Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 121
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Biochim Biophys Acta Biomembr ; 1864(1): 183749, 2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-34506795

RESUMO

Gangliosides induced a smelting process in nanostructured amyloid fibril-like films throughout the surface properties contributed by glycosphingolipids when mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC)/Aß(1-40) amyloid peptide. We observed a dynamical smelting process when pre-formed amyloid/phospholipid mixture is laterally mixed with gangliosides. This particular environment, gangliosides/phospholipid/Aß(1-40) peptide mixed interfaces, showed complex miscibility behavior depending on gangliosides content. At 0% of ganglioside covered surface respect to POPC, Aß(1-40) peptide forms fibril-like structure. In between 5 and 15% of gangliosides, the fibrils dissolve into irregular domains and they disappear when the proportion of gangliosides reach the 20%. The amyloid interfacial dissolving effect of gangliosides is taken place at lateral pressure equivalent to the organization of biological membranes. Domains formed at the interface are clearly evidenced by Brewster Angle Microscopy and Atomic Force Microscopy when the films are transferred onto a mica support. The domains are thioflavin T (ThT) positive when observed by fluorescence microscopy. We postulated that the smelting process of amyloids fibrils-like structure at the membrane surface provoked by gangliosides is a direct result of a new interfacial environment imposed by the complex glycosphingolipids. We add experimental evidence, for the first time, how a change in the lipid environment (increase in ganglioside proportion) induces a rapid loss of the asymmetric structure of amyloid fibrils by a simple modification of the membrane condition (a more physiological situation).


Assuntos
Peptídeos beta-Amiloides/química , Gangliosídeos/química , Glicoesfingolipídeos/química , Lipídeos de Membrana/química , Nanoestruturas/química , Fragmentos de Peptídeos/química , Amiloide/química , Peptídeos beta-Amiloides/ultraestrutura , Microscopia de Força Atômica , Nanoestruturas/ultraestrutura , Fragmentos de Peptídeos/ultraestrutura , Fosfatidilcolinas/química , Propriedades de Superfície
2.
Molecules ; 26(16)2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34443412

RESUMO

Palmarosa essential oil (PEO) is an alternative to synthetic fungicides to control the contamination by food-deteriorating fungi, such as Aspergillus nomius. Nonetheless, the low long-term stability and volatility hamper its utilization. Thus, this study aimed to develop nanostructured lipid carriers (NLCs) containing PEO to improve its stability and consequently prolong the activity against A. nomius. A mixture design was applied to find the best preparation conditions for antifungal activity. The characterization analyses included size measurements, zeta potential (ζ-potential), entrapment efficiency (EE), and antifungal activity (by inhibition of mycelial growth (IMG) and/or in situ test (pre-contaminated Brazil nuts) tests). The nanocarriers presented particle sizes smaller than 300 nm, homogeneous size distribution, ζ-potential of -25.19 to -41.81 mV, and EE between 73.6 and 100%. The formulations F5 and F10 showed the highest IMG value (98.75%). Based on the regression model, three optimized formulations (OFs) were tested for antifungal activity (IMG and in situ test), which showed 100% of inhibition and prevented the deterioration of Brazil nuts by A. nomius. The preliminary stability test showed the maintenance of antifungal activity and physicochemical characteristics for 90 days. These results suggest a promising system as a biofungicide against A. nomius.


Assuntos
Aspergillus/efeitos dos fármacos , Cymbopogon/química , Portadores de Fármacos/química , Nanoestruturas/química , Óleos Voláteis/farmacologia , Antifúngicos/farmacologia , Bertholletia/microbiologia , Composição de Medicamentos , Cromatografia Gasosa-Espectrometria de Massas , Testes de Sensibilidade Microbiana , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática
3.
Int J Nanomedicine ; 16: 833-850, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33584096

