MG63 Osteoblast-like Cells Research Articles

Chitosan and cellulose-based composite hydrogels with embedded titanium dioxide nanoparticles as candidates for biomedical applications

Hydrogel based matrices and titanium dioxide (TiO2) nanoparticles (NPs) are well established materials in bone tissue engineering. Nevertheless, there is still a challenge to design appropriate composites with enhanced mechanical properties and improved cell growth. Progressing in this direction, we synthesized nanocomposite hydrogels by impregnating TiO2 NPs in a chitosan and cellulose-based hydrogel matrix containing polyvinyl alcohol (PVA), to enhance the mechanical stability and swelling capacity. Although, TiO2 has been incorporated into single and double component matrix systems, it has rarely been combined with a tri-component hydrogel matrix system. The doping of NPs was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and small- and wide-angle X-ray scattering. Our results showed that incorporation of TiO2 NPs improved the tensile properties of the hydrogels significantly. Furthermore, we performed biological evaluation of scaffolds, swelling degree, bioactivity assessment, and hemolytic tests to prove that all types of hydrogels were safe for use in the human body. The culturing of human osteoblast-like cells MG-63 on hydrogels showed better adhesion of cells in the presence of TiO2 and showed increasing proliferation with increasing amount of TiO2. Our results showed that the sample with the highest TiO2 concentration, CS/MC/PVA/TiO2 (1 %) had the best biological properties.

Dexamethasone and doxycycline functionalized nanoparticles enhance osteogenic properties of titanium surfaces.

To evaluate the effect of doxycycline and dexamethasone doped nanoparticles covering titanium surfaces, on osteoblasts proliferation and differentiation. Doxycycline and dexamethasone doped polymeric nanoparticles were applied on titanium discs (Ti-DoxNPs and Ti-DexNPs). Undoped NPs and uncovered Ti discs were used as control. Human MG-63 osteoblast-like cells were cultured. Osteoblasts proliferation was tested by MTT assay. Alkaline phosphatase activity was analyzed. Differentiation gene expression was assessed by real-time quantitative polymerase chain reaction. Scanning Electron Microscopy was performed to assess osteoblasts morphology. Mean comparisons were conducted by ANOVA and Wilcoxon or Tukey tests (p<0.05). No differences in osteoblasts proliferation were found. Osteoblasts grown on Ti-DoxNPs significantly increased alkaline phosphatase activity. Doxycycline and dexamethasone nanoparticles produced an over-expression of the main osteogenic proliferative genes (TGF-β1, TGF-βR1 and TGF-βR2). The expression of Runx-2 was up-regulated. The osteogenic proteins (AP, OSX and OPG) were also overexpressed on osteoblasts cultured on Ti-DoxNPs and Ti-DexNPs. The OPG/RANKL ratio was the highest when DoxNPs were present (75-fold increase with respect to the control group). DexNPs also produced a significantly higher OPG/RANKL ratio with respect to the control (20 times higher). Osteoblasts grown on titanium discs were mainly flat and polygonal in shape, with inter-cellular connections. In contrast, osteoblasts cultured on Ti-DoxNPs or Ti-DexNPs were found to be spindle-shaped and had abundant secretions on their surfaces. DoxNPs and DexNPs were able to stimulate osteoblasts differentiation when applied on titanium surfaces, being considered potential inducers of osteogenic environment when performing regenerative procedures around titanium dental implants.

Development of innate immune memory by non-immune cells during Staphylococcus aureus infection depends on reactive oxygen species.

