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Mesoporous silica nanoparticles were synthesized using a microemulsion-assisted sol-gel method, and calcium, gallium or a combination of both, were used as dopants. The influence of these metallic ions on the physicochemical properties of the nanoparticles was investigated by scanning and transmission electron microscopy, as well as N2 adsorption-desorption methods. The presence of calcium had a significant impact on the morphology and textural features of the nanoparticles. The addition of calcium increased the average diameter of the nanoparticles from 80 nm to 150 nm, while decreasing their specific surface area from 972 m2/g to 344 m2/g. The nanoparticles of all compositions were spheroidal, with a disordered mesoporous structure. An ion release study in cell culture medium demonstrated that gallium was released from the nanoparticles in a sustained manner. In direct contact with concentrations of up to 100 µg/mL of the nanoparticles, gallium-containing nanoparticles did not exhibit cytotoxicity towards pre-osteoblast MC3T3-E1 cells. Moreover, in vitro cell culture tests revealed that the addition of gallium to the nanoparticles enhanced osteogenic activity. Simultaneously, the nanoparticles disrupted the osteoclast differentiation of RAW 264.7 macrophage cells. These findings suggest that gallium-containing nanoparticles possess favorable physicochemical properties and biological characteristics, making them promising candidates for applications in bone tissue regeneration, particularly for unphysiological or pathological conditions such as osteoporosis.
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Gálio , Nanopartículas , Osteoclastos , Osteogênese , Gálio/química , Gálio/farmacologia , Animais , Camundongos , Osteoclastos/efeitos dos fármacos , Nanopartículas/química , Osteogênese/efeitos dos fármacos , Dióxido de Silício/química , Dióxido de Silício/farmacologia , Células RAW 264.7 , Porosidade , Diferenciação Celular/efeitos dos fármacosRESUMO
The development of intricated and interconnected porous mats is desired for many applications in biomedicine and other relevant fields. The mats that comprise the use of natural, bioactive, and biodegradable polymers are the focus of current research activities. In the present work, crosslinked fibers with improved characteristics were produced by incorporating 1,4-butanediol diglycidyl ether (BDDE) into a polymer formulation containing polycaprolactone (PCL), chitosan (CS), and κappa-carrageenan (κ-C). A slight variation of formic acid (FA)/acetic acid (AA) ratio used as a solvent system, significantly affected the characteristics of the produced fiber mats. Both polysaccharides and BDDE played a major role in tailoring mechanical properties when fibrous scaffolds were reticulated under KCl-mediated basic conditions for determined periods of time at 50 °C. In vitro biological assessment of the electrospun fiber mats revealed proliferation of MC3T3-E1 cells when incubated for 1 and 7 days. After staining the cells with 4',6-diamidino-2-phenylindole (DAPI)/rhodamine phalloidin an autofluorescence response was observed by fluorescence microscopy in the scaffold manufactured using a solvent with higher FA/AA ratio due to the formation of microfibers. The results demonstrated the potential of the BDDE-crosslinked PCL/CS/κ-C electrospun fibers as promising materials for biomedical applications that may include soft and bone tissue regeneration.
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Quitosana , Carragenina , Engenharia Tecidual/métodos , Poliésteres , Polímeros , Solventes , Compostos Orgânicos , Alicerces TeciduaisRESUMO
Novel and eco-friendly solutions are extensively needed for wastewater treatment. This work capitalizes on the combination of waste vitrification and additive manufacturing to produce an efficient photocatalyst for the specific purpose. Fine powders of waste-derived glass, containing Fe3O4 inclusions, by simple suspension (for a solid loading of 65 wt %) in alkaline solution (5 M NaOH), were transformed into pastes for direct ink writing. 3D-printed reticulated scaffolds were stabilized by the progressive hardening of a zeolite-like gel, formed by glass/solution interaction, at nearly room temperature. The printed scaffolds were successfully tested for the removal of methylene blue, realized by combining the high sorption capacity of the gel with the catalytic activity of magnetite inclusions, under UV light. A complete degradation of methylene blue is achieved by 90 min exposure, comparing favorably with other reported photocatalytic materials, requiring from 60 to 360 min. The photocatalytic activity was tested for several cycles, with no significant degradation. In other words, a waste-derived material can be reused for multiple times, to remediate wastewaters, with evident benefits on waste minimization.
