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3D multifunctional scaffold has been designed based on Cs/SA/NS/NPHA. Nanoparticles hydroxyapatite (NPHA) was prepared via precipitation method of sodium dihydrogen phosphate in presence calcium chloride. Different ratios of Chitosan (CS)/Sodium Alginate (SA) were used to prepare Cs/SA scaffolds in presence of CaCl 2 as a cross linker. NPHA was incorporated in CS/SA scaffold and neomycin sulfate (NS) was added as an antimicrobial agent. The structure and surface morphology of the scaffolds were investigated via infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal gravimetric analysis (TGA) techniques. Additionally, Antimicrobial activity of the scaffold has evaluated against Gram- negative and Gram- positive bacteria. The result showed promising antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Furthermore, cytotoxicity against MG63 osteosarcoma cell and fibroblast normal cell line has investigated. The result showed anti-proliferative against MG63. DFT calculations and molecular docking were used to study the reactivity of the compounds. The results exhibited that Cs/SA/NS/NPHA is potent expected to be used in bone tissue regeneration., Competing Interests: Declaration of competing interest The author declares that there is no conflict to interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bioceramics are widely used in bone tissue engineering, yet the inherent high brittleness and low ductility of the ceramics lead to poor machinability, which restricts their clinical applications. Here, a flexible and processable 3D printed bioceramic scaffold with high ceramic content (66.7 %) and shape fidelity (volume shrinkage rate < 5 %) was developed by freeze-thaw cycles, which was assisted by polyvinyl alcohol (PVA) and silk fibroin (SF). The hydrogen bonding between PVA imparted printability to the ceramic ink and enabled the subsequent formation of flexible scaffolds, which can be twisted, bend and cut to match bone defects. After adding SF, the printability of the inks and hydrophilicity of the scaffolds were enhanced, owing to the interactions between PVA and SF. Further, combined with the formation of β-sheet in SF, the scaffolds exhibited superior mechanical strength and excellent thermal stability, and can fully recover at 35 % compressive strain, which was breaking through the brittleness bottleneck of conventional ceramic scaffolds. Moreover, in vitro experiments showed excellent mineralization ability, osteogenic and angiogenic activities of the scaffolds, demonstrating its potential in bone regeneration. This initial study offers a promising personalized material for bone repair that can be used rapidly during surgery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Age-related macular degeneration (AMD) is a retinal disease that affects 196 million people and causes nearly 9% of blindness worldwide. While several pharmacological approaches slow the effects of AMD, in our opinion, cell-based strategies offer the most likely path to a cure. We describe the design and initial characterization of a kerateine (obtained by reductive extraction from keratin proteins) aerogel-electrospun polycaprolactone fiber scaffold system. The scaffolds mimic key features of the choroid and the Bruch's membrane, which is the basement membrane to which the cells of the retinal pigment epithelium (RPE) attach. The scaffolds had elastic moduli of 2-7.2 MPa, a similar range as native choroid and Bruch's membrane. ARPE-19 cells attached to the polycaprolactone fibers, remained viable for one week, and proliferated to form a monolayer reminiscent of that needed for retinal repair. These constructs could serve as a model system for testing cell and/or drug treatment strategies or directing ex vivo retinal tissue formation in the treatment of AMD., (© 2021. Biomedical Engineering Society.)

The application of chitosan nanofibers in biological tissue-engineering materials has attracted wide attention. A novel and organic solvent-free method was developed for the fabrication of rootlike chitosan nanofibers (CSNFs) with diameters of 40-250 nm. This method includes three-step mechanical processing of swelling-beating-centrifugation or swelling-beating-homogenization. The obtained nanofibers showed high yields (>95%) and positive specific surface charges (up to +375 μeq/g) and could be uniformly dispersed in the aqueous phase. The unique fiber shape and the good length-to-diameter ratio of CSNFs endowed chitosan nanofiber paper (CSNFP) products with excellent mechanical properties, and the wet tensile strength of the CSNFPs was nearly five times higher than common chitosan films. In addition, the calvaria-derived preosteoblastic cells exhibited a higher adherence efficiency and proliferation on CSNFP than on chitosan films. The chitosan nanofiber scaffold products also benefited the attachment of preosteoblastic cells and allowed them to grow in three dimensions. This method has significant industrial potential for the industrialization of chitosan nanofibers, which may have broad applications in various biomaterials.