The mechanisms underlying innate immune memory (trained immunity) comprise epigenetic reprogramming of transcriptional pathways associated with alterations of intracellular metabolism. While the mechanisms of innate immune memory carried out by immune cells are well characterized, such processes in non-immune cells, are poorly understood. The opportunistic pathogen, Staphylococcus aureus, is responsible for a multitude of human diseases, including pneumonia, endocarditis and osteomyelitis, as well as animal infections, including chronic cattle mastitis that are extremely difficult to treat. An induction of innate immune memory may be considered as a therapeutic alternative to fight S. aureus infection. In the current work, we demonstrated the development of innate immune memory in non-immune cells during S. aureus infection employing a combination of techniques including Enzyme-linked immunosorbent assay (ELISA), microscopic analysis, and cytometry. We observed that training of human osteoblast-like MG-63 cells and lung epithelial A549 cells with β-glucan increased IL-6 and IL-8 production upon a stimulation with S. aureus, concomitant with histones modifications. IL-6 and IL-8 production was positively correlated with an acetylation of histone 3 at lysine 27 (H3K27), thus suggesting epigenetic reprogramming in these cells. An addition of the ROS scavenger N-Acetylcysteine, NAC, prior to β-glucan pretreatment followed by an exposure to S. aureus, resulted in decreased IL-6 and IL-8 production, thereby supporting the involvement of ROS in the induction of innate immune memory. Exposure of cells to Lactococcus lactis resulted in increased IL-6 and IL-8 production by MG-63 and A549 cells upon a stimulation with S. aureus that was correlated with H3K27 acetylation, suggesting the ability of this beneficial bacterium to induce innate immune memory. This work improves our understanding of innate immune memory in non-immune cells in the context of S. aureus infection. In addition to known inducers, probiotics may represent good candidates for the induction of innate immune memory. Our findings may help the development of alternative therapeutic approaches for the prevention of S. aureus infection.

Piezoelectric Biocomposites for Bone Grafting in Dentistry.

In this research, Hydroxyapatite-Potassium, Sodium Niobate-Chitosan (HA-KNN-CSL) biocomposites were synthesized, both as hydrogel and ultra-porous scaffolds, to offer two commonly used alternatives to biomaterials in dental clinical practice. The biocomposites were obtained by varying the content of low deacetylated chitosan as matrix phase, mesoporous hydroxyapatite nano-powder, and potassium-sodium niobate (K0.47Na0.53NbO3) sub-micron-sized powder. The resulting materials were characterized from physical, morpho-structural, and in vitro biological points of view. The porous scaffolds were obtained by freeze-drying the composite hydrogels and had a specific surface area of 18.4-24 m2/g and a strong ability to retain fluid. Chitosan degradation was studied for 7 and 28 days of immersion in simulated body fluid without enzymatic presence. All synthesized compositions proved to be biocompatible in contact with osteoblast-like MG-63 cells and showed antibacterial effects. The best antibacterial effect was shown by the 10HA-90KNN-CSL hydrogel composition against Staphylococcus aureus and the fungal strain Candida albicans, while a weaker effect was observed for the dry scaffold.

Synergetic effect of Fe/Ag ions incorporated HAp on AZ31 Mg alloy to improve corrosion resistance and osteogenic activity

In clinical applications, the rapid deterioration of biodegradable magnesium alloys under in-vitro and in-vivo conditions is a key problem. However, to overcome the limitations surface modification treatments on this material are performed. In this work, a Fe/Ag-HAp coating was developed for biodegradable AZ31 Mg alloy to enhance the corrosion resistance and osteoconductive of the material. The surface morphological studies displayed a flaky-like aggregated structure. In addition to validating the functional groups with Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy and X-Ray Diffraction (XRD) were used to analyze the crystal structure of the samples. Moreover, real-time corrosion was monitored by hydrogen evolution, indicating 2.8 ml of gas was evolved in the coated sample compared with bare material. The potentiodynamic polarization and electrochemical impedance studies revealed the significant corrosion rate and strong impedance resistance of the coating materials. After 7 days of immersion in SBF solution, the coating recruited calcium/phosphate from the entire sample, as observed in the cauliflower-like structure, and the functional group was confirmed by ATR-IR spectroscopy. MTT was performed using MG-63 osteoblast-like cells, the samples were incubated for 24 h and revealed better adhesion on the surface which was observed by SEM. Osteogenic differentiation was evaluated in 3 and 5 days and it showed a significant increase in cell proliferation rate.

Interaction between ferroptosis and TNF-α: Impact in obesity-related osteoporosis.

