Evolution of phase morphology in compatibilized polymer blends at constant quench depths: Complementary studies by light scattering and transmission electron microscopy

1997 ◽  
Vol 37 (9) ◽  
pp. 1449-1458 ◽  
Author(s):  
C. L. Jackson ◽  
L. Sung ◽  
C. C. Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Scattering ◽  
Polymer Blends ◽  
Phase Morphology ◽  
Transmission Electron

Polyethyleneimine Modified Biocompatible Poly(N-isopropylacrylamide)-Based Nanogels for Drug Delivery

2008 ◽  
Vol 8 (5) ◽  
pp. 2377-2384 ◽  
Author(s):  
Chang-Yun Quan ◽  
Hua Wei ◽  
Yun-Xia Sun ◽  
Si-Xue Cheng ◽  
Kun Shen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drug Delivery ◽  
Transmission Electron Microscopy ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Transmission Electron ◽  
Potential Applications ◽  
Different Temperatures ◽  
The Mean ◽  
Stimuli Sensitive

A series of biocompatible and stimuli-sensitive poly(N-isopropylacrylamide-co-propyl acrylic acid) (P(NIPAAm-co-PAAc)) nanogels were synthesized by emulsion polymerization. In addition, polyethyleneimine (PEI) was further grafted to modify the PNIPAAm-based nanogels. The P(NIPAAm-co-PAAc)-g-PEI nanogels exhibited good thermosensitivity as well as pH sensitivity. Transmission electron microscopy (TEM) showed that the P(NIPAAm-co-PAAc)-g-PEI and P(NIPAAm-co-PAAc) nanogels displayed well dispersed spherical morphology. The mean sizes of the nanogels measured by dynamic light scattering (DLS) were from 100 nm to 500 nm at different temperatures. The cytotoxicity study indicated P(NIPAAm-co-PAAc) nanogels exhibited a better biocompatibility than both PNIPAAm nanogel and P(NIPAAm-co-PAAc)-g-PEI nanogel although all the three kinds of nanogels did not exhibit apparent cytotoxicity. The drug-loaded nanogels, especially the PEI-grafted nanogels, showed temperature-trigged controlled release behaviors, indicating the potential applications as an intelligent drug delivery system.

Preparation of Size and Morphology Controlled Gold Nanoparticles in Micro-Emulsion and in Aqueous

2012 ◽  
Vol 184-185 ◽  
pp. 1138-1141
Author(s):  
Yan Biao Zhang ◽  
Xiao Hui Zhang ◽  
Hong Zong Yin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Light Scattering ◽  
Homogeneous Distribution ◽  
Mass Ratio ◽  
Optimum Ratio ◽  
Transmission Electron ◽  
Micro Emulsion ◽  
Size And Morphology

In this study, we prepared gold nanoparticles in micro-emulsion and found the optimum ratio of micro-emulsion for preparing gold nanoparticles. We reported a new stabilizer for preparing gold nanoparticles in aqueous and found the optimum mass ratio between the stabilizer and chlorauric acid. All gold nanoparticles prepared by these two methods were characterized by transmission electron microscopy, ultraviolet-visible spectrophotometer and synchronous light-scattering spectrophotometer. The results of transmission electron microscopy showed that the diameter range of gold nanoparticles prepared in micro-emulsion was 5~10 nm, and that in aqueous was 10~15 nm. They all had homogeneous distribution and dense structures.

scholarly journals The Depolarization-Evoked, Ca2+-Dependent Release of Exosomes From Mouse Cortical Nerve Endings: New Insights Into Synaptic Transmission

2021 ◽  
Vol 12 ◽  
Author(s):  
Guendalina Olivero ◽  
Francesca Cisani ◽  
Danilo Marimpietri ◽  
Daniela Di Paolo ◽  
Maria Cristina Gagliani ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Light Scattering ◽  
Biochemical Analysis ◽  
Nerve Terminals ◽  
Transmission Electron ◽  
Presynaptic Release ◽  
Presynaptic Nerve Terminals ◽  
Active Release

