Fabrication Of Porous Scaffolds Research Articles

3D Printing of a Porous Zn-1Mg-0.1Sr Alloy Scaffold: A Study on Mechanical Properties, Degradability, and Biosafety.

In recent years, the use of zinc (Zn) alloys as degradable metal materials has attracted considerable attention in the field of biomedical bone implant materials. This study investigates the fabrication of porous scaffolds using a Zn-1Mg-0.1Sr alloy through a three-dimensional (3D) printing technique, selective laser melting (SLM). The results showed that the porous Zn-1Mg-0.1Sr alloy scaffold featured a microporous structure and exhibited a compressive strength (CS) of 33.71 ± 2.51 MPa, a yield strength (YS) of 27.88 ± 1.58 MPa, and an elastic modulus (E) of 2.3 ± 0.8 GPa. During the immersion experiments, the immersion solution showed a concentration of 2.14 ± 0.82 mg/L for Zn2+ and 0.34 ± 0.14 mg/L for Sr2+, with an average pH of 7.61 ± 0.09. The porous Zn-1Mg-0.1Sr alloy demonstrated a weight loss of 12.82 ± 0.55% and a corrosion degradation rate of 0.36 ± 0.01 mm/year in 14 days. The Cell Counting Kit-8 (CCK-8) assay was used to check the viability of the cells. The results showed that the 10% and 20% extracts significantly increased the activity of osteoblast precursor cells (MC3T3-E1), with a cytotoxicity grade of 0, which indicates safety and non-toxicity. In summary, the porous Zn-1Mg-0.1Sr alloy scaffold exhibits outstanding mechanical properties, an appropriate degradation rate, and favorable biosafety, making it an ideal candidate for degradable metal bone implants.

Conducting biointerface of spider-net-like chitosan-adorned polyurethane/SPIONs@SrO2–fMWCNTs for bone tissue engineering and antibacterial efficacy

In pursuit of enhancing bone cell proliferation, this study delves into the fabrication of porous scaffolds through the integration of nanomaterials. Specifically, we present the development of highly conductive chitosan (CS) nanonets on fibro-porous polyurethane (PU) bio-membranes. These nanofibers comprise functionalized multiwall carbon nanotubes (fMWCNTs), well-dispersed superparamagnetic iron oxide (SPIONs), and strontium oxide (SrO2) nanoparticles. The resulting porous scaffold exhibits remarkable interfacial biocompatibility, antibacterial properties, and load-bearing capability. Through meticulous in vitro investigations, the CS-PU/SPIONs/SrO2-fMWCNTs nanofibrous scaffolds have demonstrated a propensity to promote bone cell regeneration. Notably, the integration of these nanomaterials has been found to upregulate crucial bone-related markers, including ALP, ARS, COL-I, RUNX2, and SPP–I. The evaluation of these markers, conducted through quantitative real-time polymerase chain reaction (qRT-PCR) and immunocytochemistry, substantiates the improved cell survival and enhanced osteogenic differentiation facilitated by the integrated nanomaterials. This comprehensive analysis underscores the efficacy of CS-PU/SPIONs/SrO2-fMWCNTs bioscaffolds in promoting MC3T3-E1 cell regeneration within, thereby holding promise for advancements in bone tissue engineering and regenerative medicine.

Review on Bioinspired Design of ECM-Mimicking Scaffolds by Computer-Aided Assembly of Cell-Free and Cell Laden Micro-Modules

Tissue engineering needs bioactive drug delivery scaffolds capable of guiding cell biosynthesis and tissue morphogenesis in three dimensions. Several strategies have been developed to design and fabricate ECM-mimicking scaffolds suitable for directing in vitro cell/scaffold interaction, and controlling tissue morphogenesis in vivo. Among these strategies, emerging computer aided design and manufacturing processes, such as modular tissue unit patterning, promise to provide unprecedented control over the generation of biologically and biomechanically competent tissue analogues. This review discusses recent studies and highlights the role of scaffold microstructural properties and their drug release capability in cell fate control and tissue morphogenesis. Furthermore, the work highlights recent advances in the bottom-up fabrication of porous scaffolds and hybrid constructs through the computer-aided assembly of cell-free and/or cell-laden micro-modules. The advantages, current limitations, and future challenges of these strategies are described and discussed.

