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1.
J Photochem Photobiol B ; 204: 111799, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32018156

RESUMO

CdSe/CdS core shelled quantum dots (QDs) were prepared by colloidal synthesis using a binary ligand system and a non-coordinating, reusable solvent n-octadecane (nOD). Both the synthesis of CdSe and CdSe/CdS core shelled quantum dots were achieved by hot injection technique at much lower temperatures than reported earlier. The use of binary ligand facilitated enough nucleation and growth. Red shift in absorption spectra, an enhanced crystallite and particle size is evidenced by XRD and TEM respectively, confirming the formation of core shell structure of CdSe/CdS. The synthesized core shells exhibited high fluorescence intensity, long term stability and good mono dispersion, making it a potential material for bio-imaging and sensing. Core shell QDs were modified with mercapto propionic acid (MPA) to impart aqueous solubility. Studies on cytotoxicity of shelled QDs reveal good bio compatibility with a very minimum toxicity of IC50 = 20 µg/L. These QDs were used for sensing E. coli. Ordinary glass slide, modified using plasma etching is surface modified through APTES aiding conjugation of antibodies. Anti- E. coli polyclonal antibody on glass matrix (slide) and antibody conjugated QDs were used for detection of E. coli in a typical sandwich model. The excellent optical transparency of glass and high emission of QDs lead to detection of E.coli with a limit of detection of 50 CFU/mL.


Assuntos
Escherichia coli/efeitos dos fármacos , Vidro/química , Pontos Quânticos/química , Animais , Compostos de Cádmio/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Compostos de Selênio/química , Sulfetos/química , Propriedades de Superfície
2.
Braz Oral Res ; 34: e004, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32022223

RESUMO

The aim of this study was to analyze the structural, morphological and mechanical properties of two different lithium disilicate glass-reinforced ceramics for CAD-CAM systems (IPS e.max CAD and Rosetta SM). Five methodologies were used for both ceramics: microstructure (n = 2) was analyzed using x-ray diffraction (XRD); morphological properties (n = 2) were analyzed by scanning electron microscopy (SEM), with and without hydrofluoric etching; porosity (n = 3) was assessed using 3D micro-computed tomography (micro-CT); flexural strength was measured (n =1 0) using the three-point bending test; and bond strength was determined with self-adhesive resin cement (n = 10), using a microshear bond test. After performing all the tests, the data were analyzed using t-Student test and two-way ANOVA. All the tests used a significance level of α = 0.05. High peak positions corresponding to standard lithium metasilicate and lithium disilicate with similar intensities were observed for both ceramics in the XRD analysis. Morphological analysis showed that the crystalline structure of the two ceramics studied showed no statistical difference after acid etching. Additionally, no significant differences were recorded in the number or size of the pores for the ceramics evaluated. Moreover, no differences in flexural strength were found for the ceramic materials tested, or in the bond strength to ceramic substrates for the resin cements. Based on the study results, no significant differences were found between the two CAD-CAM lithium disilicate glass-reinforced ceramics tested, since they presented similar crystalline structures with comparable intensities, and similar total porosity, flexural strength and bond strength.


Assuntos
Cerâmica/química , Projeto Auxiliado por Computador , Porcelana Dentária/química , Vidro/química , Análise de Variância , Colagem Dentária/métodos , Resistência à Flexão , Teste de Materiais , Microscopia Eletrônica de Varredura , Porosidade , Valores de Referência , Reprodutibilidade dos Testes , Cimentos de Resina/química , Resistência ao Cisalhamento , Propriedades de Superfície , Difração de Raios X
3.
Chem Commun (Camb) ; 56(10): 1561-1564, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31930270

RESUMO

A glass nanopipette functionalized with ATP-responsive gold nanoparticle assemblies was developed for ATP detection in single-cells and used for analysing the content change of ATP during electrostimulus (ES)-induced apoptosis. The variation of ATP content in single normal cells and cancer cells during apoptosis was detected by the method.


