Porosity Of Scaffolds Research Articles

A nanofibrous polycaprolactone/collagen neural guidance channel filled with sciatic allogeneic schwann cells and platelet-rich plasma for sciatic nerve repair.

Sciatic nerve damage, a common condition affecting approximately 2.8% of the US population, can lead to significant disability due to impaired nerve signal transmission, resulting in loss of sensation and motor function in the lower extremities. In this study, a neural guidance channel was developed by rolling a nanofibrous scaffold produced via electrospinning. The scaffold's microstructure, biocompatibility, biodegradation rate, porosity, mechanical properties, and hemocompatibility were evaluated. Platelet-rich plasma (PRP) activated with 30,000 allogeneic Schwann cells (SCs) was injected into the lumen of the channels following implantation into a rat model of sciatic nerve injury. Recovery of motor function, sensory function, and muscle re-innervation was assessed using the sciatic function index (SFI), hot plate latency time, and gastrocnemius muscle wet weight loss. Results showed mean hot plate latency times of Autograft: 7.03, PCL/collagen scaffolds loaded with PRP and SCs (PCLCOLPRPSCs): 8.34, polymer-only scaffolds (PCLCOL): 10.66, and untreated animals (Negative Control): 12.00. The mean SFI values at week eight were Autograft: -49.30, PCLCOLPRPSCs: -64.29, PCLCOL: -75.62, and Negative Control: -77.14. The PCLCOLPRPSCs group showed a more negative SFI compared to the Autograft group but performed better than both the PCLCOL and Negative Control groups. These findings suggest that the developed strategy enhanced sensory and functional recovery compared to the negative control and polymer-only scaffold groups.

Impact of Porosity and Stiffness of 3D Printed Polycaprolactone Scaffolds on Osteogenic Differentiation of Human Mesenchymal Stromal Cells and Activation of Dendritic Cells.

Despite the potential of extrusion-based printing of thermoplastic polymers in bone tissue engineering, the inherent nonporous stiff nature of the printed filaments may elicit immune responses that influence bone regeneration. In this study, bone scaffolds made of polycaprolactone (PCL) filaments with different internal microporosity and stiffness was 3D-printed. It was achieved by combining three fabrication techniques, salt leaching and 3D printing at either low or high temperatures (LT/HT) with or without nonsolvent induced phase separation (NIPS). Printing PCL at HT resulted in stiff scaffolds (modulus of elasticity (E): 403 ± 19 MPa and strain: 6.6 ± 0.1%), while NIPS-based printing at LT produced less stiff and highly flexible scaffolds (E: 53 ± 10 MPa and strain: 435 ± 105%). Moreover, the introduction of porosity by salt leaching in the printed filaments significantly changed the mechanical properties and degradation rate of the scaffolds. Furthermore, this study aimed to show how these variations influence proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSC) and the maturation and activation of human monocyte-derived dendritic cells (Mo-DC). The cytocompatibility of the printed scaffolds was confirmed by live-dead imaging, metabolic activity measurement, and the continuous proliferation of hBMSC over 14 days. While all scaffolds facilitated the expression of osteogenic markers (RUNX2 and Collagen I) from hBMSC as detected through immunofluorescence staining, the variation in porosity and stiffness notably influenced the early and late mineralization. Furthermore, the flexible LT scaffolds, with porosity induced by NIPS and salt leaching, stimulated Mo-DC to adopt a pro-inflammatory phenotype marked by a significant increase in the expression of IL1B and TNF genes, alongside decreased expression of anti-inflammatory markers, IL10 and TGF1B. Altogether, the results of the current study demonstrate the importance of tailoring porosity and stiffness of PCL scaffolds to direct their biological performance toward a more immune-mediated bone healing process.

Bio-mechanical analysis of porous Ti-6Al-4V scaffold: a comprehensive review on unit cell structures in orthopaedic application.

