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1.
PLoS One ; 15(5): e0232992, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32392263

RESUMO

Although scanning electron microscopy (SEM) can generate high-resolution images of nanosized objects, it requires a high vacuum to do so, which precludes direct observations of living organisms and often produces unwanted structural changes. It has previously been reported that a simple surface modification gives rise to a nanoscale layer, termed the "NanoSuit", which can keep small animals alive under the high vacuum required for field-emission scanning electron microscopy (FE-SEM). We have previously applied this technique to plants, and successfully observed healthy petals in a fully hydrated state using SEM. The flower petals protected with the NanoSuit appeared intact, although we still lack a fundamental understanding of the images of other plants observed using FE-SEM. This report presents and evaluates a rich set of images, acquired using the NanoSuit, for a taxonomically diverse set of plant species. This dataset of images allows the surface features of various plants to be analyzed and thus provides a further complementary morphological profile. Image data can be accessed and viewed through Figshare (https://doi.org/10.6084/m9.figshare.c.4446026.v1).


Assuntos
Microscopia Eletrônica de Varredura/métodos , Nanoestruturas , Plantas/ultraestrutura , Animais , Flores/ultraestrutura , Microscopia Eletrônica de Varredura/instrumentação , Microscopia Eletrônica de Transmissão/métodos , Nanotecnologia , Propriedades de Superfície , Vácuo
2.
Arq Bras Oftalmol ; 83(2): 146-148, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32159595

RESUMO

Lisch corneal dystrophy is a rare corneal disease characterized by the distinctive feature of highly vacuolated cells. Although this feature is important, the nature of these vacuoles within corneal cells remains unknown. Here, we sought to analyze corneal cells from a patient diagnosed with Lisch dystrophy to characterize the vacuoles within these cells. Analyses using histopathology examination, confocal microscopy, and transmission electron microscopy were all consistent with previous descriptions of Lisch cells. Importantly, the vacuoles within these cells appeared to be autophagosomes and autolysosomes, and could be stained with an anti-microtubule-associated protein 1A/1B-light chain 3 (LC3) antibody. Taken together, these findings indicate that the vacuoles we observed within superficial corneal cells of a patient with Lisch corneal dystrophy constituted autophagosomes and autolysosomes; this finding has not been previously reported and suggests a need for further analyses to define the role of autophagy in this ocular disease.


Assuntos
Autofagossomos/patologia , Distrofias Hereditárias da Córnea/patologia , Vacúolos/patologia , Adulto , Distrofias Hereditárias da Córnea/diagnóstico por imagem , Opacidade da Córnea/diagnóstico por imagem , Opacidade da Córnea/patologia , Feminino , Humanos , Microautofagia , Microscopia Confocal/métodos , Microscopia Eletrônica de Transmissão/métodos , Tomografia de Coerência Óptica/métodos
3.
PLoS One ; 15(1): e0227584, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31917807

RESUMO

Ultrasensitive detection of heavy metal ions in available water around us is a great challenge for scientists since long time. We developed an optical technique that combines Rayleigh scattering of UV light (365 nm) and post-sample fluorescence detection from colloidal silver (Ag) nanoparticles (NPs) having a surface plasmon resonance (SPR) band at 420 nm. The efficacy of the technique is tested by the detection of several model toxic ions, including mercury, lead, and methylmercury in aqueous media. The light scattering from the Hg-included/inflated Ag NPs at 395 nm was observed to saturate the light sensor even with ppm-order concentrations of Hg ions in the water sample. However, the pollutant is not detected at lower concentrations at this wavelength. Instead, the fluorescence of a high-pass filter (cut-off at 400 nm) at 520 nm is applied to detect pollutant concentrations of up to several hundreds of ppm in the water sample. We also detected lead and methylmercury as model pollutants in aqueous media and validated the efficacy of our strategy. Finally, we report the development of a working prototype based on the strategy developed for efficient detection of pollutants in drinking/agricultural water.