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Glasses activated with europium show promising potential for use in applications relating to photonics, in particular solid-state laser generation. In the current work, Eu2O3 incorporated gemanium borate glasses were developed and explored their potentiality towards lasing active medium by probing physical, structural, optical and lasing properties in detail. The physical and structural features of each glass indicated the presence of non-bridging oxygens (NBOs) and an enhancement in network stability on account of the inclusion of europium ions into the GeO2 glass network. Optical energy band gaps, Ed, Eo, no, So, and λo values were obtained by absorption spectra and found to be increased with europium content. The sequence of Judd-Ofelt (JO) intensity parameters (Ω2, Ω4, and Ω6) exhibited the trend Ω2 > Ω4 > Ω6, and it confirmed the covalent nature of the as-developed glasses. 1 mol% Eu2O3 doped glasses exhibited the highest photoluminescence, quantum efficiency and fluorescence intensity ratio (R). The decay profiles showed single exponential nature for 5D0 state of Eu3+ ions and their lifetime values were calculated. The results amply demonstrated the viability of the manufactured glasses as a potential solid-state active laser medium, with the CIE diagram confirming the intense red color emission as seen from the PL spectra.
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Mesoporous bioactive glass (MBG) is widely acknowledged in bone tissue engineering due to its mesoporous structure, large surface area, and bioactivity. Recent research indicates that introduction of metallic ions has beneficial impacts on bone metabolism and angiogenesis. Thus, the features of MBG can be modified by incorporating combinations of ions, such as magnesium (Mg) and copper (Cu), which can play a considerable role in bone formation, influencing angiogenesis, osteogenesis, as well as antibacterial properties. In this study, Mg and Cu were co-doped for the first time (in a ratio of 1 : 1) in 80SiO2-5P2O5-(15 - 2x)CaO-xMgO-xCuO glass composition with x = 0, 0.5, 1, and 2 mol%, synthesized using the sol-gel and evaporation-induced self-assembly method. X-ray diffraction analysis confirmed the amorphous nature of the powders, while inductively coupled plasma-optical emission spectrometry verified the existence of dopant ions in the respective amounts. The nitrogen sorption method indicated the formation of uniform cylindrical mesopores which are open at both ends and a high surface area of the powders. TEM images show fringes, indicating an ordered mesoporous structure in all MgCu co-doped systems. In vitro bioactivity was observed in all MBG powders, confirmed by the formation of an apatite phase when placed in simulated body fluid (SBF). Flake-like microstructure characteristics of HAp crystals found on the surface of MBG powders were visualized using FESEM. Cytotoxicity tests at lower concentrations (0.1 and 1 wt/vol%) of co-doped 2MC MBG (co-doping up to 2 mol%) showed cell proliferation and viability of osteoblast-like MG-63 cells and normal human dermal fibroblast (NHDF) cells similar to the basic glass 80S. Antibacterial study of MBG pellets showed an increment in the zone of inhibition with the sequential addition of doping ions. The turbidity measurement of bacterial cultures revealed that the optimal concentration for effectively inhibiting bacterial growth was 1 wt/vol% (i.e., 10 mg mL-1) concentration of MBG extracts. The result suggested that the incorporation of Mg and Cu ions in MBG in lower concentrations of up to 2 mol% can be useful in bone regeneration owing to bioactivity, cell proliferation, and antibacterial characteristics.
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Cobre , Magnésio , Humanos , Cobre/química , Regeneração Óssea , Antibacterianos/farmacologia , Antibacterianos/química , ÍonsRESUMO
A porous membrane was developed through alkali activation of pharmaceutical boro-alumino-silicate glass powders suspended in diluted NaOH and KOH aqueous solutions (2.5 M). A consolidated porous structure was obtained by the binding of unreacted particles mediated by a surface gel, developed upon drying of the suspensions and their curing at 40 °C for 14 days. The binding phase was sufficiently stable to resist immersion in boiling water and in acidic solutions. Copper adsorption tests were carried out under acidic pH, immersing the membranes in a Cu(NO3)2 solution for different periods of time. To determine the effect of surface washing on capture of copper ions, adsorption experiments with washed and unwashed membranes were also carried out, at varying pH. It was determined that the adsorption kinetics follow the pseudo-second-order kinetic model. The main adsorption mechanism observed is the electrostatic interaction between the negative surface charge of the washed membrane and the Cu2+ ions present in solution. An adsorption higher than 60% was observed at pH = 5, while at pH = 2 the efficiency decreased due to the presence of H3O+ ions. To ensure immobilization of copper, the membranes were densified by viscous flow sintering at a moderate temperature (700 °C). Leaching tests on membranes demonstrated the efficiency of the process in terms of copper ions immobilization.
