Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, ...bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery.
This work studied the influence of two sol-gel synthesis routes in obtaining a bioactive glass-ceramic derived from the 45S5 composition: a polymeric and a colloidal route. The main difference ...between the routes is in the silica precursor employed. The tetraethyl orthosilicate metal alkoxide (Si(OC2H5)4 - TEOS) is used in polymeric route and the silicic acid (H4SiO4) was used in the colloidal route. The synthesized xerogels were calcined at different temperatures to eliminate undesirable compounds and to verify the crystallization behavior. Afterwards, the calcined xerogels were submitted to in vitro bioactivity assay. The samples were also characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and laser diffraction. After calcination, the glass-ceramics obtained by the colloidal route showed greater number of bioactive phases and, consequently, of NBO bonds. The larger amount of NBO bonds resulted in a higher bioactivity of the materials synthesized by the colloidal route. In addition, the long hydrolysis step of the metal alkoxides was eliminated with colloidal synthesis. This allowed a significant reduction in the total synthesis time from 13 days to 24 h. To the best of our knowledge, this seems to be the first time this colloidal route has been employed in the synthesis of bioglass 45S5.
Porous polymeric scaffolds provide a physical substrate for cells to attach and proliferate, allowing the formation of new tissue. These materials are broadly used in the tissue engineering field due ...to their ability to mimic native tissue. Each application requires specific morphologies and resistance, among other several features. To accomplish these requirements, various techniques are available, each one with its advantages and disadvantages. Among the most relevant techniques are salt leaching, solvent casting, gas foaming, thermally induced phase separation, freeze-drying, electrospinning, thermally induced self-agglomeration, and three-dimensional (3D) printing. In this review, a brief and simple explanation of each method is described, along with some recent results and each technique's advantages and disadvantages. It is expected that this review will bring important guidance in the production of polymer scaffolds for tissue engineering.
The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the ...structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.
The phase of crystalline α-wollastonite (α-CaSiO3) powders was prepared at low temperature via sol gel method. The formation mechanisms of α-wollastonite (α-CaSiO3) using different calcium salts were ...examined. The synthesis was carried out in absence of organic solvents, using as starting materials silicic acid and inorganic salts (CaCl2.H2O and Ca(NO3)2.4H2O). The samples were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetry/Differential Scanning Calorimetry (TGA-DSC), X-Ray Diffraction (XRD) and Field Emission Gun-Scanning Electron Microscopy (FEG-SEM). The experimental results demonstrate that the calcium source strongly influences the characteristics of the resultant powders, as phase purity and morphology of the wollastonite particles. XRD analysis showed that, using CaCl2.H2O on the synthesis, α-wollastonite started to crystallize as majority phase at 700 °C. The complete crystallization of α-wollastonite was observed after the calcination at 1000 °C for 5 h, while samples prepared with Ca(NO3)2.4H2O, only crystallized α-wollastonite at 1200 °C. This difference in crystallization temperature is probably related to the higher homogeneity and the elevated number of Si–O–Ca bonds present in samples prepared with CaCl2.H2O.
Behavior studies of thermoplastic polymers during non-isothermal crystallization are extremely important since most of their properties are influenced by degree of crystallinity and the ...crystallization process. In general, an approach based on a model-fitting method is used to perform crystallization kinetic studies. Due to their inability to uniquely determine the reaction mode, many studies have used the isoconversional method, where it is not necessary to assume a crystallization model to obtain the kinetic parameters. Therefore, in this work, the influence of acid and octadecylamine functionalized carbon nanotubes (CNTs) in the crystallization kinetic of polyethylene (PE) was studied using an isoconversional method with differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The kinetic parameters and the crystallization model were determined. The incorporation of functionalized and non-functionalized CNTs into PE did not change the Johnson-Mehl-Avrami crystallization model. However, the CNTs increased the crystallization temperature and reduced the activation energy for crystallization. In addition, the Avrami coefficient values were lower for the nanocomposites when compared to pure PE. The incorporation of CNTs accelerated the crystallization of PE, reducing the crystallite sizes and modifying their morphology.
