Fabrication and finite element simulation of antibacterial 3D printed Poly L-lactic acid scaffolds coated with alginate/magnesium oxide for bone tissue regeneration.

This study proposes 3D-printed Poly L-lactic acid (PLA) scaffolds coated with alginate/MgO, and includes three different cellular topologies. Three unique scaffold models were considered: Perovskite type 1 (P1), Perovskite type 2 (P2), and IWP. Each scaffold was coated with alginate/MgO at the concentrations of 0 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%. For morphological and phase study, the microstructure of fabricated scaffolds was characterized using a Field Emission Scanning Electron Microscope (FESEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. Besides, the biological characteristics of scaffolds, such as biocompatibility, antibacterial activity, and cell survival were studied after 21 days of soaking in the simulated body fluid (SBF). The results of biological studies indicate that the apatite layer covered the majority of composite scaffold's surface and sealed the pores' surface. The material properties of Alginate/MgO RVEs were evaluated under PBC, and it described that the elastic modulus enhanced from 100 (pure Alginate) to 130 MPA by adding 20 wt% MgO nanoparticles. The presented findings were compared to the results obtained by the experimental procedure and revealed satisfactory agreement. RVE-achieved material properties were used in the additional studies on the scaffolds to find the best candidate due to the material properties and architectures. Furthermore, experiment and finite element simulation were used to evaluate the mechanical properties of scaffolds under the compressive deformation. According to the results, the compressive strength of structures follows the order σPerovskite type 1>σPerovskite type 2 >σIWP. The results indicate that increasing MgO content from 0 wt% to 20 wt% enhances each structure's compressive strength and elastic modulus. In conclusion, based on the biological findings and simulation results, PLA scaffold with Perovskite type 1 (P1) architecture coated with Alginate/ 20 wt% MgO had the best response which is the final research candidate.

Development of Porous Photopolymer Resin-SWCNT Produced by Digital Light Processing Technology Using for Bone Femur Application.

BACKGROUND: Although bone tissue has the unique characteristic of self-repair in fractures, bone grafting is needed in some situations. The synthetic substances that are used in such situations should bond to the porous bones, be biocompatible and biodegradable, and do not stimulate the immune responses. Biomaterial engineering is the science of finding and designing novel products. In principle, the most suitable biodegradable matrix should have adequate compressive strength of more than two megapascals. At this degradation rate, the matrix can eventually be replaced by the newly formed bone, and the osteoprogenitor cells migrate into the scaffold. This study aimed to evaluate the fabrication of a scaffold made of polymer-ceramic nanomaterials with controlled porosity resembling that of spongy bone tissue. METHODS: A compound of resin polymer, single-walled carbon nanotube (SWCNT) as reinforcement, and hydroxyapatite (HA) were dissolved using an ultrasonic and magnetic stirrer. A bio-nano-composite scaffold model was designed in the SolidWorks software and built using the digital light processing (DLP) method. Polymer-HA scaffolds with the solvent system were prepared with similar porosity to that of human bones. RESULTS: HA-polymer scaffolds had a random irregular microstructure with homogenizing porous architecture. The SWCNT improved the mechanical properties of the sample from 25 MPa to 36 MPa besides having a proper porosity value near 55%, which can enhance the transformation and absorption of protein in human bone. CONCLUSION: The combined bio-nanocomposite had a suitable porous structure with acceptable strength that allowed it to be used as a bone substitute in orthopedic surgery.

Investigation of the mechanical properties of a bony scaffold for comminuted distal radial fractures: Addition of akermanite nanoparticles and using a freeze-drying technique.