The relationship of obesity and osteoporosis has been widely studied over the past years. However, the implications of obesity for bone health remain controversial, and the underlying molecular mechanism is not yet fully understood. This study demonstrated that high-fat diet-induced obesity leads to significantly decreased bone volume/tissue volume (BV/TV), trabecular number (Tb.N), and cortical thickness (Ct.Th) of male rat femur after mechanical loading effects of body weight were controlled. HFD-induced obese rats exhibited attenuated expression of ferroptosis inhibitory protein SLC7A11 and GPX4 in bone tissues, which was correlated with elevated serum TNF-α concentration. Ferroptosis inhibitor administration could effectively rescue decreased osteogenesis-associated type H vessels and osteoprogenitors, and downregulate serum levels of TNF-α to ameliorate bone loss in obese rats. Since ferroptosis and TNF-α both affect bone and vessel formation, we further investigated the interaction between ferroptosis and TNF-α, and its impact in osteogenesis and angiogenesis in vitro. In human osteoblast-like MG63 and umbilical vein endothelial cells (HUVEC), TNF-α/TNFR2 signaling promoted cystine uptake and GSH biosynthesis to provide protection against low-dose ferroptosis inducer erastin. While, TNF-α/TNFR1 facilitated ferroptosis in the presence of high-dose erastin through ROS accumulation. Moreover, TNF-α regulated ferroptosis-induced osteogenic and angiogenic dysfunctions based on its ferroptosis regulatory role. Meanwhile, ferroptosis inhibitors could reduce intracellular ROS overproduction and enhance osteogenesis and angiogenesis in TNF-α-treated MG63 and HUVECs. This study revealed the interaction between ferroptosis and TNF-α and its impact in osteogenesis and angiogenesis, which provides new insights into the pathogenesis and regenerative therapy of obesity-related osteoporosis.

Porous Zirconia Scaffolds Functionalized with Calcium Phosphate Layers and PLGA Nanoparticles Loaded with Hydrophobic Gentamicin.

Implant-related infections are a worldwide issue that is considered very challenging. Conventional therapies commonly end up failing; thus, new solutions are being investigated to overcome this problem. The in situ delivery of the drug at the implant site appears to be more sufficient compared to systemic antibiotic therapy. In this study, we manufactured porous zirconia scaffolds using the foam replication method. To improve their overall bioactivity, they were coated with a calcium phosphate (CaP) layer containing antibiotic-loaded degradable polymer nanoparticles (NPs) obtained by the double emulsion method to achieve the antibacterial effect additionally. Encapsulation efficiency (EE) and drug loading (DL) were superior and were equal to 99.9 ± 0.1% and 9.1 ± 0.1%, respectively. Scaffolds were analyzed with scanning electron microscopy, and their porosity was evaluated. The porosity of investigated samples was over 90% and resembled the microstructure of spongy bone. Furthermore, we investigated the cytocompatibility with osteoblast-like MG-63 cells and antimicrobial properties with Staphylococcus aureus. Scaffolds coated with a CaP layer were found non-toxic for MG-63 cells. Moreover, the presence of antibiotic-loaded nanoparticles had no significant influence on cell viability, and the obtained scaffolds inhibited bacteria growth. Provided processes of fabrication of highly porous zirconia scaffolds and surface functionalization allow minimizing the risk of implant-related infection.

Surface Multifunctionalization of Inert Ceramic Implants by Calcium Phosphate Biomimetic Coating Doped with Nanoparticles Encapsulating Antibiotics.