RESUMO

PURPOSE: In deep burns, wound contraction and hypertrophic scar formation can generate functional derangement and debilitation of the affected part. In order to improve the quality of healing in deep second-degree burns, we developed a new treatment in a preclinical model using nanostructured membranes seeded with mesenchymal stem cells (MSCs). METHODS: Membranes were obtained by reconstitution of bacterial cellulose (reconstituted membrane [RM]) and produced by a dry-cast process, then RM was incorporated with 10% tamarind xyloglucan plus gellan gum 1:1 and 10% lysozyme (RMGT-LZ) and with 10% gellan gum and 10% lysozyme (RMG-LZ). Membrane hydrophobic/hydrophilic characteristics were investigated by static/dynamic contact-angle measurements. They were cultivated with MSCs, and cell adhesion, proliferation, and migration capacity was analyzed with MTT assays. Morphological and topographic characteristics were analyzed by scanning electron microscopy. MSC patterns in flow cytometry and differentiation into adipocytes and osteocytes were checked. In vivo assays used RMG-LZ and RMGT-LZ (with and without MSCs) in Rattus norvegicus rats submitted to burn protocol, and histological sections and collagen deposits were analyzed and immunocytochemistry assay performed. RESULTS: In vitro results demonstrated carboxyl and amine groups made the membranes moderately hydrophobic and xyloglucan inclusion decreased wettability, favoring MSC adhesion, proliferation, and differentiation. In vivo, we obtained 40% and 60% reduction in acute/chronic inflammatory infiltrates, 96% decrease in injury area, increased vascular proliferation and collagen deposition, and complete epithelialization after 30 days. MSCs were detected in burned tissue, confirming they had homed and proliferated in vivo. CONCLUSION: Nanostructured cellulose-gellan-xyloglucan-lysozyme dressings, especially when seeded with MSCs, improved deep second-degree burn regeneration.


Assuntos
Bandagens , Queimaduras/terapia , Celulose/química , Glucanos/química , Células-Tronco Mesenquimais/citologia , Muramidase/química , Nanoestruturas/química , Polissacarídeos Bacterianos/química , Xilanos/química , Animais , Vasos Sanguíneos/patologia , Queimaduras/patologia , Adesão Celular , Diferenciação Celular , Proliferação de Células , Celulose/ultraestrutura , Colágeno/metabolismo , Inflamação/patologia , Masculino , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/ultraestrutura , Nanoestruturas/ultraestrutura , Ratos Wistar , Cicatrização , Ratos
4.
J Appl Microbiol ; 130(6): 1883-1892, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32970915

RESUMO

AIMS: This study aimed to determine in vitro activity of copper nanoparticles and copper nanowires against Candida albicans strains and to assess their effects on morphology and submicron structure. METHODS AND RESULTS: The microdilution method determined the minimal inhibitory concentration (MIC) of copper nanoparticles (CuNPs) and copper nanowires (CuNWs) against three strains of C. albicans: ATCC 10231 and two clinical strains (C and E). Effects on the morphology and ultrastructure of C. albicans strains were examined by scanning electron microscopy and transmission electron microscopy. MIC for CuNPs was 129·7 µg ml-1 for strain ATCC 10231, 1037·5 µg ml-1 for strain C and 518·8 µg ml-1 for strain E. MIC for CuNWs was similar for all strains tested (260·3 µg ml-1 ). SEM and TEM studies showed alterations in morphology, cell wall and the complete collapse of the yeast after incubation with CuNPs. In contrast, most of the yeast cells maintained their structure with an intact cell wall, and only decreased the number and size of fimbriae when C. albicans was exposed to CuNWs. CuNPs and CuNWs formed hierarchical copper oxide nanostructures growing in situ in the culture medium. Results suggest a dual mechanism for antifungal activity: (i) free Cu2+ ions act as a biocide, (ii) sharp edges of marigold-like petal nanostructures could injure the cellular wall and membrane and cause the death of the yeast. CONCLUSIONS: CuNPs and CuNWs inhibited the growth of the three strains of C. albicans tested. Moreover, CuNPs disrupted cell wall with leakage of the cytoplasmic content. Each concentration of the series used for the determination of the activity of CuNPs and nanowires against C. albicans formed copper oxide marigold-like nanostructures. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that CuNPs and CuNWs are good candidates for formulating new therapeutic agents for candidiasis.


Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Cobre/farmacologia , Nanoestruturas/química , Nanofios/química , Antifúngicos/química , Candidíase/tratamento farmacológico , Cobre/química , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanoestruturas/ultraestrutura , Nanofios/ultraestrutura
5.
Int J Biol Macromol ; 165(Pt B): 1881-1888, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33096179