One of the methods of repairing the damaged bone is the fabrication of porous scaffold using synergic methods like three-dimensional (3D) printing and freeze-drying technology. These techniques improve the damaged and fracture parts rapidly for better healing bone lesions using bioactive ceramic and polymer. This research, due to the need to increase the mechanical strength of 3D bone scaffolds for better mechanical performance. Akermanite bioceramic as a bioactive and calcium silicate bioceramic has been used besides the polymeric component. In this study, the porous scaffolds were designed using solid work with an appropriate porosity with a Gyroid shape. The prepared Gyroid scaffold was printed using a 3D printing machine with Electroconductive Polylactic Acid (EC-PLA) and then coated with a polymeric solution containing various amounts of akermanite bioceramic as reinforcement. The mechanical and biological properties were investigated according to the standard test. The mechanical properties of the porous-coated scaffold showed stress tolerance up to 30 MPa. The maximum strain obtained was 0.0008, the maximum stress was 32 MPa and the maximum displacement was 0.006 mm. Another problem of bone implants is the impossibility of controlling bone cancer and tumor size. To solve this problem, an electroconductive filament containing Magnetic Nanoparticles (MNPs) is used to release heat and control cancer cells. The mechanical feature of the porous scaffold containing 10 wt% akermanite was obtained as the highest stress tolerance of about 32 MPa with 46% porosity. Regarding the components and prepare the bony scaffold, the MNPs release heat when insert into the magnetic field and control the tumor size which helps the treatment of cancer. In general, it can be concluded that the produced porous scaffold using 3D printing and freeze-drying technology can be used to replace broken bones with the 3D printed EC-PLA coated with 10 wt% akermanite bioceramic with sufficient mechanical and biological behavior for the orthopedic application.

Therapy with new generation of biodegradable and bioconjugate 3D printed artificial gastrointestinal lumen.

OBJECTIVES: Many patients die due to vascular, gastrointestinal lumen problems, and coronary heart diseases. Synthetic vessels that are made of biodegradable-nanofiber polymers have significant properties such as proper biodegradability and efficient physical properties such as high strength and flexibility. Some of the best options for supporting cells in soft tissue engineering and design are applications of thermoplastic polyurethane polymer in the venous tissue. In this study, the first nanoparticle-reinforced polymeric artificial prosthesis was designed and tested to be used in the human body. MATERIALS AND METHODS: In this study, artificial gastrointestinal lumen were fabricated and prepared using a 3D printer. To improve cell adhesion, wettability properties and mechanical stability of elastin biopolymer with magnetic nanoparticles (MNPs) as well as single-walled carbon nanotubes (SWCNT) were prepared as separate filaments. MNPs were made in 5-7 mm sizes and then examined for mechanical, biological, and hyperthermia properties. Then, the obtained results of the gastrointestinal lumen were simulated using the Abaqus software package with a three-branch. The results were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for morphology and phase analysis. RESULTS: The obtained results of the designed vessels showed remarkable improvement in mechanical properties of the SWCNT vessels and hyperthermia properties of the vessels containing the MNPs. The results of computational fluid dynamics (CFD) analysis showed that the artificial vessels had lower shear stress at the output. CONCLUSION: Five-mm MNP containing vessels showed noticeable chemical and biological properties along with ideal magnetic results in the treatment of thrombosis and vascular obstruction.

A Narrative Review of COVID-19: The New Pandemic Disease.

Nearly every 100 years, humans collectively face a pandemic crisis. After the Spanish flu, now the world is in the grip of coronavirus disease 2019 (COVID-19). First detected in 2019 in the Chinese city of Wuhan, COVID-19 causes severe acute respiratory distress syndrome. Despite the initial evidence indicating a zoonotic origin, the contagion is now known to primarily spread from person to person through respiratory droplets. The precautionary measures recommended by the scientific community to halt the fast transmission of the disease failed to prevent this contagious disease from becoming a pandemic for a whole host of reasons. After an incubation period of about two days to two weeks, a spectrum of clinical manifestations can be seen in individuals afflicted by COVID-19: from an asymptomatic condition that can spread the virus in the environment, to a mild/moderate disease with cold/flu-like symptoms, to deteriorated conditions that need hospitalization and intensive care unit management, and then a fatal respiratory distress syndrome that becomes refractory to oxygenation. Several diagnostic modalities have been advocated and evaluated; however, in some cases, diagnosis is made on the clinical picture in order not to lose time. A consensus on what constitutes special treatment for COVID-19 has yet to emerge. Alongside conservative and supportive care, some potential drugs have been recommended and a considerable number of investigations are ongoing in this regard.