A scaffold is a three-dimensional porous structure that is used as a template to provide structural support for cell adhesion and the formation of new cells. Metallic cellular scaffolds are a good choice as a replacement for human bones in orthopaedic implants, which enhances the quality and longevity of human life. In contrast to conventional methods that produce irregular pore distributions, 3D printing, or additive manufacturing, is characterized by high precision and controlled manufacturing processes. AM processes can precisely control the scaffold's porosity, which makes it possible to produce patient specific implants and achieve regular pore distribution. This review paper explores the potential of Ti-6Al-4V scaffolds produced via the SLM method as a bone substitute. A state-of-the-art review on the effect of design parameters, material, and surface modification on biological and mechanical properties is presented. The desired features of the human tibia and femur bones are compared to bulk and porous Ti6Al4V scaffold. Furthermore, the properties of various porous scaffolds with varying unit cell structures and design parameters are compared to find out the designs that can mimic human bone properties. Porosity up to 65% and pore size of 600 μm was found to give optimum trade-off between mechanical and biological properties. Current manufacturing constraints, biocompatibility of Ti-6Al-4V material, influence of various factors on bio-mechanical properties, and complex interrelation between design parameters are discussed herein. Finally, the most appropriate combination of design parameters that offers a good trade-off between mechanical strength and cell ingrowth are summarized.

Microstructure, Mechanical Properties, and Corrosion Resistance of Porous Bio Mg Alloy Scaffolds Prepared via a Novel Method

Mg alloy scaffolds can be used as repair materials for human bone defects. Herein, porous Mg–1Zn–1Ca–0.5Mn alloy scaffolds with different pore sizes of the primitive model are prepared by combining 3D‐printed pure Ti templates and infiltration casting Mg alloy method. The results exhibit that the scaffold porosity ranges from 58.8 ± 1.4% to 63.3 ± 5.3% and the surface quality is good. Complete connectivity inside the scaffolds and the precise control of the pore structure are realized simultaneously. The mechanical properties of the scaffolds increase with increasing pore size; therefore, the LP scaffold displays the best mechanical performance with a yield strength of 9.88 ± 0.33 MPa. The simulation results are in good consistent with the experimental results. The reticular second phase provides a barrier to the Mg matrix during corrosion, which improves the corrosion resistance of the scaffolds as the increase of pore size. Therefore, the corrosion rate of the LP scaffolds is only 2.35 ± 1.28 mm year−1 after 200 h of immersion. Furthermore, MC‐3T3 cells adhere on the surface of Mg–1Zn–1Ca–0.5Mn alloy scaffolds, indicating that Mg–1Zn–1Ca–0.5Mn alloy scaffolds have excellent biocompatibility.

Galectin-3/Gelatin Electrospun Scaffolds Modulate Collagen Synthesis in Skin Healing but Do Not Improve Wound Closure Kinetics.

Chronic wounds remain trapped in a pro-inflammatory state, with strategies targeted at inducing re-epithelialization and the proliferative phase of healing desirable. As a member of the lectin family, galectin-3 is implicated in the regulation of macrophage phenotype and epithelial migration. We investigated if local delivery of galectin-3 enhanced skin healing in a full-thickness excisional C57BL/6 mouse model. An electrospun gelatin scaffold loaded with galectin-3 was developed and compared to topical delivery of galectin-3. Electrospun gelatin/galectin-3 scaffolds had an average fiber diameter of 200 nm, with 83% scaffold porosity approximately and an average pore diameter of 1.15 μm. The developed scaffolds supported dermal fibroblast adhesion, matrix deposition, and proliferation in vitro. In vivo treatment of 6 mm full-thickness excisional wounds with gelatin/galectin-3 scaffolds did not influence wound closure, re-epithelialization, or macrophage phenotypes, but increased collagen synthesis. In comparison, topical delivery of galectin-3 [6.7 µg/mL] significantly increased arginase-I cell density at day 7 versus untreated and gelatin/galectin-3 scaffolds (p < 0.05). A preliminary assessment of increasing the concentration of topical galectin-3 demonstrated that at day 7, galectin-3 [12.5 µg/mL] significantly increased both epithelial migration and collagen content in a concentration-dependent manner. In conclusion, local delivery of galectin 3 shows potential efficacy in modulating skin healing in a concentration-dependent manner.