Aseptic loosening and periprosthetic infections are complications that can occur at the interface between inert ceramic implants and natural body tissues. Therefore, the need for novel materials with antibacterial properties to prevent implant-related infection is evident. This study proposes multifunctionalizing the inert ceramic implant surface by biomimetic calcium phosphate (CaP) coating decorated with antibiotic-loaded nanoparticles for bioactivity enhancement and antibacterial effect. This study aimed to coat zirconium dioxide (ZrO2) substrates with a bioactive CaP-layer containing drug-loaded degradable polymer nanoparticles (NPs). The NPs were loaded with two antibiotics, gentamicin or bacitracin. The immobilization of NPs happened by two deposition methods: coprecipitation and drop-casting. X-ray diffraction (XRD), scanning electron microscopy (SEM), and cross-section analyses were used to characterize the coatings. MG-63 osteoblast-like cells and human mesenchymal stem cells (hMSC) were chosen for in vitro tests. Antibacterial activity was assessed with S. aureus and E. coli. The coprecipitation method allowed for a favorable homogeneous distribution of the NPs within the CaP coating. The CaP coating was constituted of hydroxyapatite and octacalcium phosphate; its thickness was 3.8 ± 1 μm with cavities of around 1 μm suitable for hosting NPs with a size of 200 nm. Antibiotics were released from the coatings in a controlled manner for 1 month. The cell culture study has confirmed the excellent behavior of the coprecipitated coating, showing cytocompatibility and a homogeneous distribution of the cells on the coated surfaces. The increase in alkaline phosphatase activity showed osteogenic differentiation. The materials were found to inhibit the growth of bacteria. Newly developed coatings with antibacterial and bioactive properties are promising candidates to prevent peri-implant infectious bone diseases.

A 3D-Printed Biomaterial Scaffold Reinforced with Inorganic Fillers for Bone Tissue Engineering: In Vitro Assessment and In Vivo Animal Studies.

This research aimed to substantiate the potential practicality of utilizing a matrix-like platform, a novel 3D-printed biomaterial scaffold, to enhance and guide host cells' growth for bone tissue regeneration. The 3D biomaterial scaffold was successfully printed using a 3D Bioplotter® (EnvisionTEC, GmBH) and characterized. Osteoblast-like MG63 cells were utilized to culture the novel printed scaffold over a period of 1, 3, and 7 days. Cell adhesion and surface morphology were examined using scanning electron microscopy (SEM) and optical microscopy, while cell viability was determined using MTS assay and cell proliferation was evaluated using a Leica microsystem (Leica MZ10 F). The 3D-printed biomaterial scaffold exhibited essential biomineral trace elements that are significant for biological bone (e.g., Ca-P) and were confirmed through energy-dispersive X-ray (EDX) analysis. The microscopy analyses revealed that the osteoblast-like MG63 cells were attached to the printed scaffold surface. The viability of cultured cells on the control and printed scaffold increased over time (p < 0.05); however, on respective days (1, 3, and 7 days), the viability of cultured cells between the two groups was not significantly different (p > 0.05). The protein (human BMP-7, also known as growth factor) was successfully attached to the surface of the 3D-printed biomaterial scaffold as an initiator of osteogenesis in the site of the induced bone defect. An in vivo study was conducted to substantiate if the novel printed scaffold properties were engineered adequately to mimic the bone regeneration cascade using an induced rabbit critical-sized nasal bone defect. The novel printed scaffold provided a potential pro-regenerative platform, rich in mechanical, topographical, and biological cues to guide and activate host cells toward functional regeneration. The histological studies revealed that there was progress in new bone formation, especially at week 8 of the study, in all induced bone defects. In conclusion, the protein (human BMP-7)-embedded scaffolds showed higher regenerative bone formation potential (week 8 complete) compared to the scaffolds without protein (e.g., growth factor; BMP-7) and the control (empty defect). At 8 weeks postimplantation, protein (BMP-7) significantly promoted osteogenesis as compared to other groups. The scaffold underwent gradual degradation and replacement by new bones at 8 weeks in most defects.