Bone Regeneration Using Bio-Nanocomposite Tissue Reinforced with Bioactive Nanoparticles for Femoral Defect Applications in Medicine.

BACKGROUND: In recent years, the method of constructing and evaluating the properties of polymer nanocomposite and bioactive ceramics in tissue engineering such as biocompatible scaffolds was studied by some researchers. METHODS: In this study, the bio-nanocomposite scaffolds of Chitosan (CS)-Hydroxyapatite (HA)-Wllastonite (WS), incorporated with 0, 10, 20 and 30 wt% of zirconium were produced using a freeze-drying method. Also, the phase structure and morphology of scaffolds were investigated using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). By analyzing the SEM images, the porosity of the scaffolds was observed in the normal bone area of the body. In the next step, bioactivity and biodegradability tests of the scaffolds were carried out. Due to the presence of hydrophilic components and the high-water absorption capacity of these materials, the bio-nanocomposite scaffolds were able to absorb water properly. After that, the mechanical properties of the scaffolds were studied. RESULTS: The mechanical test results showed that the preparation of reinforced bionanocomposites containing 10 wt% of zirconium presented better properties compared to incorporated bio-nanocomposites with different loadings of zirconium. CONCLUSION: According to MTT assay results, the prepared scaffolds did not have cytotoxicity at different concentrations of scaffold extracts. Consequently, the investigated scaffold can be beneficial in bone tissue engineering applications because of its similarity to natural bone structure and its proper porosity.

Improvement in osseointegration of tricalcium phosphate-zircon for orthopedic applications: an in vitro and in vivo evaluation.

Similar to metallic implant, using the compact bio-nanocomposite can provide a suitable strength due to its high stiffness and providing sufficient adhesion between bone and orthopedic implant. Therefore, using zirconia-reinforced calcium phosphate composites with new generation of calcium silicate composites was considered in this study. Additionally, investigation of microstructure, apatite formation, and mechanical characteristic of synthetic compact bio-nanocomposite bones was performed. Desired biodegradation, optimal bioactivity, and dissolution of tricalcium phosphate (TCP) were controlled to optimize its mechanical properties. The purpose of this study was to prepare the nanostructured TCP-wollastonite-zirconia (TCP-WS-Zr) using the space holder (SH) technique. The X-ray diffraction technique (XRD) was used to confirm the existence of favorable phases in the composite's structure. Additionally, the effects of calcination temperature on the fuzzy composition, grain size, powder crystallinity, and final coatings were investigated. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) was used for fundamental analysis of the resulting powder. In order to examine the shape and size of powder's particles, particle size analysis was performed. The morphology and microstructure of the sample's surface was studied by scanning electron microscopy (SEM), and to evaluate the dissolution rate, adaptive properties, and the comparison with the properties of single-phase TCP, the samples were immersed in physiological saline solution (0.9% sodium chloride) for 21 days. The results of in vivo evaluation illustrated an increase in the concentration of calcium ion release and proper osseointegration ratio, and the amount of calcium ion release in composite coatings was lower than that in TCP single phase. Nanostructured TCP-WS-Zr coatings reduced the duration of implant fixation next to the hardened tissue, and increased the bone regeneration due to its structure and dimensions of the nanometric phases of the forming phases. Finally, the animal evaluation shows that the novel bio-nanocomposite has increasing trend in healing of defected bone after 1 month.

Effect of magnetite nanoparticles on the biological and mechanical properties of hydroxyapatite porous scaffolds coated with ibuprofen drug.

