Maria Helena V Fernandes

Maria Helena V Fernandes
University of Aveiro | UA · CICECO - Centre for Research in Ceramics and Composite Materials

PhD

About

185
Publications
15,259
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1,442
Citations

Publications

Publications (185)
Article
Currently, most of the red colored glasses are still produced using cadmium sulfoselenide, despite its high toxicity. Alternative solutions, more environmentally friendly, have been sought, most of them going through the use of gold or copper nanoparticle, the color being obtained by striking. This work presents a new methodology for production of...
Article
Full-text available
This paper reports a study on the development of bioactive glass powders for biofabrication of scaffolds by an additive manufacturing technique, three-dimensional printing (3DP). Several formulations of the glass were developed from the CaO·P2O5·TiO2 system and prepared on the basis of the results for the commercial powder characterization (average...
Article
The non-isothermal crystallization kinetics of polycaprolactone (PCL) and PCL–glass composites, used in fused filament fabrication (FFF), was investigated. Films of PCL and PCL reinforced with powders of a bioactive glass, from the CaO·P2O5·MgO·SiO2 system, were prepared by solvent casting process. Crystal structure of the samples was examined by X...
Article
Tissue engineering is evolving towards the production of smart platforms exhibiting stimulatory cues to guide tissue regeneration. This work explores the benefits of electrical polarization to produce more efficient neural tissue engineering platforms. Poly (l-lactic) acid (PLLA)-based scaffolds were prepared as solvent cast films and electrospun a...
Article
In this work we developed improved bioactive glasses and glass-ceramics for biomedical applications, investigating their in vitro bioactivity, biocompatibility and antibacterial properties against E-Coli. A melt-quenched bioactive glass of the SiO2-CaO-P2O5-MgO system was modified with the addition of 1 and 2 mol% Ag2O and the 1 mol% Ag2O-containin...
Article
Poly (L-lactic acid) (PLLA) is a biodegradable and biocompatible polymer that has been put forward as a promising material for therapeutic approaches aiming to restore neuronal function. The topographic cues present in PLLA-based scaffolds, defined by the technique used in their preparation, have been shown to play a role on the cellular behavior o...
Conference Paper
Background: Some researchers try to unveil if preparing the abutment of one-piece zirconia implants can modify the surface allowing the occurrence of micro-cracks and, consequently, in a long-term, decreasing zirconia mechanical properties, such as fracture strength. In the zirconia system stabilized by yttrium oxide it is possible to obtain zircon...
Article
Three novel borosilicate bioactive glasses (BBGs) were prepared and used to investigate their bioactive and antibacterial properties. The BBGs were prepared by melt quenching using different glass modifiers, i.e. Mg2+, Ca2+ and Sr2+, and their amorphous nature was confirmed by X-ray diffraction. Scanning electron microscopy with energy dispersive X...
Conference Paper
The purpose of this study is characterizing the surface of zirconia implants and compare with titanium and titanium-zirconium implants already commercialized, investigating the roughness of their surfaces. Another purpose is to verify if the micrometric and nanometric topography of the zirconia are similar to the titanium and titanium-zirconium imp...
Article
Two new examples of uncommon three-dimensional Ca-bearing metal organic frameworks, [Ca(H2O)3(HPXBP)] (CaP1) and [Ca2(H2O)2(HPXBP)1.5] (CaP2) (PXBP: p-xylylenebisphosphonate), were prepared and their structures characterized by single crystal X-ray diffraction. CaP1 crystallizes in the monoclinic C2/c space group, with three water molecules occupyi...
Poster
Full-text available
The osseointegration of the implant depends upon the surface itself. In addition to the biofunctional aspects, aesthetic considerations began to gain relevance, and thus came the ceramic implants (eg zirconia) as an alternative to titanium implants.
Article
The last two decades have seen a remarkable growth in the design of new hybrid materials applied to different areas, from photonics to biomaterials, together with new coating materials with self-cleaning features. Among the various systems studied, the PDMS-SiO2 system remains as a good basis for further developments by adding other compounds such...
Article
PDMS–SiO2 hybrid materials obtained by sol–gel process have been extensively studied over the past years due to its promising biomedical applications namely as bone substitutes, catheters, and drug delivery devices. Regardless of the intended biomedical application, all these materials should go through a sterilization process before interfacing wi...
Article
Glass scaffolds were obtained by the salt sintering method, using mixtures of calcium phosphate glass, 25.42%SiO2–10.89%P2O5–32.68%CaO–31%MgO(mol%), and salt, NaCl, pressed and sintered bellow the salt melting point, followed by leaching of the salt in water. The sintering behaviour of glass/salt powder mixtures was followed by dilatometry, BET and...
