Preparation Of Scaffolds Research Articles

Preparation of osteoinductive – Antimicrobial nanocomposite scaffolds based on poly (D,L-lactide-co-glycolide) modified with copper – Doped bioactive glass nanoparticles

The aim of this study was to explore the preparation of porous nanocomposite scaffolds with simultaneous osteogenic – antibacterial properties by incorporating copper – doped bioactive glass nanoparticles into Poly (D,L-lactide-co-glycolide) lactide:glycolide. Bioactive glass nanoparticles were synthesized by using sol–gel technique from the SiO2 – P2O5 – CaO – Na2O – CuO system. Poly (D,L-lactide-co-glycolide) lactide:glycolide nanocomposite scaffolds with different nanoparticle contents were prepared by combined lyophilization/salt leaching. The in vitro bioactivity of the scaffolds was assessed in simulated body fluid, and cell viability and osteogenic differentiation assays were performed with stem cells. Antibacterial activity of the materials was assessed against Staphylococcus aureus. Copper – dopped bioactive glass nanoparticles particles with ∼70 nm in size and relatively crystalline structure were synthesized. Porous nanocomposite scaffolds prepared with the copper – doped nanoparticles are cytocompatible, promoted the mineralization of bone-like apatite in simulated body fluid, and stimulated the osteogenic differentiation of stem cells as judged by an increased activity the enzyme alkaline phosphatase. The antibacterial activity exhibited by the nanocomposite scaffolds was not statistically superior to that of the neat polymer scaffold. Development of greater antibacterial activity in these nanocomposites would requires further research primarily related to the synthesis of more amorphous and soluble copper – dopped bioactive glass nanoparticles.

Preparation and Characterization of Bioactive Glass-Manganese Dioxide Composite Scaffolds

Preparation and Characterization of Bioactive Glass-Manganese Dioxide Composite Scaffolds

Preparation and characterization of biomimetic gradient multi-layer cell-laden scaffolds for osteochondral integrated repair.

A cell-laden tissue engineering scaffold for osteochondral integrated repair is one of the ideal strategies for osteochondral lesions. In this study, we fabricated cell-laden porous hydrogel scaffolds with gradient nano-hydroxyapatite using methacrylic anhydride gelatin (GelMA), nano-hydroxyapatite (nHA), and polyethylene oxide (PEO) solution for osteochondral tissue regeneration. The scaffold possessed interconnected pores and a nano-hydroxyapatite gradient in the vertical direction. The chemical, physical, mechanical, and biological properties of the hydrogel solutions and scaffolds were characterized. In vitro experiments confirmed that cells were distributed homogeneously and that different pore structures could affect the proliferation and differentiation of BMSCs. The Nonporous hydrogel was beneficial for the chondrogenic differentiation of BMSCs and interconnected pores were conducive to BMSC proliferation and osteogenic differentiation. The osteochondral integrative repair capacity of the scaffold was assessed by implanting the scaffolds into the intercondylar defect of the rabbit femur. By constructing pore structures in different layers, the cells in different layers of the hydrogels were in an intrinsic environment for survival and differentiation. Animal experiments confirmed that tissue engineering scaffolds for osteochondral lesions require different pore structures in different layers, and gradient structure facilitated integrated repair.

Alginate/TiO2@LDH microspheres: A promising bioactive scaffold with cytocompatibility and antibacterial activity

In this study, a hybrid of TiO2@LDH was applied to fabricate a bone scaffold to take the advantages of both nanostructures. In addition to the role of LDH in the biomineralization process, it was used to provide a suitable bed for the better dispersion of TiO2 nanoparticles and prevent them from aggregations. The main limitation in the usage of these nanoceramics in the preparation of bone scaffolds is their powder state, which prevents their fixation in the desired place. So, alginate (Alg) was selected as the matrix to embed this nanohybrid and support its stability and fixation. Bioactivity of the prepared Alg/TiO2@LDH scaffolds was assessed by incubation in the simulated body fluid at 37 °C for 28 days. Field emission scanning electron microscopy as well as energy dispersive X-ray were used to prove the biomineralization on the scaffolds. MTT test showed that the scaffold containing 6 wt% of the TiO2@LDH do not have any toxicity effects on the MG-63 cell line. Also, this scaffold presented outstanding antibacterial ability against Staphylococcus aureus, which is known as an important infecting agent in the bone scaffolds. The proposed Alg/TiO2@LDH scaffold in this study could be a proper candidate to be used in bone tissue engineering.