Gelatin (GN) is a polymer, which is similar to the protein derived from collagen, an organic element in the bone. GN can incorporate into the mineral part of the bone, hydroxyapatite (HA). The HA bioceramic has properties very close to the natural bone characteristics. Therefore, in this research, bio-nanocomposite scaffolds made of the HA composed with magnetite nanoparticles (MNPs) are fabricated. For this purpose, the space holder technique is put to use using NaCl particles as the spacers. The HA-X%MNP (X = 0 wt%, 5 wt%, 10 wt%, and 15 wt%) scaffolds are coated via gelatin-ibuprofen (GN-IBO) in order to determine the capabilities of the scaffolds for compatibility and fibroblastic cells of the related tissue. The coated bio-nanocomposite scaffolds are characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tools. Then, the porosity and bioactivity of the prepared samples are tested in the simulated body fluid (SBF), and the associated compressive strength, fracture toughness, porosity and hardness are investigated. Also, the magnetic behavior of the scaffolds during the release of IBO in the phosphate buffer saline (PBS) is monitored after 21 days incubation. Finally, an analytical sandwich plate model is developed to analyze the vibrational response of an axially loaded plate-type HA-MNP bio-nanocomposite implants. The obtained X-ray diffraction (XRD) confirms the presence of IBO peaks after removing the samples from the PBS which proves the lower release speed of the sample containing 10 wt% MNPs. It is found that the interaction between IBO and HA affects the mechanical performance of the scaffolds. IBO release profiles present a burst release that depends on the HA content. The given results indicate that the manufactured scaffolds have good potentials for biological as well as hyperthermia applications in bone tissue engineering.

A porous polymeric-hydroxyapatite scaffold used for femur fractures treatment: fabrication, analysis, and simulation.

BACKGROUND: One of the most common fractures in the skeleton happens in the femur. One of the important reasons for this fracture is because it is the longest bone in the body and osteoporosis affect this part a lot. The geometric complexity and anisotropy properties of this bone have received a lot of attention in the orthopedic field. METHODS: In this research, a femur designed using 3D printing machine using the middle part of the hip made of polylactic acid-hydroxyapatite (PLA-HA) nanocomposite containing 0, 5, 10, 15, and 25 wt% of ceramic nanoparticle. Three different types of loadings, including centralized loading, full-scale, and partially loaded, were applied to the designed femur bone. The finite element analysis was used to analyze biomechanical components. RESULTS: The results of the analysis showed that it is possible to use the porous scaffold model for replacement in the femur having proper strength and mechanical stability. Stress-strain analysis on femoral implant with biometric HA and PLA after modeling was performed using the finite element method under static conditions in Abaqus software. CONCLUSION: Three scaffold structures, i.e., mono-, hybrid, and zonal structures, that can be fabricated using current bioprinting techniques are also discussed with respect to scaffold design.

Influence of MgO nanoparticles on the mechanical properties of coated hydroxyapatite nanocomposite scaffolds produced via space holder technique: Fabrication, characterization and simulation.

In the current study, hydroxyapatite (HA)-MgO scaffolds are fabricated with the aid of the space holder technique using NaCl as the spacer type. After that, the fabricated samples are deposited in gelatin (GN) with ibuprofen (IBO) substitution to create GN-IBO thin surface coating. The samples are then synthesized chemically and the associated properties are studied using X-ray diffraction (XRD) and scan electron microscopy (SEM) equipped with the energy dispersive spectroscopy (EDS). The compressive strength, fracture toughness, hardness, porosity, bioactivity, degradation rate, wettability, and roughness of the manufactured HA-MgO bio-nanocomposite scaffolds containing different weight fractions of MgO nanoparticles are predicted. Accordingly, nonlinear mechanical behaviors including nonlinear free vibration and nonlinear vibrations associated with the prebuckling and postbuckling domains of an axially loaded plate-type bone implant made of the HA-MgO bio-nanocomposites coated with the GN-IBO thin layers are investigated analytically via a sandwich plate model. The obtained results reveal that magnesium has no considerable effect on the porosity, however it causes to enhance the compressive strength significantly. The presence of magnesium ions also leads to reduce the crystallinity of HA about 30-100 nm due to entering MgO nanoparticles into the network. The results related to the sample with 10 wt% MgO nanoparticles indicate that the microscopic structure of the fabricated bio-nanocomposite scaffold is three-dimensional with porous architecture. Also, it is shown that the solubility of the HA composed with MgO nanoparticles decreases with higher bioactivity.

Diopside-magnetite; A novel nanocomposite for hyperthermia applications.