369Fabrication of 3D gel-printed β-tricalcium phosphate/titanium dioxide porous scaffolds for cancellous bone tissue engineering.

Human bone is composed of cortical bone and cancellous bone. The interior portion of natural bone is cancellous with a porosity of 50%-90%, but the outer layer is made of dense cortical bone, of which porosity was not higher than 10%. Porous ceramics were expected to be research hotspot in bone tissue engineering by virtue of their similarity to the mineral constituent and physiological structure of human bone. However, it is challenging to utilize conventional manufacturing methods to fabricate porous structures with precise shapes and pore sizes. Three-dimensional (3D) printing of ceramics is currently the latest research trend because it has many advantages in the fabrication of porous scaffolds, which can meet the requirements of cancellous bone strength, arbitrarily complex shapes, and individualized design. In this study, β-tricalcium phosphate (β-TCP)/titanium dioxide (TiO2) porous ceramics scaffolds were fabricated by 3D gel-printing sintering for the first time. The chemical constituent, microstructure, and mechanical properties of the 3D-printed scaffolds were characterized. After sintering, a uniform porous structure with appropriate porosity and pore sizes was observed. Besides, biological mineralization activity and biocompatibility were evaluated by in vitro cell assay. The results demonstrated that the incorporation of TiO2 (5 wt%) significantly improved the compressive strength of the scaffolds, with an increase of 283%. Additionally, the in vitro results showed that the β-TCP/TiO2 scaffold had no toxicity. Meanwhile, the adhesion and proliferation of MC3T3-E1 cells on scaffolds were desirable, revealing that the β-TCP/TiO2 scaffolds can be used as a promising candidate for repair scaffolding in orthopedics and traumatology.

Biomedical porous scaffold fabrication using additive manufacturing technique: Porosity, surface roughness and process parameters optimization

Titanium is a most common and best biocompatible material. The demand and application of Ti alloy is increasing rapidly in orthopedics for clinical operations. The porous structures have been designed for bone tissue engineering or orthopedic applications due to its moderate Young's modulus, excellent compressive strength, biocompatibility and sufficient space for cell accommodation. The porous scaffolds with individual complex internal and external shape can be manufactured by additive manufacturing (AM) processes especially selective laser melting (SLM), both of these have great importance for repairing of large sectional bone defects. This advantage makes the SLM process one of the most competitive AM processes used in the biomedical fields. Seven different Ti–6Al–4V porous scaffolds (Diamond, Grid, Cross, Vinties, Tesseract, Star and Octet) of 15 mm cube with 65% porosity were designed using Rhino 6 software and fabricated through SLM using Ti–6Al–4V powders. This work mainly focused on porous scaffolds design and manufacturing by AM particularly SLM, can able to produce scaffolds of nanoscale grains because of its higher heating rate and lower holding time. But this process generally results insufficient compaction where desired function is not achieved. The scaffolds manufactured by SLM have relatively high accuracy of pore structure and low mechanical strength. Grid type structure exhibits lower surface roughness value and better manufacturing ability where error percentage of porosity is lower than the other scaffolds.The process parameters employed in the study like laser power, scanning speed, hatch distancing and layer thickness are the most significant factors that influence the defect behaviour and morphology of the SLM-fabricated samples. Porosity percentage and surface roughness of the scaffold palys a vital role on its desired functions. While the porosity percentage are also effected by input process parameters resulting the variation on effective elastic modulus. The increase in scanning speed leads to elevation of the cooling rate, which results in a finer microstructure. On the other hand, with lower scanning speeds, coarse microstructure is observed.