Fabrication of novel 316L stainless steel scaffolds by combining freeze-casting and 3D-printed gyroid templating techniques

Porous metals have been widely investigated as bioimplants to repair cancellous bone defects. Nevertheless, how to endure extreme stress and strike a balance between load-bearing performance, elastic modulus, and permeability are important issues. Freeze-casting is a novel technique for manufacturing micro-scale open-cellular lamellar porous materials. However, the pore size is relatively small because of the inherent constraints of the ice template. On the other hand, the scaffold with gyroid pore structures has been proven to have higher permeability due to its larger and smoother channels. To combine the advantages of both porous structures, the present study aims to develop dual-scale 316L stainless steel (316L SS) porous structures by incorporating the 3D-printed gyroid templates into the freeze-casting to further improve the lightweight, specific strength, energy absorption, and permeability of the porous structures. The results showed that macro-scale gyroid channels were successfully built into the micro-scale open-cellular lamellar porous scaffolds. The porosity of dual-scale scaffolds was 70.1 %–74.4 %, which was higher than that of 53.1 %–66.5 % in the single-scale scaffolds. The elastic moduli of the single-scale scaffolds were higher than that of the dual-scale scaffolds; both were within the range of human cancellous bone, demonstrating their mechanical compatibility. Furthermore, the dual-scale scaffolds presented a prominent rise in permeability compared to the single-scale scaffolds. Notably, the permeability of the 3G series scaffolds was comparable to human cancellous bone. In summary, the hierarchical 316L SS scaffolds with controllable macro-scale gyroid channels exhibit great potential for biomedical applications.

Impact of internal phase volume on the physical, morphological and mechanical characteristics of emulsion templated scaffolds

Objectives: The high porosity of tissue engineering scaffolds is advantageous as they provide a high degree of infiltration of nutrients, enable cell penetration, and support vascularisation. However, the mechanical strength is also critical for providing structural support to the defect site throughout the regeneration process. In this study, we aimed to establish a relationship between internal phase volume and emulsion-templated scaffolds' physical, morphological and mechanical characteristics. Methods: In this work, tetra methacrylate functionalised polycaprolactone (4PCLMA) polymers were synthesised via ring-opening polymerisation followed by methacrylation. 4PCLMA-based emulsion templated matrices with 60%, 75% and 82% internal phase volumes were fabricated (P60, P75, and P82). These scaffolds' densities, porosities, average pore and window sizes, degree of interconnectivity values, and mechanical properties were investigated. Results: Increasing internal phase volume reduced the density of the foams by almost two-fold. No direct correlation was observed between average pore size and internal phase volume. Both the average window sizes and the degree of interconnectivity values increase with increasing internal phase volume. Compression modulus values are calculated as 0.46±0.04 MPa, 0.23±0.02 MPa and 0.14±0.01 MPa for P60, P75, and P82, respectively. Increasing internal phase volume from 60% to 82% caused a more than 2-fold reduction in the stiffness of the emulsion-templated matrices. Conclusions: Accordingly, by reporting on this experimental framework, we established a relationship between internal phase volume and the physical, morphological and mechanical characteristics of 4PCMA-based scaffolds to precisely engineer these characteristics for specific tissue engineering applications.

Optimizing silicon doping levels for enhanced osteogenic and angiogenic properties of 3D-printed biphasic calcium phosphate scaffolds: An in vitro screening and in vivo validation study

Biphasic calcium phosphate (BCP) ceramics are valued for their osteoconductive properties but have limited osteogenic and angiogenic activities, which restricts their clinical utility in bone defect repair. Silicon doping has emerged as an effective strategy to enhance these biological functions of BCP. However, the biological impact of BCP is influenced by the level of silicon doping, necessitating determination of the optimal concentration to maximize efficacy in bone repair. This study investigated the effects of silicon doping on both the physicochemical and biological properties of BCP, with a specific focus on osteogenic and angiogenic potentials. Results indicated that silicon doping exceeding 4 mol.% led to the formation of α-TCP, accelerating BCP degradation, enhancing silicon ion release, and promoting mineralization product formation. Simultaneously, silicon doping increased the porosity of BCP scaffolds, which typically reduces their compressive strength. Nevertheless, scaffolds doped with ≤4 mol.% silicon maintained compressive strengths exceeding 2 MPa. In vitro biological experiments indicated that higher levels of silicon doping (≥6 mol.%) partially inhibited the successful differentiation of stem cells and the vascularization of endothelial cells. Optimal conditions for promoting osteogenic differentiation and angiogenesis were identified between 2 and 4 mol.% silicon doping, with an optimal level of approximately 4 mol.%. Subsequent in vivo experiments confirmed that BCP scaffolds doped with 4 mol.% silicon effectively promoted vascularization and new bone formation, highlighting their potential for clinical bone defect repair.