Article
Full-text available
The ceramics in the system CaO-MgO-SiO2 has recently received a great deal of attention because they exhibit good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics was prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO(2) was thermally treated at 1300 degrees...
Article
Full-text available
Several types of glass-ceramics in the CaO-MgO-SiO 2 system are shown to be bioactive, biocompatible and exhibiting various advantages for bone regeneration. A polyphase calcium-magnesium-silicate glass-ceramics is prepared by the sol-gel method including a two-step thermal treatment procedure aiming to investigate the effect of its phase compositi...
Article
Full-text available
The morphological plasticity of scleractinian corals can be influenced by numerous factors in their natural environment. However, it is difficult to identify in situ the relative influence of a single biotic or abiotic factor, due to potential interactions between them. Light is considered as a major factor affecting coral skeleton morphology, due...
Article
In this work, the crystallization process of a SiO2–3CaO·P2O5–MgO glass was studied by non-isothermal measurements using differential thermal analysis carried out at various heating rates. X-ray diffraction at room and high temperature was used to identify and follow the evolution of crystalline phases with temperature. The activation energy associ...
Article
The aim of this study was to investigate the potential anti-inflammatory and anti-oxidant effects of gabapentin (GBP) in mice. The anti-inflammatory and anti-oxidant effects were evaluated using various mediators that induce paw edema, peritonitis model, myeloperoxidase (MPO) activity, proinflammatory cytokine levels, glutathione (GSH) consumption,...
Article
The crystallization kinetics of a glass with a molar composition 40BaO–20ZnO–30B2O3–10SiO2 was investigated. The kinetic parameters, activation energy for crystallization (Ec) and Avrami exponent (n), were evaluated under non-isothermal conditions using the results obtained by differential thermal analysis (DTA) performed at different heating rates...
Article
To design bone cements with predictable intraoperative and postoperative behavior, researchers must understand how cement formulations affect the polymerization reaction and specially the properties of the end product. In this study, a bioactive filler (commercial hydroxyapatite, HA) was incorporated into poly(methyl methacrylate)-co-ethyl hexyl ac...
Article
Hybrid materials of the polydimethylsiloxane (PDMS)–Tetraethyl orthosilicate (TEOS) system have already been widely described by several authors, being their potential for biological applications largely studied. For some bone related applications, the addition of Ca to these systems is commonly accepted as necessary for the enhancement of bioactiv...
Article
Full-text available
The CaO-P2O5-SiO2-MgO system presents several compounds used as biomaterials such as hydroxyapatite (HA), tricalcium phosphate (TCP) and TCP with magnesium substituting partial calcium (TCMP). The β-TCMP phase with whitlockite structure has interesting biological features and mechanical properties, meeting the requirements of a bioactive material f...
Article
Full-text available
In this work, the crystallization process of lithium disilicate glass-ceramic was investigated with SiO2 from rice husk silica replacing the high-purity SiO2 starting powder form commercial source. Glasses were developed at the stoichiometric composition of 66%.molSiO2:33%.molLiO2 using commercial SiO2 and the one obtained by thermochemical treatme...
Article
Full-text available
In the present study four functionalized mesoporous silica materials denoted as BIS-1, BIS-2, BIS-3 and BIS-4 have been synthesized through a simple co-condensation of bis-[3-(trimethoxyosilyl)propyl] amine (BTPA) and tetraethyl orthosilicate (TEOS). The influence of the BTPA amount on the structural and adsorption properties of the resultant mater...
Article
Full-text available
Sol–gel silica materials are amorphous, porous materials that have a large number of exploited and potential applications. In this study we report the synthesis and characterization of porous organic-inorganic hybrid materials which are characterized by micro and meso pores, derived by co-condensation of tetraethoxysilane and functionalized trialko...
Article
Bioactive bone cements can promote bone growth and the formation of a strong chemical bond between the implant and bone tissue increasing the lifetime of the prosthesis. This study aims at synthesizing a new bioactive bone cement with different amounts of ibuprofen (5, 10 and 20 wt%) using a low toxicity activator, and investigating its in vitro re...
Conference Paper
Full-text available
The increasing interest in the effect of strontium in bone tissue repair has heightened the need for the development of bioactive materials with strontium release capability. In fact, the incorporation of strontium in bioactive glasses, for example, has been studied extensively 1. According with published studies 2 , hybrid materials have been cons...