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The mechanical qualities of AZ31B magnesium alloys make them a promising material for biodegradable metallic implants. However, rapid degradation limits the application of these alloys. In the present study, 58S bioactive glasses were synthesized using the sol-gel method and several polyols such as glycerol, ethylene glycol, and polyethylene glycol, were used to improve the sol stability and to control the degradation of AZ31B. The synthesized bioactive sols were dip-coated onto AZ31B substrates and then, characterized by various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical techniques (potentiodynamic and electrochemical impedance spectroscopy), among them. FTIR analysis confirmed the formation of a silica, calcium, and phosphate system and the XRD the amorphous nature of the 58S bioactive coatings obtained by sol-gel. The contact angle measurements confirmed that all the coatings were hydrophilic. The biodegradability response under physiological conditions (Hank's solution) was investigated for all the 58S bioactive glass coatings, observing a different behaviour depending on the polyols incorporated. Thus, for 58S PEG coating, an efficient control of the release of H2 gas was observed, and showing a pH control between 7.6 and 7.8 during all the tests. A marked apatite precipitation was also observed on the surface of the 58S PEG coating after the immersion test. Thus, the 58S PEG sol-gel coating is considered a promising alternative for biodegradable magnesium alloy-based medical implants.
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The optical characteristics of Dy3+-doped phosphate and borophosphate glasses with different divalent network modifiers prepared by melt-quenching are studied. The glass sets (A) with a molar composition of 40MO-60P2O5 and (B) with a molar composition of 40MO-20B2O3-40 P2O5 are investigated, both with M = (Zn2+, Mg2+, Ca2+, Sr2+, or Ba2+) and all doped with 0.1 mol% Dy2O3. Raman and fluorescence spectroscopy are used to analyse the structure and optical characteristics of these glasses. Four typical Dy3+ emission bands in the yellow (572 nm), blue (483 nm) and red (633 and 752 nm) regions of the spectrum are observed in both sets. The fluorescence lifetimes in each glass set are correlated to the network modifier's ionic field strength. The Mg2+ and Zn2+ containing glasses have the longest fluorescence lifetimes. The yellow to blue emission intensity ratio of the respective bands can be used to indicate a symmetric environment around Dy3+ ions and varies with the ionic field strength of the modifier cations: a higher ionic field strength leads to a higher yellow to blue ratio, which in turn indicates a higher asymmetrical local coordination environment of Dy3+ ions in the glassy host network.
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Realizing the neurological information processing by analyzing the complex data transferring behavior of populations and individual neurons is one of the fast-growing fields of neuroscience and bioelectronic technologies. This field is anticipated to cover a wide range of advanced applications, including neural dynamic monitoring, understanding the neurological disorders, human brain-machine communications and even ambitious mind-controlled prosthetic implant systems. To fulfill the requirements of high spatial and temporal resolution recording of neural activities, electrical, optical and biosensing technologies are combined to develop multifunctional bioelectronic and neuro-signal probes. Advanced two-dimensional (2D) layered materials such as graphene, graphene oxide, transition metal dichalcogenides and MXenes with their atomic-layer thickness and multifunctional capabilities show bio-stimulation and multiple sensing properties. These characteristics are beneficial factors for development of ultrathin-film electrodes for flexible neural interfacing with minimum invasive chronic interfaces to the brain cells and cortex. The combination of incredible properties of 2D nanostructure places them in a unique position, as the main materials of choice, for multifunctional reception of neural activities. The current review highlights the recent achievements in 2D-based bioelectronic systems for monitoring of biophysiological indicators and biosignals at neural interfaces.
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Mesoporous bioactive glass (MBG) is an extensively studied biomaterial used for the healing of bone defects. Its biological applications can be tailored by introducing metallic ions, such as strontium (Sr) and copper (Cu), which can enhance its functionalities, including osteogenetic, angiogenetic and antibacterial functionalities. In this study, Cu and Sr ions were co-doped (ratio 1:1) with x = 0.5, 1 and 2 mol% each in glass with an intended nominal composition of 80SiO2-(15-2x)CaO-5P2O5-xCuO-xSrO and synthesized with an evaporation-induced self-assembly (EISA)-based sol-gel technique. XRD confirmed the amorphous nature of the glass, while compositional analysis using ICP-OES confirmed the presence of dopant ions with the required amounts. A TEM study of the MBG powders showed fringes that corresponded to the formation of a highly ordered mesoporous structure. The Cu-Sr-doped MBG showed a positive effect on apatite formation when immersed in SBF, although the release of Cu and Sr ions was relatively slow for 1 mol% of each co-dopant, which signified a stable network structure in the glass. The impact of the Cu and Sr ions on the osteoblast-like cell line MG-63 was assessed. At the particle concentrations of 1 wt./vol.% or lower, the cell viability was above 50%. An antibacterial test was conducted against Gram-negative E. coli and Gram-positive S. aureus bacteria. With a sequential increase in the co-doped ion content in the glass, the zone of inhibition for bacteria increased. The results suggest that the doping of MBG with Cu and Sr ions at up to 2 mol% can result in tailored sustained release of ions to enhance the applicability of the studied glass as a functional biomaterial for bone regeneration applications.
