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- Production and characterization of chitosan/gelatin/β-TCP scaffolds for improved bone tissue regenerationPublication . Serra, Inês Raquel Tavares; Fradique, Ricardo Gil; Vallejo, Mariana C. da S.; Correia, Tiago R.; Miguel, Sónia P.; Correia, Ilídio Joaquim SobreiraRecently, bone tissue engineering emerged as a viable therapeutic alternative, comprising bone implants and new personalized scaffolds to be used in bone replacement and regeneration. In this study, biocompatible scaffolds were produced by freeze-drying, using different formulations (chitosan, chitosan/gelatin, chitosan/β-TCP and chitosan/gelatin/β-TCP) to be used as temporary templates during bone tissue regeneration. Sample characterization was performed through attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction and energy dispersive spectroscopy analysis. Mechanical characterization and porosity analysis were performed through uniaxial compression test and liquid displacement method, respectively. In vitro studies were also done to evaluate the biomineralization activity and the cytotoxic profile of the scaffolds. Scanning electron and confocal microscopy analysis were used to study cell adhesion and proliferation at the scaffold surface and within their structure. Moreover, the antibacterial activity of the scaffolds was also evaluated through the agar diffusion method. Overall, the results obtained revealed that the produced scaffolds are bioactive and biocompatible, allow cell internalization and show antimicrobial activity against Staphylococcus aureus. Such, make these 3D structures as potential candidates for being used on the bone tissue regeneration, since they promote cell adhesion and proliferation and also prevent biofilm development at their surfaces, which is usually the main cause of implant failure.
- New therapeutic approaches for bone regenerationPublication . Fradique, Ricardo Gil; Correia, Ilídio Joaquim SobreiraThe aging of the worldwide population has led to an increase in bone tissue diseases. Wether due to trauma or pathology, if the bone tissue is compromised it constitutes a serious threat to the well being of the individual. Current solutions for bone defects involve the use of bone grafts, particularly autografts. However, these present serious limitations for their use, such as limited availability, or the possibility of chronic pain, and may not allow the patient’s full recovery. In this context, Tissue Engineering emerged as a potential solution, since it uses biomaterials and bioactive molecules to develop devices that allow the repair or regeneration of bone tissue. One of the most researched approaches are scaffolds, that are three dimensional matrices, aimed to act as temporary templates for cell adhesion and proliferation, offering mechanical support while the bone tissue regenerates. A particularly promising approach uses rapid prototyping technology to produce 3D scaffolds with highly controlled structure, either from CAD models, or routine exam medical data. The present study describes the physicochemical, mechanical and biological characterization of 3D β-TCP/Alginate scaffold, produced by rapid prototyping. Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, Contact Angle, and Scanning Electron Microscopy were used to characterize the porosity, surface hydrophilic character and chemical composition of the produced scaffolds. In addition, the mechanical stability (Compressive Strength and Young’s Modulus) was also evaluated. The biocompatibility of the scaffolds was evaluated by in vitro MTS assays, using human osteoblasts as model cells. The results obtained showed that the produced scaffolds present excellent biological and physicochemical properties, allowing for the adhesion and proliferation of human osteoblasts. Moreover, the produced scaffolds presented remarkable mechanical strength, matching or surpassing the properties of native trabecular bone, which is fundamental for their potential use in the regeneration of bone tissue.
- Production of new 3D scaffolds for bone tissue regeneration by rapid prototypingPublication . Fradique, Ricardo Gil; Correia, Tiago R.; Miguel, Sónia P.; Sá, Kevin; Figueira, Daniela Sofia Rodrigues; Mendonça, António; Correia, Ilídio Joaquim SobreiraThe incidence of bone disorders, whether due to trauma or pathology, has been trending upward with the aging of the worldwide population. The currently available treatments for bone injuries are rather limited, involving mainly bone grafts and implants. A particularly promising approach for bone regeneration uses rapid prototyping (RP) technologies to produce 3D scaffolds with highly controlled structure and orientation, based on computer-aided design models or medical data. Herein, tricalcium phosphate (TCP)/alginate scaffolds were produced using RP and subsequently their physicochemical, mechanical and biological properties were characterized. The results showed that 60/40 of TCP and alginate formulation was able to match the compression and present a similar Young modulus to that of trabecular bone while presenting an adequate biocompatibility. Moreover, the biomineralization ability, roughness and macro and microporosity of scaffolds allowed cell anchoring and proliferation at their surface, as well as cell migration to its interior, processes that are fundamental for osteointegration and bone regeneration.