Preparation and characterization of hybrid nanofibrous polymer scaffolds for tissue engineering applications

This paper endeavours towards the scientific study of infusion of silver nanoparticles (Ag NPs) into biodegradable polymer scaffold for bone tissue engineering. Highly biocompatible Ag NPs have been synthesized using chitosan as stabilizing and reducing agent. The synthesized Ag NPs have been uniformly suspended in polyvinyl alcohol (PVA) and sodium alginate (SA) solution and nanofibrous mat like scaffolds have been fabricated using electrospinning process. The proposed process of infusing Ag NPs in PVA/SA medium resulted in nanofibers of smaller diameter and reduced pore size resulted in high surface area which is due to electrostatic charge interaction of Ag NPs during electrospinning. Thus, the improved surface area has facilitated better growth of extracellular matrix (ECM) compared to traditional coating method. The effect of coating nanoparticles on prepared polymeric scaffolds proves less than infusion of nanoparticles prior to electrospinning.

Preparation of mesh-like collagen scaffolds for tissue engineering

Collagen meshes with large or small openings were prepared after selective removal of PLGA mesh from PLGA–collagen composite mesh or collagen-coated PLGA mesh. The collagen meshes support human skin fibroblast adhesion and promote cell proliferation.

Development of Silk Fibroin Scaffolds by Using Indirect 3D-Bioprinting Technology.

Due to the excellent biocompatibility of natural polymers, a variety of natural polymers have been widely used as biomaterials for manufacturing tissue engineered scaffolds. Despite the excellent biological activity of natural polymers, there have been obstacles in using them on their own to prepare 3D scaffolds with sufficient mechanical strength. Although multiple 3D-bioprinting technologies have recently emerged as effective manufacturing tools for scaffold preparation, scaffold preparation using only natural polymers with tunable mechanical properties is still difficult. Herein, we introduce novel scaffold fabrication methods using the natural polymer silk fibroin via indirect 3D-bioprinting technology. The developed silk fibroin scaffolds showed biocompatibility and tunable mechanical strength by changing the concentration of the silk fibroin. Furthermore, controlling the flexibility of the silk fibroin scaffolds was made possible by changing the solvent for the silk fibroin solution used to fabricate the scaffold. Consequently, silk fibroin scaffolds fabricated via our method can be considered for various applications in the bioengineering of either soft or musculoskeletal tissues.

Enzymatically functionalized RGD-gelatin scaffolds that recruit host mesenchymal stem cells in vivo and promote bone regeneration

Critical-size bone defects are imposing a substantial biomedical burden. Despite being long regarded as a potential approach to mitigate this burden or an alternative to bone grafts, bone tissue engineering (BTE) has virtually not proceeded to widespread clinical practices. In the BTE field, it is highly required to find a facile method to prepare active scaffolds with tailored biological functions. Here, we immobilized cell adhesive RGD motifs onto gelatin sponge (GS) scaffolds through enzymatic linking. On the basis of the resulting RGD-functionalized GS (RGD/GS) scaffolds, we developed a new and convenient strategy for bone defect repair, in which the scaffolds were first used to recruit mesenchymal stem cells (MSCs) from skeletal muscle, immediately followed by their engraftment into bone defect. We demonstrated significantly enhanced host cells homing into RGD/GS scaffolds as a result of specific RGD-integrin interactions, and the recruited host cells showed a strong osteogenic differentiation potential. After ectopic implantation of cell-laden RGD/GS scaffolds into critical-size mouse bone defects, marked bone tissue regeneration occurred. The presented strategy not only provides an agile route for the preparation of bioactive scaffolds and the construction of osteoinductive bone-graft substitutes, but also avoids or minimizes the complicated and laborious cell isolation, in vitro expansion and cell seeding procedures used in the conventional BTE.