Fabrication and characterization of wollastonite-titanium porous scaffold for pharmaceutical application: Representative volume element simulation

The use of modern methods for the fabrication of porous scaffolds has led to the construction of complex composite scaffolds with a very similar bone structure. One of these useful methods is called the space holder method which uses the NaCl microparticles as space agents. In this study, the novel calcium silicate bioceramic (Wollastonite: WS) particles are used as the based ceramic with the addition of various amounts of titanium particle (TiO2-TiNP). The combination of WS-TiNP with various amounts of Ti-NP (pure WS (S1), WS-5 wt% TiO2 (S2), WS-10 wt% TiO2 (S3), and WS-15 wt% TiO2 (S4)) composed with NaCl space agent under 200 MPa using space holder technique is performed. The materials characterization is performed using Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis for morphological and phase analysis. After analyzing the mechanical features such as compressive strength and fracture toughness, the biological properties such as biodegradation rate and bioactivity are evaluated after 28 days of soaking in phosphate buffer saline (PBS) and simulated body fluid (SBF), respectively. As the porosity value affects the mechanical performance the Abaqus software was utilized to predict the atomic structure of the porous bio-composite WS-TiNP. The obtained results indicate that the compressive strength and porosity increased and decrease from 5.2 to 8.5 MPa and 62% to 45%, respectively. Also, the Abaqus models and experimental data have an error of 18% to evaluate the influence of the porosity on the compressive strength. The observation indicate that the sample with 10 wt% TiO2 has a potential for pharmaceutical and maxilla facial application.

Poly-l-Lactic Acid (PLLA)-Based Biomaterials for Regenerative Medicine: A Review on Processing and Applications.

Synthetic biopolymers are effective cues to replace damaged tissue in the tissue engineering (TE) field, both for in vitro and in vivo application. Among them, poly-l-lactic acid (PLLA) has been highlighted as a biomaterial with tunable mechanical properties and biodegradability that allows for the fabrication of porous scaffolds with different micro/nanostructures via various approaches. In this review, we discuss the structure of PLLA, its main properties, and the most recent advances in overcoming its hydrophobic, synthetic nature, which limits biological signaling and protein absorption. With this aim, PLLA-based scaffolds can be exposed to surface modification or combined with other biomaterials, such as natural or synthetic polymers and bioceramics. Further, various fabrication technologies, such as phase separation, electrospinning, and 3D printing, of PLLA-based scaffolds are scrutinized along with the in vitro and in vivo applications employed in various tissue repair strategies. Overall, this review focuses on the properties and applications of PLLA in the TE field, finally affording an insight into future directions and challenges to address an effective improvement of scaffold properties.

A porous calcium-zirconia scaffolds composed of magnetic nanoparticles for bone cancer treatment: Fabrication, characterization and FEM analysis

One of the most critical challenges in tissue engineering is the fabrication of porous scaffolds with high porosity and proper mechanical properties. Conventional synthetic scaffolds are typically made of ceramic composed with other ceramics; however, a better combination of nanocomposite can be obtained using magnetite nanoparticles (MNPs), which benefits both ceramic materials. The current study used the space holder method and mechanical activation to create a porous magnetic-zirconia calcium bio-nanocomposite scaffold for bone tissue applications. The samples were made with varying amounts of reinforcement (0, 5, 10, and 15 wt%). The addition of sodium chloride has the main effect on the porosity size of the architecture. The prepared magnetic-zirconia calcium bio-nanocomposite scaffold was coated with a 5% solution of chitosan polymer, and its mechanical and biological properties were investigated. Powders and scaffolds were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The cell viability and non-toxicity of porous scaffolds were evaluated by MTT assay. The results showed that the addition of 15 wt% of MNPs changed the mechanical and biological properties of the composite scaffold. According to the SEM results, addition of 15% MNPs did not significantly change the porosity. However, it improves the porosity percentages. After being placed in the simulated body fluid (SBF), SEM images of the scaffolds showed the formation of a bone-like apatite layer on the surfaces of the sample with a higher amount of MNPs. Biocompatibility assessment by MTT test showed that composite scaffolds did not show any toxicity in contact with bone marrow stem cells and increased cell growth and proliferation. The mechanical simulation shows that the specimen's mechanical strength can be predicted by low error and can be a suitable option for bone tissue engineering applications.