- 3D Printed scaffolds with bactericidal activity aimed for bone tissue regenerationPublication . Correia, Tiago R.; Figueira, Daniela Sofia Rodrigues; Sá, Kevin; Miguel, Sónia P.; Fradique, Ricardo Gil; Mendonça, António; Correia, I.J.Nowadays, the incidence of bone disorders has steeply ascended and it is expected to double in the next decade, especially due to the ageing of the worldwide population. Bone defects and fractures lead to reduced patient’s quality of life. Autografts, allografts and xenografts have been used to overcome different types of bone injuries, although limited availability, immune rejection or implant failure demand the development of new bone replacements. Moreover, the bacterial colonization of bone substitutes is the main cause of implant rejection. To vanquish these drawbacks, researchers from tissue engineering area are currently using computer-aided design models or medical data to produce 3D scaffolds by Rapid Prototyping (RP). Herein, Tricalcium phosphate (TCP)/Sodium Alginate (SA) scaffolds were produced using RP and subsequently functionalized with silver nanoparticles (AgNPs) through two different incorporation methods. The obtained results revealed that the composite scaffolds produced by direct incorporation of AgNPs are the most suitable for being used in bone tissue regeneration since they present appropriate mechanical properties, biocompatibility and bactericidal activity.
- Bioactive polymeric–ceramic hybrid 3D scaffold for application in bone tissue regenerationPublication . Torres, Ana; Gaspar, V. M.; Serra, Inês Raquel Tavares; Carlos, Gabriela Soares Diogo; Fradique, Ricardo Gil; Silva, Abílio P.; Correia, I.J.The regeneration of large bone defects remains a challenging scenario from a therapeutic point of view. In fact, the currently available bone substitutes are often limited by poor tissue integration and severe host inflammatory responses, which eventually lead to surgical removal. In an attempt to address these issues, herein we evaluated the importance of alginate incorporation in the production of improved and tunable β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) three-dimensional (3D) porous scaffolds to be used as temporary templates for bone regeneration. Different bioceramic combinations were tested in order to investigate optimal scaffold architectures. Additionally, 3D β-TCP/HA vacuum-coated with alginate, presented improved compressive strength, fracture toughness and Young's modulus, to values similar to those of native bone. The hybrid 3D polymeric–bioceramic scaffolds also supported osteoblast adhesion, maturation and proliferation, as demonstrated by fluorescence microscopy. To the best of our knowledge this is the first time that a 3D scaffold produced with this combination of biomaterials is described. Altogether, our results emphasize that this hybrid scaffold presents promising characteristics for its future application in bone regeneration.
- Manufacture of β-TCP/alginate scaffolds through a Fab@home model for application in bone tissue engineeringPublication . Carlos, Gabriela Soares Diogo; Gaspar, Vítor Manuel Abreu; Serra, Inês Raquel Tavares; Fradique, Ricardo Gil; Correia, Ilídio Joaquim SobreiraThe growing need to treat bone-related diseases in an elderly population compels the development of novel bone substitutes to improve patient quality of life. In this context, the advent of affordable and effective rapid prototyping equipment, such as the Fab@home plotter, has contributed to the development of novel scaffolds for bone tissue engineering. In this study, we report for the first time the use of a Fab@home plotter for the production of 3D scaffolds composed by beta-tricalcium phosphate (β-TCP)/alginate hybrid materials. β-TCP/alginate mixtures were used in a proportion of 50/50% (w/w), 30/70% (w/w) and 20/80% (w/w). The printing parameters were optimized to a nozzle diameter of 20 Gauge for the production of rigid scaffolds with pre-defined architectures. We observed that, despite using similar printing parameters, both the precision and resolution of the scaffolds were significantly affected by the blend's viscosity. In particular, we demonstrate that the higher viscosity of 50/50 scaffolds (150.0 ± 3.91 mPa s) provides a higher precision in the extrusion process. The physicochemical and biological characterization of the samples demonstrated that the 50/50 scaffolds possessed a resistance to compression comparable to that of native trabecular bone. Moreover, this particular formulation also exhibited a Young's modulus that was higher than that of trabecular bone. Scanning electron microscopy and fluorescence microscopy analysis revealed that osteoblasts were able to adhere, proliferate and also penetrate into the scaffold's architecture. Altogether, our findings suggest that the Fab@home printer can be employed in the manufacture of reproducible scaffolds, using a formulation 50/50 alginate-β-TCP that has suitable properties to be applied as bone substitutes in the future.