15 research outputs found
Magnetic Polymer Composite as a Thermosensitive Agent for Induced Hyperthermia
No full textPolyetheretherketone (PEEK) - magnetite (Fe3O4) blended compounds were produced by high speed vibration milling of PEEK-Fe 3O4 powders exposed to hexane and heated to the melting point (~350 °C) to form the homogeneous magnetic polymer composite, which provided a uniform dispersion of magnetite with low agglomerations in the polymer matrix. Polymer composite with 10 wt.% of magnetite displayed a magnetic saturation of 8 emu/g, tensile strength of 60 MPa and Young’s modulus of 4.4 GPa. Biotoxicity assessment was conducted via in vitro assay. The composite did not induce any adverse reactions, permitting use in medical applications. This study develops analytical relationships and computation of power dissipation of a magnetic material subjected to an alternating magnetic field. Calorimetric measurements of specific power absorption showed about 202 W/g upon cancelling the Brownian motion of magnetite through the encapsulation of the magnetic particles within the polymeric matrices leaving only Neel as the heat loss mechanism
Nanoporous Metals: From Plasmonic Properties to Applications in Enhanced Spectroscopy and Photocatalysis
No full textThe field of plasmonics is capable of enabling interesting applications in different wavelength ranges, spanning from the ultraviolet up to the infrared. The choice of plasmonic material and how the material is nanostructured has significant implications for ultimate performance of any plasmonic device. Artificially designed nanoporous metals (NPMs) have interesting material properties including large specific surface area, distinctive optical properties, high electrical conductivity, and reduced stiffness, implying their potentials for many applications. This paper reviews the wide range of available nanoporous metals (such as Au, Ag, Cu, Al, Mg, and Pt), mainly focusing on their properties as plasmonic materials. While extensive reports on the use and characterization of NPMs exist, a detailed discussion on their connection with surface plasmons and enhanced spectroscopies as well as photocatalysis is missing. Here, we report on different metals investigated, from the most used nanoporous gold to mixed metal compounds, and discuss each of these plasmonic materials' suitability for a range of structural design and applications. Finally, we discuss the potentials and limitations of the traditional and alternative plasmonic materials for applications in enhanced spectroscopy and photocatalysis
Advances in Plasmonic Biosensing Towards Detection, Quantitative Analysis and Molecular Profiling of Single Exosomes for Cancer Diagnostics
No full textExosomes are small (∼30 nm to ∼250 nm in diameter), single phospholipid-membrane, extracellular vesicles secreted by all mammalian cells into the bloodstream. Exosomes share the same topology as the parent cell, including selective surface proteins, lipids, and internally stored nucleic acids. Exosomes are responsible for intercellular communication through the transportation of genetic molecules (DNA, RNA, miRNA, etc.) and play a crucial role in human health from developing immunity to cancer. The transition of a parent cell from healthy to cancerous results in the dysregulation of exosomal surface proteins and stored genetic molecules. In turn, profiling exosomal properties can provide an insight into the state of the parent cell undergoing physical/property changes which include cancer progression. However, due to the nanoscale size of exosomes, currently available analytical tools suffer immense limitations such as detection due to insufficient light, low throughput/yield, and require extensive labeling for molecular content. To address these limitations, we developed plasmonic platforms based on arrayed substrates fabricated by our group called nanoporous gold disk (NPGD) array and arrayed gold nanodisks on invisible (AGNIS). Fabricated NPGD and AGNIS possess a remarkable plasmonic property called localized surface plasmon resonance (LSPR). LSPR describes the interaction of free electrons in the metal with electromagnetic waves and results in a strong absorption peak. Due to the highly tunable LSPR absorbance peak of the NPGD array, plasmonic microbubbles of controlled size are generated upon irradiating near-infrared (NIR) light. Plasmonic microbubble can direct and concentrate dispersed micro-/nanoparticles in the liquid at any location on the NPGD surface. Redistributing particles through plasmonic microbubbles facilitates profiling exosomes at concentrations below the dynamic range and the detection limit of the analytical system. Next, we used the AGNIS to develop an imaging technique called plasmonic nanoaperture label-free imaging (PANORAMA) that detects dielectric nanoparticles based on unscattered light. This procedure could determine the size, number, and availability of nanoparticles past 25 nm and measure their distance from the plasmonic surface within a few milliseconds. Combining PANORAMA with fluorescence microscopy allows label-free counting, sizing, and surface protein and cargo micro-RNA characterization at the single exosome level. Finally, using the PANORAMA-fluorescence imaging system, we identify healthy donor plasmas from cancer patients by label-free detection of retained exosomes and MIR-21 occurrence among retained exosomes from plasma
Paisajes (in)visibles del Caribe en dos relatos de Edwidge Danticat
