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- Novas abordagens terapêuticas para regeneração ósseaPublication . Sá, Kevin Domingos de; Correia, Ilídio Joaquim Sobreira; Correia, Tiago Ruivo; Miguel, Sónia Alexandra PereiraBone limited capacity to fully repair large defects demands the development of new implants that are able to improve the healing process. In this context, new approaches for promoting bone regeneration process and also to avoid side effects associated with the therapeutics in use, are currently being studied. Herein 3D tricalcium phosphate/alginic acid scaffolds were produced using a Fab@Home and then coated with an electrospun mesh (composed by polycaprolactone and gelatin) loaded with two different antibacterial agents (silver nanoparticles and salicylic acid). The obtained results show that the produced scaffolds presented mechanical properties, swelling, macro/microporosity, biodegradation and biomineralization capacity, that are compatible with their application for bone tissue engineering purposes. Moreover, the presence of a nanofibrous mesh at the surface of produced 3D constructs enhanced cellular adhesion/proliferation and also avoided biofilm formation at scaffolds’ surface, for at least 5 days. Such results emphasize that the 3D hybrid scaffolds produced herein have the required properties for being used in the proposed biomedical application.
- Coaxial electrospun PCL/Gelatin-MA fibers as scaffolds for vascular tissue engineeringPublication . Coimbra, Patrícia; Santos, Patrícia; Alves, Patrícia; Miguel, Sónia P.; Carvalho, Marco António Paulo de; Sá, Kevin; Correia, Ilídio Joaquim Sobreira; Ferreira, PaulaCoaxial electrospinning is a technique that allows the production of nanofibers with a core–shell structure. Such fibers present several advantages as materials for the preparation of scaffolds, namely due to the possibility of combining a core with the desired mechanical properties with a shell prepared from biocompatible materials that will establish proper interactions with the host. Herein, core-shell fibrous meshes, composed of a polycaprolactone (PCL) core and a functionalized gelatin shell, were prepared by coaxial electrospinning and then photocrosslinked under UV light aiming to be used in vascular tissue regeneration. The suitability of the meshes for the pretended biomedical application was evaluated by assessing their chemical/physical properties as well as their haemo and biocompatibility in vitro. The obtained results revealed that meshes’ shell prepared with a higher content of gelatin showed fibers with diameters presenting a unimodal distribution and a mean value of 600 nm. Moreover, those fibers with higher content of gelatin also displayed lower water contact angles, and therefore higher hydrophilicities. Such features are crucial for the good biologic performance displayed by these meshes, when in contact with blood and with Normal Human Dermal Fibroblasts cells.
- Photocrosslinkable electrospun fiber meshes for tissue engineering applicationsPublication . Ferreira, Paula; Santos, Patrícia; Alves, P.; Carvalho, Marco António Paulo de; Sá, Kevin; Miguel, Sónia P.; Correia, Ilídio Joaquim Sobreira; Coimbra, Patrícia Manuela AlmeidaElectrospun polymeric meshes are known to exhibit promising properties for the regeneration of several soft tissues. Herein, electrospun polymeric meshes were prepared from blends of polycaprolactone and functionalized gelatin. The meshes were then photocrosslinked under UV light using Irgacure® 2959 as the photoinitiator, aiming to improve membranes’ stability in biological fluids. Moreover, meshes suitability to be used as vascular grafts was evaluated by characterizing their chemical/physical properties as well as their haemo and biocompatibility in vitro. The obtained results show that the blended polymeric meshes are biodegradable and those with a higher content of gelatin display a lower water contact angle. Blood compatibility studies showed that the photocrosslinked membranes are haemocompatible, i.e. they display low values of thrombogenicity and do not trigger any haemolytic effect. Also, Normal Human Dermal Fibroblasts cells were incubated in the presence of the produced membranes and they were able to adhere and proliferate, thus revealing the biocompatibility of the photocrosslinked meshes.
- 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.