RESUMO

Bell peppers are susceptible to postharvest diseases caused by the fungus Alternaria alternata that limit its commercialization. Nowadays, nanotechnology allows encapsulation of natural components such as terpenes. The objective of this work was to develop chitosan nanoparticles with α-pinene (P-CSNPs) and a nanostructured edible coating (EC-P-CSNPs). The P-CSNPs were characterized by TEM (Transmission Electron Microscopy), FTIR (Fourier-Transform Infrared Spectroscopy), DLS (Dynamic Light Scattering) and ζ potential. The P-CSNPs and the EC-P-CSNPs were applied to the bell peppers inoculated with A. alternata under cold storage for either 0, 7, 14 and 21 days at 12 ±â€¯2 °C followed by a shelf-life period of 5 days at 20 ±â€¯2 °C to assess their post-harvest quality. Nanoparticles size was 3.9 ±â€¯0.5 nm and the ζ potential value was between 13.4 and 14.9 mV. The incorporation of α-pinene was corroborated by FTIR. Significant changes in weight loss were obtained for P-CSNPs and EC-P-CSNPs at percentage of 3 and 6% compared to the control. For firmness, color, total soluble solids, titratable acids, maturity index, total flavonoid content and antioxidant capacity, no differences were found. Total carotenes were higher in bell peppers without A. alternata. The chitosan nanoparticles and edible coating inhibited A. alternata during the cold storage period of bell pepper and preserved the physicochemical quality.


Assuntos
Alternaria/fisiologia , Monoterpenos Bicíclicos/farmacologia , Capsicum/crescimento & desenvolvimento , Capsicum/microbiologia , Quitosana/química , Nanoestruturas/química , Doenças das Plantas/prevenção & controle , Antioxidantes/análise , Carotenoides/análise , Etilenos/metabolismo , Flavonoides/análise , Frutas/química , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Pigmentação , Solubilidade
6.
Molecules ; 25(12)2020 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-32580500

RESUMO

In industry, silica nanoparticles (NPs) are obtained by the fuming and the precipitation method. Fumed silica NPs are commonly used in the preparation of nanocomposites because they have an extremely low bulk density (160-190 kg/m3), large surface area (50-600 m2/g), and nonporous surface, which promotes strong physical contact between the NPs and the organic phase. Fumed silica has fewer silanol groups (Si-OH) on its surface than the silica prepared by the Stöber method. However, the number of -OH groups on the fumed silica surface can be increased by pretreating them with sodium hydroxide (NaOH) before further surface modification. In this study, the effectiveness of the NaOH pretreatment was evaluated on commercial fumed silica NPs with a surface area of 200 m2/g. The number of surface -OH groups was estimated by potentiometric titration. The pretreated fumed NPs, and the precipitated NPs (prepared by the Stöber method) were modified with 3-aminopropyltriethoxysilane (APTES) to obtain A200S and nSiO2-APTES, respectively. The NPs were characterized using electron dispersive scanning (EDS), scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), BET (Brunauer-Emmett-Teller) analysis, and ζ-potential. XRD confirmed the presence of the organo-functional group on the surface of both NPs. After the amino-functionalization, the ζ-potential values of the nSiO2 and A200 changed from -35.5 mV and -14.4 mV to +26.2 mV and +11.76 mV, respectively. Consequently, we have successfully synthesized functionalized NPs with interesting, specific surface area and porosity (pore volume and size), which can be attractive materials for chemical and energy industries.


Assuntos
Aminas/química , Nanopartículas/química , Nanoestruturas/química , Dióxido de Silício/química , Difusão Dinâmica da Luz , Nanopartículas/ultraestrutura , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Propilaminas/química , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
7.
Sci Rep ; 10(1): 5786, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32238903

RESUMO

Photonic crystals are some of the more spectacular realizations that periodic arrays can change the behavior of electromagnetic waves. In nature, so-called structural colors appear in insects and even plants. Some species create beautiful color patterns as part of biological behavior such as reproduction or defense mechanisms as a form of biomimetics. The interaction between light and matter occurs at the surface, producing diffraction, interference and reflectance, and light transmission is possible under suitable conditions. In particular, there are two Colombian butterflies, Morpho cypris and Greta oto, that exhibit iridescence phenomena on their wings, and in this work, we relate these phenomena to the photonic effect. The experimental and theoretical approaches of the optical response visible region were studied to understand the underlying mechanism behind the light-matter interaction on the wings of these Colombian butterflies. Our results can guide the design of novel devices that use iridescence as angular filters or even for cosmetic purposes.


