improve biocompatibility, and design an experimental scheme to evaluate optimal coating parameters.
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Project description:This work investigated the ability of electropolished Ti surface to induce Hydroxyapatite (HA) nucleation and growth in vitro via a biomimetic method in Simulated Body Fluid (SBF). The HA induction ability of Ti surface upon electropolishing was compared to that of Ti substrates modified with common chemical methods including alkali, acidic and hydrogen peroxide treatments. Our results revealed the excellent ability of electropolished Ti surfaces in inducing the formation of bone-like HA at the Ti/SBF interface. The chemical composition, crystallinity and thickness of the HA coating obtained on the electropolished Ti surface was found to be comparable to that achieved on the surface of alkali treated Ti substrate, one of the most effective and popular chemical treatments. The surface characteristics of electropolished Ti contributing to HA growth were discussed thoroughly.
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Project description:Biofunctionalized surfaces for implants are currently receiving much attention in the health care sector. Our aims were (1) to create bioactive Ti-coatings doped with Ca, P, Si, and Ag produced by microarc oxidation (MAO) to improve the surface properties of biomedical implants, (2) to investigate the TiO2 layer stability under wear and corrosion, and (3) to evaluate human mesenchymal stem cells (hMSCs) responses cultured on the modified surfaces. Tribocorrosion and cell experiments were performed following the MAO treatment. Samples were divided as a function of different Ca/P concentrations and treatment duration. Higher Ca concentration produced larger porous and harder coatings compared to the untreated group (p < 0.001), due to the presence of rutile structure. Free potentials experiments showed lower drops (-0.6 V) and higher coating lifetime during sliding for higher Ca concentration, whereas lower concentrations presented similar drops (-0.8 V) compared to an untreated group wherein the drop occurred immediately after the sliding started. MAO-treated surfaces improved the matrix formation and osteogenic gene expression levels of hMSCs. Higher Ca/P ratios and the addition of Ag nanoparticles into the oxide layer presented better surface properties, tribocorrosive behavior, and cell responses. MAO is a promising technique to enhance the biological, chemical, and mechanical properties of dental implant surfaces.
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Project description:The appropriate immune microenvironment plays crucial roles in bone regeneration. Surface structure and chemisty are key factors affecting immune cells behaivor and subsequently regulating the activity of bone-related cells. To achieve rapid osteointegration, this study prepared a biomimetic calcium phosphate (CaP) coating on Ti-based substrates (THCaP) with the help of oleic acid under hydrothermal condition. The coating was composed of hydroxyapatite nanowires and further self-assembled into macropores. Also, the effect of the biomimetic CaP coating on the immune response of macrophages and the impact on angiogenesis and osteogenesis were investigated. In vitro cell culture results showed that compared with pristine Ti and similar titanate nanowire structure (TH), THCaP not only stimulated the polarization of macrophages towards to pro-healing M2 phenotype, but also enhanced the angiogenic and osteogenic differentiation of endothelial cells and preosteoblastic cells, respectively. Especially, macrophages on THCaP induced a favorable immune microenvironment and further facilitated the osteogenic diffferention of preosteoblastic cells. In vivo tests confirmed the aforementioned results, which proved that the implanted THCaP could decrease the inflammatory response and facilitate new bone formation when compared with pristine Ti and TH implants. These findings indicate that preparation of biomimetic CaP network structure is a promising strategy to surface design of Ti-based substrates, which is beneficial to generate a favorable osteoimmunomodulatory microenvironment for enhancing osteointegration.
2024-03-01 | GSE250308 | GEO
Project description:Biomimetic calcium phosphate (BioCaP) coatings were used to deliver bone morphogenetic protein 2 (BMP2), and enhance osteogenesis. However, the mechanism for BioCaP coatings interacting with the immune response during bone regeneration remains unclear. In this preliminary study, the effect of BioCaP coatings on macrophage polarization without (BioCaP group) or with BMP2 (BioCaP+Inc.BMP2 group) was investigated. RAW 264.7 cells were cultured on the rough and platelike surfaces of coatings in BioCaP and BioCaP+Inc.BMP2 groups, while cultured on smooth surfaces in the group without material for 5 days. The BioCaP coatings per se modulated the switch of M1 to M2 phenotype from day 3, which promoted the expressions of Arg1 and CD 206 but reduced the expression of TNF-α compared with No material group. To detect the microenvironmental changes, the concentrations of calcium ion (Ca2+) and inorganic phosphate (Pi), pH values, as well as calcium phosphate crystal pattern were examined. The trends of ionic environmental changes were closely related with macrophage phenotype switch. These results suggest that BioCaP coating itself may affect the macrophage polarization through surface topography, surrounding ionic environment and calcium phosphate crystal pattern.