Bacteriostatic coatings formed on titanium dental implants for veterinary applications

Titanium (Ti) dental implants were anodized in calcium hypophosphite solution to obtain a porous, bioactive layer. The anodized implant surface was covered by a poly(sebacic anhydride) (PSBA) layer with amoxicillin. SEM analysis showed an irregular distribution of the antibiotic on the surface. However, confocal microscopy images revealed the formation of a uniform polymer layer. The thickness of the oxide and polymer layers was similar, between 6 and 9 μm. PSBA is an easy, hydrolysable polymer. After the polymer with amoxicillin was immersed in phosphate buffered solution (PBS) for 1 h, >53 % of hydrolysis products were detected by 1H NMR spectroscopy. After 9 days of polymer immersion, the hydrolysis product content was >67 %. Drug release was analyzed using high-performance liquid chromatography (HPLC). After 1 h of implant immersion in PBS an average of 6.0 μg/mL of amoxicillin was released. Importantly, the released concentration of amoxicillin was enough to inhibit S. aureus and S. epidermidis growth, minimal inhibitory concentration (inhibition zones between 27 mm and 30 mm) and decrease bacteria adhesion to the implant surface were achieved. This paper presents the cytocompatibility results of PSBA, amoxicillin, and extracts collected from the implants exposed to mouse fibroblast L929 and osteoblast-like MG-63 cells. PSBA concentrations up to 1 % did not significantly affect cell viability. Amoxicillin concentrations up to 150 μL/mL were cytocompatible with both cell lines. Cell viability was >70 % for both cell lines after 24 h of treatment with extracts from modified implants that were immersed in PBS for 72 h prior to viability experiments. This work presents a simple method to obtain a hybrid, bacteriostatic and biocompatible layer on long-term implant surfaces. These techniques may find application in the surface treatment of various Ti implants with a variety of shapes and sizes for veterinary applications.

Distinctions in bone matrix nanostructure, composition, and formation between osteoblast-like cells, MG-63, and human mesenchymal stem cells, UE7T-13

Osteoblast-like cells and human mesenchymal stem cells (hMSCs) are frequently employed as osteoprogenitor cell models for evaluating novel biomaterials in bone healing and tissue engineering. In this study, the characterization of UE7T-13 hMSCs and MG-63 human osteoblast-like cells was examined. Both cells can undergo osteogenesis and produce calcium extracellular matrix; however, calcium nodules produced by MG-63 lacked a central mass and appeared flatter than UE7T-13. The absence of growing calcium nodules in MG-63 was discovered by SEM-EDX to be associated with the formation of alternating layers of cells and calcium extracellular matrix. The nanostructure and composition analysis showed that UE7T-13 had a finer nanostructure of calcium nodules with a higher calcium/phosphate ratio than MG-63. Both cells expressed high intrinsic levels of collagen type I alpha 1 chain, while only UE7T-13 expressed high levels of alkaline phosphatase, biomineralization associated (ALPL). High ALP activity in UE7T-13 was not further enhanced by osteogenic induction, but in MG-63, low intrinsic ALP activity was greatly induced by osteogenic induction. These findings highlight the differences between the two immortal osteoprogenitor cell lines, along with some technical notes that should be considered while selecting and interpreting the pertinent in vitro model.

Effect of pectin on the crystallization of strontium substituted HA for bone reconstruction application

The biomacropolymers of bone extracellular matrix (ECM) guide the growth of hydroxyapatite (HA) with various ionic substitutions. Pectin, a plant polysaccharide with chemical similarities to ECM, was investigated for its potential to promote the crystallization of strontium-substituted HA (SH). The influence of pectin (0.5 and 1.0 wt%) on the in situ mineralization of SH (10 and 30 mol% calcium substitution with strontium) was studied. The preferential affinity of pectin to strontium over calcium favoured the incorporation of strontium in apatite, decreased crystal size (18.85–26.22 nm) and retained more pectin residues (8–16%). The residual pectin strongly interacted with small SH particles, resulting in high microhardness (0.43–0.85 GPa) and high surface charge (−32.1 to −30.3 mV), while weak interaction with large HA particles resulted in low microhardness (0.15–0.25 GPa) and low surface charge (−35.4 to −34.6 mV). The in vitro cellular study using human osteoblast-like MG-63 cells demonstrated that inorganic size and material crystallinity play a vital role in regulating osteogenesis. The study suggests that the synchronization of low pectin concentration (0.5 wt%) and high strontium substitution in HA (30 mol%) offers the desired microhardness and in vitro osteogenic properties to emulate natural bone.