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Additive manufacturing (AM) technologies enable the fabrication of objects with complex geometries in much simpler ways than conventional shaping methods. With the fabrication of recyclable filters for contaminated waters, the present work aims at exploiting such features as an opportunity to reuse glass from discarded pharmaceutical containers. Masked stereolithography-printed scaffolds were first heat-treated at relatively low temperatures (680 and 730 °C for 1 h) and then functionalized by alkali activation, with the formation of zeolite and sodium carbonate phases, which worked as additional adsorbing centers. As-sintered and activated scaffolds were characterized in terms of the efficiency of filtration and removal of methylene blue, used as a reference dye. The adsorption efficiency of activated printed glass was 81%. The 3D-printed adsorbent can be easily separated from the solution for reuse.
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'Silica-defective glasses', combined with a silicone binder, have been already shown as a promising solution for the manufacturing of glass-ceramics with complex geometries. A fundamental advantage is the fact that, after holding glass powders together from room temperature up to the firing temperature, the binder does not completely disappear. More precisely, it converts into silica when heat-treated in air. A specified 'target' glass-ceramic formulation results from the interaction between glass powders and the binder-derived silica. The present paper is dedicated to the extension of the approach to the coating of titanium substrates (to be used for dental and orthopedic applications), with a bioactive wollastonite-diopside glass-ceramic layer, by the simple airbrushing of suspensions of glass powders in alcoholic silicone solutions. The interaction between glass and silica from the decomposition of the binder led to crack-free glass-ceramic coatings, upon firing in air; in argon, the glass/silicone mixtures yielded novel composite coatings, embedding pyrolytic carbon. The latter phase enabled the absorption of infrared radiation from the coating, which is useful for disinfection purposes.
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We report the successful preparation and characterization of chitosan-Zn complex (ChiZn) in the form of films, intended to enhance the biological performance of chitosan by the presence of Zn as antibacterial agent and biologically active ion. The influence of Zn chelation on morphology and structure of chitosan was assessed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and infrared spectroscopy. The biodegradability study of ChiZn showed a sustained release of Zn up to 2 mg/mL. No toxic response was observed toward stromal cell line ST-2 in indirect contact with the ChiZn films. The dissolution product of ChiZn showed improved wound closure (88% closure) compared to the positive control group (70% closure). Moreover, ChiZn exhibited antibacterial activity against S. aureus together with a slight increase (~30%) in the secretion of VEGF and moderate decrease in nitric oxide evolution. Our findings indicate that ChiZn could be used as a safe and effective wound healing agent.
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Quitosana , Antibacterianos/química , Anti-Inflamatórios , Movimento Celular , Quitosana/química , Quitosana/farmacologia , Staphylococcus aureus , Cicatrização , Zinco/farmacologiaRESUMO
The present COVID-19 emergency has dramatically increased the demand for pharmaceutical containers, especially vials. End-of-life containers, however, cannot be easily recycled in the manufacturing of new articles. This paper presents some strategies for upcycling of pharmaceutical glass into various porous ceramics. Suspensions of a fine glass powder (70 vol%) are used as a starting material. Highly uniform cellular structures may be easily prepared by vigorous mechanical stirring of partially gelified suspensions with added surfactant, followed by drying and firing at 550-650 °C. Stabilization of the cellular structures at temperatures as low as the glass transition temperature (Tg) of the used glass is facilitated by thermal decomposition of the gel phase, instead of viscous flow sintering of glass. This finding enabled the preparation of glass membranes (â¼78 vol% open porosity), by direct firing of hardened suspensions, avoiding any surfactant addition and mechanical stirring. The powders obtained by crushing of hardened suspensions, even in unfired state, may be used as a low-cost sorbent for dye removal.