Assuntos
Borboletas/anatomia & histologia , Asas de Animais/anatomia & histologia , Animais , Borboletas/química , Borboletas/fisiologia , Borboletas/ultraestrutura , Cristalização , Iridescência , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Fótons , Pigmentação , Asas de Animais/química , Asas de Animais/fisiologia , Asas de Animais/ultraestrutura
8.
Colloids Surf B Biointerfaces ; 187: 110673, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31812452

RESUMO

Soluplus® (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) is a solubilizing copolymer commonly applied as carrier in solid dispersions of poorly soluble drugs. This polymer is used to increase the apparent solubility of drugs with low aqueous solubility and consequently enhance drug absorption by the human gastrointestinal tract. To select the appropriate carrier to compose solid dispersions, in vitro supersaturation studies were applied as a pre-formulation tool, using different dissolution media. During in vitro supersaturation studies performed for the poorly soluble drug candesartan cilexetil, it was found that Soluplus® may interact with components of the biorelevant medium Fasted State Simulated Intestinal Fluid, lowering the drug apparent solubility. Dynamic Light Scattering and Transmission Electron Microscopy analyses were performed, as well as fluorescence measurements, aiming to characterize the interaction behavior and determine the polarity of the microenvironment. It was evidenced that Soluplus® interacted preferentially with lecithin, forming mixed micelles with a more polar microenvironment, which lowered the candesartan cilexetil solubilization capacity and consequently reduced its apparent solubility in the biorelevant medium. These findings are important to emphasize the key role of the media selection for in vitro solubility-supersaturation studies, where media that could mimic the human gastrointestinal environment are recommended.


Assuntos
Benzimidazóis/química , Compostos de Bifenilo/química , Polietilenoglicóis/química , Polivinil/química , Tetrazóis/química , Soluções Tampão , Meios de Cultura/química , Difusão Dinâmica da Luz , Fluorescência , Trato Gastrointestinal/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Lecitinas/química , Micelas , Microscopia Eletrônica de Transmissão , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Solubilidade
9.
Nanoscale ; 11(40): 18604-18611, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31578534

RESUMO

DNA nanotechnology creates precise shape-specific nanostructures through the self-assembly of short ssDNA oligonucleotides. One such shape, which has relevant biomedical applications due to its multivalency, is the star. However, building star-like nanostructures with a large size (>100 nm) using ssDNA is complex and challenging. This study presents a novel strategy to prepare stiff and large dsDNA nanostars by assembling duplex DNA fragments into star-shapes that are subsequently coated with a virus-inspired protein. The protein binds dsDNA and overcomes the high structural flexibility of naked dsDNA. The nanostar-like dsDNA templates with up to six arms were prepared by self-assembly of PCR-produced dsDNA fragments (211 to 722 bp) with a central DNA junction. Through gel electrophoresis and Atomic Force Microscopy it is demonstrated that single dsDNA nanostars are self-assembled and coated with the protein, and this has a large stiffening effect on the nanostar. Furthermore, the coating significantly enhances stability at high temperatures and protects nanostars against nuclease degradation for at least 10 hours. This study shows that DNA-binding proteins can be harnessed as structural "rigidifiers" of flexible branched dsDNA templates. This strategy opens a way to prepare structurally defined hybrid protein-dsDNA nanostructures that could be exploited as building blocks for novel DNA nanomaterials.


Assuntos
DNA/química , Temperatura Alta , Nanoestruturas/química , Conformação de Ácido Nucleico , Estreptavidina/química , Microscopia de Força Atômica , Nanoestruturas/ultraestrutura
10.
Molecules ; 24(18)2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31505873

RESUMO

In this work we report the synthesis of new hybrid nanomaterials in the core/shell/shell morphology, consisting of a magnetite core (Fe3O4) and two consecutive layers of oleic acid (OA) and phthalocyanine molecules, the latter derived from cashew nut shell liquid (CNSL). The synthesis of Fe3O4 nanoparticle was performed via co-precipitation procedure, followed by the nanoparticle coating with OA by hydrothermal method. The phthalocyanines anchorage on the Fe3O4/OA core/shell nanomaterial was performed by facile and effective sonication method. The as obtained Fe3O4/OA/phthalocyanine hybrids were investigated by Fourier transform infrared spectroscopy, X-ray diffraction, UV-visible spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis and magnetic measurements. TEM showed round-shaped nanomaterials with sizes in the range of 12-15 nm. Nanomaterials presented saturation magnetization (Ms) in the 1-16 emu/g and superparamagnetic behavior. Furthermore, it was observed that the thermal stability of the samples was directly affected by the insertion of different transition metals in the ring cavity of the phthalocyanine molecule.