- 3D scaffolds coated with nanofibers displaying bactericidal activity for bone tissue applicationsPublication . Sá, Kevin; Figueira, Daniela Sofia Rodrigues; Miguel, Sónia P.; Correia, Tiago R.; Silva, Abílio Manuel Pereira da; Correia, I.J.Bone-limited capacity to fully repair large defects requires the development of new implants. In this context, new approaches have been used to promote bone regeneration and also to avoid the side effects associated with the therapeutics currently used in the clinic. Herein, 3D tricalcium phosphate/alginic acid scaffolds were produced and then coated with an electrospun mesh loaded with two different antibacterial agents, silver nanoparticles, and salicylic acid. The obtained results showed that the produced scaffolds have suitable mechanical properties, swelling, biodegradation, biomineralization activity, enhanced cellular adhesion/proliferation and bactericidal activity, and features essential for bone regeneration.
- Preparation of Gel Forming Polymer-Based Sprays for First Aid Care of Skin InjuriesPublication . Alves, Patrícia; Luzio, Diana; Sá, Kevin; Correia, I.J.; Ferreira, PaulaCurrently, there are several types of materials for the treatment of wounds, burns, and other topical injuries available on the market. The most used are gauzes and compresses due to their fluid absorption capacity; however, these materials adhere to the surface of the lesions, which can lead to further bleeding and tissue damage upon removal. In the present study, the development of a polymer-based gel that can be applied as a spray provides a new vision in injury protection, respecting the requirements of safety, ease, and quickness of both applicability and removal. The following polymeric sprays were developed to further obtain gels based on different polymers: hydroxypropyl cellulose (HPC), polyvinyl pyrrolidone (PVP) and hydroxypropyl methylcellulose (HPMC) using polyethylene glycol (PEG) as a plasticizer. The developed sprays revealed suitable properties for use in topical injuries. A protective film was obtained when sprayed on a surface through a casting mechanism. The obtained films adhered to the surface of biological tissue (pig muscle), turning into a gel when the exudate was absorbed, and proved to be washable with saline solution and contribute to the clotting process. Moreover, biocompatibility results showed that all materials were biocompatible, as cell viability was over 90% for all the materials.
- Production and characterization of polycaprolactone- hyaluronic acid/chitosan-zein electrospun bilayer nanofibrous membrane for tissue regenerationPublication . Figueira, Daniela Sofia Rodrigues; Miguel, Sónia P.; Sá, Kevin; Correia, Ilídio Joaquim SobreiraA bilayered electrospun membrane was produced in this study, using the electrospinning technique, to be applied as a skin substitute. The upper layer of the membrane was comprised by hyaluronic acid and polycaprolactone in order to provide mechanical support and also to act as a physical barrier against external threats. Chitosan and zein were used to produce the bottom layer that was loaded with salicylic acid, in order to confer anti-inflammatory and antimicrobial activity to this layer. The physicochemical properties of the membranes were determined and the obtained results showed that the produced electrospun membrane display an ideal porosity, appropriate mechanical properties, controlled water loss and a suitable salicylic acid release profile. In addition, membranes did not exhibit any toxic effects for human fibroblast cells, since cells were able to adhere, spread and proliferate. Furthermore, no biofilm formation was noticed on membranes’ surface along the experiments. In conclusion, the gathered data reveal that this electrospun membrane has suitable properties to be used as a wound dressing.
- Photocrosslinkable Nanofibrous Asymmetric Membrane Designed for Wound DressingPublication . Alves, P.; Santos, Marta; Mendes, Sabrina; Miguel, Sónia; Sá, Kevin; Cabral, C.S.D.; Correia, I.J.; Ferreira, PaulaRecently, the biomedical scientists who are working in the skin regeneration area have proposed asymmetric membranes as ideal wound dressings, since they are able to reproduce both layers of skin and improve the healing process as well as make it less painful. Herein, an electrospinning technique was used to produce new asymmetric membranes. The protective layer was composed of a blending solution between polycaprolactone and polylactic acid, whereas the underlying layer was comprised of methacrylated gelatin and chitosan. The chemical/physical properties, the in vitro hemo- and biocompatibility of the nanofibrous membranes were evaluated. The results obtained reveal that the produced membranes exhibited a wettability able to provide a moist environment at wound site. Moreover, the membranes' hemocompatibility and fibroblast cell adhesion, spreading and proliferation at the surface of the membranes were also noticed in the in vitro assays. Such results highlight the suitability of these asymmetric membranes for wound dressing applications.