Solubilization mechanism and structural properties of high‐denatured peanut protein treated by shearing

AbstractHigh‐denatured peanut protein (PP), which exhibited a surface structure dominated by hydrophobic groups due to the high temperature and pressure in oil extraction, was limited in application with poor hydration property. To improve the interaction between PP and water molecules, high‐speed shearing homogenization (HSH) technique was used to depolymerize the aggregates. The results showed that the concentration of soluble protein was increased from 0.22 to 0.79 mg/mL at 15 min, followed by enhanced water holding ability, decreased particle size, and thermal stability. Otherwise, the decrease of α‐helix structure and the exposure of chromophoric groups indicated that the secondary and tertiary structure were unfolded. The stretching vibration of C–O, C=O, C–H, the increase of β‐turn structure, and the exposure of hydrophilic groups (–OH) were the main reason for the improved hydration property. Furthermore, the increased hydration property facilitated the formation of a stable emulsion via stabilizing the water phase. The enhanced hydration property of PP contributed to extending its application in the preparation of beverages and delivery products such as Pickering emulsion and gel for drugs.Practical applicationsAs one of the non‐thermal processing technologies, HSH technology has been widely used in the field of food processing. HSH treatment depolymerized the materials via producing strong shear force, vortex, and cavitation, which was easy to operate and avoided pollution. This study used the HSH technology to improve the hydration property of PP, which has great research potential for the preparation of drug delivery carriers, nutritional products, tissue scaffolds, and food packaging materials.

Skin Substitute Preparation Method Induces Immunomodulatory Changes in Co-Incubated Cells through Collagen Modification.

Chronic ulcerative and hard-healing wounds are a growing global concern. Skin substitutes, including acellular dermal matrices (ADMs), have shown beneficial effects in healing processes. Presently, the vast majority of currently available ADMs are processed from xenobiotic or cadaveric skin. Here we propose a novel strategy for ADM preparation from human abdominoplasty-derived skin. Skin was processed using three different methods of decellularization involving the use of ionic detergent (sodium dodecyl sulfate; SDS, in hADM 1), non-ionic detergent (Triton X-100 in hADM 2), and a combination of recombinant trypsin and Triton X-100 (in hADM 3). We next evaluated the immunogenicity and immunomodulatory properties of this novel hADM by using an in vitro model of peripheral blood mononuclear cell culture, flow cytometry, and cytokine assays. We found that similarly sourced but differentially processed hADMs possess distinct immunogenicity. hADM 1 showed no immunogenic effects as evidenced by low T cell proliferation and no significant change in cytokine profile. In contrast, hADMs 2 and 3 showed relatively higher immunogenicity. Moreover, our novel hADMs exerted no effect on T cell composition after three-day of coincubation. However, we observed significant changes in the composition of monocytes, indicating their maturation toward a phenotype possessing anti-inflammatory and pro-angiogenic properties. Taken together, we showed here that abdominoplasty skin is suitable for hADM manufacturing. More importantly, the use of SDS-based protocols for the purposes of dermal matrix decellularization allows for the preparation of non-immunogenic scaffolds with high therapeutic potential. Despite these encouraging results, further studies are needed to evaluate the beneficial effects of our hADM 1 on deep and hard-healing wounds.

Synthesis and Applications of Polysubstituted Bicyclo[1.1.0]butanes

Bicyclo[1.1.0]butanes (BCBs) are valuable substrates in the "strain release" synthesis of polysubstituted four-membered ring systems, with applications including bioconjugation agents. The introduction of substituents onto the BCB bridges is challenging due to limitations in current methods for the preparation of this bicyclic scaffold, typically necessitating linear syntheses with limited functional group tolerance and/or substituent scope. Here, we report the synthesis of tri- and tetrasubstituted BCBs via directed metalation of readily accessed BCB amides; this straightforward "late stage" approach generates a wide variety of bridge-substituted BCBs that can be easily converted into other useful small ring building blocks. Access to a monodeuterated BCB afforded unprecedented insight into the mechanism of dihalocarbene insertion into BCBs to afford bicyclo[1.1.1]pentanes (BCPs).