Assuntos
Anacardium/química , Indóis/química , Nanopartículas/química , Nanoestruturas/química , Compostos Férricos/química , Óxido Ferroso-Férrico/química , Isoindóis , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Nanoestruturas/ultraestrutura , Nozes/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
11.
Sci Rep ; 9(1): 10553, 2019 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332259

RESUMO

Bacterial nanocellulose (BNC) is a promising biomedical material. However, the haemocompatibility (haemolysis and thrombogenicity) and acute and sub-chronic immune responses to three-dimensional (3D) BNC biomaterials have not been evaluated. Accordingly, this manuscript focused on the effect of 3D microporosity on BNC haemocompatibility and a comparison with 2D BNC architecture, followed by the evaluation of the immune response to 3D BNC. Blood ex vivo studies indicated that compared with other 2D and 3D BNC architectures, never-dried 2D BNC presented antihemolytic and antithrombogenic effects. Nevertheless, in vivo studies indicated that 3D BNC did not interfere with wound haemostasis and elicited a mild acute inflammatory response, not a foreign body or chronic inflammatory response. Moreover, compared with the polyethylene controls, the implant design with micropores ca. 60 µm in diameter showed a high level of collagen, neovascularization and low fibrosis. Cell/tissue infiltration increased to 91% after 12 weeks and was characterized by fibroblastic, capillary and extracellular matrix infiltration. Accordingly, 3D BNC biomaterials can be considered a potential implantable biomaterial for soft tissue augmentation or replacement.


Assuntos
Materiais Biocompatíveis/química , Celulose/química , Tecido Conjuntivo/cirurgia , Teste de Materiais/métodos , Nanoestruturas/química , Próteses e Implantes , Acetobacteraceae/química , Animais , Celulose/ultraestrutura , Tecido Conjuntivo/irrigação sanguínea , Tecido Conjuntivo/patologia , Hemólise , Humanos , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Eletrônica de Varredura , Nanoestruturas/ultraestrutura , Tempo de Coagulação do Sangue Total
12.
Colloids Surf B Biointerfaces ; 180: 141-149, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31039515

RESUMO

The synthesis and applications of anisotropic nanostructures have attracted much attention in the last decade. The nanoflower-type structures are one of the nanomaterials with anisotropic structures most investigated because of owing to high densities of edges, corners, and stepped atoms present on their nano-petals. Here, silver nanoparticles obtained by a one-step green synthesis method using extract from Kalanchoe Daigremontiana´s leaves are reported. To identify the compounds responsible for reduction of silver ions, the functional groups present in plant extract were investigated by UV-vis and FTIR. Ag nanoparticles were characterized by UV-vis, XPS, ζ-potential, XRD, and SEM-EDS. Different solvents were used to eliminate agglomeration of the silver nanoparticles. These solvents produced nanoflower-like morphology with abundant nano-petals. This is the first report of the synthesis of Ag nanoflowers formed by green synthesis method using Kalanchoe Daigremontiana extract. The synthesized Ag nanoflowers are faced center cubic structure in nature with a petal thickness approximately of 25 nm. Photocatalytic activity of the different Ag nanostructures was evaluated through the degradation of methylene blue, where the degradation time as low as 1 min is reported. Furthermore these green synthesized Ag nanoflowers were found to show high antibacterial activity against Gram-negative bacteria Escherichia coli and Gram-positive Staphylococcus aureus.


Assuntos
Antibacterianos/química , Química Verde , Kalanchoe/química , Nanopartículas Metálicas/química , Nanoestruturas/química , Prata/química , Anisotropia , Antibacterianos/farmacologia , Catálise , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Nanopartículas Metálicas/ultraestrutura , Azul de Metileno/química , Nanoestruturas/ultraestrutura , Oxirredução , Tamanho da Partícula , Processos Fotoquímicos , Extratos Vegetais/química , Folhas de Planta/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento
13.
ACS Appl Mater Interfaces ; 11(22): 19751-19762, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31074956