This paper reports on the hybrid process we have used for producing hierarchical scaffolds made of poly(lactic-co-glycolic) acid (PLGA) and nanohydroxyapatite (nHA), analyzes their internal structures via scanning electron microscopy, and presents the results of our in vitro proliferation of MC3T3-E1 cells and alkaline phosphatase activity (ALP) for 0 and 21 days. These scaffolds were produced by combining additive manufacturing (AM) and thermally induced phase separation (TIPS) techniques. Slow cooling at a rate of 1.5 °C/min during the TIPS process was used to enable a uniform temperature throughout the scaffolds, and therefore, a relatively uniform pore size range. We produced ten different scaffold compositions and topologies in this study. These scaffolds had macrochannels with diameters of ∼300 µm, ∼380 µm, and ∼460 µm, generated by the extraction of embedded porous 3D-plotted polyethylene glycol (PEG) matrices. The other experimental factors included different TIPS temperatures (-20 °C, -10 °C, and 0 °C), as well as varying PLGA concentrations (8%, 10%, and 12% w/v) and nHA content (0%, 10%, and 20% w/w). Our results indicated that almost all these macro/microporous scaffolds supported cell growth over the period of 21 days. Nevertheless, significant differences were observed among some scaffolds in terms of their support of cell proliferation and differentiation. This paper presents the results of our in vitro cell culture for 0 and 21 days. Our optimal scaffold with a porosity of ∼90%, a modulus of ∼5.2 MPa, and a nHA content of 20% showed a cell adhesion of ∼29% on day 0 and maintained cell proliferation and ALP activity over the 21-day in vitro culture. Hence, the use of additive manufacturing and designed experiments to optimize the scaffold fabrication parameters resulted in superior mechanical properties that most other studies using TIPS.

Cellulose, a polysaccharide of β (1-4) linked D-glucose units, is a cheap, eco-friendly and most abundant natural polymer on this planet. Among various cellulosic materials, cotton cellulose is readily available, lignin-free, FDA approved, and widely used in the medical field because of its higher degree of biocompatibility and non-cytotoxic nature. Though cotton cellulose showed essential material properties for scaffold design, the least priority had been given to this material. The present study aimed at exploring the fabrication of scaffold using cotton microfibers for bone tissue engineering application. The study also aimed at improving the mechanical, physio-chemical and osteogenic properties of the microfibrous scaffold by crosslinking with citric acid and further modified with gelatin. FTIR indicated some interactions between cellulose, citric acid and gelatin within the scaffolds, while XRD results demonstrated the crystalline nature of scaffolds. Porosity and swelling studies demonstrated that all scaffolds are hydrophilic and porous. The microporous interconnected network of scaffolds was confirmed by FESEM. FESEM micrographs and MTT assay confirmed that all scaffolds were nontoxic to MG 63. Based on findings, it was concluded that gelatin coated cotton cellulose microfibers crosslinked with citric acid scaffold would be a potential template for bone tissue engineering.

This study intended to design novel nanofibrillated cellulose/cyclodextrin-based 3D scaffolds loaded with raloxifene hydrochloride for bone regeneration. The scaffolds were prepared using two different types of cyclodextrins namely; beta-cyclodextrin and methyl-beta-cyclodextrin. The prepared scaffolds were evaluated by characterizing their porosity, compressive strength, in-vitro drug release, FT-IR and XRD as well as their morphological properties using SEM. Results presented that the prepared scaffolds were highly porous, additionally, the scaffold containing drug/beta-cyclodextrin kneaded complex (SC5) showed the most controlled drug release pattern with the least burst effect and reached almost complete release at 480 h. The in-vitro cytocompatibility and regenerative effect of the chosen scaffold (SC5) was assessed using Saos-2 cell line. Results proved that SC5 was biocompatible. Moreover, it enhanced the cell adhesion, alkaline phosphatase enzyme expression and calcium ion deposition which are essential factors for bone mineralization. The obtained observations presented a novel, safe and propitious approach for bone engineering., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Three-dimensional (3D) porous scaffolds made of biopolymers have attracted significant attention in tissue engineering applications. In this study, cellulose-nanofibers/polyethylene glycol diacrylate (CNFs/PEGDA) mixture, a novelty 3D material, was prepared by physical mixing the CNFs with a waterborne photopolymerizable acrylic resin (PEGDA). Then the CNFs/PEGDA mixture was used to fabricate 3D cytocompatibility CNFs/PEGDA hydrogel scaffold by stereolithograph（SLA）process. The CNFs/PEGDA hydrogels were shaped by SLA, and then the aerogel scaffolds were prepared by the freeze-drying of hydrogels. The results showed that the CNFs/PEGDA mixtures with different CNFs contents are all transparent, homogeneous and with obvious shear-thinning property. The SLA fabricated CNFs/PEGDA aerogel scaffolds possess high and tunable compressive modulus and high porosity of approximately 90%. It is found that CNFs in the composite scaffolds played a significant role in structural shape integrity, porous structure and mechanical strength. In addition, the NIH 3T3 cells tightly adhere on the CNFs/PEGDA materials and spread on the scaffolds with good differentiation and viability. These results have revealed a superior method to prepare tissue engineering scaffolds which possesses suitable mechanical strength and biocompatibility for 3D cell cultivation.