Processing and properties of PLA/Mg filaments for 3D printing of scaffolds for biomedical applications

PurposeThis paper aims to develop a novel strategy to manufacture poly-lactic acid (PLA) filaments reinforced with Mg particles for fused filament fabrication of porous scaffolds for biomedical applications.Design/methodology/approachThe mixture of PLA pellets and Mg particles was extruded twice, the second time using a precision extruder that produces a filament with zero porosity, constant diameter and homogeneous dispersion of Mg particles. The physico-chemical properties of the extruded filaments were carefully analysed to determine the influence of Mg particles on the depolymerisation of PLA during high temperature extrusion and the optimum melt flow index to ensure printability.FindingsIt was found that the addition of a polyethylene glycol (PEG) plasticizer was necessary to allow printing when the weight fraction of Mg was above 4%. It was possible to print porous face-centre cubic scaffolds with good geometrical accuracy and minimum porosity with composite filaments containing PEG.Originality/valueThe new strategy is easily scalable and seems to be very promising to manufacture biodegradable thermoplastic/metal composite filaments for 3D printing that can take advantage of the different properties of both components from the viewpoint of tissue engineering.

3D Printing of Macro Porous Sol-Gel Derived Bioactive Glass Scaffolds and Assessment of Biological Response.

3D printing emerged as a potential game-changer in the field of biomedical engineering. Robocasting in particular has shown excellent capability to produce custom-sized porous scaffolds from pastes with suitable viscoelastic properties. The materials and respective processing methods developed so far still need further improvements in order to obtain completely satisfactory scaffolds capable of providing both the biological and mechanical properties required for successful and comprehensive bone tissue regeneration. This work reports on the sol-gel synthesis of an alkali-free bioactive glass and on its characterization and processing ability towards the fabrication of porous scaffolds by robocasting. A two-fold increase in milling efficiency was achieved by suitably adjusting the milling procedures. The heat treatment temperature exerted a profound effect on the surface area of mesoporous powders. Robocasting inks containing 35 vol.% solids were prepared, and their flow properties were characterized by rheological tests. A script capable of preparing customizable CAD scaffold geometries was developed. The printing process was adjusted to increase the technique’s resolution. The mechanical properties of the scaffolds were assessed through compressive strength tests. The biomineralization ability and the biological performance were assessed by immersing the samples in simulated body fluid (SBF) and through MTT assays, respectively. The overall results demonstrated that scaffolds with macro porous features suitable for bone ingrowth (pore sizes of ~340 μm after sintering, and a porosity fraction of ~70%) in non-load-bearing applications could be successfully fabricated by 3D printing from the bioactive glass inks. Moreover, the scaffolds exhibited good biomineralization activity and good biocompatibility with human keratinocytes, suggesting they are safe and thus suited for the intended biomedical applications.

Development of 3D Printed Electrospun Scaffolds for the Fabrication of Porous Scaffolds for Vascular Applications.