Assuntos
Monitoramento Ambiental/métodos , Nanopartículas Metálicas/química , Metais Pesados/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental/instrumentação , Desenho de Equipamento , Fluorescência , Limite de Detecção , Metais Pesados/química , Microscopia Eletrônica de Transmissão/instrumentação , Microscopia Eletrônica de Transmissão/métodos , Espalhamento de Radiação , Sensibilidade e Especificidade , Prata/química , Espectrofotometria Ultravioleta , Ressonância de Plasmônio de Superfície/métodos , Raios Ultravioleta , Poluição da Água/análise
4.
Anal Bioanal Chem ; 412(2): 425-438, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31776639

RESUMO

Dynamic light scattering (DLS), transmission electron microscopy (TEM), and reversed phase-high performance liquid chromatography (RP-HPLC) are staples of nanoparticle characterization for size distribution, shape/morphology, and composition, respectively. These techniques are simple and provide important details on sample characteristics. However, DLS and TEM are routinely done in batch-mode, while RP-HPLC affords separation of components within the entire sample population, regardless of sample polydispersity. While batch-mode analysis is informative and should be a first-step analysis for any material, it may not be ideal for polydisperse formulations, such as many nanomedicines. Herein, we describe the utility of asymmetric flow field-flow fractionation (AF4) as a useful tool for a more thorough understanding of these inherently polydisperse materials. AF4 was coupled with in-line DLS for an enhanced separation and resolution of various size populations in a nanomaterial. Additionally, the various size populations were collected for offline analysis by TEM for an assessment of different shape populations, or RP-HPLC to provide a compositional analysis of each individual size population. This technique was also extended to assess nanoparticle stability, i.e., drug release, both in buffer and physiologically relevant matrix, as well as qualitatively evaluate the protein binding capacity of nanomedicines. Overall, AF4 is proven to be a very versatile technique and can provide a wealth of information on a material's polydispersity and stability. Moreover, the ability to conduct analysis in physiological matrices provides an advantage that many other routine analytical techniques do not. Graphical Abstract.


Assuntos
Fracionamento por Campo e Fluxo/métodos , Nanomedicina , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/métodos , Difusão Dinâmica da Luz/métodos , Humanos , Microscopia Eletrônica de Transmissão/métodos , Nanopartículas/química
5.
Eur J Histochem ; 63(4)2019 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-31833331

RESUMO

The main step in the assessment of nanomaterial safety and suitability for biomedical use is the location and the dynamic tracking of nanoparticles (NPs) inside cells or tissues. To precisely investigate the uptake mechanisms and intracellular fate of NPs, transmission electron microscopy is the technique of choice; however, the detection of NPs may sometimes be problematic. In fact, while NPs containing strongly electron dense (e.g., metal) components do not require specific detection methods at the ultrastructural level, organic NPs are hardly detectable in the intracellular environment due to their intrinsic moderate electron density. In this study, the critical-electrolyte-concentration Alcian Blue method set up by Schofield et al. in 1975 was applied to track hyaluronic-acid-based NPs in muscle cells in vitro. This long-established histochemical method proved to be a powerful tool allowing to identify not only whole NPs while entering cells and moving into the cytoplasm, but also their remnants following lysosomal degradation and extrusion.


Assuntos
Azul Alciano/química , Corantes/química , Ácido Hialurônico/metabolismo , Nanopartículas/metabolismo , Animais , Linhagem Celular , Lisossomos/metabolismo , Camundongos , Microscopia Eletrônica de Transmissão/métodos , Mioblastos/ultraestrutura , Coloração e Rotulagem
6.
Molecules ; 24(22)2019 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-31717559

