Electrodeposition of a porous strontium-substituted hydroxyapatite/zinc oxide duplex layer on AZ91 magnesium alloy for orthopedic applications

Biosurfactant-Assisted Cu Doping of Brushite Coatings: Enhancing Structural, Electrochemical, and Biofunctional Properties

Stainless steel (316L SS) has been widely used in orthopedic, cardiovascular stents, and other biomedical implant applications due to its strength, corrosion resistance, and biocompatibility. To address the weak interaction between steel implants and tissues, it is a widely adopted strategy to enhance implant performance through the application of bioactive coatings. In this study, Cu-doped brushite coatings were deposited successfully through pulse electrodeposition on steel substrates facilitated with a biosurfactant (BS) (i.e., surfactin). Further, the combined effect of various concentrations of Cu ions and BS on the structural, electrochemical, and biological properties was studied. The X-ray diffraction (XRD) confirms brushite composition with Cu substitution causing lattice contraction and a reduced crystallite size. The scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) studies reveal the morphological changes of the coatings with the incorporation of Cu, which is confirmed by X-ray photoelectron spectroscopy (XPS) and elemental mapping. The Fourier transform infrared (FTIR) and Raman spectroscopy confirm the brushite and Cu doping in the coatings, respectively. Increased surface roughness and mechanical properties of Cu-doped coatings were analyzed by using atomic force microscopic (AFM) and nanohardness tests, respectively. Electrochemical assessments demonstrate corrosion resistance enhancement in Cu-doped coatings, which is further improved with the addition of biosurfactants. In vitro biomineralization studies show the Cu-doped coating's potential for osseointegration, with added stability. The cytocompatibility of the coatings was analyzed using live/dead and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays; cell adhesion, proliferation, and migration studies were evaluated using SEM. Antibacterial assays highlight significant improvement in the antibacterial properties of Cu-doped coatings with BS. Thus, the developed Cu-doped brushite coatings with BS demonstrate their potential in the realm of biomedical implant technologies, paving the way for further exploration.

In-vivo bone remodeling potential of Sr-d-Ca-P /PLLA-HAp coated biodegradable ZK60 alloy bone plate

Magnesium and its alloys are widely applied biomaterials due to their biodegradability and biocompatibility. However, rapid degradation and hydrogen gas evolution hinder its applicability on a commercial scale. In this study, we developed an Mg alloy bone plate for bone remodeling and support after a fracture. We further coated the Mg alloy plate with Sr-D-Ca-P (Sr dopped Ca-P coating) and Sr-D-Ca-P/PLLA-HAp to evaluate and compare their biodegradability and biocompatibility in both in vitro and in vivo experiments. Chemical immersion and dip coating were employed for the formation of Sr-D-Ca-P and PLLA-HAp layers, respectively. In vitro evaluation depicted that both coatings delayed the degradation process and exhibited excellent biocompatibility. MC3T3-E1cells proliferation and osteogenic markers expression were also promoted. In vivo results showed that both Sr-D-Ca-P and Sr-D-Ca-P/PLLA-HAp coated bone plates had slower degradation rate as compared to Mg alloy. Remarkable bone remodeling was observed around the Sr-D-Ca-P/PLLA-HAp coated bone plate than bare Mg alloy and Sr-D-Ca-P coated bone plate. These results suggest that Sr-D-Ca-P/PLLA-HAp coated Mg alloy bone plate with lower degradation and enhanced biocompatibility can be applied as an orthopedic implant.

Electrochemical Surface Biofunctionalization of Titanium through Growth of TiO2 Nanotubes and Deposition of Zn Doped Hydroxyapatite

The current research aim is to biofunctionalize pure titanium (Ti, grade IV) substrate with titania nanotubes and Zn doped hydroxyapatite-based coatings by applying a duplex electrochemical treatment, and to evaluate the influence of Zn content on the physico-chemical properties of hydroxyapatite (HAp). The obtained nanostructured surfaces were covered with HAp-based coatings doped with Zn in different concentrations by electrochemical deposition in pulsed galvanostatic mode. The obtained surfaces were characterized in terms of morphology, elemental and phasic composition, chemical bonds, roughness, and adhesion. The nanostructured surface consisted of titania nanotubes (NT), aligned, vertically oriented, and hollow, with an inner diameter of ~70 nm. X-ray Diffraction (XRD) analysis showed that the nanostructured surface consists of an anatase phase and some rutile peaks as a secondary phase. The morphology of all coatings consisted of ribbon like-crystals, and by increasing the Zn content the coating became denser due to the decrement of the crystals’ dimensions. The elemental and phase compositions evidenced that HAp was successfully doped with Zn through the pulsed galvanostatic method on the Ti nanostructured surfaces. Fourier Transform Infrared spectroscopy (FTIR) and XRD analysis confirmed the presence of HAp in all coatings, while the adhesion test showed that the addition of a high quantity leads to some delamination. Based on the obtained results, it can be said that the addition of Zn enhances the properties of HAp, and through proper experimental design, the concentration of Zn can be modulated to achieve coatings with tunable features.