Assuntos
Trifosfato de Adenosina/análise , Ouro/química , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Apoptose , Linhagem Celular , Eletricidade , Vidro/química , Células HeLa , Humanos , Microscopia de Fluorescência , Nanoporos , Análise de Célula Única
4.
J Phys Chem Lett ; 11(3): 1170-1177, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31967479

RESUMO

Understanding nanoscale protein conformational changes at solid-liquid interfaces is critical for predicting how proteins will impact the performance of biomaterials in vivo. Crowding is an important contributor to conformational stability. Here we apply single-molecule high resolution imaging with photobleaching to directly measure dye-conjugated fibronectin's unfolding in varying conditions of crowding with human serum albumin on aminosilanized glass. Using this approach, we identify serum albumin's crowding mechanism. We find that fibronectin achieves larger degrees of unfolding when not crowded by coadsorbed serum albumin. Serum albumin does not as effectively constrict fibronectin's conformation if it is sequentially, rather than simultaneously, introduced, suggesting that serum albumin's crowding mechanism is dependent on its ability to sterically block fibronectin's unfolding during the process of adsorption. Because fibronectin's conformation is dependent on interfacial macromolecular crowding under in vitro conditions, it is important to consider the role of in vivo crowding on protein activity.


Assuntos
Fibronectinas/química , Albumina Sérica/química , Fibronectinas/metabolismo , Vidro/química , Humanos , Nanotecnologia/métodos , Estabilidade Proteica , Desdobramento de Proteína , Albumina Sérica/metabolismo , Propriedades de Superfície
5.
Food Microbiol ; 87: 103354, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948611

RESUMO

Viruses are transmissible via their interaction with contact surfaces of food containers or tools. This study evaluated the recoveries of MS2 coliphage, a virus surrogate, from polypropylene (PP), polyvinyl chloride (PVC), polyethylene (PE), and glass (borosilicate and soda lime), as influenced by the surface chemistry and topography. MS2 (5-6 logs) in PBS with 1% TSB was inoculated onto each of 9 different surfaces, 24-h cold-incubated, and recovery was quantified by infectivity. The order of MS2 recovery efficiency from smooth surfaces was PP > PE ≥ soda lime glass, which classified into 3 ANOVA groups, p = 0.05. The MS2 recovery ratios of smooth vs. rough surfaces were 1.4-1.5. Atomic force microscopy revealed 21-nm diam pinholes (<28-nm of MS2 size) in the borosilicate glass. The lowest and highest MS2 recoveries among the 9 surfaces were demonstrated by the hole-bearing borosilicate glass (34 ±â€¯8%) and smooth PP (69 ±â€¯14%) respectively. Generally greater MS2 recovery was obtained from smooth PP and PE surfaces compared to glass, but topographic alterations (pinholes or increased roughness) decreased recovery possibly by trapping the viruses.


Assuntos
Vidro/química , Levivirus/fisiologia , Polímeros/química , Levivirus/química , Levivirus/crescimento & desenvolvimento , Levivirus/isolamento & purificação , Microscopia de Força Atômica , Propriedades de Superfície , Ligação Viral
6.
Food Chem ; 311: 125929, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855772

RESUMO

The effects of sugar component ratio, water fraction, and storage conditions on crystallisation and glass transition temperature (Tg) of three Chilean dried raisins were examined by using differential scanning calorimetry (DSC), polarised light microscopy and X-ray diffraction (XRD) techniques. Thompson, Flame and Golden raisins differed in fructose:glucose and glucose:water ratios, impacting on their measured Tgs (P < 0.05) and propensity of sugaring. The ratios of fructose:glucose (1:3, 1:2 and 1:1) and glucose:water (1.7, 1.9 and 2.1) also influenced the measured Tgs (P < 0.05) and sugaring of fructose-glucose-water model solutions. Measurement of Tgs in the raisins as a function of water activity (aw 0.11-0.74) showed that water acts as a strong plasticiser decreasing the Tgs (-16.4 to -61.6 °C). XRD results revealed that sugaring in Thompson raisins was delayed at low temperatures (5 & 15 °C) compared to that stored at 25 °C. The refrigeration may be a simple approach to delay the sugaring in raisins.