RESUMO

In this study, we prepared complex nanoparticles from a combination of two proteins and one polysaccharide for the encapsulation and delivery of lipophilic bioactive compounds. Two proteins, zein and sodium caseinate (NaCas), provided a hydrophobic core for the encapsulation of a lipophilic compound (curcumin), while a polysaccharide dialdehyde, oxidized dextran, served as the coating material and macromolecular crosslinker to create covalent linkage with two proteins for stabilization purposes. The heating time and crosslinker concentration were optimized to achieve the desirable colloidal stability in simulated gastric and intestinal fluids. Our results suggested that heating time played a more important role than the concentration of oxidized dextran. The optimized complex nanoparticles had a particle size of around 150 nm with a PDI < 0.1 and negative surface charge. Morphological observation by transmission electron microscopy revealed a spherical shape and uniform size distribution. Fourier transform infrared and fluorescence spectroscopies evidenced the formation of Schiff base complex, confirming the validity of covalent crosslinking. Furthermore, the complex nanoparticles demonstrated superior encapsulation properties for curcumin, showing an efficiency of >90% at 10% loading. A rather slow kinetic release profile of curcumin from complex nanoparticles was observed under simulated gastrointestinal conditions. The complex nanoparticles prepared from zein, NaCas, and oxidized dextran hold promising potential for the oral delivery of lipophilic bioactive compounds.


Assuntos
Caseínas/química , Curcumina/química , Dextranos/química , Nanopartículas/química , Zeína/química , Varredura Diferencial de Calorimetria/métodos , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Interações Hidrofóbicas e Hidrofílicas , Cinética , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula
7.
ACS Appl Mater Interfaces ; 11(50): 46637-46644, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31747242

RESUMO

Metallofullerenes have attracted considerable attention as potential novel noninvasive high-relaxivity magnetic resonance contrast agents. However, the applications of metallofullerenes as stimuli-responsive biosensors to monitor biological processes are still scarce. Herein, manganese-fullerenes core-shell nanocomposites are prepared via a facile one-pot approach to achieve GSH-activatable magnetic resonance/fluorescence bimodal imaging functions. The nanocomposites initially have a FRET-induced quenched fluorescence, and water-resisting stimulated low T1-MRI contrast. Upon exposure to GSH, collapse of the outer MnO2 shell led to reconstruction of the nanoprobes and subsequently resulted in multicolor fluorescence recovery and longitudinal (T1) relaxivity enhancement (r1 value up to 29.8 mM-1 s-1 at 0.5 T based on Mn ion). Our work demonstrates feasibility of using fullerenes to fabricate activatable probes for molecular imaging of GSH, which may promote the development of new fullerene-based stimuli-responsive multimodal probes for the detection and regulation of particular biological processes in vivo.


Assuntos
Técnicas Biossensoriais , Fulerenos/química , Glutationa/isolamento & purificação , Imagem Molecular/métodos , Animais , Meios de Contraste/química , Meios de Contraste/farmacologia , Fluorescência , Glutationa/química , Humanos , Íons/química , Imagem por Ressonância Magnética , Manganês/química , Compostos de Manganês/química , Metais/química , Camundongos , Microscopia Eletrônica de Transmissão/métodos , Nanocompostos/química
8.
Med Sci Monit Basic Res ; 25: 218-228, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31645540

RESUMO

BACKGROUND Most eukaryocytes release nano vesicles (30-120 nm), named exosomes, to various biological fluids such as blood, lymph, and milk. Hepatocellular carcinoma (HCC) is one of the tumors with the highest incidence rate in primary malignant carcinoma of the liver. However, the mechanism of HCC proliferation remains elusive. In this study, we aim to explore whether HCC cell-derived exosomes affect the proliferation of cancer cells. MATERIAL AND METHODS Exosomes were isolated from HCC cells by ultracentrifugation and were visualized the phenotype by transmission electron microscopy. Cell proliferation was detected by Cell Counting Kit-8 assays and EdU (5-ethynyl-2-deoxyuridine) incorporation assays. Dual-luciferase assays were performed to validate the paired correlation of miR-155 and 3'-UTR of PTEN (gene of phosphate and tension homology deleted on chromosome 10). A xenograft mice model was constructed to verify the effect of exosome-mediated miR-155 on cell proliferation in vivo. RESULTS Our finding showed that miR-155 was enriched in exosomes released from HCC cells. The exosome-containing miR-155 transferred into new HCC targeted cells and lead to the elevation of HCC cells' proliferation. Besides, the exosomal miR-155 directly bound to 3'-UTR of PTEN leading to the reduction of relevant targets in recipient liver cells. The knockdown of PTEN attenuated the proliferation of HCC cells treated with the exosomal miR-155. Moreover, nude-mouse experiment results revealed a promotional effect of the exosomal miR-155 on HCC cell-acquired xenografts. CONCLUSIONS Our study indicated that exosomal-specific miR-155 transfers to adjacent and/or more distant cells and stimulates the proliferation of HCC cells.