(Invited) Organic Electrochemical Bioelectronic Devices Based on 3D Conductive Polymer Scaffolds

The integration of 3D tissue-engineered microporous scaffolds based on conductive polymers (CPs) into bioelectronic devices have led to the possibility of dynamic monitoring of biological phenomena through electrical measurements. The 3D structure and morphology of the porous scaffolds mimics the topographical features of human physiology, while the electrically conductive nature of the polymers allows for electrical measurements for label-free monitoring and live-sensing of cells. 3D scaffolds based on the polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) prepared by the freeze drying process have been the focus of many studies and well integrated into bioelectronic devices such as electrodes[1] and organic electrochemical transistors[2].The influence of the different protocols and freezing rates on the pore size and structure was examined by scanning electron microscopy and micro computed tomography. Pores of circular and elongated ellipses were observed by SEM and a pore size distribution (the longest dimension of the ellipsoid) between 80 µm and 220 µm was measured. It was observed that a higher cooling rate generated larger pores with more elongated pore morphology as well as a wider pore size distribution. The pre-cooling treatment with 0.5°C/min cooling rate was most useful in generating scaffolds with a more homogenous pore structure and a pore size of approximately 100 µm.The different scaffolds were incorporated into electronic devices such as transmembrane electrodes to characterize the electrical properties and evaluate the reproducibility of the scaffolds prior to cell culture. No significant change in the electrochemical impedance spectra was observed despite the large difference in porosity of the different scaffolds. In addition, the different scaffolds were used to host and monitor biological cells like fibroblasts and endothelial cells. Cell growth and proliferation in the different scaffolds was also monitored by immunofluorescence microscopy. It was observed that a pre-cooling protocol and a freezing rate of 0.5°C/min helps to fabricate scaffolds with an optimized, uniform and homogenous pore morphology. This design protocol is highly beneficial in reducing the random artifacts of the nucleation process and generating scaffolds highly conducive to cell growth and survival and to create a versatile bioelectronic platform for studying in-vitro cell models.A new, sophisticated bioelectronic device was constructed with the scaffolds with the operation mode of an electrode and an organic electrochemical transistor. The device operation models an electrochemical cell with two or three electrodes and is used to build different in vitro organ models. In this presentation, I show the use of electrochemical techniques to monitor biological phenomenon based on 3D conducting polymer scaffolds.

Decellularized Extracellular Matrix Scaffolds for Soft Tissue Augmentation: From Host-Scaffold Interactions to Bottlenecks in Clinical Translation.

Along with a paradigm shift in looking at soft tissue fillers from space-filling to bioactive materials, decellularized extracellular matrix (DEM) fillers have gained more attention considering their superior bioactivity. However, the complex mechanisms that govern the interaction between host tissues and DEMs have been partially understood. This review first covers the mechanisms that determine immunogenicity, angiogenesis and vasculogenesis, and recellularization and remodeling after DEM implantation into host tissue, with a particular focus on related findings from filler materials. Accordingly, the review delves into the dual role of macrophages and their M1/M2 polarization paradigm to form both constructive and destructive immune responses to DEM implants. Moreover, the contribution of macrophages in angiogenesis has been elucidated, which includes but is not limited to the secretion of angiogenic growth factors and extracellular matrix (ECM) remodeling. The findings challenge the traditional view of immune cells as solely destructive entities in biomaterials and indicate their multifaceted roles in tissue regeneration. Furthermore, the review discusses how the compositional factors of DEMs, such as the presence of growth factors and matrikines, can influence angiogenesis, cell fate, and differentiation during the recellularization process. It is also shown that the biomechanical properties of DEMs, including tissue stiffness, modulate cell responses through mechanotransduction pathways, and the structural properties of DEMs, such as scaffold porosity, impact cell-cell and cell-ECM interactions. Finally, we pointed out the current clinical applications, the bottlenecks in the clinical translation of DEM biomaterials into soft tissue fillers, as well as the naïve research areas of the field.

