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- Hyaluronic acid - Based wound dressings: A reviewPublication . Graça, Mariana F. P.; Miguel, Sónia P.; Cabral, Cátia S. D.; Correia, I.J.Hyaluronic acid (HA), a non-sulfated glycosaminoglycan (GAG), is a major component of skin extracellular matrix (ECM) and it is involved in the inflammatory response, angiogenesis, and tissue regeneration process. Due to the intrinsic properties of HA (such as biocompatibility, biodegradability and hydrophilic character), it has been used to produce different wound dressings, namely sponges, films, hydrogels, and electrospun membranes. Herein, an overview of the different HA-based wound dressings that have been produced so far is provided as well as the future directions regarding the strategies aimed to improve the mechanical stability of HA-based wound dressings, along with the incorporation of biomolecules intended to ameliorate their biological performance during the healing process.
- Reduced graphene oxide–reinforced tricalcium phosphate/gelatin/chitosan light-responsive scaffolds for application in bone regenerationPublication . Cabral, Cátia S. D.; Melo-Diogo, Duarte de; Ferreira, Paula; Moreira, André F.; Correia, I.J.Bone is a mineralized tissue with the intrinsic capacity for constant remodeling. Rapid prototyping techniques, using biomaterials that mimic the bone native matrix, have been used to develop osteoinductive and osteogenic personalized 3D structures, which can be further combined with drug delivery and phototherapy. Herein, a Fab@Home 3D Plotter printer was used to promote the layer-by-layer deposition of a composite mixture of gelatin, chitosan, tricalcium phosphate, and reduced graphene oxide (rGO). The phototherapeutic potential of the new NIR-responsive 3D_rGO scaffolds was assessed by comparing scaffolds with different rGO concentrations (1, 2, and 4 mg/mL). The data obtained show that the rGO incorporation confers to the scaffolds the capacity to interact with NIR light and induce a hyperthermy effect, with a maximum temperature increase of 16.7 °C after under NIR irradiation (10 min). Also, the increase in the rGO content improved the hydrophilicity and mechanical resistance of the scaffolds, particularly in the 3D_rGO4. Furthermore, the rGO could confer an NIR-triggered antibacterial effect to the 3D scaffolds, without compromising the osteoblasts' proliferation and viability. In general, the obtained data support the development of 3D_rGO for being applied as temporary scaffolds supporting the new bone tissue formation and avoiding the establishment of bacterial infections.
- In situ green reduced graphene oxide functionalized 3D printed scaffolds for bone tissue regenerationPublication . Cabral, C.S.D.; Miguel, Sónia; Diogo, Duarte Miguel De Melo; Louro, Ricardo; Correia, IlidioThe incorporation of reduced graphene oxide (rGO) nanomaterials into scaffolds structure can be explored to enhance the properties of these 3D matrices in bone regeneration applications. However, the weak water solubility and poor colloidal stability of rGO have hindered its incorporation in blends aimed to produce scaffolds by 3D printing. Furthermore, rGO is generally obtained by treating graphene oxide (GO) with hydrazine hydrate, which is a highly hazardous reducing agent. To overcome these problems, herein a novel environmentally-friendly method was developed to assemble 3D printed scaffolds incorporating rGO. Such was achieved through the in situ reduction mediated by l-Ascorbic acid of the GO already present on tricalcium phosphate/gelatin/chitosan scaffolds. The scaffolds functionalized with rGO through the in situ method (TGC_irGO) displayed enhanced wettability and improved mechanical properties without impairing their porosity when compared to their equivalents functionalized with GO and non-functionalized scaffolds (TGC_GO and TGC, respectively). Moreover, the TGC_irGO scaffolds displayed an improved calcium deposition at their surface and an enhanced alkaline phosphatase (ALP) activity, along 21 days of incubation. Additionally, scaffolds also displayed antimicrobial activity without compromising osteoblasts’ viability and proliferation. Such features reveal the potential of the TGC_irGO scaffolds for bone tissue regeneration applications.