Emerging zero-dimensional to four-dimensional biomaterials for bone regeneration

Bone is one of the most sophisticated and dynamic tissues in the human body, and is characterized by its remarkable potential for regeneration. In most cases, bone has the capacity to be restored to its original form with homeostatic functionality after injury without any remaining scarring. Throughout the fascinating processes of bone regeneration, a plethora of cell lineages and signaling molecules, together with the extracellular matrix, are precisely regulated at multiple length and time scales. However, conditions, such as delayed unions (or nonunion) and critical-sized bone defects, represent thorny challenges for orthopedic surgeons. During recent decades, a variety of novel biomaterials have been designed to mimic the organic and inorganic structure of the bone microenvironment, which have tremendously promoted and accelerated bone healing throughout different stages of bone regeneration. Advances in tissue engineering endowed bone scaffolds with phenomenal osteoconductivity, osteoinductivity, vascularization and neurotization effects as well as alluring properties, such as antibacterial effects. According to the dimensional structure and functional mechanism, these biomaterials are categorized as zero-dimensional, one-dimensional, two-dimensional, three-dimensional, and four-dimensional biomaterials. In this review, we comprehensively summarized the astounding advances in emerging biomaterials for bone regeneration by categorizing them as zero-dimensional to four-dimensional biomaterials, which were further elucidated by typical examples. Hopefully, this review will provide some inspiration for the future design of biomaterials for bone tissue engineering.

Graphene Family Nanomaterials: Properties and Potential Applications in Dentistry

Graphene family nanomaterials, with superior mechanical, chemical, and biological properties, have grabbed appreciable attention on the path of researches seeking new materials for future biomedical applications. Although potential applications of graphene had been highly reviewed in other fields of medicine, especially for their antibacterial properties and tissue regenerative capacities, in vivo and in vitro studies related to dentistry are very limited. Therefore, based on current knowledge and latest progress, this article aimed to present the recent achievements and provide a comprehensive literature review on potential applications of graphene that could be translated into clinical reality in dentistry.

An Innovative Approach to Manganese-Substituted Hydroxyapatite Coating on Zinc Oxide⁻Coated 316L SS for Implant Application

In this paper, the synthesis of porous manganese substituted hydroxyapatite (Mn-HAp) coating on zinc oxide (ZnO) coated stainless steel (316L SS) using the electrodeposition technique is reported. The structural, functional, morphological, and elemental analyses are characterized by various analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Results of electrochemical techniques such as cyclic polarization and impedance show that the Mn-HAp coating on ZnO coated 316L SS has the highest corrosion resistance in simulated body fluid (SBF) solution. Moreover, dissolution of metal ions was extremely reduced, as evaluated by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The adhesion and hardness of Mn-HAp/ZnO bilayer coatings have superior mechanical properties over individual coatings. Further, the biocompatibility of in vitro osteoblast attachment, cell viability, and live/dead assessment also confirmed the suitability of Mn-HAp/ZnO bilayer coating on 316L SS for orthopedic applications.

The enhancement of osseointegration using a graphene oxide/chitosan/hydroxyapatite composite coating on titanium fabricated by electrophoretic deposition

Titanium (Ti) has been commonly used as an implant material in dentistry and bone surgery for several decades. Meanwhile, surface modification of titanium can enhance the osseointegration of implants. In this study, a graphene oxide/chitosan/hydroxyapatite (GO/CS/HA) composite coating was fabricated by electrophoretic deposition on Ti substrates. Subsequently, the surface morphology, phase composition, wettability, and bonding strength of this composite coating were researched. Additionally, in vitro cytological examination was performed, including evaluations of cell adhesion, cell viability, cell differentiation, cell mineralization, and osteogenetic factor expression. Finally, the in vivo osteogenetic properties were evaluated through an animal study, including a histological analysis, a microcomputed tomography, and biomechanical tests. The results showed that a homogeneous and crack-free GO/CS/HA composite coating was coated on Ti, and the wettability and bonding strength of the GO/CS/HA composite coating were enhanced compared with HA, GO/HA, and CS/HA coatings. Furthermore, the GO/CS/HA coating greatly heightened the cell-material interactions in vitro. Additionally, this GO/CS/HA-Ti implant could enhance osseointegration in vivo. Consequently, GO/CS/HA-Ti may have potential applications in the field of dental implants. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 635-645, 2019.