A hybrid hydrogel (GHC-SBA15) based on spruce xylan (HC), 2-hydroxyethyl methacrylate (HEMA), and mesoporous silica (SBA15) was prepared with the intended use of fibroblast attachment and growth. Xylan was functionalized with acryloyl chloride to introduce vinyl groups and was crosslinked by radical polymerization with HEMA in presence of SBA15. Infrared spectroscopy and nuclear magnetic resonance confirmed the copolymerization of HEMA with xylan. Up to 20 wt.% addition, SBA15 was homogenously incorporated in the structured hydrogel network as observed by SEM. Moreover, nitrogen adsorption-desorption, small angle X-ray scattering and transmission electron microscopy indicated that the mesoporous SBA15 framework was maintained and that the hybrid hydrogel was a physical mixture of SBA15 with the copolymer HC/HEMA. Rheological analysis revealed that addition of 20% w/w SBA15 into hydrogel enhanced significantly the mechanical properties. In addition, we demonstrate that fibroblast L929 cells grew and spread on GHC-SBA15. Cell viability was within the expected range., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The three-dimensional (3D) printed scaffolds were prepared by partial cross-linking of TEMPO-oxidized cellulose nanofibril/alginate hydrogel using calcium ions for printing the hydrogel while maintaining its shape, fidelity, and preventing the collapse of the filaments. The prepared scaffolds were fully cross-linked using calcium ions immediately after printing to provide the rigidity of the hydrogel and give it long-term stability. The composition of the prepared pastes was adjusted in view of the description of the hydrogel and 3D printing parameters. The rheological properties in terms of thixotropic behavior and viscosity recovery of hydrogels were investigated by performing steady shear rate experiments. The results show that the viscosity recovery for pure alginate hydrogel was only about 16% of the initial value, whereas it was 66% when adding cellulose nanofibrils to alginate. Consequently, the shape of the pure alginate scaffold was soft and easy to collapse contrarily to the composite scaffold. The biomimetic mineralization process of printed scaffolds using simulated body fluid, mimicking the inorganic composition of human blood plasma, was performed and the hydroxyapatite nucleation on the hydrogel was confirmed. The strength properties of the fabricated scaffolds in terms of compressive strength analysis were also investigated and discussed. The results show that the alginate/TEMPO-oxidized cellulose nanofibril system may be a promising 3D printing scaffold for bone tissue engineering.

Tissue engineering using three-dimensional porous scaffolds has shown promise for the restoration of normal function in injured and diseased tissues and organs. Rigorous control over scaffold architecture in melt extrusion additive manufacturing is highly restricted mainly due to pronounced variations in the deposited strand diameter upon any variations in process conditions and polymer viscoelasticity. We have designed an I-optimal, split-plot experiment to study the extrudate swell in melt extrusion additive manufacturing and to control the scaffold architecture. The designed experiment was used to generate data to relate three responses (swell, density, and modulus) to a set of controllable factors (plotting needle diameter, temperature, pressure, and the dispensing speed). The fitted regression relationships were used to optimize the three responses simultaneously. The swell response was constrained to be close to 1 while maximizing the modulus and minimizing the density. Constraining the extrudate swell to 1 generates design-driven scaffolds, with strand diameters equal to the plotting needle diameter, and allows a greater control over scaffold pore size. Hence, the modulus of the scaffolds can be fully controlled by adjusting the in-plane distance between the deposited strands. To the extent of the model's validity, we can eliminate the effect of extrudate swell in designing these scaffolds, while targeting a range of porosity and modulus appropriate for bone tissue engineering. The result of this optimization was a predicted modulus of 14 MPa and a predicted density of 0.29 g/cm 3 (porosity ≈ 75%) using polycaprolactone as scaffold material. These predicted responses corresponded to factor levels of 0.6 μm for the plotting needle diameter, plotting pressure of 2.5 bar, melt temperature of 113.5 °C, and dispensing speed of 2 mm/s. The validation scaffold enabled us to quantify the percentage difference for the predictions, which was 9.5% for the extrudate swell, 19% for the density, and 29% for the modulus.