Assuntos
Carcinoma Hepatocelular/genética , MicroRNAs/genética , Animais , Biomarcadores Tumorais/sangue , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/genética , Exossomos/metabolismo , Regulação Neoplásica da Expressão Gênica/genética , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Masculino , Camundongos , Camundongos Nus , MicroRNAs/metabolismo , Microscopia Eletrônica de Transmissão/métodos , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Ensaios Antitumorais Modelo de Xenoenxerto
9.
Nat Commun ; 10(1): 4837, 2019 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-31645558

RESUMO

We describe the observation of stimuli-induced peptide-based nanoscale assemblies by liquid cell transmission electron microscopy (LCTEM). LCTEM offers the opportunity to directly image nanoscale materials in liquid. Despite broad interest in characterizing biological phenomena, electron beam-induced damage remains a significant problem. Concurrently, methods for verifying chemical structure during or following an LCTEM experiment have been few, with key examples limited to electron diffraction or elemental analysis of crystalline materials; this strategy is not translatable to biopolymers observed in nature. In this proof-of-concept study, oligomeric peptides are biologically or chemically stimulated within the liquid cell in a TEM to assemble into nanostructures. The resulting materials are analyzed by MALDI-imaging mass spectrometry (MALDI-IMS) to verify their identity. This approach confirms whether higher-order assemblies observed by LCTEM consist of intact peptides, verifying that observations made during the in situ experiment are because of those same peptides and not aberrant electron beam damage effects.


Assuntos
Microscopia Eletrônica de Transmissão/métodos , Nanoestruturas/ultraestrutura , Peptídeos/análise , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Nanoestruturas/química , Peptídeos/química , Estudo de Prova de Conceito
10.
Artigo em Inglês | MEDLINE | ID: mdl-31605597

RESUMO

Nanotechnology presents a modern field of science that in the last twenty-five years plays a dominant role in the biomedicine. Different analytical methods are used for evaluation of the physico-chemical properties of nanoparticles including chromatography, electrophoresis, X-ray scattering, spectroscopy, mass spectrometry, zeta potential measurement and microscopy on which this article will focus. Herein, we present novel application of the long-established TEM technique that is focused on characterization and evaluation of various nanoparticles in development of drug delivery systems. Transmission electron microscopy images were taken of samples from native nanoparticles, nanoparticles labeled using stannous chloride labeling procedure, inorganic silica nanoparticles loaded with budesonide and native micelles and micelles carrier of anticancer drug camptothecin. In the case of radiolabeled nanoparticles, beside for nanoparticle characterization, TEM technique was used to confirm the stability of the nanoparticles after radiolabeling. Furthermore, the porous structure of hybrid silica particles loaded with budesonide was examined under TEM. Transmission electron microscopy technique offers exceptional benefits for nanoparticle characterization. Additionally, the necessity of ultrastructural analysis demonstrates the potential of TEM in the field of nanomedicine. Hence, the long-established and well-known TEM has been only partially exploited and offer researchers very detailed images of specimens at microscopic and nano scale.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Microscopia Eletrônica de Transmissão/instrumentação , Nanopartículas/ultraestrutura , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/uso terapêutico , Budesonida/administração & dosagem , Budesonida/uso terapêutico , Camptotecina/administração & dosagem , Camptotecina/uso terapêutico , Cromatografia/métodos , Eletroforese/métodos , Glucocorticoides/administração & dosagem , Glucocorticoides/uso terapêutico , Humanos , Espectrometria de Massas/métodos , Microscopia Eletrônica de Transmissão/métodos , Nanopartículas/química , Espalhamento de Radiação , Análise Espectral/métodos
11.
PLoS One ; 14(9): e0222322, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31518380