Influences of ionic liquid and temperature on the tailorable surface morphology of F-apatite nanocomposites for enhancing biological abilities for orthopedic implantation

This report has approached for the green synthesis of morphological controlled novel metal-doped fluorinated apatite/polymeric nanocomposites. The synthesized nanocomposites have investigated for hard tissue engineering and bone substitute applications. The selected fluoro ionic liquid explored the dual performances as fluorine precursor and as a soft template for the morphological development of apatite nanocomposite synthesis. The structural and surface studies (XRD, FTIR, FE-SEM, EDS, AFM, HR-TEM & SAED) confirmed the crystalline and morphological changes of synthesized fluorohydroxyapatite nanostructures at two different reaction temperatures. The fluorinated apatite nanocomposites doped with silver for metal-doped composites, which have effective antibacterial efficacy and favorable biocompatibility. The silver-doped nanocomposites showed excellent antibacterial ability against Staphylococcus aureus and Escherichia coli bacterial pathogens with the uniform release of silver and fluorine ions. These antibacterial performances have systematically tested by the quantitative and qualitative methods. The rod-like fluorinated apatite nanocrystals promote cell adhesion and viability of human osteosarcoma (MG-63) cell lines and these studies compared with the sheet-like apatite nanocomposites. This type of biomedical apatite materials may be a promising material for orthopedic implant and regeneration applications.

Micromorphological effect of calcium phosphate coating on compatibility of magnesium alloy with osteoblast

Octacalcium phosphate (OCP) and hydroxyapatite (HAp) coatings were developed to control the degradation speed and to improve the biocompatibility of biodegradable magnesium alloys. Osteoblast MG-63 was cultured directly on OCP- and HAp-coated Mg-3Al-1Zn (wt%, AZ31) alloy (OCP- and HAp-AZ31) to evaluate cell compatibility. Cell proliferation was remarkably improved with OCP and HAp coatings which reduced the corrosion and prevented the H2O2 generation on Mg alloy substrate. OCP-AZ31 showed sparse distribution of living cell colonies and dead cells. HAp-AZ31 showed dense and homogeneous distribution of living cells, with dead cells localized over and around corrosion pits, some of which were formed underneath the coating. These results demonstrated that cells were dead due to changes in the local environment, and it is necessary to evaluate the local biocompatibility of magnesium alloys. Cell density on HAp-AZ31 was higher than that on OCP-AZ31 although there was not a significant difference in the amount of Mg ions released in medium between OCP- and HAp-AZ31. The outer layer of OCP and HAp coatings consisted of plate-like crystal with a thickness of around 0.1 μm and rod-like crystals with a diameter of around 0.1 μm, respectively, which grew from a continuous inner layer. Osteoblasts formed focal contacts on the tips of plate-like OCP and rod-like HAp crystals, with heights of 2-5 μm. The spacing between OCP tips of 0.8-1.1 μm was wider than that between HAp tips of 0.2-0.3 μm. These results demonstrated that cell proliferation depended on the micromorphology of the coatings which governed spacing of focal contacts. Consequently, HAp coating is suitable for improving cell compatibility and bone-forming ability of the Mg alloy.

In situ incorporation of heparin/bivalirudin into a phytic acid coating on biodegradable magnesium with improved anticorrosion and biocompatible properties

Drugs were incorporated into a phytic acid coating on Mg by an in situ chemical route for corrosion control and biocompatibility.

Fabrication of Minerals Substituted Porous Hydroxyapaptite/Poly(3,4-ethylenedioxy pyrrole-co-3,4-ethylenedioxythiophene) Bilayer Coatings on Surgical Grade Stainless Steel and Its Antibacterial and Biological Activities for Orthopedic Applications

Current strategies of bilayer technology have been aimed mainly at the enhancement of bioactivity, mechanical property and corrosion resistance. In the present investigation, the electropolymerization of poly(3,4-ethylenedioxypyrrole-co-3,4-ethylenedioxythiophene) (P(EDOP-co-EDOT)) with various feed ratios of EDOP/EDOT on surgical grade stainless steel (316L SS) and the successive electrodeposition of strontium (Sr(2+)), magnesium (Mg(2+)) and cerium (Ce(3+)) (with 0.05, 0.075 and 0.1 M Ce(3+)) substituted porous hydroxyapatite (M-HA) are successfully combined to produce the bioactive and corrosion resistance P(EDOP-co-EDOT)/M-HA bilayer coatings for orthopedic applications. The existence of as-developed coatings was confirmed by Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), proton nuclear magnetic resonance spectroscopy ((1)H NMR), high resolution scanning electron microscopy (HRSEM), energy dispersive X-ray analysis (EDAX) and atomic force microscopy (AFM). Also, the mechanical and thermal behavior of the bilayer coatings were analyzed. The corrosion resistance of the as-developed coatings and also the influence of copolymer (EDOP:EDOT) feed ratio were studied in Ringer's solution by electrochemical techniques. The as-obtained results are in accord with those obtained from the chemical analysis using inductively coupled plasma atomic emission spectrometry (ICP-AES). In addition, the antibacterial activity, in vitro bioactivity, cell viability and cell adhesion tests were performed to substantiate the biocompatibility of P(EDOP-co-EDOT)/M-HA bilayer coatings. On account of these investigations, it is proved that the as-developed bilayer coatings exhibit superior bioactivity and improved corrosion resistance over 316L SS, which is potential for orthopedic applications.