Bioactive polymer composite scaffolds fabricated from 3D printed negative molds enable bone formation and vascularization

Scaffolds for bone defect treatment should ideally support vascularization and promote bone formation, to facilitate the translation into biomedical device applications. This study presents a novel approach utilizing 3D-printed water-dissolvable polyvinyl alcohol (PVA) sacrificial molds to engineer polymerized High Internal Phase Emulsion (polyHIPE) scaffolds with microchannels and distinct multiscale porosity. Two sacrificial mold variants (250 µm and 500 µm) were generated using fused deposition modeling, filled with HIPE, and subsequently dissolved to create polyHIPE scaffolds containing microchannels. In vitro assessments demonstrated significant enhancement in cell infiltration, proliferation, and osteogenic differentiation, underscoring the favorable impact of microchannels on cell behavior. High loading efficiency and controlled release of the osteogenic factor BMP-2 were achieved, with microchannels facilitating release of the growth factor. Evaluation in a mouse critical-size calvarial defect model revealed enhanced vascularization and bone formation in microchanneled scaffolds containing BMP-2. This study not only introduces an accessible method for creating multiscale porosity in polyHIPE scaffolds but also emphasizes its capability to enhance cellular infiltration, controlled growth factor release, and in vivo performance. The findings suggest promising applications in bone tissue engineering and regenerative medicine, and are expected to facilitate the translation of this type of biomaterial scaffold. Statement of significanceThis study holds significance in the realm of biomaterial scaffold design for bone tissue engineering and regeneration. We demonstrate a novel method to introduce controlled multiscale porosity and microchannels into polyHIPE scaffolds, by utilizing 3D-printed water-dissolvable PVA molds. The strategy offers new possibilities for improving cellular infiltration, achieving controlled release of growth factors, and enhancing vascularization and bone formation outcomes. This microchannel approach not only marks a substantial stride in scaffold design but also demonstrates its tangible impact on enhancing osteogenic cell differentiation and fostering robust bone formation in vivo. The findings emphasize the potential of this methodology for bone regeneration applications, showcasing an interesting advancement in the quest for effective and innovative biomaterial scaffolds to regenerate bone defects.

Investigating mechanical properties of 3D printed porous titanium scaffolds for bone tissue engineering

Objective. Three-dimensional (3D) printed porous titanium scaffolds serve as a bone tissue engineering technology that offers a promising solution for addressing bone defects. The scaffold’s pore structure offers structural support and facilitates the proliferation of bone cells. Therefore, investigating the aperture and pore shape is of crucial for the development of 3D printed porous titanium scaffolds. Methods. Ti6Al4V scaffolds with the specified structure were fabricated using selective laser melting (SLM) technology. The scaffolds comprised fifteen cylindrical models measuring 20 mm in diameter and 20 mm in height. These models featured five scaffold shapes: imitation diamond-60°, imitation diamond-90°, imitation diamond-120°, regular tetrahedron and regular hexahedron. Each of these structural shapes was characterized by three different aperture sizes (400 μm, 600 μm and 800 μm). The porosity and mechanical properties of Ti6Al4V scaffolds were examined. Results. The measured porosity of Ti6Al4V scaffolds varied between 56.50% and 95.28%. The porosity increased with the size of the aperture. The mechanical properties tests revealed that, for identical apertures, the compressive strength and torsional strength were influenced by the configuration of the unit structure. Furthermore, the positive and lateral compressive strength as well as torsional strength of various unit structures exhibited distinct advantages and disadvantages. Within a uniform unit structure shape, the compressive strength and torsional strength were found to be correlated with the size of apertures, indicating that larger apertures result in decreased compressive and torsional strength. Conclusion. The configuration of the aperture and the shape of the pore were identified as significant factors that influenced the compressive strength. The compressive strength of Ti6Al4V scaffolds with various unit structure shapes exhibited both advantages and disadvantages when subjected to positive, lateral, and torsional forces. The enlarged aperture augmented the scaffold’s porosity while diminishing its compressive and torsional strength.