RESUMO

In this study, we describe the synthesis and characterization of silver nanoparticles (Ag-NPs) of different sizes and evaluated their antibacterial activity. Particles size and morphology were characterized by transmission electron microscopy. Evaluation of the bacteriostatic effects was performed by ultraviolet-visible spectrophotometry and comet assays. The smaller the particle size of Ag-NPs, the smaller the value of the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC), indicating the greater the antibacterial activity. The antibacterial activity was determined by the generation of reactive oxygen species (ROS) by bacteria and by bacterial membrane damage. In this study, we determined ROS-induced damage of bacteria caused by Ag-NPs. In conclusion, our findings indicated that Ag-NPs were effective at different particle sizes and concentrations and that the smaller the particle size of Ag-NPs, the greater the antibacterial activity.


Assuntos
Antibacterianos/farmacologia , Nanopartículas Metálicas/administração & dosagem , Prata/farmacologia , Vibrio/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula , Espectrofotometria Ultravioleta/métodos
12.
Eur J Pharm Biopharm ; 144: 165-173, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31546021

RESUMO

Among anticancer nanomedicines, squalenoyl nanocomposites have obtained encouraging outcomes in a great variety of tumors. The prodrug squalenoyl-gemcitabine has been chosen in this study to construct a novel multidrug nanosystem in combination with edelfosine, an alkyl-lysophopholipid with proven anticancer activity. Given their amphiphilic nature, it was hypothesized that both anticancer compounds, with complementary molecular targets, could lead to the formation of a new multitherapy nanomedicine. Nanoassemblies were formulated by the nanoprecipitation method and characterized by dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopy. Because free edelfosine is highly hemolytic, hemolysis experiments were performed using human blood erythrocytes and nanoassemblies efficacy was evaluated in a patient-derived metastatic pediatric osteosarcoma cell line. It was observed that these molecules spontaneously self-assembled as stable and monodisperse nanoassemblies of 51 ±â€¯1 nm in a surfactant/polymer free-aqueous suspension. Compared to squalenoyl-gemcitabine nanoassemblies, the combination of squalenoyl-gemcitabine with edelfosine resulted in smaller particle size and a new supramolecular conformation, with higher stability and drug content, and ameliorated antitumor profile.


Assuntos
Desoxicitidina/análogos & derivados , Lisofosfolipídeos/química , Éteres Fosfolipídicos/química , Pró-Fármacos/química , Esqualeno/química , Antineoplásicos/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Desoxicitidina/química , Humanos , Microscopia Eletrônica de Transmissão/métodos , Nanomedicina/métodos , Tamanho da Partícula
13.
Clin Hemorheol Microcirc ; 73(1): 157-167, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31561340

RESUMO

BACKGROUND: Doxorubicin is a cytostatic drug from the group of anthracycline antibiotics that is widely used as a chemotherapeutic agent. Side effects of the active substance include cardiotoxicity and nephrotoxicity. Doxorubicin-treated renal epithelial cells and (sarcoma) tumors are examined by correlative light and electron microscopy (CLEM) to investigate the subcellular localization of doxorubicin. METHODS: The kidney epithelial cell line MDCK II (Madin-Darby Canine Kidney) grown on culture dishes were treated with doxorubicin. Subsequently, the cells are analyzed by means of fluorescence and transmission electron microscopy (TEM). In vivo, alveolar rhabdomyosarcoma (RH 30) tumor cells are transferred to the chorioallantoic membrane (CAM) of the chicken embryo. Doxorubicin is injected into a vein of the chicken embryo. After 24 hours, the tumor is removed and examined using CLEM. RESULTS: The kidney epithelial cells and the doxorubicin-injected tumors show a clear staining of the cell nucleus, which correlates with electron-dense regions (heterochromatin). High-resolution TEM shows that doxorubicin treatment leads to an enormous stress situation with an increased formation of membrane blebbings. CONCLUSIONS: CLEM is a promising new method to visualize the pattern of fluorescing drugs (e.g. doxorubicin) in renal epithelial cells and tumors, and to localize the drug in its subcellular context combined with high resolution.