In the present work, the releasing heat, scaffold apatite formation, and magnetic behavior of a novel diopside-magnetite nanocomposite with various contents of magnetite (Fe3O4) were evaluated. The N´eel and Brown relaxations did not have a significant effect on the specific absorption rate (SAR) of the composite samples. Indeed, magnetic saturation, Ms, indicated a crucial effect on the heat release of the samples. The sample with 30wt% magnetite had the highest value of SAR, while the sample with 20wt% magnetite, in the form of scaffold, allowed the high amount of apatite formation on its surface.

Electrospun Polycaprolactone/lignin-based Nanocomposite as a Novel Tissue Scaffold for Biomedical Applications.

BACKGROUND: Biopolymer scaffolds have received great interest in academic and industrial environment because of their supreme characteristics like biological, mechanical, chemical, and cost saving in the biomedical science. There are various attempts for incorporation of biopolymers with cheap natural micro- or nanoparticles like lignin (Lig), alginate, and gums to prepare new materials with enhanced properties. METHODS: In this work, the electrospinning (ELS) technique as a promising cost-effective method for producing polymeric scaffold fibers was used, which mimics extracellular matrix structure for soft tissue engineering applications. Nanocomposites of Lig and polycaprolactone (PCL) scaffold produced with ELS technique. Nanocomposite containings (0, 5, 10, and 15 wt.%) of Lig were prepared with addition of Lig powder into the PCL solution while stirring at the room temperature. The bioactivity, swelling properties, morphological and mechanical tests were conducted for all the samples to investigate the nanocomposite scaffold features. RESULTS: The results showed that scaffold with 10 wt.% Lig have appropriate porosity, biodegradation, minimum fiber diameter, optimum pore size as well as enhanced tensile strength, and young modulus compared with pure PCL. Degradation test performed through immersion of samples in the phosphate-buffer saline showed that degradation of PCL nanocomposites could accelerate up to 10% due to the addition of Lig. CONCLUSIONS: Electrospun PCL-Lig scaffold enhanced the biological response of the cells with the mechanical signals. The prepared nanocomposite scaffold can choose for potential candidate in the biomedical science.

Preparing diopside nanoparticle scaffolds via space holder method: Simulation of the compressive strength and porosity.

In the present study, diopside nanopowders were prepared via mechanical milling with eggshell as the calcium source. The space holder method (compaction of ceramic powder and spacer) as one of the most important methods to produce ceramic/metal scaffolds was used to produce diopside scaffolds. For the first time, the effect of the spacer size on mechanical properties and porosity of the obtained scaffolds was experimentally discussed. According to the results obtained, the NaCl particles (as the spacer) with the size of 400-600µm maintained their original spherical shape during the compaction and sintering processes. As a new work, the most important parameters including the spacer type, spacer concentration, spacer size, and applied pressure were considered, and their effects on mechanical properties and porosity of diopside scaffolds were simulated. Gene Expression Programming (GEP), as one of the most branches of the artificial intelligence, was used for simulation process. By using the GEP, two equations were introduced to predict the compressive strength and porosity of the obtained scaffolds with the lowest error values. The 3D diagrams extracted from the model were used to evaluate the combined effect of the process parameters on the compressive strength and porosity of the scaffolds. The GEP model presented in this work has a very low level of error and a high level of the squared regression for predicting the compressive strength and porosity of diopside scaffolds.

Study of in vitro bioactivity and mechanical properties of diopside nano-bioceramic synthesized by a facile method using eggshell as raw material.

In this study, diopside bioceramic was synthesized using a mechanical milling process and subsequent heat treatment. The simplicity of experiments and also the high energy available in ball milling lead to rapid synthesis of the products in comparison with other synthesis methods. Magnesium oxide (MgO), silicon dioxide (SiO2) and eggshell (as the calcium source) powders were weighted in stoichiometric conditions and milled to initial activation of the surface of the powder's mixture. Then a sintering process was conducted to complete formation of diopside nanopowder and also evaluates its thermal stability. The mechanisms occurred during the synthesis of this bioceramic were carefully investigated. X-Ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), and inductive coupled plasma atomic emission spectroscopy (ICP-AES) were used for gathering and analyzing data. The ability and rate of apatite formation on the sample surface were evaluated by Simulated Body Fluid (SBF) test, a method that is well recognized to characterize the in vitro bioactivity of ceramic materials. According to the results obtained, the diopside samples had a significant potential to form apatite layer on their surface during soaking in the SBF solution. Besides, the bonding strength of this bioceramic was about 350±7MPa which was almost more than three times of that reported for hydroxyapatite. An excellent fracture toughness of 4±0.3MPam0.5 was also obtained for this ceramic which was higher than that of previously reported works.