Decellularization Agents on Porosity and Pore Size in Bovine Pericardium Scaffolds for Pediatric Heart Surgery

Background: Tissue engineering in pediatric and congenital heart surgery relies on developing biomaterials with extracellular matrix (ECM)-like properties. The acellular bovine pericardium membrane (BPM) is a promising scaffold due to its strength, low infection rates, and cost-effectiveness. Decellularization is essential to optimize BPM's properties for tissue regeneration. This study investigates the effects of different decellularization methods on BPM's porosity and pore size. Methods: A true experimental design was used to evaluate BPM scaffolds treated with sodium dodecyl sulfate (SDS), hydrogen peroxide (H2O2), or ASB-16, compared to a control group. Porosity and pore size were measured using image analysis software after 4 weeks of incubation. Statistical analysis was performed using the Kruskal-Wallis test, Mann-Whitney U test, and one-way ANOVA. Results: ASB-16 decellularization significantly increased BPM porosity (50.14 ± 3.71%) compared to the control (3.06 ± 0.99%) and other treatments (SDS: 6.23 ± 2.94%, H2O2: 4.47 ± 1.34%). Pore size was also significantly larger in the ASB-16 group (26.9 ± 5.93 µm) compared to SDS (8.99 ± 2.77 µm), H2O2 (3.13 ± 1.00 µm), and control (2.00 ± 0.29 µm). Conclusion: ASB-16 decellularization effectively enhances BPM porosity and pore size, making it a promising method for optimizing scaffolds in tissue engineering applications. Further research should focus on its impact on cell proliferation and tissue regeneration.

Evaluating mechanical and biological responses of bipolymeric drug-chitosan-hydroxyapatite scaffold for wounds: Fabrication, characterization, and finite element analysis

This study aims to explore the potential of a scaffold composed of drug-chitosan-hydroxyapatite (HA) in improving tissue treatment. The focus of the investigation lies in analyzing the physical and biological properties of the scaffold and evaluating its mechanical characteristics through finite-element analysis. To synthesize microcapsules containing dextran-diclofenac sodium, the electrospraying method was employed. The drug-chitosan-HA scaffold with varying volume fractions (VF) of the synthesized microcapsules (10, 15, and 20) was fabricated using the freeze-drying technique. Microscopic and scanning electron microscopy (SEM) images were utilized to evaluate the morphology, shape, and size of the microcapsules, as well as the porosity of the scaffolds for wound healing purposes. The mechanical properties of the synthesized microcapsules were determined via a nanoindentation test, while the mechanical behavior of the fabricated scaffolds was assessed through compression testing. Additionally, a multiscale finite-element model was developed to predict the mechanical properties of tissue scaffolds containing pharmaceutical microcapsules. The findings indicate that the incorporation of drug-chitosan-hydroxyapatite into the tissue significantly enhances both mechanical and biological responses. The mechanical evaluations demonstrate that the drug-chitosan-hydroxyapatite tissue exhibits excellent resistance to pressure, making it a suitable protective covering for skin wounds. Moreover, biological evaluations reveal that an increase in scaffold porosity leads to higher swelling behavior. The scaffold containing 20 % pharmaceutical microcapsules demonstrated the greatest swelling and desirable antibacterial properties, thereby indicating its potential as an effective wound dressing. Furthermore, a multiscale finite-element model was developed to predict the mechanical properties of tissue containing pharmaceutical microcapsules. The results indicated that the average size of the microcapsules was in the range of 170 to 180 µm, and the porosity of the prepared tissue was between 52 % and 61 %. The experimental compressive properties revealed that an increase in the volume fraction of the embedded microcapsules led to an increase in the maximum compressive stress and compressive modulus of the scaffolds by up to 54.95 % and 53.18 %, respectively, for the scaffold containing 20 % VF of pharmaceutical microcapsules compared to the specimen containing 10 % VF. In conclusion, the developed scaffold has the potential to serve as an effective wound dressing, with the ability to provide structural support, facilitate controlled drug release, and promote wound healing.

Degradable biporous polymeric networks based on 2-methylene-1,3-dioxepane: Towards hierarchically structured materials meant for biomedical applications

For the first time, the preparation of doubly porous “poly(ε-caprolactone)-like” networks through free-radical ring-opening copolymerization of 2-methylene-1,3-dioxepane with divinyl adipate was achieved via a double porogen templating approach. This versatile strategy allowed for the formation of macropores of around 150 μm generated by removal of sieved and sintered NaCl particles in water, while smaller pores in the 1–10 μm range were created by phase separation during the copolymerization process through a syneresis mechanism in the presence of a porogenic solvent. The chemical nature of the as-obtained scaffolds was evidenced by Raman spectroscopy. The two distinct porosity levels could be examined by scanning electron microscopy and mercury intrusion porosimetry. The nature of the porogenic solvent as well as its volume proportion and the amount of crosslinking agent in the polymerization feed allowed for finely tuning the porous features of the micropores. The crucial role of the double porosity of such biporous scaffolds on their water uptake and mechanical properties under compression was assessed by comparing them with their monoporous analogues, while their degradability was investigated in different alkaline aqueous media. The double porosity enabled a synergistic effect regarding the water uptake of the resulting scaffolds when compared to their monoporous counterparts. Doubly porous polymeric materials with appropriate mechanical properties were obtained, possessing high compressibility and shape memory behavior upon consecutive compression cycles. Finally, these materials display degradation rates that could be controlled depending on medium pH.