Additive manufacturing of Ca–Mg silicate scaffolds supported by flame-synthesized glass microspheres

Novel manufacturing techniques such as additive manufacturing also referred to as 3D printing hold a critical role in the preparation of novel bioactive three-dimensional glass-ceramic scaffolds. The present paper focuses on the use of Ca–Mg silicates microspheres (Ca2MgSi2O7, i.e. 40 mol% CaO, 20% MgO and 40% SiO2) for the fabrication of 3D structures by additive manufacturing. In the first step, the crystallization of the åkermanite system was avoided, by feeding nearly fully crystallized precursor powders prepared by conventional melt quenching into oxygen-methane (O2/CH4) torch, and solid glass microspheres (SGMs) with diameters bellow 63 μm were prepared. In the second step, the crystallization was utilized to control the viscous flow of SGMs during firing of reticulated scaffolds, obtained by digital light processing (DLP) of the SGMs suspended in a photocurable acrylate binder. The spheroidal shape facilitated a high solid content, up to 77 wt% of the SGMs in the suspension. After burn-out of the organic binder, a fast sintering treatment at 950 °C, for 30 min, led to scaffolds preserving the macro-porosity from 3D printing model (diamond cell lattice) but with well densified struts. The crystallization of 3D scaffolds during the sintering process led to 3D structures with adequate strength-to-density ratio.

Preparation and Characterization of Nanocellulose/Chitosan Aerogel Scaffolds Using Chemical-Free Approach.

Biopolymer-based aerogels are open three-dimensional porous materials that are characterized by outstanding properties, such as a low density, high porosity and high surface area, in addition to their biocompatibility and non-cytotoxicity. Here we fabricated pure and binary blended aerogels from cellulose nanofibers (CNFs) and chitosan (CS), using a chemical-free approach that consists of high-pressure homogenization and freeze-drying. The prepared aerogels showed a different porosity and density, depending on the material and mixing ratio. The porosity and density of the aerogels ranged from 99.1 to 90.8% and from 0.0081 to 0.141 g/cm3, respectively. Pure CNFs aerogel had the highest porosity and lightest density, but it showed poor mechanical properties and a high water absorption capacity. Mixing CS with CNFs significantly enhance the mechanical properties and reduce its water uptake. The two investigated ratios of aerogel blends had superior mechanical and thermal properties over the single-material aerogels, in addition to reduced water uptake and 2-log antibacterial activity. This green fabrication and chemical-free approach could have great potential in the preparation of biopolymeric scaffolds for different biomedical applications, such as tissue-engineering scaffolds.

Poly(vinyl alcohol)-methacrylate with CRGD peptide: A photocurable biocompatible hydrogel.

Polyvinyl alcohol (PVA)-based hydrogels are promising biomaterials for tissue engineering printing applications. However, one of their main disadvantages is their inability to support cell attachment, which is a critical feature for the preparation of biological scaffolds. The goal of this study was to develop a printable, cell-supportive PVA-based bioink with tunable mechanical properties, without using animal-derived polymers which potentially harbor human pathogens. An ultraviolet light (UV) curable PVA-methacrylate (PVA-MA) polymer mixed with Cys-Arg-Gly-Asp (CRGD) peptide was developed. This peptide holds the integrin receptor binding sequence - RGD, that can enhance cell attachment. The additional cysteine was designed to enable its thiol binding under UV to methacrylate groups of the UV curable PVA-MA. Vero cell, as an adherent cell model was used to assess the hydrogel's cell adhesion. It was found that the PVA-MA-CRGD formula enables the preparation of hydrogels with excellent cell attachment and had even shown superior cell attachment properties relative to added gelatin. Adding hyaluronic acid (HA) as a rheologic modulator enabled the printing of this new formula. Our overall data demonstrates the applicability of this mixture as a bioink for soft tissue engineering such as skin, adipose, liver or kidney tissue.

Decellularization with triton X-100 provides a suitable model for human kidney bioengineering using human mesenchymal stem cells