Whether exosomes can be actively released from presynaptic nerve terminals is a matter of debate. To address the point, mouse cortical synaptosomes were incubated under basal and depolarizing (25 mM KCl-enriched medium) conditions, and extracellular vesicles were isolated from the synaptosomal supernatants to be characterized by dynamic light scattering, transmission electron microscopy, Western blot, and flow cytometry analyses. The structural and biochemical analysis unveiled that supernatants contain vesicles that have the size and the shape of exosomes, which were immunopositive for the exosomal markers TSG101, flotillin-1, CD63, and CD9. The marker content increased upon the exposure of nerve terminals to the high-KCl stimulus, consistent with an active release of the exosomes from the depolarized synaptosomes. High KCl-induced depolarization elicits the Ca2+-dependent exocytosis of glutamate. Interestingly, the depolarization-evoked release of exosomes from cortical synaptosomes also occurred in a Ca2+-dependent fashion, since the TSG101, CD63, and CD9 contents in the exosomal fraction isolated from supernatants of depolarized synaptosomes were significantly reduced when omitting external Ca2+ ions. Differently, (±)-baclofen (10 µM), which significantly reduced the glutamate exocytosis, did not affect the amount of exosomal markers, suggesting that the GABAB-mediated mechanism does not control the exosome release. Our findings suggest that the exposure of synaptosomes to a depolarizing stimulus elicits a presynaptic release of exosomes that occurs in a Ca2+-dependent fashion. The insensitivity to the presynaptic GABAB receptors, however, leaves open the question on whether the release of exosomes could be a druggable target for new therapeutic intervention for the cure of synaptopathies.

scholarly journals Scanning Transmission Electron Microscopy for Polymer Blends

2017 ◽  
Vol 4 (1) ◽  
pp. 31-36
Author(s):  
Pradeep Singh ◽  
B. R. Venugopal ◽  
Radha Kamalakaran
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Polymer Blends ◽  
Scanning Transmission Electron Microscopy ◽  
Critical Role ◽  
Polymer Materials ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Butadiene Styrene

Physical properties of the polymer can be altered by mixing one or more polymers together also known as polymer blending. The miscibility of polymers is a key parameter in determining the properties of polymer blend. Conventional transmission electron microscopy (CTEM) plays a critical role in determining the miscibility and morphology of the polymers in blend system. One of the most difficult part in polymer microscopy is the staining by heavy metals to generate contrast in CTEM. RuO4 and OsO4 are commonly used to stain the polymer materials for CTEM imaging. CTEM imaging is difficult to interpret for blends due to lack of clear distinction in contrast. Apart from having difficulty in contrast generation, staining procedures are extremely dangerous as improper handling could severely damage skin, eyes, lungs etc. We have used scanning transmission electron microscopy (STEM) to image polymer blends without any staining processes. In current work, Acrylonitrile Butadiene Styrene (ABS)/Methacrylate Butadiene Styrene (MBS) and Styrene Acrylonitrile (SAN) along with filler additive were dispersed on Polycarbonate (PC) matrix and studied by STEM/HAADF (high angle annular dark field). By using HAADF, contrast was generated through molecular density difference to differentiate components in the blend.

scholarly journals Estudio comparativo de la síntesis de nanopartículas de magnetita monodispersas

2018 ◽  
pp. 5-11
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Thermal Decomposition ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Aqueous Suspension ◽  
The Body ◽  
Synthesis Route ◽  
Transmission Electron ◽  
Co Precipitation