Nanoparticles (NPs) have been studied for a wide variety of applications, due to the elevated surface area and outstanding properties. Several types of NPs are available nowadays, each one with ...particular characteristics and challenges. Bionanocomposites, especially composed by polymer matrices, are gaining attention in the biomedical field. Although, several studies have shown the potential of adding NPs into these materials, some investigation is still needed until their clinical use for in vivo application is consummated. Besides that, is essential to evaluate whether the addition of nanoparticles changes the matrix property. In this review, we summarize the latest advances concerning polymeric bionanocomposites incorporated with organic (polymeric, cellulosic, carbon-based), and inorganic (metallic, magnetics, and metal oxide) NPs.
Life expectancy has been growing, and more people are developing bone diseases such as arthritis and osteoporosis. Degenerative pathologies, injuries, and trauma can damage the bone tissues, ...requiring treatments that facilitate its repair, replacement, or regeneration. In this context, many materials have been developed to match this demand. Bioglasses and ceramics are promising inorganic materials to produce scaffolds for bone regeneration due to their attractive properties, such as biocompatibility, osteoinduction, and osteoconduction, besides their similarity with bone composition. Although their established advantages, these materials present limitations such as inadequate mechanical properties and fast degradation rate. Research work has been widely carried out to develop bioglasses, silicate, and phosphate calcium ceramics scaffolds with appropriated properties to enlarge their applications in bioengineering. Different fabrication techniques have also been evaluated. Incorporating other materials or particles, such as polymers, oxides and metal particles into the scaffolds has shown beneficial effects in mechanical strength and bone production stimulation. In this review, we provide an overview concerning the recent advances in developing calcium phosphates, calcium silicates, bioglasses, and composites scaffolds for bone regeneration in medical and dental applications.
Super hydrophilic scaffolds of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 3 wt % of acetylated (CNC-Ac) and PEGylated (CNC-PEG) cellulose nanocrystals (CNC) were prepared. PHBV, ...PHBV/CNC-Ac, and PHBV/CNC-PEG scaffolds were characterized with respect to their morphology by scanning electron microscopy (SEM) and X-ray microtomography. The crystallinity was evaluated by differential scanning calorimetry (DSC) and the mechanical properties by uniaxial compression tests. The presence of residual solvent was identified by gas chromatography (GC), wettability measured by static contact angle and aqueous adsorption by gravimetry. All the scaffolds showed porous morphology, being that, for neat PHBV the morphology was more regular with oriented pores. The porosity was reduced by 26% with the introduction of CNC-Ac and CNC-PEG, and the compression modulus increased by 25% and 72% for PHBV/CNC-Ac and PHBV/CNC-PEG scaffolds, respectively, compared to neat PHBV. Even with lower porosities, PHBV/CNC-Ac and PHBV/CNC-PEG adsorbed 16% and 67% more water than PHBV scaffold, following the intraparticle diffusion model for all the samples. No residual solvents were found and the crystallinity was slightly increased upon addition of CNC-Ac and CNC-PEG. Therefore, the addition of CNC-Ac and CNC-PEG can improve both compressive modulus and water uptake, turning PHBV nanocomposite scaffolds suitable for tissue engineering applications.
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•Super hydrophilic scaffolds of PHBV with functionalized cellulose nanocrystals were produced.•The addition of functionalized cellulose nanocrystals enhanced not only the water uptake, but also the compression modulus.•For all the conditions, porous and with no residual solvent scaffolds were obtained.•Scaffolds with reinforced mechanical and improved water adsorption properties were described.
Silver vanadate, especially β-AgVO
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, have a wide range of technological applications due to remarkable biological, optical, and electrical features. The structure, morphology, and properties of ...β-AgVO
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are directly affected by synthesis conditions. A comparative study between two different synthesis routes (precipitation and hydrothermal) of β-AgVO
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was systematically investigated in this work. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, zeta potential, and UV–visible spectrometry results showed that the hydrothermal method produced more homogeneous samples of β-AgVO
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, with elevated purity and crystallinity. In addition, the sample of β-AgVO
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obtained by hydrothermal method had a wire-like morphology while that obtained by precipitation had irregular shape. Finally, the hydrothermal procedure showed more elevated reproducibility.
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