AimsRegeneration of discarded human kidneys has been considered as an ideal approach to overcome organ shortage for the end-stage renal diseases (ESRDs). The aim of this study was to develop an effective method for preparation of kidney scaffolds that retain the matrix structure required for proliferation and importantly, differentiation of human adipose-derived mesenchymal stem cells (hAd-MSCs) into renal cells. Main methodsWe first compared two different methods using triton X-100 and sodium dodecyl sulfate (SDS) for human kidney decellularization; followed by characterization of the prepared human renal extracellular matrix (ECM) scaffolds. Then, hAd-MSCs were seeded on the scaffolds and cultured for up to 3 weeks. Next, viability, proliferation, and migration of seeded hAd-MSCs underwent histological and scanning electron microscopy (SEM) assessments. Moreover, differentiation of hAd-MSCs into kidney-specific cell types was examined using immunohistochemistry (IHC) staining and qRT-PCR. Key findingsOur results indicated that triton X-100 was a more effective detergent for decellularization of human kidneys compared with SDS. Moreover, attachment and proliferation of hAd-MSCs within the recellularized human kidney scaffolds, were confirmed. Seeded cells expressed epithelial and endothelial differentiation markers, and qRT-PCR results indicated increased expression of platelet and endothelial cell adhesion molecule 1 (PECAM-1), paired box 2 (PAX2), and E-cadherine (E-CDH) as markers of differentiation into epithelial and endothelial cells. SignificanceThese observations indicate the effectiveness of decellularization with triton X-100 to generate suitable human ECM renal scaffolds, which supported adhesion and proliferation of hAd-MSCs and could induce their differentiation towards a renal lineage.

Construction and evaluation of co-electrospun poly (butylene succinate)/gelatin materials as potential vascular grafts

In this study, a series of poly (butylene succinate) (PBSU)/gelatin composites were prepared by electrospinning. The morphology, physicochemical analysis, biomechanical properties, biocompatibility, and biodegradability of the materials were evaluated. The results showed that the ultimate tensile stress of the vascular PBSU/gelatin grafts at (95/5), (90/10), (85/15), and (80/20) was (4.17 ± 0.54) MPa, (3.81 ± 0.44) MPa, 2.94 ± 0.69 MPa and 2.11 ± 0.72 MPa respectively, and the burst pressure was (282.7 ± 22.3) kPa, (295.3 ± 3.9) kPa, (306.8 ± 13.9) kPa and (307.6 ± 9.0) kPa respectively, which met the requirements of tissue-engineered blood vessels. Furthermore, the addition of gelatin improved the hydrophilicity and degradation properties of PBSU, thus enhancing cell adhesion and promoting the inward growth of vascular smooth muscle cells. In summary, the research in this paper provides a useful reference for the preparation and optimization of vascular scaffolds.

Cryogel‐based Injectable 3D Microcarrier Co‐culture for Support of Hematopoietic Progenitor Niches

Although hematopoietic stem cell (HSC) transplantation can restore functional hematopoiesis upon immune or chemotherapy-induced bone marrow failure, complications often arise during recovery, leading to up to 25% transplant-related mortality in treated patients. In hematopoietic homeostasis and regeneration, HSCs in the bone marrow give rise to the entirety of cellular blood components. One of the challenges in studying hematopoiesis is the ability to successfully mimic the relationship between the stroma and hematopoietic stem and progenitor cells (HSPCs). This study and the described protocols propose an advantageous method for culturing and assessing stromal hematopoietic support in three dimensions, representing a simplified in vitro model of the bone marrow niche that can be transplanted in vivo by injection. By co-culturing OP9 bone marrow-derived stromal cells (BMSCs) and cKit+ Sca-1+ Lin- (KLS+ ) HSPCs on collagen-coated carboxymethylcellulose scaffolds for 2 weeks in the absence of cytokines, we established a methodology for in vivo subcutaneous transplantation. With this model we were able to detect early signs of extramedullary hematopoiesis. This work can be useful for studying various stromal cell populations in co-culture, as well as simple transfer by injection of these scaffolds in vivo for heterotopic regeneration of the marrow microenvironment. © 2021 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Isolation of HSPCs from mice Basic Protocol 2: Co-seeding of HSPCs and BMSCs on collagen-coated CCMs Basic Protocol 3: Maintenance, real-time imaging, and analysis of co-seeded scaffolds Basic Protocol 4: End-point analysis of co-seeded scaffolds using flow cytometry and CFU assays Basic Protocol 5: Transplantation of scaffolds by subcutaneous injection Support Protocol: Preparation of custom scaffold drying device.

Poly (vinyl alcohol)/Silk Fibroin/Ag NPs composite nanofibers for bone tissue engineering.