Over the past two decades, electrospinning has emerged as a common technique to produce biomedical scaffolds composed of ultrafine fibers formed from many natural and synthetic polymers. A major advantage of this technique is the ability to produce scaffolds that resemble the native extracellular matrix in physical, chemical, and topological properties. However, scaffolds fabricated via electrospinning are not formed with a controlled architecture and typically do a poor job of directing cell growth into prescribed structures for tissue/organ development. To address these weaknesses, 3D bioprinting has recently been used to develop scaffolds that have a highly organized and precise global topology. Unfortunately, these 3D bioprinted scaffolds do not typically resemble the native extracellular matrix in physical properties, such as porosity, fiber diameter, and pore size (e.g., the microarchitecture). Thus, the goal of the current study was to develop a technique that harnesses the intrinsic advantages of both conventional electrospinning and 3D bioprinting techniques to produce scaffolds that have the potential to be used within biomedical applications. The physical properties of formed 3D printed electrospun scaffolds were compared with conventional electrospun and 3D printed scaffolds. Further, we conducted initial proof-of-concept biocompatibility studies to illustrate the applicability of the scaffolds within vascular applications. Our results illustrate that 3D printed electrospun scaffolds can be developed, via our technique, that have highly tailored and organized arbitrary geometries with scaffold properties in the range of the innate extracellular matrix. In addition, these scaffolds were shown to support endothelial cell growth. Therefore, we illustrate the development and testing of a novel bioscaffold fabrication technique that may be used for many tissue engineering and regenerative medicine applications, which allows for the direct printing of electrospun scaffolds into well-defined macro-scale geometries that also retain the micro-structures commonly observed in electrospun scaffolds.

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.

Recent Progress on Biodegradable Tissue Engineering Scaffolds Prepared by Thermally-Induced Phase Separation (TIPS).

Porous biodegradable scaffolds provide a physical substrate for cells allowing them to attach, proliferate and guide the formation of new tissues. A variety of techniques have been developed to fabricate tissue engineering (TE) scaffolds, among them the most relevant is the thermally-induced phase separation (TIPS). This technique has been widely used in recent years to fabricate three-dimensional (3D) TE scaffolds. Low production cost, simple experimental procedure and easy processability together with the capability to produce highly porous scaffolds with controllable architecture justify the popularity of TIPS. This paper provides a general overview of the TIPS methodology applied for the preparation of 3D porous TE scaffolds. The recent advances in the fabrication of porous scaffolds through this technique, in terms of technology and material selection, have been reviewed. In addition, how properties can be effectively modified to serve as ideal substrates for specific target cells has been specifically addressed. Additionally, examples are offered with respect to changes of TIPS procedure parameters, the combination of TIPS with other techniques and innovations in polymer or filler selection.

Design and development of poly-L/D-lactide copolymer and barium titanate nanoparticle 3D composite scaffolds using breath figure method for tissue engineering applications

In tissue engineering, the scaffold topography influences the adhesion, proliferation, and function of cells. Specifically, the interconnected porosity is crucial for cell migration and nutrient delivery in 3D scaffolds. The objective of this study was to develop a 3D porous composite scaffold for musculoskeletal tissue engineering applications by incorporating barium titanate nanoparticles (BTNPs) into a poly-L/D-lactide copolymer (PLDLA) scaffold using the breath figure method. The porous scaffold fabrication utilised 96/04 PLDLA, dioleoyl phosphatidylethanolamine (DOPE), and different types of BTNPs, including uncoated BTNPs, Al2O3-coated BTNPs, and SiO2-coated BTNPs. The BTNPs were incorporated into the polymer scaffold, which was subsequently analysed using field emission scanning electron microscopy (FE-SEM). The biocompatibility of each scaffold was tested using ovine bone marrow stromal stem cells. The cell morphology, viability, and proliferation were evaluated using FE-SEM, LIVE/DEAD staining, and Prestoblue assay. Porous 3D composite scaffolds were successfully produced, and it was observed that the incorporation of uncoated BTNPs increased the average pore size from 1.6 μm (PLDLA) to 16.2 μm (PLDLA/BTNP). The increased pore size in the PLDLA/BTNP scaffolds provided a suitable porosity for the cells to migrate inside the scaffold, while in the pure PLDLA scaffolds with their much smaller pore size, cells elongated on the surface. To conclude, the breath figure method was successfully used to develop a PLDLA/BTNP scaffold. The use of uncoated BTNPs resulted in a composite scaffold with an optimal pore size while maintaining the honeycomb-like structure. The composite scaffolds were biocompatible and yielded promising structures for future tissue engineering applications.