Article
Full-text available
Nanoporous ceramic materials was functionalized by co-condensation of tetraethyl orthosilicate (TEOS) and different 3-aminopropyltriethoxysilane (APTES) amounts in the presence of amphiphilic triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (EO20PO70EO20), who was previously dissolved in acid solutio...
Article
The preparation of PDMS–TEOS–CaO hybrid materials by sol–gel techniques has been widely described in previous works. Calcium nitrate is the most common source of calcium used in these preparations. However, to remove possible toxic nitrate by-products a thermal treatment is necessary at temperatures above 500 °C, which leads to the degradation of t...
Article
A novel sealing method is proposed for encapsulating devices comprised of glass substrates. This sealing method is based on applying a glass frit paste cord onto the substrate and then using a laser beam to locally supply the necessary energy to allow the formation of a hermetic bonding layer. A detailed description of the laser bonding technique,...
Article
Barium zinc borosilicate glasses with a molar composition xBaO‐(60−x)ZnO‐30B2O3‐10SiO2, where x ranged from 0 to 60 mol%, were prepared using melt‐quenching method. The effect of BaO substitution for ZnO on the sintering, crystallization, and dielectric characteristics has been investigated. The behavior of the studied barium zinc borosilicate glas...
Article
Materials filled with a silicate glass (MSi) and a borate glass (MB) were developed and compared in terms of their in vitro behavior. The effect of filler composition and concentration (0, 30, 40 and 50 wt%) on the curing parameters, residual monomer, water uptake, weight loss, bioactivity, mechanical properties (bending and compression) and osteob...
Article
Since the discovery of the piezoelectric character of bone, the suitability of some piezoelectric materials have been studied for bone repair; they are thought to act like transducers converting the mechanical energy of skeletal deformation in electrical stimuli capable of controlling osteogenic growth. The mechanisms underlying this process are fa...
Article
The crystallization process of lithium disilicate glass-ceramic with SiO2 from rice husk silica replacing the high-purity SiO2 starting powder has been investigated in this work. Glasses were developed at the stoichiometric composition of 66%.molSiO2:33%.molLiO2 using commercial SiO2 and the one obtained by thermochemical treatment of rice husk. Th...
Article
This paper describes the decay kinetics of electrically induced polarization of poly(L-lactic) acid (PLLA) via piezoresponse force microscopy. Two crystalline forms of PLLA (α and α′) were electrically poled at different temperatures (room and above glass transition). Poling at temperatures above glass transition allowed obtaining polarization stab...
Article
Full-text available
Silicate hybrid materials were prepared by the sol–gel process with the addition of x mass% of zirconium propoxide (x = 0 and 1). The thermal behaviour as well as the influence of Zr addition was studied by thermal gravimetric analysis and differential thermal analysis. The microstructure evolution with temperature was investigated by X-ray diffrac...
Article
Purpose: The formation of a calcium phosphate layer on the surface of bone tissue engineering biomaterials is crucial for their integration in bone. Simulated biological fluids used to study the in vitro formation of those layers do not usually contain important organic components present in vivo-notably proteins. In this work the influence of bov...
Article
The aim of this study is to report on the development and characterization of bioactive glass and glass-ceramics from the 3CaO.P(2)O(5)-SiO(2)-MgO-system, using different degrees of cristallinity for applications as an implant material. A methodology was proposed to induce crystallization of phases. Bioglass samples of the nominal composition (wt %...
Article
Full-text available
In this work we present the experimental results on synthesis structure and in vitro bioactivity of collagen (C)/calcium phosphate silicate (CPS)/chondroitin sulfate (ChS) composites with C/CPS ratio of 25:75 wt. % and 75:25wt. %. The synthesized composites were characterized by XRD, FTIR and SEM/EDS. XRD and FTIR before in vitro test proved that t...
Article
Full-text available
A new type of material from polyamide coated with calcium phosphate was developed aiming to have potential application as biomaterial. Coating was obtained by the sol-gel method and calcium phosphate was obtained after contact with body fluid solution. The coated polyamide (before and after contact with body fluid solution) was characterized by the...
Chapter
Aunque muchos han sido los dispositivos innovadores biocompatibles producidos al abrigo del descubrimiento de novedosos biomateriales, un nuevo paradigma comienza a surgir en el ambito de la salud, dando paso a la nueva medicina regenerativa. En este atractivo campo de investigacion, las versatiles propiedades de los vidrios y vitroceramicos bioact...
Article
In this work, the effect of the indentation load on the results of hardness and fracture toughness, determined by Vickers micro-hardness measurements, of some glasses and glass–ceramics has been investigated. Furthermore, in order to verify the effect of crystallinity on the results, glasses of composition 52.75 wt.% 3CaO·P2O5, 30 wt.% SiO2 and 17....