In this paper we explore the use of native bacterial cellulose (BC) in combination with functionalized multi-walled carbon nanotubes (MWNTs) as an original biomaterial, suitable three-dimensional (3D) scaffold for osteoblastic cell culture. Functionalized MWNTs were mixed with native BC (secreted by Gluconacetobacter xylinus) with the aim of reinforcing the mechanical properties of BC. The results indicate that BC-MWNTs scaffolds support osteoblast viability, adhesion and proliferation at higher levels as compared to traditional culture substrates. Chemically functionalized MWNTs are also an excellent material to be used as scaffold because these did not affect cell viability and showed an enhanced osteoblast adhesion. These results suggest the potential for this combination of biomaterials, i.e. BC and carbon nanomaterials, as scaffolds for bone regeneration., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study reports the development of biological/synthetic scaffolds for bone tissue engineering (TE) via 3D bioplotting. These scaffolds were composed of poly(L-lactic-co-glycolic acid) (PLGA), type I collagen, and nano-hydroxyapatite (nHA) in an attempt to mimic the extracellular matrix of bone. The solvent used for processing the scaffolds was 1,1,1,3,3,3-hexafluoro-2-propanol. The produced scaffolds were characterized by scanning electron microscopy, microcomputed tomography, thermogravimetric analysis, and unconfined compression test. This study also sought to validate the use of finite-element optimization in COMSOL Multiphysics for scaffold design. Scaffold topology was simplified to three factors: nHA content, strand diameter, and strand spacing. These factors affect the ability of the scaffold to bear mechanical loads and how porous the structure can be. Twenty four scaffolds were constructed according to an I-optimal, split-plot designed experiment (DE) in order to generate experimental models of the factor-response relationships. Within the design region, the DE and COMSOL models agreed in their recommended optimal nHA (30%) and strand diameter (460 μm). However, the two methods disagreed by more than 30% in strand spacing (908 μm for DE; 601 μm for COMSOL). Seven scaffolds were 3D-bioplotted to validate the predictions of DE and COMSOL models (4.5-9.9 MPa measured moduli). The predictions for these scaffolds showed relative agreement for scaffold porosity (mean absolute percentage error of 4% for DE and 13% for COMSOL), but were substantially poorer for scaffold modulus (51% for DE; 21% for COMSOL), partly due to some simplifying assumptions made by the models. Expanding the design region in future experiments (e.g., higher nHA content and strand diameter), developing an efficient solvent evaporation method, and exerting a greater control over layer overlap could allow developing PLGA-nHA-collagen scaffolds to meet the mechanical requirements for bone TE.

Purpose: To evaluate the biological, immunological, and biomechanical properties of a scaffold derived by architectural modification of a fresh-frozen porcine patella tendon using a decellularization protocol that combines physical, chemical, and enzymatic modalities., Methods: Porcine patellar tendons were processed using a decellularization and oxidation protocol that combines physical, chemical, and enzymatic modalities. Scaffolds (n = 88) were compared with native tendons (n = 70) using histologic, structural (scanning electron microscopy, porosimetry, and tensile testing), biochemical (mass spectrometry, peracetic acid reduction, DNA quantification, alpha-galactosidase [α-gal] content), as well as in vitro immunologic (cytocompatibility, cytokine induction) and in vivo immunologic nonhuman primate analyses., Results: A decrease in cellularity based on histology and a significant decrease in DNA content were observed in the scaffolds compared with the native tendon (P < .001). Porosity and pore size were increased significantly (P < .001). Scaffolds were cytocompatible in vitro. There was no difference between native tendons and scaffolds when comparing ultimate tensile load, stiffness, and elastic modulus. The α-gal xenoantigen level was significantly lower in the decellularized scaffold group compared with fresh-frozen, nondecellularized tissue (P < .001). The in vivo immunological response to implanted scaffolds measured by tumor necrosis factor-α and interleukin-6 levels was significantly (P < .001) reduced compared with untreated controls in vitro. These results were confirmed by an attenuated response to scaffolds in vivo after implantation in a nonhuman primate model., Conclusions: Porcine tendon was processed via a method of decellularization and oxidation to produce a scaffold that possessed significantly less inflammatory potential than a native tendon, was biocompatible in vitro, of increased porosity, and with significantly reduced amounts of α-gal epitope while retaining tensile properties., Clinical Relevance: Porcine-derived scaffolds may provide a readily available source of material for musculoskeletal reconstruction and repair while eliminating concerns regarding disease transmission and the morbidity of autologous harvest., (Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

