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Projeto de investigação
CICECO – Aveiro Institute of Materials
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Publicações
Bioactivity Enhancement of Plasma-Sprayed Hydroxyapatite Coatings through Non-Contact Corona Electrical Charging
Publication . Prezas, Pedro R.; Soares, Manuel J.; Borges, João P.; Silva, Jorge C.; Oliveira, Filipe J.; Graça, Manuel Pedro F.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MDPI AG
Atmospheric plasma spray (APS) remains the only certified industrial process to produce hydroxyapatite (Hap) coatings on orthopaedic and dental implants intended for commercialization. Despite the established clinical success of Hap-coated implants, such as hip and knee arthroplasties, a concern is being raised regarding the failure and revision rates in younger patients, which are increasing rapidly worldwide. The lifetime risk of replacement for patients in the 50–60 age interval is about 35%, which is significantly higher than 5% for patients aged 70 or older. Improved implants targeted at younger patients are a necessity that experts have been alerted to. One approach is to enhance their bioactivity. For this purpose, the method with the most outstanding biological results is the electrical polarization of Hap, which remarkably accelerates implant osteointegration. There is, however, the technical challenge of charging the coatings. Although this is straightforward on bulk samples with planar faces, it is not easy on coatings, and there are several problems regarding the application of electrodes. To the best of our knowledge, this study demonstrates, for the first time, the electrical charging of APS Hap coatings using a non-contact, electrode-free method: corona charging. Bioactivity enhancement is observed, establishing the promising potential of corona charging in orthopedics and dental implantology. It is found that the coatings can store charge at the surface and bulk levels up to high surface potentials (>1000 V). The biological in vitro results show higher Ca2+ and P5+ intakes in charged coatings compared to non-charged coatings. Moreover, a higher osteoblastic cellular proliferation is promoted in the charged coatings, indicating the promising potential of corona-charged coatings when applied in orthopedics and dental implantology.
Atmosphere-Assisted FLASH Sintering of Nanometric Potassium Sodium Niobate
Publication . Serrazina, Ricardo; Pereira, Luís; Vilarinho, Paula M.; Senos, Ana M.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MDPI AG
Dicarboxymethyl cellulose (DCMC) was synthesized and tested for protein adsorption. The prepared polymer was characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and solid state nuclear magnetic resonance (ssNMR) to confirm the functionalization of cellulose. This work shows that protein adsorption onto DCMC is charge dependent. The polymer adsorbs positively charged proteins, cytochrome C and lysozyme, with adsorption capacities of 851 and 571 mg g−1, respectively. In both experiments, the adsorption process follows the Langmuir adsorption isotherm. The adsorption kinetics by DCMC is well described by the pseudo second-order model, and adsorption equilibrium was reached within 90 min. Moreover, DCMC was successfully reused for five consecutive adsorption–desorption cycles, without compromising the removal efficiency (98–99%).
Biopolymers Derived from Forest Biomass for the Sustainable Textile Industry
Publication . Dias, Juliana C.; Marques, Susana; Branco, Pedro C.; Rodrigues, Thomas; Torres, Cristiana A.V.; Freitas, Filomena; Evtyugin, Dmitry V.; Silva, Carla J.; UCIBIO - Applied Molecular Biosciences Unit; MDPI - Multidisciplinary Digital Publishing Institute
In line with environmental awareness movements and social concerns, the textile industry is prioritizing sustainability in its strategic planning, product decisions, and brand initiatives. The use of non-biodegradable materials, obtained from non-renewable sources, contributes heavily to environmental pollution throughout the textile production chain. As sustainable alternatives, considerable efforts are being made to incorporate biodegradable biopolymers derived from residual biomass, with reasonable production costs, to replace or reduce the use of synthetic petrochemical-based polymers. However, the commercial deployment of these biopolymers is dependent on high biomass availability and a cost-effective supply. Residual forest biomass, with lignocellulosic composition and seasonably available at low cost, constitutes an attractive renewable resource that might be used as raw material. Thus, this review aims at carrying out a comprehensive analysis of the existing literature on the use of residual forest biomass as a source of new biomaterials for the textile industry, identifying current gaps or problems. Three specific biopolymers are considered: lignin that is recovered from forest biomass, and the bacterial biopolymers poly(hydroxyalkanoates) (PHAs) and bacterial cellulose (BC), which can be produced from sugar-rich hydrolysates derived from the polysaccharide fractions of forest biomass. Lignin, PHA, and BC can find use in textile applications, for example, to develop fibers or technical textiles, thus replacing the currently used synthetic materials. This approach will considerably contribute to improving the sustainability of the textile industry by reducing the amount of non-biodegradable materials upon disposal of textiles, reducing their environmental impact. Moreover, the integration of residual forest biomass as renewable raw material to produce advanced biomaterials for the textile industry is consistent with the principles of the circular economy and the bioeconomy and offers potential for the development of innovative materials for this industry.