- Development of a poly(vinyl alcohol)/lysine electrospun membrane-based drug delivery system for improved skin regenerationPublication . Sequeira, Rosa Maria Saraiva; Miguel, Sónia; Cabral, Cátia S. D.; Moreira, André; Ferreira, Paula; Correia, I.J.Nanofiber-based wound dressings are currently being explored as delivery systems of different biomolecules for avoiding skin infections as well as improve/accelerate the healing process. In the present work, a nanofibrous membrane composed of poly(vinyl alcohol) (PVA) and lysine (Lys) was produced by using the electrospinning technique. Further, anti-inflammatory (ibuprofen (IBP)) and antibacterial (lavender oil (LO)) agents were incorporated within the electrospun membrane through blend electrospinning and surface physical adsorption methods, respectively. The obtained results demonstrated that the PVA_Lys electrospun membranes incorporating IBP or LO displayed the suitable morphological, mechanical and biological properties for enhancing the wound healing process. Moreover, the controlled and sustained release profile attained for IBP was appropriate for the duration of the wound healing inflammatory phase, whereas the initial burst release of LO is crucial to prevent wound bacterial contamination. Indeed, the PVA_Lys_LO electrospun membranes were able to mediate a strong antibacterial activity against both S. aureus and P. aeruginosa, without compromising human fibroblasts viability. Overall, the gathered data emphasizes the potential of the PVA_Lys electrospun membranes-based drug delivery systems to be used as wound dressings.
- Preparation of biodegradable functionalized polyesters aimed to be used as surgical adhesivesPublication . Cernadas, Maria Teresa; Gonçalves, Filipa A.M.M.; Alves, P.; Miguel, Sónia P.; Cabral, C.S.D.; Correia, I.J.; Ferreira, PaulaThe study and development of new biocompatible materials to be applied as UV-curable adhesives is extremely important to grant the preparation of matrices with suitable mechanical, biological and thermal properties with a fast curing rate. Herein, photocrosslinkable biodegradable copolymers composed of unsaturated polyesters (UP) and lactic acid oligomers functionalized with 2-isocyanatoethyl methacrylate (IEMA) were produced. Henceforth, three different stoichiometric proportions were tested, which, after the addition of a biocompatible photoinitiator (Irgacure® 2959), resulted in flexible, resistant and uniform matrices after 2 minutes and 30 seconds of crosslinking. The synthesized materials were then further characterized in terms of chemical composition and thermal/mechanical behaviour. The gel content, dynamic contact angles, water sorption capacity and hydrolytic degradation were also assessed. The biocompatibility and antibacterial activity of the produced materials was also evaluated. Taking into account all the data obtained, it may be concluded that the new synthesized biodegradable bioadhesives present promising properties to be used as surgical adhesives.
- Chitin- and chitosan-based strategies in wound healingPublication . Cabral, Cátia S. D.; Graça, Mariana F. P.; Moreira, André F.; Diogo, Duarte de Melo; Correia, I.J.Nowadays, chronic wounds are still a huge health problem with a high impact on the patients’ quality of life. In this way, the development of an ideal wound dressing is of utmost importance. To accomplish that, researchers have been using natural polymers to produce new types of dressings, that can activate/direct specific cellular responses, leading to an improved healing process. Among the natural polymers, chitin presents notable antibacterial and antiinflammatory properties that are crucial for enhancing the wound healing process. Moreover, chitosan, a deacetylated form of chitin, has been one of the most used biopolymers due to its straightforward processability into different forms, antimicrobial activity, and capacity to promote/accelerate the healing process. This chapter provides an overview of the properties exhibited by chitin and chitosan as well as examples of their application in the development of dressings aimed to improve the healing process.
- Production and characterization of a novel asymmetric 3D printed construct aimed for skin tissue regenerationPublication . Miguel, Sónia; Cabral, Cátia S. D.; Moreira, André; Correia, I.J.Skin is a complex organ that act as the first protective barrier against any external threat. After an injury occurs, its structure and functions must be re-established as soon as possible. Among different available skin substitutes (epidermal, dermal and dermo-epidermal), none of them is fully capable of reproducing/re-establishing all the features and functions of native skin. Herein, a three-dimensional skin asymmetric construct (3D_SAC) was produced using electrospinning and 3D bioprinting techniques. A poly(caprolactone) and silk sericin blend was electrospun to produce a top layer aimed to mimic the epidermis features, i.e. to provide a protective barrier against dehydration and hazard agents. In turn, the dermis like layer was formed by printing layer-by-layer a chitosan/sodium alginate hydrogel. The results obtained in the in vitro assays revealed that the 3D_SAC display a morphology, porosity, mechanical properties, wettability, antimicrobial activity and a cytotoxic profile that grants their application as a skin substitute during the healing process.