Assuntos
Açúcares/química , Vitis/química , Varredura Diferencial de Calorimetria , Chile , Temperatura Baixa , Cristalização , Frutas/química , Vidro/química , Temperatura de Transição , Vitrificação , Água/análise , Difração de Raios X
7.
Environ Sci Pollut Res Int ; 26(36): 36287-36295, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713827

RESUMO

Preparation of the value-added products from e-waste resources is an important step in the recycling process. The present paper aims to propose a methodology for the recovery of In from scrap LCD panel via preparation of InBO3 nanostructure. Discarded LCD panel was subjected to a recycling process through crushing, milling, and oxalic acid leaching to prepare In2(C2O4)3·6H2O. Through the leaching process, B(OH)3 from glass part (alumina borosilicate) has been leached out along with indium oxalate hydrated. Further thermal treatment on these extracted materials at 600 °C could result in the formation of InBO3 nanostructures with an average particle size of 20 nm. A multistep mechanism based on thermodynamic calculations for the recycling of the InBO3 form extracted precursors was proposed. Graphical abstract.


Assuntos
Resíduo Eletrônico , Cristais Líquidos/química , Nanoestruturas/química , Reciclagem/métodos , Compostos de Boro/química , Vidro/química , Temperatura Alta , Índio/química , Ácido Oxálico/química , Tamanho da Partícula
8.
Niger J Clin Pract ; 22(10): 1441-1447, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31607737

RESUMO

Background: There was no enough data about the appropriate surface cleaning of core composite material after temporary cementation. Aim: To evaluate the effects of surface cleaning techniques on initial shear bond strength (SBS) between core composite material and resin nanoceramic crown materials after temporary cementation. Material and Methods: Cubic specimens were prepared from prosthetic materials, including Lava Ultimate. Cylinder-shaped composites were cemented to glass slides with eugenol-free temporary cement, resulting in a total of 44 cylinders (n = 11). The surfaces of composite cylinders were then cleaned with an Er, Cr:YSGG laser, 37% orthophosphoric acid, yellow tape diamond bur, or dental explorer. Cleaned cylinders were bonded to cubic specimens with resin cement. Initial SBS tests were performed with a universal testing machine at 0.5 mm/min crosshead speed. One-way ANOVA and post hoc Tukey tests were used to analyze the obtained data (P =0.05). Results: Initial SBS values were significantly affected by the different surface cleaning methods (P <.05). The highest SBS value was obtained with the laser group (SBS = 17.14), while the lowest was obtained with dental explorer group (SBS = 5.95). There was no significant difference between the diamond bur group and the laser group (P =0.982). Conclusions: Laser irradiation or yellow tape diamond bur cleaning of the core composite surface could be recommended to strengthen bond strength between the resin luting cement and the core composite. Before adhesive or conventional cementation of prosthetic restoration, the core composite surface should be cleaned.


Assuntos
Colagem Dentária/métodos , Cimentos Dentários/química , Corrosão Dentária/métodos , Adesivos Dentinários/química , Vidro/química , Lasers de Estado Sólido/uso terapêutico , Cimentos de Resina/química , Cimentação , Resinas Compostas/química , Cimentos de Ionômeros de Vidro , Humanos , Teste de Materiais , Resistência ao Cisalhamento , Propriedades de Superfície
9.
Anal Chim Acta ; 1088: 35-44, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31623714