Extrusion-based 3D printed biodegradable porous iron

Extrusion-based 3D printing followed by debinding and sintering is a powerful approach that allows for the fabrication of porous scaffolds from materials (or material combinations) that are otherwise very challenging to process using other additive manufacturing techniques. Iron is one of the materials that have been recently shown to be amenable to processing using this approach. Indeed, a fully interconnected porous design has the potential of resolving the fundamental issue regarding bulk iron, namely a very low rate of biodegradation. However, no extensive evaluation of the biodegradation behavior and properties of porous iron scaffolds made by extrusion-based 3D printing has been reported. Therefore, the in vitro biodegradation behavior, electrochemical response, evolution of mechanical properties along with biodegradation, and responses of an osteoblastic cell line to the 3D printed iron scaffolds were studied. An ink formulation, as well as matching 3D printing, debinding and sintering conditions, was developed to create iron scaffolds with a porosity of 67%, a pore interconnectivity of 96%, and a strut density of 89% after sintering. X-ray diffracometry confirmed the presence of the α-iron phase in the scaffolds without any residuals from the rest of the ink. Owing to the presence of geometrically designed macropores and random micropores in the struts, the in vitro corrosion rate of the scaffolds was much improved as compared to the bulk counterpart, with 7% mass loss after 28 days. The mechanical properties of the scaffolds remained in the range of those of trabecular bone despite 28 days of in vitro biodegradation. The direct culture of MC3T3-E1 preosteoblasts on the scaffolds led to a substantial reduction in living cell count, caused by a high concentration of iron ions, as revealed by the indirect assays. On the other hand, the ability of the cells to spread and form filopodia indicated the cytocompatibility of the corrosion products. Taken together, this study shows the great potential of extrusion-based 3D printed porous iron to be further developed as a biodegradable bone substituting biomaterial.

Mechanical strength improvement of chitosan/hydroxyapatite scaffolds by coating and cross-linking

Coating and cross-linking have been widely used to improve the properties of materials in tissue engineering. A chitosan/hydroxyapatite (CS/HA) comby scaffold with high porosity was prepared via a 3D printed pore-forming mold. The scaffold was then treated with gelatin (Gel) coating and was cross-linked by glutaraldehyde (GA) in order to improve the mechanical strength. The materials were characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD). The structure of the scaffolds was observed by Scanning Electron Microscopy (SEM). Compression tests were carried out to evaluate the strength of the scaffolds. The behaviors and responses of preosteoblast cells on the scaffolds were studied as well. The results showed that gelatin coating and cross-linking significantly enhanced the mechanical strength of the porous scaffolds. Cell culture experiment indicated that the scaffold had good cytocompatibility. The combined application of 3DP structure construction and biopolymer coating/cross-linking would offer some new ideas in fabrication of porous scaffolds with enhanced strength and good biocompatibility for tissue engineering.

Fabrication of porous bovine pericardium scaffolds incorporated with bFGF for tissue engineering applications.

The design and fabrication of porous scaffolds are important issues for tissue engineering applications. In this study, we attempted to fabricate porous scaffolds using bovine pericardium (BP) and examined whether these scaffolds were beneficial for cell ingrowth and bioactive factors delivery. A vacuum-freeze-thawing-Triton X-100 (VFTT) protocol was used to fabricate porous BP scaffolds. The porous and mechanical properties were assessed using histology, scanning electron microscopy, and mechanical assay. The fabricated scaffolds were seeded with mesenchymal stem cells (MSCs), and cell ingrowth was evaluated. Basic fibroblast growth factor (bFGF) was subsequently incorporated into the fabricated scaffolds. The bioactive factor delivery capacity was evaluated using loading and release studies. The bioactivity of released bFGF was assessed using a rat subcutaneous model. The BP scaffolds fabricated by the VFTT protocol displayed interconnected porous structures with porosity of 6.82±1.36%.There were no significant differences in thickness, ultimate load, Young's modulus, and ultimate tensile strength between the fabricated porous BP scaffolds and native BPs (all P>.05). However, the water content of BPs was slightly reduced after VFTT treatment (P<.05). Cell ingrowth analysis showed that the seeded MSCs penetrated into the porous BP scaffolds with time of culture, while MSCs were limited to the surface layers of native BPs. Furthermore, bFGF was observed to be effectively loaded onto and released from the porous BP scaffolds. The released bFGF increased the phosphorylation levels of Akt, ERK 1/2, and MEK1/2, promoted host MSC recruitment, and inhibited myofibroblast differentiation in vivo. The porous BP scaffolds fabricated using a VFTT protocol were promising natural scaffolds for tissue engineering applications, since they had considerable mechanical properties as native BPs, supplied porous channels for cell ingrowth, and possessed bioactive factors delivery capability.