RESUMO

Surfaces were prepared with polyelectrolyte derivatives of poly(styrene- alt-maleic anhydride) (PSMA) functionalized with amino acids of different hydropathy indices, with the aim of evaluating the effect of the chemical functionality of polyelectrolytes on SH-SY5Y neuroblastoma cell adhesion. Functionalizing PSMA derivatives with l-glutamine, l-methionine, and l-tyrosine yielded PSMA-Gln, PSMA-Met, and PSMA-Tyr polyelectrolytes, respectively. We first studied the adsorption behavior of PSMA functionalized with amino acids on silicon wafer surfaces modified with 3-aminopropyltriethoxysilane at pH 4.0 and 7.0 and at low and high ionic strengths. The highest rate of polyelectrolyte adsorption was at pH 4.0 and high ionic strength and was higher with the glutamine and tyrosine films. The advance contact angles (θA) of the polyelectrolyte surfaces showed a moderate effect of ionic strength and pH on polyelectrolyte film wettability, with PSMA-Tyr being slightly more hydrophobic. Atomic force microscopy images of the polyelectrolyte surfaces showed two types of morphology: the well-defined globular nanostructure of PSMA-Met and PSMA-Tyr and densely packed nanofibrous-like structure of PSMA-Gln. The highest level of ionic strength caused a slight decrease in the size of the nanostructure that formed the surface domains, which was reflected in the degree of surface roughness. Cell adhesion assays with the polyelectrolyte film showed that SH-SY5Y neuroblastoma cells cultured on PSMA-Met present a well-extended morphology characterized by a stellate shape, with five or more actin-rich thin processes, whereas SH-SY5Y cells that were seeded on PSMA-Gln and PSMA-Tyr have a round morphology, with fewer and shorter processes. These results indicate that it is possible to modulate the surface characteristics of polyelectrolyte films based on their chemical functionality and environmental parameters such as pH and ionic strength in order to evaluate their effect on cell adhesion. Thus, surfaces prepared from polyelectrolytes functionalized with amino acids are an attractive and simple platform for cell adhesion, which can be used in developing biomaterials with modulated surface properties.


Assuntos
Aminoácidos/química , Nanoestruturas/química , Polieletrólitos/química , Polímeros/química , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Concentração de Íons de Hidrogênio , Maleatos/química , Microscopia Eletrônica de Varredura , Nanoestruturas/ultraestrutura , Polímeros/farmacologia , Poliestirenos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Molhabilidade
14.
Mater Sci Eng C Mater Biol Appl ; 99: 1502-1508, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30889686

RESUMO

Nanostructured capacitive biosensors, combined with inexpensive fabrication technologies, may provide simple, sensitive devices for detecting clinically relevant cancer biomarkers. Herein, we report a novel platform for detecting the pancreatic cancer biomarker CA19-9 using low-cost screen-printed interdigitated electrodes (SPIDEs). The SPIDEs were modified by carbon nano-onions (CNOs) and graphene oxide (GO) films, on which a layer of anti-CA19-9 antibodies was immobilized. The modification with CNOs and GO significantly improved the analytical performance of the biosensor, which displayed superior results to those prepared only with GO. The biossensor exhibited high reproducibility and a relatively low limit of detection of 0.12 U mL-1. Using these devices in combination with information visualization methods we were able to detect CA19-9 in whole cell lysates of colorectal adenocarcinoma. The fabrication of these low-cost, disposable immunosensors is a successful attempt to explore CNOs in capacitive biosensors, which may be extended for detection of different cancer biomarkers.


Assuntos
Biomarcadores Tumorais/análise , Antígeno CA-19-9/análise , Carbono/química , Nanoestruturas/química , Anticorpos/metabolismo , Capacitância Elétrica , Eletrodos , Grafite/química , Humanos , Nanoestruturas/ultraestrutura , Impressão
15.
Colloids Surf B Biointerfaces ; 167: 73-81, 2018 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-29627680

RESUMO

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) represent promising alternatives for drug delivery to the central nervous system. In the present work, four different nanoformulations of the antiepileptic drug Carbamazepine (CBZ) were designed and prepared by the homogenization/ultrasonication method, with encapsulation efficiencies ranging from 82.8 to 93.8%. The formulations remained stable at 4 °C for at least 3 months. Physicochemical and microscopic characterization were performed by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), atomic force microscopy (AFM); thermal properties by differential scanning calorimetry (DSC), thermogravimetry (TGA) and X-ray diffraction analysis (XRD). The results indicated the presence of spherical shape nanoparticles with a mean particle diameter around 160 nm in a narrow size distribution; the entrapped CBZ displayed an amorphous state. The in vitro release profile of CBZ fitted into a Baker-Lonsdale model for spherical matrices and almost the 100% of the encapsulated drug was released in a controlled manner during the first 24 h. The apparent permeability of CBZ-loaded nanoparticles through a cell monolayer model was similar to that of the free drug. In vivo experiments in a mice model of seizure suggested protection by CBZ-NLC against seizures for at least 2 h after intraperitoneal administration. The developed CBZ-loaded lipid nanocarriers displayed optimal characteristics of size, shape and drug release and possibly represent a promising tool to improve the treatment of refractory epilepsy linked to efflux transporters upregulation.