RESUMO

A polyaminosaccharide (chitosan, CS) and an aminosaccharide (d-galactosamine, GalN) were integrated together via hydrothermal assembly to obtain a bis-aminosaccharides composite (CS-GalN), and a novel and facile chiral sensing platform based on CS-GalN modified glassy carbon electrode (CS-GalN/GCE) was fabricated and used for electrochemical recognition of tyrosine (Tyr) enantiomers. CS-GalN composite was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and contact angle goniometry. It was observed that CS-GalN composite exhibited different binding ability for Tyr enantiomers. Under optimized experimental conditions, the oxidation peak current ratio of L-Tyr to D-Tyr (IL/ID) and the difference between their peak potentials (ΔEp = ED-EL) were 1.70 and 28 mV at CS-GalN/GCE by square wave voltammetry (SWV). In addition, the peak currents increase linearly with the concentration of Tyr enantiomers in the concentration range 0.01-1.00 mM with detection limits of 0.65 µM and 0.86 µM for L-Tyr and D-Tyr (S/N = 3), respectively. CS-GalN/GCE also exhibited the ability to determine the percentage of D-Tyr in the racemic mixture. In addition, CS-GalN/GCE possessed remarkable sensitivity, great stability as well as fine reproducibility. It could be concluded that the chiral interface of CS-GalN/GCE can provide an ideal platform for electrochemical recognition and determination of Tyr enantiomers.


Assuntos
Amino Açúcares/química , Carbono/química , Eletroquímica/instrumentação , Vidro/química , Tirosina/análise , Tirosina/química , Eletrodos , Concentração de Íons de Hidrogênio , Limite de Detecção , Modelos Moleculares , Conformação Molecular , Estereoisomerismo , Temperatura Ambiente
10.
Molecules ; 24(19)2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31561457

RESUMO

Porous glass was prepared by the hydrothermal reaction of sodium borosilicate glass, and oxygen-ion characterization was used to identify the hydroxyl groups in its surface area. A substantial amount of "water" was introduced into the ionic structure as either OH- groups or H2O molecules through the hydrothermal reaction. When the hydrothermally treated glass was reheated at normal pressures, a porous structure was formed due to the low-temperature foaming resulting from the evaporation of H2O molecules and softening of the glass. Although it was expected that the OH- groups would remain in the porous glass, their distribution required clarification. Oxygen K-edge X-ray absorption fine structure (XAFS) spectroscopy enables the bonding states of oxygen ions in the surface area and interior to be characterized using the electron yield (EY) and fluorescence yield (FY) mode, respectively. The presence of OH- groups was detected in the O K-edge XAFS spectrum of the porous glass prepared by hydrothermal reaction with a corresponding pre-edge peak energy of 533.1 eV. In addition, comparison of the XAFS spectra obtained in the EY and FY modes revealed that the OH- groups were mainly distributed in the surface area (depths of several tens of nanometers).


Assuntos
Vidro/química , Íons/química , Oxigênio/química , Silicatos/química , Espectroscopia por Absorção de Raios X , Porosidade , Temperatura Ambiente , Água/química
11.
Artigo em Inglês | MEDLINE | ID: mdl-31507308

RESUMO

A very small number of biomaterials investigated for bone regeneration was reported as able to prevent the oxidative stress. In this study beads based on alginate hydrogel and mesoporous glasses (MG) containing different amounts of cerium oxides (Ce3+/Ce4+) exhibiting antioxidant properties were investigated as a good approach to mimic the action of antioxidant enzymes in our organism. The effect of cerium contents on the bioactivity and biocompatibility of beads were investigated. Moreover, the potential capability of Ce-containing MG to prevent the oxidative stress caused by the activity of reactive oxygen species (ROS) was here investigated for the first time. The increment of cerium oxide from 1.2, to 3.6 and 5.3 mol-% decreases the surface area and porosity of MG and increases the catalase mimetic activity after 168 h. Swelling tests in different cell culture media (D- and α-MEM) demonstrated the rehydration capability of beads. The presence of beads with the highest Ce-contents (3.6 and 5.3 %) improved the proliferation of pre-osteoblastic cells MC3T3-Cl cells. However, the cell differentiation decreased when increased the cerium content. Lactate dehydrogenase assays showed beads are cytocompatible materials. Moreover, oxidative stress tests with H2O2 showed a better response related to cell viability and the elimination of oxidant species when increased cerium content. Beads of glasses with 1.2 and 3.6 % of CeO2 are excellent candidates as bioactive scaffolds for bone regeneration capable of counteract the oxidative stress.