Assuntos
Antibióticos Antineoplásicos/uso terapêutico , Doxorrubicina/uso terapêutico , Células Epiteliais/efeitos dos fármacos , Rim/efeitos dos fármacos , Rim/diagnóstico por imagem , Microscopia Eletrônica de Transmissão/métodos , Microscopia de Fluorescência/métodos , Animais , Antibióticos Antineoplásicos/farmacologia , Cães , Doxorrubicina/farmacologia , Humanos , Rim/patologia
14.
Nat Methods ; 16(10): 1016-1020, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31562475

RESUMO

Transmission electron microscopy (TEM) of rapidly frozen biological specimens, or cryo-EM, would benefit from the development of a phase plate for in-focus phase contrast imaging. Several types of phase plates have been investigated, but rapid electrostatic charging of all such devices has hindered these efforts. Here, we demonstrate electron phase manipulation with a high-intensity continuous-wave laser beam, and use it as a phase plate for TEM. We demonstrate the laser phase plate by imaging an amorphous carbon film. The laser phase plate provides a stable and tunable phase shift without electrostatic charging or unwanted electron scattering. These results suggest the possibility for dose-efficient imaging of unstained biological macromolecules and cells.


Assuntos
Lasers , Microscopia Eletrônica de Transmissão/métodos , Elétrons , Luz , Eletricidade Estática
15.
Mater Sci Eng C Mater Biol Appl ; 104: 109966, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31499942

RESUMO

In this study we present the first crystal structure model for bone apatite based on the analysis of individual nanocrystals by high resolution transmission electron microscopy (HRTEM). Crystallographic image processing of the obtained HRTEM images from different projections indicates symmetry reduction with respect to P63/m stoichiometric apatites and the presence of threefold symmetry along the c axis. Based on HRTEM observations and the measured Ca/P = 2 ratio we propose a structural model with phosphate-to-carbonate substitution and O vacancies localized along c axis, which explains the observed loss of 63 screw axis parallel, and the shift of mirror plane perpendicular to the c axis. Also, the presence of non-equivalent (010) surfaces has been proven. These results on the atomic structure of bone apatite nanocrystals contribute to the understanding of their biochemically controlled nucleation processes.


Assuntos
Apatitas/química , Osso e Ossos/química , Nanopartículas/química , Carbonatos/química , Cristalografia/métodos , Microscopia Eletrônica de Transmissão/métodos
16.
Mater Sci Eng C Mater Biol Appl ; 104: 109876, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500007

RESUMO

Nanosilver immobilized on TiO2 nanometric fibers (Ag/TiO2) was produced by solution blow spinning and characterized using scanning electron microscopy, transmission electron microscopy, N2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, water contact angle, and inductively coupled plasma emission spectroscopy analyses. The in vitro antimicrobial and anticancer activities of the produced nanofibers was also investigated. Ag/TiO2 nanofibers revealed a crystalline structure compatible with the rutile crystalline phase, as well as a mesoporous and superhydrophilic nature. XPS profiles showed Ti4+ and Ag0, indicating a strong interaction between the Ag nanoparticles and TiO2. The Ag/TiO2 nanofibers presented antimicrobial activity against Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. The release of silver ions from 5 mg∙mL-1 and 50 mg∙mL-1 of Ag/TiO2 nanofibers was approximately 0.08 µg∙mL-1 and 0.18 µg∙mL-1, respectively. The nanofiber cytotoxicity in both macrophages (ATCC RAW 264.7) and cancer cells (murine AT-84 oral squamous carcinoma cells) was dose-dependent. A concentration of 5 mg∙mL-1 induced partial suppression growth and migration of cancer cells, while a concentration of 50 mg∙mL-1 resulted in complete inhibition of proliferation and migration of murine AT-84 cells. The overall results indicate that Ag/TiO2 nanofibers can selectively inhibit the cellular mechanism of AT-84 by apoptosis with DNA damage and cell death. The antimicrobial and anticancer performance of Ag/TiO2 nanofibers is probably the result of its nanometric dimension, high surface reactivity, and the interaction between TiO2 and Ag. Electron transfer at the metal-semiconductor interface and reactive oxygen species production, in addition to the biological activity of released silver ions, confirm the potential for use as an agent in antimicrobial and anticancer therapy.