Novel Bioactive Magnesium-Hopeite composite by friction stir processing for orthopedic implant applications

Magnesium (Mg) shows excellent potential for orthopedic implant applications owing to its equivalent mechanical properties compared to cortical bone and its biocompatibility. However, the rapid degradation rate of magnesium and its alloys in the physiological environment results in losing their mechanical integrity before complete bone healing. In light of this, friction stir processing (FSP), a solid-state process, is used to fabricate Hopeite (Zn(PO4)2.4H2O) reinforced novel magnesium composite. As a result of the novel composite fabricated by FSP, grain refinement of the matrix phase occurs significantly. The samples were immersed in simulated body fluid (SBF) for in-vitro bioactivity and biodegradability tests. The corrosion behavior of pure Mg, FSP Mg, and FSP Mg-Hopeite composite samples was compared using electrochemical and immersion tests in SBF. It found that Mg-Hopeite composite has better corrosion resistance than FSP Mg and pure Mg. Because of grain refinement and the presence of secondary phase Hopeite in the composite, the mechanical properties and corrosion resistance improved. The bioactivity test was performed in the SBF environment, and a rapid apatite layer was formed on the surface of Mg-Hopeite composite samples during the test. Osteoblast-like MG63 cells were exposed to samples, and the MTT assay confirmed the non-toxicity of the FSP Mg-Hopeite composite. The wettability of the Mg-Hopeite composite was improved than pure Mg. The present research findings showed that the novel Mg-Hopeite composite fabricated by FSP is a promising candidate for orthopedic implant applications, unreported in the literature.

Modulation of MG-63 Osteogenic Response on Mechano-Bactericidal Micronanostructured Titanium Surfaces.

Despite recent advances in the development of orthopedic devices, implant-related failures that occur as a result of poor osseointegration and nosocomial infection are frequent. In this study, we developed a multiscale titanium (Ti) surface topography that promotes both osteogenic and mechano-bactericidal activity using a simple two-step fabrication approach. The response of MG-63 osteoblast-like cells and antibacterial activity toward Pseudomonas aeruginosa and Staphylococcus aureus bacteria was compared for two distinct micronanoarchitectures of differing surface roughness created by acid etching, using either hydrochloric acid (HCl) or sulfuric acid (H2SO4), followed by hydrothermal treatment, henceforth referred to as either MN-HCl or MN-H2SO4. The MN-HCl surfaces were characterized by an average surface microroughness (Sa) of 0.8 ± 0.1 μm covered by blade-like nanosheets of 10 ± 2.1 nm thickness, whereas the MN-H2SO4 surfaces exhibited a greater Sa value of 5.8 ± 0.6 μm, with a network of nanosheets of 20 ± 2.6 nm thickness. Both micronanostructured surfaces promoted enhanced MG-63 attachment and differentiation; however, cell proliferation was only significantly increased on MN-HCl surfaces. In addition, the MN-HCl surface exhibited increased levels of bactericidal activity, with only 0.6% of the P. aeruginosa cells and approximately 5% S. aureus cells remaining viable after 24 h when compared to control surfaces. Thus, we propose the modulation of surface roughness and architecture on the micro- and nanoscale to achieve efficient manipulation of osteogenic cell response combined with mechanical antibacterial activity. The outcomes of this study provide significant insight into the further development of advanced multifunctional orthopedic implant surfaces.

Surface Characteristics and Bone Biocompatibility of Cold-Sprayed Porous Titanium on Polydimethylsiloxane Substrates.