Technical, Environmental, and Cost Assessment of Granite Sludge Valorisation
Publication . Surra, Elena; Sousa, João; Correia, Manuela; Carvalheiras, João; Labrincha, João A.; Marques, José C.; Lapa, Nuno; Delerue-Matos, Cristina; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Featured Application: This work provides fundamental information regarding the technical, environmental, and economic viability of granite sludge valorisation as a substitute for feldspar in a ceramic paste and as a substitute for fine–medium inert in structural concrete. The granite sludge (GS) produced during block sawing can be exploited as alternative raw material in ceramic and concrete industries. Based on the case study of a Portuguese granite processing plant, this work analysed, by experimental tests and Environmental and Cost Life Cycle analyses, the feasibility of GS valorisation as a substitute (i) for feldspar in a ceramic paste and (ii) fine–medium inert filler in structural concrete. The results demonstrated that both the valorisation pathways are more advantageous than GS landfilling. Due to granulometric, mineralogical composition and shrinkage, GS can substitute feldspar in sandstone tiles or tableware products, although its tinting effect can limit noble whitish ceramic applications. In structural concrete mixes, 5% w/w GS instead of fine inert filler reduces the compressive strength and increases the water:cement ratio. The GS generates lower environmental impacts as a substitute for inert filler than as a substitute for feldspar in most of the impact categories analysed, even though the latter valorisation pathway provides higher benefits in Climate Change and the Depletion of Fossil resources, Water, and Ozone. If no monetary value is recognised for GS valorisation by the market, the sustainability of GS life cycle cost decreases when compared to its landfilling.
Microalgae Biomass Biorefinery: Development and Implementation of Processing Strategies in an Industrial Unit in Portugal
Publication . Pereira, Bruno Alexandre das Neves; Brazinha, Carla; Ventura , Sónia Patrícia; Crespo , João Paulo
The development of sustainable biorefinery strategies for high-value biomolecules from microalgae is essential to promote more efficient and circular resource-use processes. This PhD focused on the extraction, stabilization, and purification of C-phycocyanin (C-PC) from Limnospira platensis, using biphasic systems based on natural deep eutectic solvents (NADES). The work was structured in two parts: the first dedicated to phase behavior studies and process engineering, and the second to the extraction and purification of C-PC from real microalgal biomass, with emphasis on scalability and industrial relevance.
In the first part, model aqueous solutions of C-PC were used to screen and optimize NaDES-based biphasic systems. From more than 70 combinations tested, the most effective one achieved high partitioning (Kp = 29.4 ± 0.3) and extraction efficiency (99%), while ensuring phase stability and measurable interfacial tension. Recovery studies demonstrated that back-extraction with a common organic solvent as antisolvent preserved protein integrity. Two recovery routes were tested: (i) membrane pre-concentration, yielding 0.29 ± 0.00 g·L⁻¹ (65.9% recovery), and (ii) centrifugation, which achieved the highest recovery (0.39 ± 0.01 g·L⁻¹) with antioxidant activity of 38.2 ± 2.4%. At the industrial level, membrane pre-concentration may enable continuous operation integrated with centrifugation. Regarding solvent recycling, the most effective solution achieved up to 80% recovery by rotary evaporation, while NaDES required additional treatment for full reuse.
The second part addressed the direct extraction of C-PC from L. platensis biomass. Screening of different solvents, including hydrophilic and hydrophobic NADES, revealed that one of tested systems, under optimized conditions, yielded 137.0 ± 8.3 mgC-PC·gdry biomass⁻¹ and significantly improved the color stability of C-PC, with a half-life of 126 days under dark storage at pH 6. Based on these results, new NADES-based biphasic systems were tested and integrated into fast centrifugal partition chromatography (FCPC). From these, one of the most promising systems showed higher selectivity (KC-PC = 1.53 vs. Kchlorophyll = 0.50), producing highly purified fractions (15.9 mgC-PC·L⁻¹, with purity five times higher relative to total proteins and chlorophylls). In contrast, a second system enabled higher C-PC concentrations (up to 615.9 mgC-PC·L⁻¹; purity five and 0.87 times higher relative to total proteins and chlorophylls, respectively), but with lower selectivity.
In summary, this thesis demonstrates that NADES allow more selective extraction and more efficient stabilization of C-PC. Furthermore, NADES-based biphasic systems enable effective compound separation, providing products of different purity grades depending on the final application, as well as scalable and sustainable strategies for microalgal biorefineries.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
LA/P/0006/2020