Transformation of Natural Resin Resina Draconis to 3D Functionalized Fibrous Scaffolds for Efficient Chronic Wound Healing.

Chronic wound healing is a major challenge in clinical practice. Secondary dressing damage and antibiotic resistance are the main obstacles for traditional wound dressings. Resina draconis (RD), a natural resin traditionally used in powder form for wound care, is now considered unsuitable due to the lack of gas permeability and moist environment required for wound healing. Here, RD is incorporated in situ by constructing a 3D coiled fibrous scaffold with polycaprolactone/polyethylene oxide. Due to the high porosity of 3D scaffold, the RD-3D dressings have a favorable swelling capacity, providing permeability and moisture for wound repair. Meanwhile, the transformation of RD powder into 3D dressings fully demonstrates capabilities of RD in rapid hemostasis, bactericidal, and inflammation-regulating activities. In vivo evaluations using pressure ulcer and infected wound models confirm the high efficacy of RD-3D dressing in early wound healing, particularly beneficial in the infected wound model compared to recombinant bovine FGF-basic. Further biological analysis shows that resveratrol, loureirin A, and loureirin B, as potentially bioactive components of RD, individually contribute to different aspects of wound healing. Collectively, RD-3D integrated dressings represent a simple, cost-effective, and safe approach to wound healing, providing an alternative therapy for translating medical dressings from bench to bedside.

Enhancing polymeric bone scaffolds mechanical characteristics using supercritical CO2 foaming and reinforcing agents

BackgroundAs an alternative to conventional medicine, scaffolds have emerged to mimic and/or replace damaged tissue. 3D porous matrix scaffolds made of biodegradable and biocompatible polymers, including PLGA, have proven to be of particular interest for use as bone substitutes in Tissue Engineering. MethodsThe study used high-pressure CO2 foaming to produce PLGA-based foams. Previously, melt-extrusion was used to introduce reinforcement agents, Mg(OH)2, Hydroxyapatite (HAp) and Mg, to achieve foams with improved properties. Foam morphology was analysed using SEM, EDS, and 3D scanner techniques, and foam strength was measured using compression tests. A statistical analysis was carried out to study the effect of pressure and temperature on foams pore size and hardness. Significant findingsThe foams produced were rigid, non-sticky and time-stable, and showed high porosity. The pressure was found to be the only significant variable to tune both porosity and cell densities of scaffolds. Setting a pore size at 500 μm, compressive stresses of 1.85 MPa, 3.81 MPa were achieved for Mg(OH)2 and HAp, respectively. Those results were comparable to literature´s trabecular bovine bone compression resistance of 4.2 MPa. This finding indicated the possibility of getting, at the same time, convenient results for porosity and mechanical resistance for their use as bone replacement agents. Finally, a 20 % w/w ratio of reinforcing agent was found to produce the best pore size-stress ratio.

Equisetum arvense and nano zinc oxide‐infused polycaprolactone scaffolds: A multifaceted approach for antibacterial, antioxidant, and hemocompatible wound dressing