Assuntos
Alginatos/farmacologia , Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Cério/farmacologia , Vidro/química , Microesferas , Espécies Reativas de Oxigênio/metabolismo , Animais , Catalase/metabolismo , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Espectroscopia de Ressonância Magnética , Camundongos , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Porosidade
12.
Mater Sci Eng C Mater Biol Appl ; 105: 110138, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546409

RESUMO

In the present study, porous (about 70 vol%) nanocomposite scaffolds made of polycaprolactone (PCL) and different amounts (0 to 15 wt%) of 45S bioactive glass (BG) nanoparticles (with a particle size of about 40 nm) containing 7 wt% strontium (Sr) were fabricated by solvent casting technique for bone tissue engineering. Then, a selected optimum scaffold was coated with a thin layer of chitosan containing 15 wt% Sr-substituted BG nanoparticles. Several techniques such as X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), tensile test, and water contact angle measurement were used to characterize the fabricated samples. In vitro experiments including degradation, bioactivity, and biocompatibility (i.e., cytotoxicity, alkaline phosphate activity, and cell adhesion) tests of the fabricated scaffold were performed. The biomedical behavior of the fabricated PCL-based composite scaffold was interpreted by considering the presence of the porosity, Sr-substituted BG nanoparticles, and the chitosan coating. In conclusion, the fabricated chitosan-coated porous PCL/BG nanocomposite containing 15 wt% BG nanoparticles could be utilized as a good candidate for bone tissue engineering.


Assuntos
Fosfatase Alcalina/metabolismo , Osso e Ossos/fisiologia , Quitosana/química , Vidro/química , Nanocompostos/química , Poliésteres/química , Estrôncio/química , Engenharia Tecidual/métodos , Tecidos Suporte/química , Adesão Celular , Linhagem Celular Tumoral , Sobrevivência Celular , Difusão Dinâmica da Luz , Humanos , Nitrogênio/química , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Molhabilidade , Difração de Raios X
13.
Mater Sci Eng C Mater Biol Appl ; 105: 109971, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546454

RESUMO

A very small number of biomaterials investigated for bone regeneration were reported as able to prevent the oxidative stress. In this study beads based on alginate hydrogel and mesoporous glasses (MG) containing different amounts of cerium oxides (Ce3+/Ce4+) exhibiting antioxidant properties were investigated as a good approach to mimic the action of antioxidant enzymes in our organism. The effect of cerium contents on the bioactivity and biocompatibility of beads were investigated. Moreover, the potential capability of Ce-containing MG to prevent the oxidative stress caused by the activity of reactive oxygen species (ROS) was here investigated for the first time. The increment of cerium oxide from 1.2, to 3.6 and 5.3 mol% decreases the surface area and porosity of MG and increases the catalase mimetic activity after 168 h. Swelling tests in different cell culture media (D- and α-MEM) demonstrated the rehydration capability of beads. The presence of beads with the highest Ce-contents (3.6 and 5.3%) improved the proliferation of pre-osteoblastic cells MC3T3-C1 cells. However, the cell differentiation decreased when increased the cerium content. Lactate dehydrogenase assays showed beads are cytocompatible materials. Moreover, oxidative stress tests with H2O2 showed a better response related to cell viability and the elimination of oxidant species when increased cerium content. Beads of glasses with 1.2 and 3.6% of CeO2 are excellent candidates as bioactive scaffolds for bone regeneration capable of counteract the oxidative stress.