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The development of anti-corrosion polymeric coatings has grown exponentially in the fields of material science, chemistry, engineering, and nanotechnology during the last century and has prompted the evolution of efficient characterization techniques. Nowadays, polymeric coatings represent a well-established protection system that provides a barrier between a metallic substrate and the environment. However, the increase in complexity and functionality of these coatings requires high-precision techniques capable of predicting failures and providing smart protection. This review summarizes the state of the art for the main electrochemical techniques, emphasizing devices that track the anti-corrosion properties of polymeric coatings from the macroscale to the nanoscale. An overview of the advances in accelerated corrosion testing and the electrochemical characterization of coatings is explored, including insights into their advantages and limitations. In addition, the challenges and potential applications of the theoretical approaches are summarized based on current knowledge. Finally, this work provides the reader with the trends and challenges of designing future technologies and models capable of tracking corrosion and predicting failures.
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Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials' surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail.
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Electrospun fibers based on biodegradable polyanionic or polycationic biopolymers are highly beneficial for biomedical applications. In this work, electrospun nanofibers made from poly(epsilon caprolactone) (PCL), chitosan (CS) andκ-carrageenan (κ-C) were successfully fabricated using several mixtures of benign solvents containing formic acid and acetic acid. The addition ofκ-C improved the preparation procedure for the production of PCL/CS fibers by electrospinning. Moreover, a polymer mixture was selected to be stored at -20 °C for one month with the purpose to study the properties of the resulting fiber mat. The results indicated that fiber characteristics were not seriously compromised compared to the ones of those fabricated with the original solution, which represents an important reduction in produced waste. Thus, the interactions that occur between positively and negatively charged hydrophilic polysaccharides might induce higher stability to the linear aliphatic polyester in the polymer mixture. All fiber mats were morphologically, physico-chemically and mechanically characterized, showing average fiber diameters in the nano scale. A direct cell viability assay using ST-2 cells demonstrated cell proliferation after seven days of incubation for all prepared fiber mats, confirming their suitability as potential candidates for bone tissue engineering and wound healing applications.
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Quitosana , Nanofibras , Carragenina , Quitosana/química , Nanofibras/química , Poliésteres/química , Polímeros/química , Engenharia Tecidual/métodos , Alicerces Teciduais/químicaRESUMO
The incorporation of gallium into bioactive materials has been reported to enhance osteogenesis, to influence blood clotting, and to induce anti-cancer and anti-bacterial activity. Gallium-doped biomaterials prepared by various techniques include melt-derived and sol-gel-derived bioactive glasses, calcium phosphate bioceramics, metals and coatings. In this review, we summarize the recently reported developments in antibacterial, anticancer, osteogenesis, and hemostasis properties of Ga-doped biomaterials and briefly outline the mechanisms leading to Ga biological effects. The key finding is that gallium addition to biomaterials has great potential for treating bone-related diseases since it can be efficiently transferred to the desired region at a controllable rate. Besides, it can be used as a potential substitute for antibiotics for the inhibition of infections during the initial and advanced phases of the wound healing process. Ga is also used as an anticancer agent due to the increased concentration of gallium around excessive cell proliferation (tumor) sites. Moreover, we highlight the possibility to design different therapeutic approaches aimed at increasing the efficiency of the use of gallium containing bioactive materials for multifunctional applications.
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Fiber glass waste (FGW) was subjected to alkali activation in an aqueous solution with different concentrations of sodium/potassium hydroxide. The activated materials were fed into a methane-oxygen flame with a temperature of around 1600 °C. X-ray diffraction analysis confirmed the formation of several hydrated compounds, which decomposed upon flame synthesis, leading to porous glass microspheres (PGMs). Pore formation was favored by using highly concentrated activating alkali solutions. The highest homogeneity and yield of PGMs corresponded to the activation with 9 M KOH aqueous solution.
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The influence of 4% acetic acid (pH~2.4) and an alkaline solution of NaOH (pH~10) on the corrosion resistance and micromechanical properties of disilicate crystals containing glass-ceramics (LS2-GC's) is studied. Partially crystallized lithium metasilicate crystal containing glass-ceramics (LS-GC's) are annealed to fully LS2-GC's using a one stage and a two-stage heating to induce nucleation. Materials with various chemical and wear resistance are prepared. The content of the crystalline phase in the material annealed in the two-stage process A is 60.0% and increases to 72.2% for the material heated in the one-stage process B. The main elements leached in the acidic medium are lithium and phosphorus, while lithium, silicon, and phosphorus leached into the alkaline environment. Material B exhibits better chemical resistance to the corrosive influence of 4% acetic acid under quasi-dynamic conditions. In the alkaline corrosion medium, silicon is leached from material A faster compared to the material B. After prolonged exposure to acidic or basic environments, both materials show evidence of surface structural changes. A decrease of the sliding wear resistance is observed after corrosion in the acidic environment under dynamic conditions. In both materials, the wear rate increases after corrosion.