In this work, electrospinning was used for the preparation of composite nanofibrous scaffold, of polyvinyl alcohol (PVA), silk fibroin (SF) extract of Bombyx mori cocoons and silver nanoparticles (Ag NPs), as a substrate for bone tissue engineering. The PVA pristine was prepared at a concentration of 10% wt. The composite nanofibers scaffolds of PVA was prepared with silk fibroin and silver nanoparticles, in relation of PVA: SF (90:10) (v/v) respectively. The formation and presence of AgNPs was confirmed by ultraviolet-visible spectroscopy (Uv-vis). The diameter distribution of the nanofibers was narrow by SEM using Image J software. The chemical composition was determined by FTIR spectra. The wettability was determined using water contact angle. The results showed the average nanofiber diameter of PVA10 pristine was 108.18 nm and to PVA10/SF/Ag NPs was 106.62 nm, no significant changes were noted in the mean diameter, but there were changes in its morphology. The average nanofiber diameter increase with the concentration of PVA at PVA15/SF/Ag NPs was 189.12 nm to PVA18/SF/Ag NPs was 224,23 nm. FTIR spectra indicated characteristic absorption peaks related to the chemical structure of PVA, fibroin and Ag NPs, it demonstrated good interactions between them, caused by strong intermolecular hydrogen bonds. The contact angle of the scaffolds PVA 10%wt decrease with the incorporation of fibroin and show hydrophilic characteristics. The achievements indicate the potential of the nanofibers of PVA15/SF/Ag NPs as a possible substitute for bone tissue engineering.Clinical Relevance-This establishes a possible substrate of PVA/SF/Ag NPs that exhibit desired properties such as porosity and high surface area to volume ratio for bone tissue engineering.

Poly-ε-Caprolactone/Halloysite Nanotube Composites for Resorbable Scaffolds: Effect of Processing Technology on Homogeneity and Electrospinning.

Polycaprolactone (PCL)/halloysite composites were prepared to compare the effect of homogenization technology on the structure and properties of the composites. Halloysite content changed from 0 to 10 vol% in six steps and homogeneity was characterized by various direct and indirect methods. The results showed that the extent of aggregation depends on technology and on halloysite content; the size and number of aggregates increase with increasing halloysite content. Melt mixing results in more homogeneous composites than the simple compression of the component powders or homogenization in solution and film casting. Homogeneity and the extent of aggregation determines all properties, including functionality. The mechanical properties of the polymer deteriorate with increasing aggregation; even stiffness depends on homogeneity. Strength and deformability decreases drastically as the number and size of aggregates increase. Not only dispersed structure, but also the physical state and crystalline structure of the polymer influence homogeneity and properties. The presence of the filler affects the preparation of electrospun fiber scaffolds as well. A part of the filler is excluded from the fibers while another part forms aggregates that complicates fiber spinning and deteriorates properties. The results indicate that spinning is easier and the quality of the fibers is better if a material homogenized previously by melt mixing is used for the production of the fibers.

Ultrathin freestanding PDA-Doped rGO/MWCNT composite paper for electromagnetic interference shielding applications

The scalable and controllable preparation of carbon nanomaterial-based scaffolds with superior electromagnetic interference (EMI) shielding properties in addition to being ultrathin, robust, lightweight, flexible, and foldable is a challenging task. However, commonly used techniques such as integrating conducting moieties and high-temperature annealing cannot simultaneously meet the demands of high specific shielding effectiveness (SSE), robustness, and flexibility. Here, we adopted a novel PDA reduction technique to integrate various functionalities, including a nitrogen doping source, extended reduction of GO, and a large accessible area to accommodate multiwall carbon nanotubes (MWCNTs). The prepared ultrathin PDA-rGO/CNT composite sheet exhibited a low density (0.26 g/cm3), high flexibility, and superior shielding effectiveness (SE) under a wide range of microwave frequencies (i.e., the X band and Ku band). The total shielding effectiveness (SET) reached 47.6 dB and 48.7 dB in the X band and Ku band, respectively, at a thickness of 82 µm and a high SSE; in particular, the SE/density reached a maximum value of 183.3 and 187.3 dB cm3/g, respectively, which are superior to those of previously reported studies. This comprehensive study revealed the synergistic effect of PDA doping and MWCNTs, resulting in excellent shielding properties. Hence, this superior SSE and flexibility makes ultrathin lightweight PDA-rGO/CNT composite sheets a suitable candidate for replacing metallic counterparts for foldable and wearable electronic components.