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Project description:Polyphenols can form functional coatings on a variety of different materials through auto-oxidative surface polymerization in a manner similar to polydopamine coatings. However, the mechanisms behind the coating deposition are poorly understood. We report the coating deposition kinetics of the polyphenol tannic acid (TA) and the simple phenolic compound pyrogallol (PG) on titanium surfaces. The coating deposition was followed in real time over a period of 24 h using a quartz crystal microbalance with dissipation monitoring (QCM-D). TA coatings revealed a multiphasic layer formation: the deposition of an initial rigid layer was followed by the buildup of an increasingly dissipative layer, before mass adsorption stopped after approximately 5 h of coating time. The PG deposition was biphasic, starting with the adsorption of a nonrigid viscoelastic layer which was followed by layer stiffening upon further mass adsorption. Coating evaluation by ellipsometry and AFM confirmed the deposition kinetics determined by QCM-D and revealed maximum coating thicknesses of approximately 50 and 75 nm for TA and PG, respectively. Chemical characterization of the coatings and polymerized polyphenol particles indicated the involvement of both physical and chemical interactions in the auto-oxidation reactions.
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Project description:Intracranial electrodes are a vital component of implantable neurodevices, both for acute diagnostics and chronic treatment with open and closed-loop neuromodulation. Their performance is hampered by acute implantation trauma and chronic inflammation in response to implanted materials and mechanical mismatch between stiff synthetic electrodes and pulsating, natural soft host neural tissue. Flexible electronics based on thin polymer films patterned with microscale conductive features can help alleviate the mechanically induced trauma; however, this strategy alone does not mitigate inflammation at the device-tissue interface. In this study, we propose a biomimetic approach that integrates microscale extracellular matrix (ECM) coatings on microfabricated flexible subdural microelectrodes. Taking advantage of a high-throughput process employing micro-transfer molding and excimer laser micromachining, we fabricate multi-channel subdural microelectrodes primarily composed of ECM protein material and demonstrate that the electrochemical and mechanical properties match those of standard, uncoated controls. In vivo ECoG recordings in rodent brain confirm that the ECM microelectrode coatings and the protein interface do not alter signal fidelity. Astrogliotic, foreign body reaction to ECM coated devices is reduced, compared to uncoated controls, at 7 and 30 days, after subdural implantation in rat somatosensory cortex. We propose microfabricated, flexible, biomimetic electrodes as a new strategy to reduce inflammation at the device-tissue interface and improve the long-term stability of implantable subdural electrodes.
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Project description:Here we show a new and effective methodology for rapid/controllable porosification of thin-film ceramics, which may be applied in medical devices/electronics and membrane nano-filtration. Dense hydroxyapatite applied to Ti6Al4V by plasma-assisted PVD was electron-beam irradiated to induce flash melting/boiling. Deposited coatings contained amorphous and nano-crystalline/stoichiometric hydroxyapatite (~35 nm). Irradiation (voltages 13-29 kV) led to ablation (up to 45% mass loss) and average/maximum pore areas from (0.07-1.66)/(0.69-92.53) μm2, mimicking the human cortical bone. Vitrification above 1150 °C formed (~62-30 nm) crystallites of α-Tri Calcium Phosphate. Unique porosification resulted from irradiation-induced sub-surface boiling and limited thermal conductivity of hydroxyapatite, causing material to expand/explode through the more quickly solidified top surface. Commercially applicable, roughened Ti6Al4V exacerbated the heating and boiling explosion phenomenon in certain regions, producing an array of pore sizes. Scaffold-like morphologies were generated by interconnection of micron/sub-micron porosity, showing great potential for facile generation of a biomimetic surface treatment for osseointegration.
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