Assuntos
Alginatos/química , Materiais Biocompatíveis/farmacologia , Regeneração Óssea/efeitos dos fármacos , Cério/farmacologia , Vidro/química , Microesferas , Espécies Reativas de Oxigênio/metabolismo , Animais , Catalase/metabolismo , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Espectroscopia de Ressonância Magnética , Camundongos , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Mater Sci Eng C Mater Biol Appl ; 104: 109962, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499969

RESUMO

Plasma poly(ethylene oxide) thin films at different thicknesses of 20, 100, 250, 500 nm were deposited by plasma-assisted physical vapor deposition on glass substrates between aluminum electrodes in capacitor form at 5 W plasma discharge power. The structural analyses were performed by Fourier transform in7frared spectroscopy. The dielectric properties such as dielectric constant κ' and electric modulus M'' were defined by dielectric spectroscopy measurements. Dielectric spectroscopy measurements were performed in the angular frequency range of 10-1-106 rad/s and temperature range of 353-173 K range. The measurement results showed that α, ß, and γ-relaxations, which are the expected relaxations in polymeric structures, are effective on total polarization in the investigated frequency and temperature range. Dielectric constant exhibits an increase till 500 nm, then reaches a saturation behavior. When resonance angular frequencies belonging to α-relaxation were fitted by Vogel-Fulcher-Tamman equation. It was observed that glass transition temperatures increase with decreasing thickness. These results support the influence of the dead layer to total polarization and the dynamics of the structure. Besides, it was shown that dielectric spectroscopy is a useful way to analyze the glass transition temperature in thin film form.


Assuntos
Vidro/química , Polietilenoglicóis/química , Polímeros/química , Varredura Diferencial de Calorimetria/métodos , Cristalização/métodos , Espectroscopia Dielétrica/métodos , Temperatura de Transição
15.
Mater Sci Eng C Mater Biol Appl ; 104: 109929, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500017

RESUMO

The clinical application of composites seeks to exploit the mechanical and chemical properties of materials which make up the composite, and in researching polymer composites for biomedical applications the aim is usually to enhance the bioactivity of the polymer, while maintaining the mechanical properties. To that end, in this study medical grade Poly(L-lactic) acid (PLLA) has been reinforced with short phosphate-based glass fibers (PGF). The materials were initially mixed by melting PLLA granules with the short fibers, before being extruded to form a homogenous filament, which was pelletized and used as feedstock for compression moulding. As made the composite materials had a bending strength of 51 MPa ±â€¯5, and over the course of eight weeks in PBS the average strength of the composite material was in the range 20-50 MPa. Human mesenchymal stromal cells were cultured on the surfaces of scaffolds, and the metabolic activity, alkaline phosphatase production and mineralization monitored over a three week period. The short fiber filler made no significant difference to cell proliferation or differentiation, but had a clear and immediate osteoinductive effect, promoting mineralization by cells at the material surface. It is concluded that the PLLA/PGF composite material offers a material with both the mechanical and biological properties for potential application to bone implants and fixation, particularly where an osteoinductive effect would be valuable.


Assuntos
Calcificação Fisiológica/efeitos dos fármacos , Vidro/química , Fosfatos/farmacologia , Poliésteres/farmacologia , Bioensaio , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Íons , Osteogênese/efeitos dos fármacos , Espectroscopia de Prótons por Ressonância Magnética , Difração de Raios X
16.
Mater Sci Eng C Mater Biol Appl ; 104: 109994, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500021

RESUMO

In this study, mesoporous bioactive glass (MBG) sub-micro particles were prepared through sol-gel synthesis and possessed a uniform and spherical structure with particle size of 302 ±â€¯43 nm, a pore size of 4 nm and a high surface area of 354 m2 g-1. Alendronate (AL) is often used for the treatment of bone associated diseases, in particular osteosarcoma. However, due to the low bioavailability and high toxicity at increased doses, local and sustained release would be an ideal approach to AL delivery. Here, MBGs and aminated MBGs (AMBG) were applied as carriers for AL loading. High encapsulation efficiency of 75% and 85% and loading efficiency of 60% and 63%, for MBG and AMBG, respectively, was achieved. The release profile of AL from AMBG showed a better sustained and controlled release mechanism compared to MBG. In vitro results demonstrated the non-cytotoxic nature of both MBG and AMBG following exposure to MG63 osteoblast like cell line. AL release from MBG and AMBG, even at lower concentration, provoked decreased MG63 proliferation. The osteogenic potential of MBG and AMBG following exposure to dental pulp stem cells was evaluated using alizarin red assay.