Assuntos
Anti-Infecciosos/química , Antineoplásicos/química , Nanopartículas Metálicas/química , Nanofibras/química , Prata/química , Titânio/química , Anti-Infecciosos/farmacologia , Antineoplásicos/farmacologia , Bactérias/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Espectroscopia Fotoeletrônica/métodos , Difração de Raios X/métodos
17.
Mater Sci Eng C Mater Biol Appl ; 104: 109981, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500056

RESUMO

Zinc oxide nanoparticles (ZnO-NPs) are multifunctional oxide metal nanoparticles that have been considered by many due to their unique properties including UV filtration, semiconducting, antimicrobial, antifungal, and photocatalytic activity. In the present study, ZnO-NPs have been synthesized from Zn(SO4)·7H2O through the use of "green synthesis" method that utilizes Prosopis farcta aqueous extract. The characterization of synthesized ZnO-NPs have been performed by UV-Vis absorption, Fourier-Transform Infrared spectroscopy (FT-IR), Raman, Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray analysis (EDX). Results have illustrated that the synthesized nanoparticles contain a hexagonal shape and sheet form with sizes of 40-80 nm. The antifungal activity of ZnO-NPs against Candida albicans has shown that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 128 and 256 µg/ml, respectively. The cytotoxicity activity of synthesized nanoparticles was tested on breast cancer cells (MCF7), while the IC50 was calculated to be 90 µg/ml.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Nanopartículas Metálicas/química , Óxido de Zinco/química , Neoplasias da Mama/tratamento farmacológico , Candida albicans/efeitos dos fármacos , Feminino , Química Verde/métodos , Humanos , Células MCF-7 , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Espectrometria por Raios X/métodos , Difração de Raios X/métodos
18.
Mater Sci Eng C Mater Biol Appl ; 104: 109977, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500068

RESUMO

Zinc oxide nanoparticles were synthesized using two silica supports largely used in pharmaceutical field as excipients, Cab-O-Sil-H5 and Syloid 244 FP characterized by high surface area and different porosity. In order to evaluate the effects of different silica on nanoparticle chemical physical properties, composites (ZnO-SiO2) containing different amounts of ZnO nanoparticles were obtained and characterized by X-ray Powder Diffraction (XRPD), Transmission Electron Microscopy (TEM), Attenuated Transmission Reflectance (ATR), UV-vis spectroscopy and finally Photoluminescence (PL). Composites showed the presence of quite uniformly distributed zinc nanostructures on the silica surface with size in the range of 30-50 nm with an estimated specific surface area ranged from ca. 20 to 70 m2/g. The formation of a Zn-O-Si interface in ZnO-SiO2 was observed as well. Photoluminescence studies revealed that ZnO-SiO2 samples based on Cab-O-Sil present a higher contribution of oxygen vacancies per unit volume. Finally, the resulting composites were tested for antibacterial and antifungal activities. Whereas silica supports did not show any antibacterial and antifungal activities, most of the prepared composites, both with Cab-O-Sil-5H and Syloid 244 FP supports, resulted active against both bacteria and fungi. In particular the contingency analysis showed that the amount of zinc oxide in the composites was partly related to MIC results in bacteria (p = 0.059), whereas it showed an interesting p = 0.022 in yeast in the case of low amount of ZnO (10%). Thus, the described ZnO-SiO2 composites can be proposed for the preparation of both pharmaceutical formulations and medical disposals with antibacterial and antifungal activities.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/química , Antifúngicos/farmacologia , Nanoestruturas/química , Dióxido de Silício/química , Óxido de Zinco/química , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Nanopartículas Metálicas/química , Testes de Sensibilidade Microbiana/métodos , Microscopia Eletrônica de Varredura/métodos , Microscopia Eletrônica de Transmissão/métodos , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos , Zinco/química
19.
Int Wound J ; 16(5): 1214-1221, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31483575