Fabrication of porous scaffold by ternary combination of chitosan, gelatin, and calcium phosphate for tissue engineering

Recently, 3D porous scaffolds using naturally derived polymers, i.e. chitosan (CHN), gelatin (GLN), and their blends have attracted attentions for tissue engineering applications. Research on the use of polymers and ceramic composites has been performed to improve biocompatibility of tissue scaffolds. However, calcium phosphate (CaP) coating on CHN/GLN blend scaffolds has not been well studied. In this study, we fabricated CHN/GLN films and scaffolds at various CHN/GLN blending ratios (100/0, 75:25, 50/50, 25/75, and 0/100) and established optimal CaP coating method on CHN/GLN blends. Increase in GLN content promoted both surface hydrophilicity and Ca/P ratio. The prepared CHN/GLN scaffolds displayed highly porous architecture with elastic nature. The effect of increase in GLN content on osteoblast proliferation was evident but no significant impact on alkaline phosphatase (ALP) activity. When the CHN/GLN scaffold was coated with CaP film, ALP activity was dramatically improved, and the 75/25 scaffold showed the highest ALP level among all CHN/GLN scaffolds. The present study demonstrated that the combination of CHN, GLN, and CaP coating can generate synergistic effects on the improvement of bioactivity of CHN/GLN scaffold and can be further used for the fabrication of hard tissue scaffolds.

Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications.

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of "reducing dimensions and designing layer by layer" was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%, (480±28) to (685±31) μm, and (263±28) to (265±28) μm, respectively. The compression results show that the Young's modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young's modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.

Effect of particle size and freezing conditions on freeze-casted scaffold

Abstract Freeze casting is one of the emerging and novel manufacturing routes to fabricate porous scaffolds for various applications including orthopedic implants, drug delivery, energy storing devices etc. Thus, it becomes important to understand this process in a deeper sense. Present work was focused to study the effect/influence of basic parameters, particle sizes, and freezing conditions on the mechanical properties and microstructures of porous scaffold fabricated by freeze casting. β-tricalcium phosphate (β-TCP) and hydroxyapatite (HAp) powder with particle sizes of 10 μm and 20 nm were used. Prepared slurries were freeze casted at constant freezing temperature (5 °C) and constant freezing rate (1.86 °C/min) to study the effect of freezing conditions on mechanical and microstructural properties of the porous scaffold. It was observed that porous scaffold fabricated by nanoparticles has given better porosity (63.22–76.16%), than scaffold fabricated by microparticles (13–43.05%) at given solid loading of both freezing conditions. Although, the range of pore size of the scaffold fabricated by nanoparticles (CFR: 2.60–0.84 μm; CFT: 1.66–0.46 μm) was lower than that of scaffold fabricated by microparticles (CFR: 9.45–4.83 μm; CFT: 4.72–2.84 μm). The compressive strength of scaffolds prepared by nanoparticles was in the range of trabecular bone. Moreover, the results of present work will pave the way for the fabrication of porous scaffold with desired pore size and porosity for various implants, energy, and drug delivery applications.