Assuntos
Anticonvulsivantes/química , Carbamazepina/química , Lipídeos/química , Nanopartículas/química , Nanoestruturas/química , Animais , Anticonvulsivantes/administração & dosagem , Anticonvulsivantes/farmacocinética , Varredura Diferencial de Calorimetria , Carbamazepina/administração & dosagem , Carbamazepina/farmacocinética , Cães , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Células Madin Darby de Rim Canino , Camundongos , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Nanopartículas/ultraestrutura , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Termogravimetria , Difração de Raios X
16.
Colloids Surf B Biointerfaces ; 163: 275-283, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29329073

RESUMO

The functionalization of alumina nanoparticles of specific morphology with antimicrobial peptides (AMP) can be a promising strategy for modeling medical devices and packaging materials for cosmetics, medicines or food, since the contamination by pathogens could be reduced. In this paper, we show the synthesis of a fibrous-like alumina nanobiostructure, as well as its functionalization with the peptide EAAA-BP100, an analog of the antimicrobial peptide BP100. The antibacterial activity of the obtained material against some bacterial strains is also investigated. The covalent binding of the peptide to the nanoparticles was promoted by a reaction between the carboxyl group of the glutamate side chain (E1) of the peptide and the amino groups of the alumina nanoparticles, previously modified by reaction with 3-aminopropyltrietoxysilane (APTES). The functionalized nanoparticles were characterized by zeta potential measurements, Fourier transform infrared spectroscopy, and other physicochemical techniques. Although the obtained alumina nanobiostructure shows a relatively low degree of substitution with EAAA-BP100, antibacterial activities against Escherichia coli and Salmonella typhimurium strains are appreciably higher than the activities of the free peptide. The obtained results can affect the design of new hybrid nanobiomaterials based on nanoparticles functionalized with AMP.


Assuntos
Óxido de Alumínio/química , Nanoestruturas/química , Oligopeptídeos/química , Oligopeptídeos/síntese química , Sequência de Aminoácidos , Antibacterianos/química , Antibacterianos/farmacologia , Fluoresceínas/química , Testes de Sensibilidade Microbiana , Nanoestruturas/ultraestrutura , Oligopeptídeos/farmacologia , Propilaminas/química , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Temperatura , Difração de Raios X
17.
Curr Drug Deliv ; 15(3): 388-396, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28745230

RESUMO

BACKGROUND: Bupivacaine is the most used local anesthetic in surgical procedures, producing prolonged anesthesia. The major limiting factor for the clinical use of bupivacaine comes from its systemic toxicity. Nanostructured lipid carriers (NLC) are vehicles for sustained drug delivery that are able to minimize the toxicity and to increase the action time of lipophilic drugs. METHODS: This work reports a 22 factorial design, which elucidates the role of the lipids mixture in the NLC, towards an optimized formulation. It also provides a new method for bupivacaine S75:R25 (BVCS75) quantification in NLC. Moreover, physicochemical stability studies on the prepared NLC formulations were carried out by monitoring particle size, polydispersity, Zeta potential and BVCS75 encapsulation efficiency for 90 days, at 25°C. RESULTS: The factorial design showed that the liquid lipid Capryol 90® has a negative effect over particle size and PDI values while cetyl palmitate presented a positive effect in size. The analytical method was accurate, reproducible, specific and linear over the concentration range of 0.16-54.00 µg.mL-1 BVCS75 with limits of quantification and detection of 0.10 and 0.03 µg.mL-1, respectively. The validated method was used to quantify the BVCS75 encapsulation (55.5 ±2.8 %). Encapsulation did not affect the nanoparticles morphology (confirmed by Transmission Electron Microscopy), but increased their Zeta potential (from -15.7 to -37.0 mV). The NLC physical stability was maintained (particles: size < 170 nm, polydispersity <0.16, and number = 8.85 ±0.11 x 1013 particles.mL-1) during storage. CONCLUSION: These results support further investigations on the use of BVCS75-in-NLC formulation for surgical anesthesia, aiming the development of a potent and less toxic nanostructured lipid carrier formulation for BVCS75.