A comparative study on the synthesis mechanism, bioactivity and mechanical properties of three silicate bioceramics.

In the present study three akermanite (Ca2MgSi2O7), diopside (CaMgSi2O6) and baghdadite (Ca3ZrSi2O9) applicable bioceramics were synthesized via a sol-gel based method. The combination of sol-gel method and the raw materials used in this study presents a new route for the synthesis of the mentioned bioceramics. By the use of thermal analysis, the mechanisms occurred during the synthesis of these bioceramics were investigated. The differences in the structural density and their relation with the degradation rate and mechanical properties of all three ceramics were studied. In vitro bioactivity and apatite formation mechanisms of the samples soaked in the simulated body fluid were considered. The results showed that baghdadite as a Zr-containing material has a more dense structure in comparison with the other ceramics, which leads to a lower degradation rate and also lower bioactivity. There were also main differences between akermanite and diopside as Mg-containing ceramics. Diopside showed a structure with lower porosity content compared to the akermanite samples which resulted in the lower degradation rate and higher compressive strength.

A novel and economical route for synthesizing akermanite (Ca2MgSi2O7) nano-bioceramic.

Despite the benefits of akermanite, there are limited reports on making powder and dense bulk akermanite (Ca2MgSi2O7) and most articles have focused on building akermanite scaffolds. This study centers on a new and economical route for the synthesis of akermanite bioceramic via high energy ball milling and subsequent sintering of a mixed powders of eggshell (as calcium source), MgO, and SiO2. The mechanisms occurred during akermanite synthesis were carefully investigated. XRD, DTA, FTIR, TGA, SEM, TEM, ICP and EDS were used for analyzing the obtained results. Simulated body fluid (SBF) was also used for assessing in vitro bioactivity of the akermanite samples. According to the results, the method presented in this study can be introduced as a facile method for preparing akermanite samples with a good compressive strength of 210±7MPa. The XRD patterns also indicated that akermanite bioceramic was synthesized after heat treating at 900°C which is very low compared to previous researches. With increasing the sintering time of the akermanite samples and the reduction of the surface porosities, the amount of the formed apatite and also the rate of apatite formation decreased and the compressive strength of the samples increased.

Surface characteristics and bioactivity of a novel natural HA/zircon nanocomposite coated on dental implants.

The surface characteristics of implant which influence the speed and strength of osseointegration include surface chemistry, crystal structure and crystallinity, roughness, strain hardening, and presence of impurities. The aim of this study was to evaluate the bioactivity and roughness of a novel natural hydroxyapatite/zircon (NHA/zircon) nanobiocomposite, coated on 316L stainless steel (SS) soaked in simulated body fluid (SBF). NHA/zircon nanobiocomposite was fabricated with 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% of zircon in NHA using ball mill for 20 minutes. The composite mixture was coated on 316L SS using plasma spray method. The results are estimated using the scanning electron microscopy (SEM) observation to evaluate surface morphology, X-ray diffraction (XRD) to analyze phase composition, and transmission electron microscopy (TEM) technique to evaluate the shape and size of prepared NHA. Surfaces roughness tester was performed to characterize the coated nanocomposite samples. The maximum average R a (14.54 µm) was found in the NHA 10 wt.% of zircon coating. In addition, crystallinity (X c ) was measured by XRD data, which indicated the minimum value (X c = 41.1%) for the sample containing 10 wt.% of zircon. Maximum bioactivity occurred in the sample containing 10 wt.% of zircon, which was due to two reasons: first, the maximum roughness and, second, the minimum crystallinity of nanobiocomposite coating.