A variant of the cold spray (CS) technique was applied for the functionalization of polymer-based materials such as polydimethylsiloxane (PDMS) to improve the extent of mammalian cell interactions with these substrates. This was demonstrated by the embedment of porous titanium (pTi) into PDMS substrates using a single-step CS technique. CS processing parameters such as gas pressure and temperature were optimized to achieve the mechanical interlocking of pTi in the compressed PDMS to fabricate a unique hierarchical morphology possessing micro-roughness. As evidenced by the preserved porous structure, the pTi particles did not undergo any significant plastic deformation upon impact with the polymer substrate. The thickness of the particle embedment layer was determined, by cross-sectional analysis, ranging from 120 μm to over 200 μm. The behavior of osteoblast-like cells MG63 coming into contact with the pTi-embedded PDMS was examined. The results showed that the pTi-embedded PDMS samples promoted 80-96% of cell adhesion and proliferation during the early stages of incubation. The low cytotoxicity of the pTi-embedded PDMS was confirmed, with cell viability of the MG63 cells being above 90%. Furthermore, the pTi-embedded PDMS facilitated the production of alkaline phosphatase and calcium deposition in the MG63 cells, as demonstrated by the higher amount of alkaline phosphatase (2.6 times) and calcium (10.6 times) on the pTi-embedded PDMS sample fabricated at 250 °C, 3 MPa. Overall, the work demonstrated that the CS process provided flexibility in the parameters used for the production of the modified PDMS substrates and is highly efficient for the fabrication of coated polymer products. The results obtained in this study suggest that a tailorable porous and rough architecture could be achieved that promoted osteoblast function, indicating that the method has promise in the design of titanium-polymer composite materials applied to biomaterials used in musculoskeletal applications.

Physicochemical, mechanical, dielectric, and biological properties of sintered hydroxyapatite/barium titanate nanocomposites for bone regeneration

Bone implants fabricated using nanocomposites containing hydroxyapatite (HA) and barium titanate (BT) show osteoconductive, osteoinductive, osteointegration, and piezoelectricity properties for bone regeneration applications. In our present study, HA and BT nanopowders were synthesized using high-energy ball-milling-assisted solid-state reaction with precursors of calcium carbonate and ammonium dihydrogen phosphate, and barium carbonate and titanium oxide powder mixtures, respectively. Hexagonal HA and tetragonal BT phases were formed after calcination at 700 and 1000 °C, respectively. Subsequently, hydroxyapatite/barium titanate (HA/BT) nanocomposites with different weight percentages of HA and BT were prepared by ball-milling, then compacted and sintered at two different temperatures to endow these bioceramics with better mechanical, dielectric, and biological properties for bone regeneration. Microstructure, crystal phases, and molecular structure characterizations of these sintered HA/BT nanocomposite compacts (SHBNCs) were performed using field-emission scanning electron microscopy, x-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. Bulk density was evaluated using the Archimedes method. HA/BT nanocomposites with increased BT content showed enhanced dielectric properties, and the dielectric constant (ϵr ) value for 5HA/95BT was ∼182 at 100 Hz. Mechanical properties such as Vicker’s hardness, fracture toughness, yield strength, and diametral tensile strength were also investigated. The hemolysis assay of SHBNCs exhibited hemocompatibility. The effect of these SHBNCs as implants on the in vitro cytocompatibility and cell viability of MG-63 osteoblast-like cells was assessed by MTT assay and live/dead staining, respectively. 15HA/85BT showed increased metabolic activity with a higher number of live cells than BT after the culture period. Overall, the SHBNCs can be used as orthopedic implants for bone regeneration applications.

Characterization of 3D printed biodegradable piezoelectric scaffolds for bone regeneration.

The primary objective of this research was to develop a poly(l-lactic acid)(PLLA) scaffold and evaluate critical characteristics essential for its biologic use as a craniofacial implant. PLLAscaffolds were designed and fabricated using fused deposition modeling technology. The surface morphology and microarchitecture were analyzed using scanning electron microscopy (SEM) and microCT, respectively. Crystallography, compressive modulus, and the piezoelectric potential generated upon mechanical distortion were characterized. Hydrolytic degradation was studied. MG63 osteoblast-like cell proliferation and morphology were assessed. The porosity of the scaffolds was 73%, with an average pore size of 450 µm and an average scaffold fiber thickness of 130 µm. The average compressive modulus was 244 MPa, and the scaffolds generated an electric potential of 25 mV upon cyclic/repeated loading. The crystallinity reduced from 27.5% to 13.9% during the 3D printing process. The hydrolytic degradation was minimal during a 12-week period. Osteoblast-like cells did not attach to the uncoated scaffold but attached well after coating the scaffold with fibrinogen. They then proliferated to cover the complete scaffold by Day 14. The PLLA scaffolds were designed and printed, proving the feasibility of 3D printing as a method of fabricating PLLA scaffolds. The elastic modulus was comparable to that of trabecular bone, and the piezoelectric properties of the PLLA were retained after 3D printing. The scaffolds were cytocompatible. These 3D-printed PLLA scaffolds showed promising properties akin to the natural bone, and they warrant further investigation for bone regeneration.