Estudio comparativo de la síntesis de nanopartículas de magnetita monodispersas J.J. Atoche Medrano, J. A. Huamani Coaquira Universidad de Brasília, Campus Universitário Darcy Ribeiro, Brasília - CEP 70910-900 DOI: https://doi.org/10.33017/RevECIPeru2015.0001/ Resumen Actualmente el tipo de nanopartículas magnéticas más estudiados son los de estructura cúbica, espinela inversa, porque estos materiales presentan características de gran interés y sus posibles aplicaciones ya que facilitan la construcción de sistemas más complejos. Debemos considerar que debido a la presencia de metales de transición en la superficie de las nanopartículas es que se dan las condiciones para poder funcionalizarlas con otras moléculas a través de grupos funcionales complejos obteniendo materiales con características polares o apolares, dependiendo del tipo de aplicación que se desee utilizar. Teniendo en consideración que cuando se trabaja con sistemas biológicos las nanopartículas son detectadas por el sistema retículo endotelial (SRE), que a través de los macrófagos son los encargados de eliminar algún cuerpo extraño inerte que pudiera estar en el organismo. De esta manera, existe una necesidad de funcionalizar las nanopartículas obtenidas antes de ser administradas en el organismo para evitar ser reconocidas por el SRE. Esta funcionalización es responsable por evitar la aglomeración de las mismas permitiendo que ellas permanezcan en suspensión estable (coloides magnéticos) que pueden ser conducidos a través de campos magnéticos externos. En este trabajo, nosotros mostramos detalladamente los resultados obtenido en la mejora de la ruta de síntesis de un sistema de nano partículas en forma de ferrofluido de magnetita (Fe3O4) utilizando el método de descomposición térmica y comparamos nuestros resultados respecto a otra ruta de síntesis para sistema nano particulados llamado método de co-precipitación química. Para poder medir el tamaño, así como conocer las propiedades morfológicas y estructurales de las nanopartículas se procedió a la caracterización de nanopartículas obtenidas por los métodos de descomposición térmica y co-precipitación química a través de microscopia electrónica de transmisión (MET). Se encontró una distribución de tamaños con un promedio de 8 nm y polidispersión de 0.14. Estos resultados fueron corroborados por los resultados obtenidos mediante análisis de patrones de difracción de rayos X. La estabilidad del ferrofluido obtenido fue medida usando la técnica conocida como DLS (Dynamic Light Scattering), donde fue encontrado un valor de 42.8 mV, que está dentro del valor esperado para un sistema estable, considerando que para un sistema nanopartículado el valor de Zetasiser arriba de 30 mV representa una estabilidad de la suspensión acuosa. Al final de las medidas de caracterización se realizó la medida del valor del potencial de hidrógeno (pH) mediante un pH-metro, para estudiar la biocompatibilidad que presenta nuestra muestra de ferrofluido ya que nuestro interés es que este ferrofluido pueda ser usado como vehículo para direccionar principios activos o fármacos sobre una región específica en el organismo. Así después de realizada la medición fue encontrado un valor del pH de 7.23 lo que evidencia un sistema biocompatible para posibles aplicaciones biológicas. Descriptores: Descomposición térmica, co-precipitación, ferrofluido, nanopartículas, microscopia electrónica de transmisión. Abstract Currently the most studied type of magnetic nanoparticles are of cubic structure, inverse spinel, because these materials have very interesting features and possible applications since they facilitate building more complex systems. We must consider that due to the presence of transition metal on the surface of nanoparticles is that the conditions for funcionalizarlas with other molecules through complex functional groups obtaining materials with polar or apolar characteristics, depending on the type of implementation that want to use. Considering that when working with biological systems nanoparticles are detected by the reticuloendothelial system (RES). This functionalization is responsible for preventing agglomeration there of allowing them to remain in stable suspension (magnetic colloids) that can be driven by external magnetic fields. In this work, we show in detail the results obtained in improving the synthesis route system in the form of nanoparticles ferrofluid magnetite (Fe3O4) using the method of thermal decomposition and compare our results with respect to another synthesis route to nano particulate system method called chemical coprecipitation. To measure the size as well as knowing the morphological and structural properties of nanoparticles proceeded to the characterization of nanoparticles obtained by the methods of thermal decomposition and chemical co-precipitation through transmission electron microscopy (TEM). Size distribution averaging 8 nm and polydispersity of 0.14 was found. These results were corroborated by the results obtained by analyzing patterns of X-ray diffraction. The stability of the ferrofluid obtained was measured using the technique known as DLS (Dynamic Light Scattering), where it was found a value of 42.8 mV, which is within the expected value for a stable system, whereas for a nanoparticle system Zetasiser value above 30 mV represents a stability of the aqueous suspensión. At the end of characterization measures the extent of the value of the potential of hydrogen (pH) was performed using a pH meter, to study our sample having biocompatibility ferrofluid as our interest is that the ferrofluid could be used as vehicle for active ingredients or drugs addressing to a specific region in the body. And after completion of the measurement it was found a pH of 7.23 which shows a biocompatible system to possible biological applications. Keywords: Thermal decomposition, co-precipitation, ferrofluid, nanoparticles, transmission electron microscopy.

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