No full textSe analizan las implicancias políticas de los paisajes representados en “Seeing Things Simply” y “A Wall of Fire Rising”. Estas historias forman parte de la colección de relatos titulada Krik? Krak! de la autora Haitiana Edwidge Danticat. En el primer cuento la protagonista, Princesse sirve de modelo a una pintora francesa quien la retrata desnuda en la playa. La muchacha, con el tiempo, se da cuenta de que ella desea ser artista también y no modelo, y dibuja en el suelo una escena de la vida cotidiana en su pueblo. En el segundo, la autora retrata un episodio en la vida de una familia muy pobre en un pueblo de Haití. Mientras el hijo aprende las palabras de un revolucionario haitiano para una obra de la escuela, el padre fantasea con escapar de la isla en globo. La noción de paisaje liga de manera patente la mirada humana con el entorno físico. A pesar de que a priori parecería que los paisajes estuvieran allí, estáticos y dispuestos simplemente para ser aprehendidos, existen innumerables mediaciones que responden de manera clara a la esfera de la cultura. Desde la geografía cultural hace ya algunas décadas se cuestionan ideas despolitizadas de percepción del paisaje y se enfatiza cada vez más su carácter político, dinámico y socialmente construido, a pesar de que pueda tratarse de espacios naturales con poca o ninguna intervención del humano. Qué califica para ser considerado un paisaje es una cuestión que involucra intereses económicos y políticos, así como también expectativas diseminadas en la cultura y repetidas a lo largo del tiempo. Las historias construyen paisajes alternativos que a su vez exponen prácticas imperialistas.“Seeing Things Simply” and “A Wall of Fire Rising” are part of the collection of stories Krik? Krak! by Haitian author Edwidge Danticat. In the first story, the protagonist, Princesse, models for a French artist, who portrays her naked on the beach. Princesse eventually realizes that she wants to be an artist herself and draws on the floor a scene from everyday life in her village. The second story narrates an event in the life of a very poor Haitian family. While the son learns the part of a Revolutionary Haitian Hero for a school play, his father, Guy, fantasizes with gaining freedom by flying a hot air balloon away from his miserable life. The notion of landscape strongly links the human gaze with the physical environment. Even though a priori it would seem that landscapes are there, static, waiting for someone to apprehend it, there exist innumerable mediations that clearly respond to the cultural sphere. From the discipline of cultural geography, the idea that landscapes are depoliticized has been put into question for some decades, and their political, dynamic and socially constructed nature is now more frequently emphasized, even if the space analyzed may display little or no human intervention as such. What qualifies as landscape is a question that involves political and economic interests, as well as expectations disseminated and naturalized throughout space and time. In the stories object of analysis one can detect the imperial and exoticizing gaze which determines what a Caribbean landscape is and how Princesse and Guy resist this gaze on the surrounding territory as well as on themselves. In this way, the stories construct alternative landscapes that expose the consequences of imperial practices.Fil: Der-ohannesian, Nadia. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Effects of solvent used for fabrication on drug loading and release kinetics of electrosprayed temozolomide‐loaded PLGA microparticles for the treatment of glioblastoma
No full textGlioblastoma multiforme (GBM) is the most common and invasive form of malignant brain tumors and despite advances in surgery, radiotherapy, and chemotherapy, the survival of patients with GBM still remains poor. Temozolomide (TMZ) is the chemotherapy drug that is most commonly given orally after surgical resection of these tumors. In this study, the effects of solvents (i.e., dichloromethane and acetonitrile) used for the fabrication of electrosprayed TMZ-loaded poly(lactic-co-glycolic acid) (PLGA) on drug loading, loading efficiency, drug release kinetics, surface morphology, and particle size were investigated. The results from this study demonstrated that by using a larger volume of a solvent with higher polarity (i.e., acetonitrile) which allows for a higher amount of hydrophilic TMZ to dissolve into the polymer solution, higher drug loading could be achieved. However, the particles fabricated with high amount of acetonitrile, which has a lower vapor pressure, had large pores and a smaller diameter which led to an initial burst release and high cumulative release at the end of the study. An optimal combination of the two solvents is needed to result in particles with a good amount of loading and minimal initial burst release. The electrosprayed microparticles were able to illicit a cytotoxic response in U-87 MG glioblastoma cells at a lower concentration of drug compared to the free drug. This work indicated that electrospraying is a promising method for the fabrication of TMZ-loaded PLGA microparticles for the treatment of GBM and solvent composition can be altered to control drug loading and release kinetics
Plasmonic nano-aperture label-free imaging
No full textLabel-free observation of nanoparticles by far-field optical microscopy is challenging because their ability to scatter or absorb light dramatically diminishes with decreasing size. Surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) imaging have shown promises and respective limitations. For instance, it is challenging to achieve diffraction-limited resolution in SPR imaging; its refractive index sensitivity is not as localized as desired. LSPR imaging is typically employed with dark-field microscopy on sparse noble metal nanostructures, leading to low light throughput and incomplete imaging. Here we demonstrate ultra near-field index modulated PlAsmonic NanO-apeRture lAbel-free iMAging (PANORAMA) that addresses existing issues for both SPR and LSPR imaging. PANORAMA produces diffraction-limited lateral resolution with higher surface sensitivity compared to SPR. Its system configuration is identical to a standard bright-field microscope using a trans-illumination tungsten-halogen lamp instead of a laser or other high-intensity light sources. Additionally, PANORAMA addresses the sparse sampling issue in LSPR imaging by achieving dense sampling with a large imaging fill factor. The bright-field approach provides much higher light throughput compared to dark-field microscopy. Overall, our technique can provide a panoramic view both laterally and longitudinally - overcoming the lack of imaging depth for both SPR and LSPR imaging and the insufficient lateral sampling for LSPR imaging. We have demonstrated that PANORAMA can size single nanoparticle down to 25 nm, count individual nanoparticles in a cluster, and dynamically monitor single nanoparticle approaching the plasmonic surface down to the millisecond timescale. PANORAMA is potentially useful in single biological nanoparticle analysis of exosomes and viruses
Author Correction: Plasmonic nano-aperture label-free imaging of single small extracellular vesicles for cancer detection
No full text