Assuntos
Alendronato/farmacologia , Neoplasias Ósseas/tratamento farmacológico , Regeneração Óssea/efeitos dos fármacos , Vidro/química , Osteoblastos/efeitos dos fármacos , Osteossarcoma/tratamento farmacológico , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Porosidade , Tecidos Suporte
17.
Mater Sci Eng C Mater Biol Appl ; 104: 109910, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500031

RESUMO

Novel bioactive glasses with different amount of zinc oxide (ZnO), namely 2, 3.8 and 5 mol%, were designed, produced by a melt-quenching route and investigated in terms of biological performance. Proper amounts of ZnO were added to a previously developed bioactive glass containing strontium and magnesium, characterized by an ultra-high crystallization temperature. Thus, the aim of the work was to obtain a bioactive glass with high crystallization temperature in view of an eventual thermal treatment, as well as antibacterial properties (due to the antimicrobial effect of zinc, as reported in the literature). Bioactivity was investigated by immersion in Simulated Body Fluid (SBF), which is a commonly used protocol to evaluate samples' bioactivity in vitro. Additionally, in order to exclude the possible cytotoxicity of Zn containing bioactive glasses, a biological investigation using MLO-Y4 cells was carried out, both by direct (NR uptake) and indirect (MTT) contact tests. Finally, the antibacterial effects of the produced bioactive glasses against Staphylococcus epidermidis (Gram-positive), Pseudomonas aeruginosa and Escherichia coli (both Gram-negative) were investigated.


Assuntos
Antibacterianos/farmacologia , Vidro/química , Temperatura Ambiente , Zinco/farmacologia , Animais , Bactérias/efeitos dos fármacos , Materiais Biocompatíveis/farmacologia , Linhagem Celular , Forma Celular/efeitos dos fármacos , Cristalização , Camundongos , Testes de Sensibilidade Microbiana , Difração de Raios X
18.
Mater Sci Eng C Mater Biol Appl ; 104: 109895, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500047

RESUMO

The repair and restoration of bone defects in orthopaedic and dental surgery remains a major challenge despite advances in surgical procedures and post-operative treatments. Bioactive glasses, ceramics, glass-ceramics and composites show considerable potential for such applications as they can promote bone tissue regeneration. This paper presents an overview of the mechanical properties of various bioactive materials, which have the potential for bone regeneration. It also identifies current strategies for improving the mechanical properties of these novel materials, as these are rarely ideal as direct replacements for human bone. For this reason bioactive organic-inorganic composites and hybrids that have tailorable mechanical properties are of particular interest. The inorganic component (bioactive glass, ceramic or glass-ceramic) can provide both strength and bioactivity, while the organic component can add structural reinforcement, toughness and processability. Another topic presented in this paper includes 3D porous scaffolds that act as a template for cell attachment, proliferation and bone growth. Mechanical limitations of existing glass and ceramic scaffolds are discussed, along with the relevant challenges and strategies for further improvement. Advantages and disadvantages of different bioactive materials are critically examined. This paper is focused on optimization of biomaterials properties, in particular mechanical properties and bioactivity.


Assuntos
Materiais Biocompatíveis/química , Cerâmica/química , Vidro/química , Animais , Materiais Biocompatíveis/administração & dosagem , Regeneração Óssea/efeitos dos fármacos , Substitutos Ósseos/química , Osso e Ossos/efeitos dos fármacos , Humanos , Teste de Materiais/métodos , Porosidade
19.
Mater Sci Eng C Mater Biol Appl ; 104: 110004, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500052