A Novel MgO-CaO-SiO₂ System for Fabricating Bone Scaffolds with Improved Overall Performance

Although forsterite (Mg₂SiO₄) possesses good biocompatibility and suitable mechanical properties, the insufficient bioactivity and degradability hinders its further application. In this study, a novel MgO-CaO-SiO₂ system was developed by adding wollastonite (CaSiO₃) into Mg₂SiO₄ to fabricate bone scaffolds via selective laser sintering (SLS). The apatite-forming ability and degradability of the scaffolds were enhanced because the degradation of CaSiO₃ could form silanol groups, which could offer nucleation sites for apatite. Meanwhile, the mechanical properties of the scaffolds grew with increasing CaSiO₃ to 20 wt %. It was explained that the liquid phase of CaSiO₃ promoted the densification during sintering due to its low melting point. With the further increase in CaSiO₃, the mechanical properties decreased due to the formation of the continuous filling phase. Furthermore, the scaffolds possessed a well-interconnected porous structure and exhibited an ability to support cell adhesion and proliferation.

Ball flower like manganese, strontium substituted hydroxyapatite/cerium oxide dual coatings on the AZ91 Mg alloy with improved bioactive and corrosion resistance properties for implant applications

Mn, Sr-HAP/CeO₂dual layer coated AZ91 Mg alloy will be a revolutionary potential material for orthopedic implants.

Synthesis and characterization of a phytic acid/mesoporous 45S5 bioglass composite coating on a magnesium alloy and degradation behavior

The composite coating consists of an interior layer of mesoporous 45S5 bioglass and an outer layer of phytic acid/magnesium phytic acid compounds.

Osteoblastic cell responses and antibacterial efficacy of Cu/Zn co-substituted hydroxyapatite coatings on pure titanium using electrodeposition method

Effective physiological bone integration and absence of bacterial infection are essential for a successful orthopaedic or dental implant.

Smart rose flower like bioceramic/metal oxide dual layer coating with enhanced anti-bacterial, anti-cancer, anti-corrosive and biocompatible properties for improved orthopedic applications

The flower like Se,Mn-HAP/ZrO2 dual layer coating on AZ91 magnesium alloy satisfies the requirements in bone cancer treatment and signifies progress in the field of implant materials.

Single walled carbon nanotubes reinforced mineralized hydroxyapatite composite coatings on titanium for improved biocompatible implant applications

Carbon nanotubes reinforced mineralized hydroxyapatite (CNT/M-HAP) composite coating on titanium by pulsed electrodeposition is a promising approach to produce bioimplants with better osseointegration capacity and improved mechanical property.

Testing the in vitro performance of hydroxyapatite coated magnesium (AZ91D) and titanium concerning cell adhesion and osteogenic differentiation

In the current study the in vitro outcome of a degradable magnesium alloy (AZ91D) and standard titanium modified by nanostructured-hydroxyapatite (n-HA) coatings concerning cell adhesion and osteogenic differentiation was investigated by direct cell culture. The n-HA modification was prepared via radio-frequency magnetron sputtering deposition and proven by field emission scanning electron microscopy and X-ray powder diffraction patterns revealing a homogenous surface coating. Human mesenchymal stem cell (hMSCs) adhesion was examined after one and 14 days displaying an enhanced initial cell adhesion on the n-HA modified samples. The osteogenic lineage commitment of the cells was determined by alkaline phosphatase (ALP) quantification. On day one n-HA coated AZ91D exhibited a comparable ALP expression to standard tissue culture polystyrene samples. However, after 14 days solely little DNA and ALP amounts were measurable on n-HA coated AZ91D due to the lack of adherent cells. Titanium displayed excellent cell adhesion properties and ALP was detectable after 14 days. An increased pH of the culture was measured for AZ91D as well as for n-HA coated AZ91D. We conclude that n-HA modification improves initial cell attachment on AZ91D within the first 24 h. However, the effect does not persist for 14 days in in vitro conditions.