The aim of this study was to evaluate the in vitro osteogenic effects and in vivo new bone formation of three-dimensional (3D) printed alendronate (Aln)-releasing poly(caprolactone) (PCL) (Aln/PCL) scaffolds in rat tibial defect models. 3D printed Aln/PCL scaffolds were fabricated via layer-by-layer deposition. The fabricated Aln/PCL scaffolds had high porosity and an interconnected pore structure and showed sustained Aln release. In vitro studies showed that MG-63 cells seeded on the Aln/PCL scaffolds displayed increased alkaline phosphatase (ALP) activity and calcium content in a dose-dependent manner when compared with cell cultures in PCL scaffolds. In addition, in vivo animal studies and histologic evaluation showed that Aln/PCL scaffolds implanted in a rat tibial defect model markedly increased new bone formation and mineralized bone tissues in a dose-dependent manner compared to PCL-only scaffolds. Our results show that 3D printed Aln/PCL scaffolds are promising templates for bone tissue engineering applications.

Swollen three-dimensional nanocellulose films and their resultant aerogels were prepared as scaffolds towards tissue engineering application. The nanocellulose hydrogels with various swelling degree (up to 500 times) and the resultant aerogels with desired porosity (porosity up to 99.7% and specific surface area up to 308m(2)/g) were prepared by tuning the nanocellulose charge density, the swelling media conditions, and the material processing approach. Representative cell-based assays were applied to assess the material biocompatibility and efficacy of the human extracellular matrix (ECM)-mimicking nanocellulose scaffolds. The effects of charge density and porosity of the scaffolds on the biological tests were investigated for the first time. The results reveal that the nanocellulose scaffolds could promote the survival and proliferation of tumor cells, and enhance the transfection of exogenous DNA into the cells. These results suggest the usefulness of the nanocellulose-based matrices in supporting crucial cellular processes during cell growth and proliferation., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Aiming to mimic a blood vessel structurally, morphologically, and mechanically, a sequential electrospinning technique using a small diameter mandrel collector was performed and a three-layered tubular scaffold composed of nanofibers of polycaprolactone, collagen, and poly(l-lactic acid) as inner, intermediate, and outer layers, respectively, was developed. Biological performances of the scaffold in terms of compatibility with blood and endothelial cells were assessed to get some insights into its potential use as a tissue engineered small-diameter vascular replacement compared to an expanded polytetrafluoroethylene vascular graft. Due to direct contact of the blood and endothelial cells with inner surface of the scaffold, polycaprolactone fibers were characterized using SEM, water contact angle measurement, and ATR-FTIR. Despite similar surface wettability of the electrospun scaffold and the expanded polytetrafluoroethylene graft, the three-layered scaffold significantly reduced platelet adhesion and hemolysis ratio compared to expanded polytetrafluoroethylene graft while comparable blood clotting profiles were observed for both electrospun scaffold and expanded polytetrafluoroethylene graft. However, inflammatory response to nanofibrous surface of the scaffold was reduced compared to expanded polytetrafluoroethylene graft. The electrospun scaffold also presented a significantly more supportive substrate for endothelialization than the expanded polytetrafluoroethylene graft. The results described herein suggested that the three-layered scaffold has superior biological properties compared to an expanded polytetrafluoroethylene graft for vascular tissue engineering., (© The Author(s) 2016.)

The repair of osteochondral defects requires a tissue engineering approach that aims at mimicking the physiological properties and structure of two different tissues (cartilage and bone) using specifically designed scaffold-cell constructs. Biphasic and triphasic approaches utilize two or three different architectures, materials, or composites to produce a multilayered construct. This article gives an overview of some of the current strategies in multiphasic/gradient-based scaffold architectures and compositions for tissue engineering of osteochondral defects. In addition, the application of finite element analysis (FEA) in scaffold design and simulation of in vitro and in vivo cell growth outcomes has been briefly covered. FEA-based approaches can potentially be coupled with computer-assisted fabrication systems for controlled deposition and additive manufacturing of the simulated patterns. Finally, a summary of the existing challenges associated with the repair of osteochondral defects as well as some recommendations for future directions have been brought up in the concluding section of this article., (© 2014 Wiley Periodicals, Inc.)