Conference Paper
Full-text available
Sol-gel processes give new possibilities in the field of chemistry and science. Using the sol-gel method new materials can be synthesized. Hybrid materials formed by the nanoscale inorganic and organic domains are attractive for the purpose of creating new materials compared to the organic or inorganic materials sepa-rately. The hybrid is formed in...
Article
Full-text available
In this work we present the experimental results on synthesis, structure evolution and in vitro bioactivity of col-lagen-silicocarnotite-chondroitin sulphate composites. The obtained samples were synthesised by mixing col-lagen (C) and silicocarnotite (S) powder with C:S ratio of 75:25 and 25:75 wt.% in the presence of chondroitin sulphate (ChS). C...
Article
Full-text available
Some studies have shown a relationship between glass structure and in vitro mineralization, generally associated with the rate of glass degradation, nature of released ions and subsequent Ca-P precipitation on glass surfaces when immersed in a Simulated Body Fluid (SBF). The knowledge of the ionic species distribution in glasses and of the involved...
Article
Full-text available
The purpose of the present work is the sol–gel synthesis, structure characterization and potential application of hybrid biomaterials based on silica precursor (MTES) and natural polymers such as gelatin or pectin. The structure formation in the biomaterials was investigated by XRD, FTIR, BET and AFM. The results showed that all studied hybrid biom...
Article
Full-text available
Bioactive materials possess properties that allow them to interact with natural tissues to induce reactions that favor the development and regeneration of those tissues. In this study, silica was prepared by the sol-gel method, using tetraethylorthosilicate as the precursor. The calcium and phosphor sources used here were calcium ethoxy and phospho...
Article
Up until now, no direct evidence of protein adsorption processes associated with polar activity of a piezoelectric has been reported. This work presents the experimental evidence of the protein adsorption process’ dependence on the surface polarization of a piezoelectric by showing at the local scale that the process of protein adsorption is highly...
Conference Paper
Full-text available
Sintered hydroxyapatite [1], Na2O-CaO-SiO2-P2O5 glasses [2] and glass-ceramics containing crystalline apatite and wollastonite [3] can bond to living bone and are currently applied as important bone repairing materials [4]. The use of metals, such as titanium and its alloys, as living bone bonding materials has been reported by Yan et al. [5]. How...
Article
Full-text available
Methylcellulose (MC) / SiO2 organic / inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC con...
Article
The study of SiO2–MgO–Na2O glasses is of particular relevance because some compositions can exhibit adequate properties for their use in biomedical applications.The influence of substitution of divalent Mg2+ ions for monovalent Na+ in the structure of silicate glasses which contain 55mol% SiO2 was investigated by Magic-Angle Spinning (MAS) Nuclear...
Article
Full-text available
The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polystep sol-gel route. The synthesized glasses were characterized by XRD, FTIR and SEM. Changes in 1.5 SBF solutions were measured by ICP-AES. XRD of the glasses stabilized at 700°C for 6 hours proved the presence of niocalite. FTIR was consistent with XRD...
Article
This work is devoted to the development of a new generation of sol-gel hybrid materials, their driving forces on the material science and technology and especially on their impact on possible advanced applications. The motivation of the carried work was to point out that the choice of the appropriate precursors can facilitate the connection between...
Article
The structure of glasses with composition x TiO2·(65 − x) P2O5·35 CaO (x = 0–30 mol%) has been studied and their glass transition temperature, Raman and NMR spectra have been analysed.For TiO2-free glass two phosphate species have been identified as Q2 and Q3. Increasing TiO2 content in glass compositions results in the disappearance of the Q3 and...
Article
Full-text available
In this work the application of hybrid materials, containing TEOS as source of SiO2 and k-carrageenan in different percentage, synthesized by the sol-gel method at room temperature was studied. They were used as matrices for entrapment of whole Bacillus sp. UG-5B cells, producers of thermostable nitrilase. The effect of the surface area and size an...
Article
Full-text available
The main purpose of the paper is the evaluation of the influence of chemical composition of the gel of the synthesized 15CaO·0.5P2O5·6SiO2 glass-ceramic on the structure, crystallization behaviour and in vitro bioactivity in static conditions for different periods of time - 3, 9 and 30 days in 1.5SBF. The obtained glass-ceramic was synthesized via...
Article
The physical, chemical and mineralogical characterisation of the ash resulting from a pulp mill boiler was performed in order to investigate the valorisation of this waste material through the production of added-value glassy materials. The ash had a particle size distribution in the range 0.06-53 microm, and a high amount of SiO(2) (approximately...