AbstractAn appropriate skin tissue‐engineered scaffold can act promptly to combat microbial infection and preserve the wound throughout all phases of healing. To achieve sufficient healing, scaffolds should also promote cell proliferation and regeneration. Therefore, it has become essential to develop skin tissue engineering scaffolds that mimic the extracellular matrices of the skin, provide a high porosity scaffold structure, and act as an antimicrobial protection during wound healing. In this study, the polycaprolactone (PCL) electrospun scaffold was modified with optimal amounts of zinc oxide nanoparticles (ZnO) and Equisetum arvense (EA) herbal extract for potential application as antibacterial and wound healing scaffolds. Full characterization was carried out for fabricated scaffolds before in‐vitro assessments. FTIR spectroscopy and SEM images verified the successful substitution of nanofibers with EA and ZnO. These substitutions increased the hydrophilicity compared to the PCL scaffold. According to the results, the PCL/ZnO/EA fabricated scaffold was hemocompatible and non‐cytotoxic, in addition to allowing proper cell attachment. Effective antibacterial efficiency against Gram‐positive and Gram‐negative bacteria was also observed in this sample. Finally, the in vitro wound healing assay indicated that the addition of ZnO and EA improves the wound healing capacity of the scaffolds. The results indicate the potential of the developed scaffolds to prevent wound contamination and the complications of chronic infection.Highlights Optimal concentrations of zinc oxide nanoparticles (ZnO) and Equisetum arvense (EA) were incorporated into electrospun polycaprolactone (PCL) nanofibers for potential wound dressing applications. The fabricated nanofibrous wound dressings offer a multitude of structural features in biomaterials. PCL fibers enable the controlled release of both ZnO and EA. The fabricated scaffolds exhibit favorable antibacterial, and antioxidant properties while maintaining biocompatibility and hemocompatibility.

Comparative Analysis of Electrospun Silk Fibroin/Chitosan Sandwich-Structured Scaffolds for Osteo Regeneration: Evaluating Mechanical Properties, Biological Performance, and Drug Release.

An intensive idea of bone tissue engineering is to design regenerative nanofibrous scaffolds that could afford a natural extracellular matrix (ECM) microenvironment with the ability to induce cell proliferation, biodegradation, sustained drug release, and bioactivity. Even the mechanical properties and orientation of the nanofibers may enhance the performance of the scaffolds. To address this issue, we designed novel sandwich-like hybrid silk fibroin (SF)/silica/poly(vinyl alcohol) (PVA) nanofibers scaffolds. The developed scaffold was further characterized using scanning electron microscopy (SEM), elemental mapping, X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and water/blood contact angle measurements. Owing to the interfacial interaction between the layers of organic (chitosan/silk fibroin) and inorganic (silica) in the nanofibrous scaffold, a biocompatibility study has been made on an osteoblast-like (MG63) cell line, which has significant statistical differences; hemocompatibility and the mechanical profile were evaluated in detail to understand the suitability as a biomaterial. To endow the scaffold biodegradation rate, antibacterial activity, porosity profile, and cephalexin monohydrate (CEM), a drug-loading/drug release study was also performed for all of the nanofibers. This strategy explored superior mechanical strength with higher biomineralization on SF/silica/PVA nanofibers. Eventually, the proposed article compared the observation of monolayered scaffolds with designed sandwich-structured scaffolds for the enhancement of bone regeneration.

In vivo characterization of a luffa-based composite scaffold for subcutaneous implantation in rats

Recent advancements in tissue engineering have witnessed luffa-derived scaffolds, exhibiting their exceptional potential in cellular proliferation, biocompatibility, appropriate interconnectivity, and biomechanical strength. In vivo studies involved implanting fabricated scaffolds subcutaneously in Wistar rats to evaluate their impact on the heart, liver, and kidneys. This approach provided a safe and minimally invasive means to evaluate scaffold compatibility with surrounding tissues. Male Wistar rats were categorized into four distinct groups, Group A, B, C, and D are referred to as 3% LC implanted scaffolds, 5% LC implanted scaffolds, control (without luffa scaffolds), and Sham (without any scaffold implantation), respectively. Histological analysis in all the groups indicated that the animal models did not exhibit any signs of inflammation or toxicity, suggesting favorable tissue response to the implanted scaffolds. Initial observations revealed elevated levels of enzymes and biomarkers in the experimental groups after a 24 h interval, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, creatine kinase-MB (CK-MB), and serum creatinine. However, these parameters normalized 3 weeks post-implantation, with no significant increase compared to the control groups, suggesting that the implanted luffa-based scaffolds did not induce adverse effects on the heart, liver, and kidneys. Furthermore, the scaffold’s significant pore size and porosity enable it to release drugs, including antibacterial medications. This study demonstrates promising results, indicating excellent scaffold porosity, sustained drug release, affirming the in vivo biocompatibility, absence of inflammatory responses, and overall tissue compatibility highlighting the immense potential of these luffa-based scaffolds in various tissue engineering and regenerative medicine applications.