RESUMO

The use of negative-pressure wound therapy (NPWT) has displayed significant clinical benefits in the healing of infected wounds. However, the effects of NPWT on bacterial colonisation and infection of traumatic wounds has been controversial. The aim of this study is to evaluate the impact of NPWT treatment in rabbits with a contaminated full-thickness wound on bacterial behaviour, including colony morphology, spatial distribution, fissional proliferation, and bacterial bioburden. Full-thickness wounds were created on the back of rabbits, and were inoculated with bioluminescent Staphylococcus aureus. The wounds were treated with sterile gauze dressings and NPWT with continuous negative pressure (-125 mm Hg). Wound samples were harvested on days 0 (6 hours after bacterial inoculation), 2, 4, 6, and 8 at the centre of wound beds before irrigation. Scanning electron microscopy and transmission electron microscopy (TEM) analyses were performed to determine the characteristic bacteriology. Laser scanning confocal microscopy was performed to obtain bioluminescent images, which were used to observe spatial distribution of the GFP-labelled S. aureus within the tissue and quantify the bacterial bioburden. NPWT resulted in sparse amounts of scattered bacteria on the wound surface or as sparsely spaced single colonies within the tissue. Wound bioburden on day 8 in the NPWT and gauze groups was 34.6 ± 5.5% and 141.9 ± 15.4% of the baseline values (N = 6), respectively (P < .0001). TEM showed a lack of S. aureus active fission within NPWT-treated tissue. NPWT can impact S. aureus colony morphology and spatial distribution both on the surface and within wound tissue, and reduce S. aureus as early as 48 hours after therapy initiation. Additionally, NPWT inhibits bacterial fissional proliferation in microcolonies.


Assuntos
Tratamento de Ferimentos com Pressão Negativa/métodos , Pele/ultraestrutura , Infecções Estafilocócicas/terapia , Cicatrização/fisiologia , Infecção dos Ferimentos/terapia , Ferimentos e Lesões/terapia , Animais , Modelos Animais de Doenças , Feminino , Microbiota/fisiologia , Microscopia Confocal/métodos , Microscopia Eletrônica , Microscopia Eletrônica de Transmissão/métodos , Coelhos , Distribuição Aleatória , Medição de Risco , Pele/microbiologia , Resultado do Tratamento , Ferimentos e Lesões/microbiologia
20.
Int J Pharm ; 570: 118650, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31470042

RESUMO

Nanoparticulate systems intended for the use in drug delivery are getting more and more complex. Composite nanoparticles, such as core-shell particles are designed in order to be used for co-delivery of drugs or a modified release profile. Often the structure can only be postulated by the preparation process, such as surface polymerization, but cannot be experimentally determined due to a lack of appropriate analytical methods. Here a core-shell particle system composed of two biodegradable and biocompatible materials, gelatin and PLGA, is developed. In order to reveal the actual polymer distribution, a combination of cryo-transmission electron microscopy and energy-filtered transmission electron microscopy was established. Using the occurrence of specific elements in combination with degradation kinetics induced by the electron beam allows to conclude on the nanoparticles' architecture. Based on these methods and thus, the particle composition, the drug delivery system can be further developed.


Assuntos
Nanopartículas/química , Polímeros/química , Materiais Biocompatíveis/química , Microscopia Crioeletrônica/métodos , Sistemas de Liberação de Medicamentos/métodos , Microscopia Eletrônica de Transmissão/métodos , Microscopia Eletrônica de Transmissão por Filtração de Energia/métodos , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Polimerização
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