RESUMO

Biodegradable materials that combine bioactivity with sustained drug release have been proved promising for the treatment and prophylaxis of bone infection. In this work, injection-molded nanocomposites were formulated from poly(3-hydroxybutyrate-co-3-6%hydroxyvalerate) (PHBV), nanodiamond (nD) and nanohydroxyapatite (nHA) loaded with vancomycin (VC). The components were compounded using a rotary evaporator (PHBV/nHA/VC/nD-R) or a spray-dryer (PHBV/nHA/VC/nD-SD). The nanoparticles acted as a nucleating agent, increasing PHBV crystallinity from 57.1% to up to 73.3% (PHBV/nHA/VC/nD-SD). The nHA particles were found to be well distributed on the formulations fracture surface observed by SEM-EDS micrographs. PHBV/nHA/VC/nD-SD presented higher glass transition temperature (18.1 vs 14.8 °C) and stronger interface than PHBV/nHA/VC/nD-R, as determined by dynamic mechanical analysis (DMA). Furthermore, the incorporation of nanoparticles increased PHBV flexural elastic modulus by 34% and match the reported for human bone. Both systems were able to present a sustained release of VC for 22 days, reaching 7.1 ±â€¯1.3%(PHBV/nHA/VC/nD-R) and 4.8 ±â€¯0.6% (PHBV/nHA/VC/nD-SD). VC presented antibacterial activity even after being processed at 178 °C in an injection molding machine. Moreover, in vitro assays showed a good adhesion and growth of cells on the specimens and suggested a non-cytotoxic and non-cytostatic behavior. These findings indicate that these systems can be further explored as bone defect filling material.


Assuntos
Doenças Ósseas/tratamento farmacológico , Osso e Ossos/efeitos dos fármacos , Nanocompostos/administração & dosagem , Nanocompostos/química , Poliésteres/química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Química Farmacêutica/métodos , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacologia , Sistemas de Liberação de Medicamentos/métodos , Vidro/química , Camundongos , Nanopartículas/administração & dosagem , Nanopartículas/química , Células RAW 264.7 , Engenharia Tecidual/métodos , Temperatura de Transição , Vancomicina/química , Vancomicina/farmacologia
20.
Molecules ; 24(17)2019 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-31480443

RESUMO

The accumulation of biofilm by Streptococcus mutans bacteria on hard tooth tissues leads to dental caries, which remains one of the most prevalent oral diseases. Hence, the development of new antibiofilm agents is of critical importance. The current study reports the results from testing the effectiveness of octyl gallate (C8-OG) against: (1) S. mutans biofilm formation on solid surfaces (polystyrene, glass), (2) acidogenicity, (3) and the expression of biofilm-related genes. The amount of biofilm formed by S. mutans bacteria was evaluated using the colorimetric method and optical profilometry. The pH of the biofilm growth medium was measured with microelectrode. A quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was used to assess the expression of genes encoding glucan binding protein B (gbpB), glucosyltransferases B, -C, -D (gtfB, -C, -D), and the F-ATPase ß subunit of the F1 protein (atpD). The results show that C8-OG significantly diminished biofilm formation by exposed S. mutans on solid surfaces and suppressed acidogenicity in a dose-dependent manner, compared to unexposed bacteria (p < 0.05). The C8-OG concentration of 100.24 µM inhibited S. mutans biofilm development on solid surfaces by 100% and prevented a decrease in pH levels by 99%. In addition, the RT-qPCR data demonstrate that the biofilm-producing bacteria treated with C8-OG underwent a significant reduction in gene expression in the case of the four genes under study (gbpB, gtfC, gtfD, and atpD), and there was a slight decrease in expression of the gtfB gene. However, C8-OG treatments did not produce significant expression change compared to the control for the planktonic cells, although there was a significant increase for the atpD gene. Therefore, C8-OG might be a potent antibiofilm and/or anticaries agent for oral formulations that aim to reduce the prevalence of dental caries.


Assuntos
Ácidos/metabolismo , Biofilmes/efeitos dos fármacos , Ácido Gálico/análogos & derivados , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Streptococcus mutans/genética , Streptococcus mutans/fisiologia , Antibacterianos/farmacologia , Biomassa , Ácido Gálico/química , Ácido Gálico/farmacologia , Genes Bacterianos , Vidro/química , Poliestirenos/química , Streptococcus mutans/efeitos dos fármacos , Propriedades de Superfície
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