Tissue engineering makes use of the principles of biology and engineering to sustain 3D cell growth and promote tissue repair and/or regeneration. In this study, macro/microporous scaffold architectures have been developed using a hybrid solid freeform fabrication/thermally induced phase separation (TIPS) technique. Poly(lactic-co-glycolic acid) (PLGA) dissolved in 1,4-dioxane was used to generate a microporous matrix by the TIPS method. The 3D-bioplotting technique was used to fabricate 3D macroporous constructs made of polyethylene glycol (PEG). Embedding the PEG constructs inside the PLGA solution prior to the TIPS process and subsequent extraction of PEG following solvent removal (1,4-dioaxane) resulted in a macro/microporous structure. These hierarchical scaffolds with a bimodal pore size distribution (<50 and >300 μm) contained orthogonally interconnected macro-channels generated by the extracted PEG. The diameter of the macro-channels was varied by tuning the dispensing parameters of the 3D bioplotter. The in vitro cell culture using murine MC3T3-E1 cell line for 21 days demonstrated that these scaffolds could provide a favorable environment to support cell adhesion and growth.

Tissue engineering makes use of 3D scaffolds to sustain three-dimensional growth of cells and guide new tissue formation. To meet the multiple requirements for regeneration of biological tissues and organs, a wide range of scaffold fabrication techniques have been developed, aiming to produce porous constructs with the desired pore size range and pore morphology. Among different scaffold fabrication techniques, thermally induced phase separation (TIPS) method has been widely used in recent years because of its potential to produce highly porous scaffolds with interconnected pore morphology. The scaffold architecture can be closely controlled by adjusting the process parameters, including polymer type and concentration, solvent composition, quenching temperature and time, coarsening process, and incorporation of inorganic particles. The objective of this review is to provide information pertaining to the effect of these parameters on the architecture and properties of the scaffolds fabricated by the TIPS technique., (© 2014 Wiley Periodicals, Inc.)

This study examines the potential use of porous polycaprolactone (PCL) and polycaprolocatone/hydroxyapatite (PCL/HA) scaffolds fabricated through melt molding and porogen leaching for bone tissue engineering. While eliminating organic solvents is desirable, the process steps proposed in this study for uniformly dispersing HA particles (~5 μm in size) within the scaffold can also contribute to homogeneous properties for these porous composites. Poly(ethylene oxide) (PEO) was chosen as a porogen due to its similar density and melting point as PCL. Pore size of the scaffold was controlled by limiting the size of PCL and PEO particles used in fabrication. The percent of HA in the fabricated scaffolds was quantified by thermogravimetric analysis (TGA). Mechanical testing was used to compare the modulus of the scaffolds to that of bone, and the pore size distribution was examined with microcomputed tomography (μCT). Scanning electron microscopy (SEM) was used to examine the effect on scaffold morphology caused by the addition of HA particles. Both μCT and SEM results showed that HA could be incorporated into PCL scaffolds without negatively affecting scaffold morphology or pore formation. Energy-dispersive X-ray spectroscopy (EDS) and elemental mapping demonstrated a uniform distribution of HA within PCL/HA scaffolds. Murine calvaria-derived MC3T3-E1 cells were used to determine whether cells could attach on scaffolds and grow for up to 21 days. SEM images revealed an increase in cell attachment with the incorporation of HA into the scaffolds. Similarly, DNA content analysis showed a higher cell adhesion to PCL/HA scaffolds.

C6-carboxy-cellulose with a carboxylate content of 0.8 mmol g(-1) was obtained by oxidation of once-dried cellulose, using the 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)/NaClO/NaClO2 system at pH 6.8 and 60 °C for 16 h. This method, with the addition of reagents in the order TEMPO, NaClO and NaClO2, was 38 h faster than a previously published method. Individualized cellulose nanofibrils with a width of 3-5 nm and a length of several hundred nanometers were prepared by homogenizing the C6-carboxy-cellulose-water suspension. Macroporous cellulose nanofibril/poly(vinyl alcohol) scaffolds with interconnected large pores of 20-100 μm diameter and small pores of 2-10 μm diameter were fabricated. The cellulose nanofilaments formed nanofibrous structures on the surface of the PVA wall, which was similar to that of the collagen skeleton of the extracellular matrix. NIH/3T3 cells were cultured in the scaffolds for 4 weeks, SEM observation showed that the cells were anchored and clustered on the cellulose nanofilaments, forming spherical colonies. The extracellular matrix (ECM) was filled with mineralized particles.