Hydroxyapatite Double Substituted with Zinc and Silicate Ions: Possibility of Mechanochemical Synthesis and In Vitro Properties

In this study, the mechanochemical synthesis of substituted hydroxyapatite (HA) containing zinc and silicon ions having a chemical formula of Ca10-xZnx(PO4)6-x(SiO4)x(OH)2-x, where x = 0.2, 0.6, 1.0, 1.5, and 2.0, was carried out. The synthesized materials were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and inductively coupled plasma spectroscopy. We found that HA co-substituted with zinc and silicate formed up to x = 1.0. At higher concentrations of the substituents, the formation of large amounts of an amorphous phase was observed. The cytotoxicity and biocompatibility of the co-substituted HA was studied in vitro on Hek293 and MG-63 cell lines. The HA co-substituted with zinc and silicate demonstrated high biocompatibility; the lowest cytotoxicity was observed at x = 0.2. For this composition, good proliferation of MG-63 osteoblast-like cells and an increased solubility compared with that of HA were detected. These properties allow us to recommend the synthesized material for medical applications, namely, for the restoration of bone tissue and manufacture of biodegradable implants.

Atmospheric-Pressure Plasma Jet-Induced Graft Polymerization of Composite Hydrogel on 3D-Printed Polymer Surfaces for Biomedical Application

Poly(lactic acid) (PLA) is currently the most widely used material in 3D printing. PLA has good mechanical properties, chemical stability, and biodegradability, but its surface is hydrophobic and cannot be effectively used. The growth metabolism of attachments, how to increase the strength of PLA with high brittleness, and 3D printing of PLA materials for the biomedical field have always been a topic of research by scientists. This experiment used fused filament fabrication (FFF) to prepare structures. First, the 3D-printed polymer surfaces were treated with an atmospheric-pressure plasma jet (APPJ) to make the surface hydrophilic and increase the number of polar functional groups on the surface. Then, UV photo-grafting polymerization of 2-hydroxyethyl methacrylate (HEMA), poly(ethylene glycol) methacrylate (PEGMA), and hydroxyapatite (HAp) was applied onto the 3D-printed polymer surfaces. The experimental results of the water contact angle for the wettability test show that APPJ-treated and UV-grafted composite hydrogels become hydrophilic to activate the 3D-printed polymer surface successfully. For the in vitro study, the effect of APPJ treatment and composite hydrogel on the viability of osteoblast-like MG63 cells was examined using the Alamar Blue cell viability assay, indicating that biocompatibility has been improved in this study. This method is expected to have potential in the application of bone scaffolds in the future.

Biological properties of chitosan/Eudragit E 100 and chitosan/poly(4-vinylpyridine) coatings electrophoretically deposited on AgNPs-decorated titanium substrate

The objective of the study was the determination of the response, in contact with human osteoblast-like MG-63 cells, of electrophoretically deposited coatings composed of chitosan (CS), Eudragit E 100 (EE100), or poly(4-vinylpyridine) (P4VP) on a silver nanoparticle (AgNPs)-decorated titanium substrate. Before deposition, the substrate was coated with silver by electro-reduction of silver nitrate. The coatings deposition was carried out in suspensions containing 0.1 % (w/w) of one of the biopolymers, EE100 or P4VP, with 0.1 % (w/w) of CS for 10 V and 1 min. Biopolymer coatings were successfully deposited while maintaining high uniformity. The deposited silver did not cause cytotoxicity. The biological study revealed that when compared to CS/P4VP, CS/EE100 coating performed better and showed a decrease in MG-63 cell viability only after three days of testing.