- In Vivo bone tissue induction by freeze-dried collagen-nanohydroxyapatite matrix loaded with BMP2/NS1 mRNAs lipopolyplexesPublication . Wang, Pinpin; Perche, Federico; Midoux, Patrick; Cabral, Cátia S. D.; Malard, Virginie; Correia, I.J.; EI-Hafci, Hanane; Petite, Hervé; Logeart-Avramoglou, Delphine; Pichon, ChantalMessenger RNA (mRNA) activated matrices (RAMs) are interesting to orchestrate tissue and organ regeneration due to the in-situ and sustained production of functional proteins. However, the immunogenicity of in vitro transcribed mRNA and the paucity of proper in vivo mRNA delivery vector need to be overcome to exert the therapeutic potential of RAM. We developed a dual mRNAs system for in vitro osteogenesis by co-delivering NS1 mRNA with BMP2 mRNA to inhibit RNA sensors and enhance BMP-2 expression. Next, we evaluated a lipopolyplex (LPR) formulation platform for in vivo mRNA delivery and adapted the LPRs for RAM preparation. The LPR formulated BMP2/NS1 mRNAs were incorporated into an optimized collagen-nanohydroxyapatite scaffold and freeze-dried to prepare ready-to-use RAMs. The loaded BMP2/NS1 mRNAs lipopolyplexes maintained their spherical morphology in the RAM, thanks to the core-shell structure of LPR. The mRNAs release from RAMs lasted for 16 days resulting in an enhanced prolonged transgene expression period compared to direct cell transfection. Once subcutaneously implanted in mice, the BMP2/NS1 mRNAs LPRs containing RAMs (RAM-BMP2/NS1) induced significant new bone tissue than those without NS1 mRNA, eight weeks post implantation. Overall, our results demonstrate that the BMP2/NS1 dual mRNAs system is suitable for osteogenic engagement, and the freeze-dried RAM-BMP2/NS1 could be promising off-the-shelf products for clinical orthopedic practice.
- Injectable in situ forming thermo-responsive graphene based hydrogels for cancer chemo-photothermal therapy and NIR light-enhanced antibacterial applicationsPublication . Sousa, Rita Lima; Diogo, Duarte de Melo; Alves, Cátia; Cabral, Cátia S. D.; Miguel, Sónia P.; Mendonça, António; Correia, I.J.Functionalized graphene oxide (GO) and reduced GO (rGO) based nanomaterials hold a great potential for cancer photothermal therapy. However, their systemic administration has been associated with an accelerated blood clearance and/or with suboptimal tumor uptake. To address these limitations, the local delivery of GO/rGO to the tumor site by 3D matrices arises as a promising strategy. In this work, injectable chitosan-agarose in situ forming thermo-responsive hydrogels incorporating GO (thermogel-GO) or rGO (thermogel-rGO) were prepared for the first time. The hydrogels displayed suitable injectability and gelation time, as well as good physicochemical properties and cytocompatibility. When irradiated with near infrared (NIR) light, the thermogel-rGO produced a 3.8-times higher temperature increase than thermogel-GO, thus decreasing breast cancer cells' viability to 60%. By incorporating an optimized molar ratio of the Doxorubicin:Ibuprofen combination on thermogel-rGO, this formulation mediated a chemo-photothermal effect that further diminished cancer cells' viability to 34%. In addition, the hydrogels' antibacterial activity was further enhanced upon NIR laser irradiation, which is an important feature considering the possible risk of infection at the site of administration. Overall, thermogel-rGO is a promising injectable in situ forming hydrogel for combinatorial chemo-photothermal therapy of breast cancer cells and NIR light enhanced antibacterial applications.
- 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.