Assuntos
Anestésicos Locais/química , Bupivacaína/química , Portadores de Fármacos/química , Nanoestruturas/química , Cromatografia Líquida de Alta Pressão , Desenho de Fármacos , Estabilidade de Medicamentos , Microscopia Eletrônica de Transmissão , Nanoestruturas/ultraestrutura , Palmitatos/química , Polímeros/química , Propilenoglicóis/química , Tensoativos/química
18.
Chemosphere ; 191: 1048-1055, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28923475

RESUMO

The present study is focused on the chemical and nano-mineralogical characterization of sludge from gold mine activities, in order to put forward diverse solution alternatives, where lack of knowledge has been found. The sample was collected from "La Estrella" mine of Suarez, located in Department of Cauca, south-west Colombia. The sludge micro-structure and chemical composition were analyzed using a high resolution transmission electron microscopy (HR-TEM) equipped with a dispersive X-ray detector (EDS). X-ray diffraction technique was employed to identify the mineralogical phases present in the sludge. Additional mineralogical characterization was done by using RAMAN spectroscopy. Main findings points to its potential to be used as a fertilizer, this is why, mine sludge contains macronutrients such as P, Ca and S, together with micronutrients like Cu. However, the presence of goethite could decrease the mobilization of nutrients to soils, thus additional alternatives, for instance, a mixture with humus or another material containing Humic Acids should be done, in order to minimizing its retention effect. Additionally, another possible uses to explore could be as construction and ceramic material or in the wastewater treatment for nutrient retention and organic material removal. Rutile (TiO2 nanoparticles) particles have been also detected, what could cause health concern due to its nanoparticle toxic character, mainly during gold extraction process.


Assuntos
Ouro , Mineração , Nanoestruturas/química , Esgotos/análise , Colômbia , Recuperação e Remediação Ambiental/métodos , Fertilizantes , Compostos de Ferro , Microscopia Eletrônica de Transmissão , Minerais , Nanoestruturas/ultraestrutura , Esgotos/química , Solo , Titânio/análise , Difração de Raios X
19.
Talanta ; 175: 535-541, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28842030

RESUMO

We report a microfluidic electrochemical immunosensor for Xanthomonas arboricola (XA) determination, based on the covalently immobilization of monoclonal anti-XA antibody (anti-XA) on a previously amino functionalized SBA-15 in situ synthesized in the central channel of a glass-poly(dimethylsiloxane) microfluidic immunosensor. The synthetized amino-SBA-15 was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy and infrared spectroscopy. XA was detected by a direct sandwich immunoassay through an alkaline phosphatase (AP) enzyme-labeled anti-XA conjugate. Later, the substrate p-aminophenyl phosphate was converted to p-aminophenol by AP. The enzymatic product was detected at +100mV on a sputtered gold electrode. The measured current was directly proportional to the level of XA in walnut trees samples. The linear range was from 5 × 102 to 1 × 104CFUmL-1. The detection limit was 1.5 × 102CFUmL-1, and the within- and between-assay coefficients of variation were below 5%. Microfluidic immunosensor is a very promising tool for the early and in situ diagnosis of XA in walnuts avoiding serious economic losses.


Assuntos
Anticorpos Imobilizados/química , Análise de Alimentos/instrumentação , Imunoensaio/instrumentação , Juglans/microbiologia , Dispositivos Lab-On-A-Chip , Nanoestruturas/química , Xanthomonas/isolamento & purificação , Aminação , Desenho de Equipamento , Microbiologia de Alimentos , Limite de Detecção , Nanoestruturas/ultraestrutura , Dióxido de Silício/química
20.
Biomed Res Int ; 2017: 2723418, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28691021

RESUMO

Essential oil of Eucalyptus globulus presents several pharmacological properties. However, their therapeutic efficacy may be affected by limitations due to several conditions, rendering it difficult to obtain stable and effective pharmaceutical formulations. The use of nanotechnology is an alternative to improve their characteristics aiming to ensure their stability and effectiveness. Furthermore, studies about the possible toxic effects of nanostructures are necessary to evaluate safety when the formulation comes into contact with human cells. Hence, in this paper, we evaluate for the first time the stability and in vitro cytogenotoxicity of nanoemulsions containing Eucalyptus globulus in peripheral blood mononuclear cells. As a result, the stability study found that the best condition for storage up to 90 days was refrigeration (4°C); it was the condition that best preserved the nanometric features. The content of the major compounds of oil was maintained after nanoencapsulation and preserved over time. In tests to evaluate the safety of this formulation, we can conclude that, at a low concentration (approximately 0.1%), Eucalyptus globulus nanoemulsion did not cause toxicity in peripheral blood mononuclear cells and also showed a protective effect in cells against possible damage when compared to oil in free form.


Assuntos
Emulsões/química , Eucalyptus/química , Nanoestruturas/química , Óleos Voláteis/farmacologia , Óleos de Plantas/farmacologia , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaio Cometa , Hemólise/efeitos dos fármacos , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Nanoestruturas/ultraestrutura , Carbonilação Proteica/efeitos dos fármacos , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA