Browsing by Author "Duarte, Marta M."
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- 3D printed bioactive interference screw and PCL bio-filler for ligament fixationPublication . Rodrigues, Mafalda; Moreira, Rui; Silva, Inês V.; Duarte, Marta M.; Ribeiro, Viviana P.; Oliveira, Ana L.; Costa, João B.Musculoskeletal injuries, widespread across all ages, genders and sociodemographic groups, are prevalent in the knee joint and require a range of treatments - from conservative methods to surgical interventions, such as meniscal resection, repair, reconstruction or tissue engineering (TE) approaches. To address one of the most significant challenges in orthopedic procedures – long-term implant fixation – an innovative solution is being developed for knee ligaments and meniscus fixation. PLA screws are being developed through the combination of 3D printing, supercritical CO2 (scCO2) foaming and impregnation technologies, aiming to achieve a biodegradable and bioactive screw with improve bone integration ability. Additionally, to improve the anchor and fixation of the ligament treatments, PCL Bio-Fillers are being developed through the use of 3D printing, electrospinning and dipping methods with the final goal to induce the bone cells to reproduce itself (osteogenesis) and create a better grip between the ligaments and the bone. PLA screws were manufactured by 3D printing and further process to induce porosity by scCO2 foaming, followed by EPS impregnation through scCO2. Scanning electron microscopy (SEM) was used to evaluate microporosity and the EPS impregnation. The CO2 concentration, density and expansion ratio of the PLA screws were evaluated. FTIR (Fourier-transform infrared spectroscopy) was performed to evaluate chemical composition changes of the samples. DSC (Differential scanning calorimetry) was applied to analyze thermal stability both before and after treatment. PCL Bio-Fillers were produced by 3D printing, coated with PCL using electrospinning and dipped with bruxite. Then, to study the PCL fibers and bruxite dispersion, we have used the scanning electron microscopy (SEM) method. Results: Several conditions of foaming were tested (pressure, time, temperature and controlled expansion measures) and then, analyzed through SEM imaging. Samples with greater porosity were selected for further testing and analysis. The CO2 concentration results revealed that the saturation increase is proportional to the increase in pressure and inversely proportional to the increase in infill density. The expansion ratio results demonstrated that it typically decreases with increasing infill density and batch pressure. To optimize the 3D printed Bio-Fillers coated with PCL several parameters were adjusted (PCL concentration, flow rate, distance, potential difference, and nozzle size). Firstly, samples with apparent macroscopy uneven coating were remove with further analysis being performed via SEM analysis. The SEM analysis showed that increasing the potential difference and decreasing the flow rate produced more dispersed and thinner fibers. It also revealed that increase PCL concentration led to higher fiber density and size. In the end, the parameters that resulted in the better PCL fibers dispersion were with a concentration of 7,5% w/v of PCL, 20 μL/min flow rate, 10 cm of distance between the nozzle and the Bio-Filler, 23 kV of potential difference and 20 G of nozzle size. Further work is being performed to optimize the dipping process with bruxite and achieve an even coating. Conclusion: The sCO2 methodologies implemented were efficient in terms of generating porosity and EPS impregnation. EPS-induced bioactivity will be studied in the future.
- Continuous production of highly tuned silk/calcium-based composites: exploring new pathways for skin regenerationPublication . Veiga, Anabela; Magalhães, Rui; Duarte, Marta M.; Dias, Juliana R.; Alves, Nuno M.; Costa-Pinto, Ana Rita; Castro, Filipa; Rocha, Fernando; Oliveira, Ana L.Calcium plays an important role in barrier function repair and skin homeostasis. In particular, calcium phosphates (CaPs) are well established materials for biomedical engineering due to their biocompatibility. To generate biomaterials with a more complete set of biological properties, previously discarded silk sericin (SS) has been recovered and used as a template to grow CaPs. Crucial characteristics for skin applications, such as antibacterial activity, can be further enhanced by doping CaPs with cerium (Ce) ions. The effectiveness of cell attachment and growth on the materials highly depends on their morphology, particle size distribution, and chemical composition. These characteristics can be tailored through the application of oscillatory flow technology, which provides precise mixing control of the reaction medium. Thus, in the present work, CaP/SS and CaP/SS/Ce particles were fabricated for the first time using a modular oscillatory flow plate reactor (MOFPR) in a continuous mode. Furthermore, the biological behavior of both these composites and of previously produced pure CaPs was assessed using human dermal fibroblasts (HDFs). It was demonstrated that both CaP based with plate-shaped nanoparticles and CaP-SS-based composites significantly improved cell viability and proliferation over time. The results obtained represent a first step towards the reinvention of CaPs for skin engineering.
- Current trends on protein driven bioinks for 3D printingPublication . Veiga, Anabela; Silva, Inês V.; Duarte, Marta M.; Oliveira, Ana L.In the last decade, three-dimensional (3D) extrusion bioprinting has been on the top trend for innovative technologies in the field of biomedical engineering. In particular, protein-based bioinks such as collagen, gelatin, silk fibroin, elastic, fibrin and protein complexes based on decellularized extracellular matrix (dECM) are receiving increasing attention. This current interest is the result of protein’s tunable properties, biocompatibility, environmentally friendly nature and possibility to provide cells with the adequate cues, mimicking the extracellular matrix’s function. In this review we describe the most relevant stages of the development of a protein-driven bioink. The most popular formulations, molecular weights and extraction methods are covered. The different crosslinking methods used in protein bioinks, the formulation with other polymeric systems or molecules of interest as well as the bioprinting settings are herein highlighted. The cell embedding procedures, the in vitro, in vivo, in situ studies and final applications are also discussed. Finally, we approach the development and optimization of bioinks from a sequential perspective, discussing the relevance of each parameter during the pre-processing, processing, and post-processing stages of technological development. Through this approach the present review expects to provide, in a sequential manner, helpful methodological guidelines for the development of novel bioinks.
- Hydrogel-forming potential of sulphated exopolysaccharide (EPS) from Porphyridium cruentum for skin wound healing applicationsPublication . Duarte, Marta M.; Suprinovych, Artem; Veiga, Anabela; Silva, Inês V.; Morais, R. M.; Oliveira, Ana L.Introduction: Gel-like materials have been on the forefront of biomedical research due to their properties such as easily adaptable shape, water-holding ability, and their adjustable degrading rate. Hydrogels from natural origin are gaining attention both for its growing popularity as “green” materials, and due to their many useful properties as compared to synthetic ones, as they are often biocompatible, and biodegradable. They can be locally absorbed, eliminating the danger of damaging the wound during its removal (4). Marine algae and their metabolites have been widely recognized for their bioactive properties with applications in various industries, such as pharmaceutical, biomedical, cosmetics, and food (5,6). The red unicellular microalgae from the genus Porphyridium (Porphyridiales, Rhodophyta) is a natural source for a variety of interesting bioactive compounds, including several pigments (such as carotenoids), phycoerythrin, oligosaccharides, phycobiliproteins, and sulfated polysaccharides (EPS) (7,8). These polysaccharides have unique, and potentially useful, rheological properties when prepared in an aqueous medium. They have relatively high viscosity, behave like non- Newtonian fluids, and undergo reversible thermal gelation upon heating (9,10). EPS have also shown to possess several biological properties of high interest as therapeutic agent, such as anti-bacterial (11), antiviral (9), immunomodulatory, and anti-oxidant properties (12). These properties make EPS an attractive natural material to be used as a new hydrogel platform for healing and regeneration of chronic wounds. Methods: Sentence on the production of the EPS…The rheological behavior of aqueous solutions of EPS formulations (0.5, 1.5, 2,5 wt% in 0.1M NaOH) in the presence of divalent and trivalent metal ions (M2+ and M3+) was measured and compared to gel-cation systems of alginate, a well-characterized polymer. Samples were assayed for their post-gelling properties using a rheometer with a flat-plate geometry. Frequency sweep tests were conducted at a low strain of 0.5%. Biocompatibility was assayed via an indirect contact assay using Human Dermal Fibroblasts (HDF). Results: In our study, EPS formulations were able to form gels in the presence of Ce3+, Fe2+, Ca2+, Mg2+, and Cu2+. Polymer and crosslinker concentration, as well as crosslinker nature, had a significant effect on gel formation, and post-gelling properties. Higher polymer concentrations (1.5 and 2.5%) led to the formation of stiffer gels. However, overall EPS formulations led to less stiff and stable hydrogels than alginate formulations, revealing that there are further optimizations needed for both gelling conditions and polymer-cation formulations. All formulations used were revealed to be biocompatible after indirect contact assay using HDF cells.
- Insights on the hydrogel-forming ability of exopolysaccharide (EPS) from porphyridium cruentum for skin wound healing applicationsPublication . Duarte, Marta M.; Suprinovych, Artem; Veiga, Anabela; Silva, Inês V.; Oliveira, Ana L.Marine algae and their metabolites have been widely recognized for their bioactive properties with applications in various industries, such as nutraceutical, cosmetical, and pharmaceutical. In this work the extracted sulfated exopolysaccharides (EPS) from Porphyridium cruentum were analyzed for their hydrogel-forming ability and potential to be used as a new platform for healing and regeneration of chronic wounds, due to their bioactive potential. The rheological behavior of aqueous solutions of EPS formulations (0.5, 1.5, 2,5%) in 0.1 M NaOH in the presence of divalent and trivalent metal ions (M2+ and M3+) was measured and compared to a more well-characterized polymer, alginate. Ionic cross-linked nature and polymer concentration was significant for the formation of gels, with higher concentrations (1.5 and 2.5%) having a broader range of success. After hydrogel formation, the overall rheological response remained similar with varying Ionic cross-linker concentration. However, overall EPS formulations led to less stiff and stable hydrogels than alginate formulations, revealing that there are further optimizations needed for gelling conditions and formulations.
- Novel knee implant fixation technology: 3D printed foamed bioactive screw/electrospun tunnel fillerPublication . Rodrigues, Mafalda; Moreira, Rui; Silva, Inês V.; Duarte, Marta M.; Ribeiro, Viviana P.; Oliveira, Ana L.; Costa, João B.Introduction: Musculoskeletal injuries, widespread across all ages, genders, and sociodemographic groups1, are prevalent in the knee joint. Besides the conservative treatments and physiotherapy, several degenerative and traumatic knee injuries require surgical intervention2. To address one of the most significant challenges in surgical orthopaedic procedures, long-term implant fixation3, an innovative solution was developed for knee ligaments and meniscus fixation. Polylactic acid (PLA) screws were developed through the combination of 3D printing, supercritical CO2 (scCO2) foaming and exopolysaccharides (EPS) impregnation. Additionally, to improve fixation efficiency, polycaprolactone (PCL) tunnel fillers supplemented with brushite particles were fabricated combining 3D printing and electrospinning4. The developed implant fixation technology aimed to combine a biodegradable and bioactive PLA screw with a PCL tunnel filler capable of creating a better implant anchorage grip and osteointegration leading to long term-term fixation. Conclusions: The novel knee implant fixation technology is fabricated of a PLA bioactive screw and a PCL tunnel filler. Regarding PLA screw, the results showed that lower infill density, as it presents a wider structure, correlates with a slightly increased CO2 saturation. Varying the batch pressures results in different CO2 states that ultimately affect not only the expansion ratio of the PLA screws but also the type of porosity induced by the foaming step. EPS CO2 impregnation process was implemented with success. The 3D printing process to produce PCL tunnel fillers was optimized with success. Electrospinning coating of the PCL tunnels fillers was also achieved. The results demonstrate that a 7.5% concentration of PCL produces high-quality fibers with good porosity, aligning with the target goal of mimicking bone porosity. A different approach will be tested to avoid clogging operational problems. In future, further tests to access EPS impregnation efficiency, mechanical properties of both screw and tunnel fillers as well in vitro cell culture studies to test cytotoxicity and bioactivity will be implemented.
- Porphyridium cruentum: a factory for the production of a new polysaccharide-based biomaterial for tissue regenerationPublication . Duarte, Marta M.; Suprinovych, Artem; Silva, Inês V.; Ramos, Oscar L.; Costa, Joana R.; Rojo, Luis; Oliveira, Ana L.Marine algae and their metabolites have been widely recognized for their bioactive properties with applications in various industries, such as nutraceutical, cosmetical, and pharmaceutical. In this study, the best strategy for the extraction and processing of the exopolysaccharides (EPS) from Poryphydium cruentum for a laboratory scale was discussed, and the collected, purified EPS fraction was extensively characterized. The results show that impurities and other co-precipitants can be significantly reduced via trichloroacetic acid (TCA) treatment, followed by dialysis, resulting in a more purified EPS fraction with a higher carbohydrate content and solubility ability, at the cost of lower mass yield. The obtained EPS fraction was of a high molecular weight, presented a high crystallinity index, was thermally stable and cytocompatible within the range of tested concentrations. These results show its potential to be used as a new platform for healing and regeneration of chronic wounds.