23 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
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 textPreliminary Results of an Examination of Electronic Cigarette User Puff Topography: The Effect of a Mouthpiece-Based Topography Measurement Device on Plasma Nicotine and Subjective Effects
No full textIntroduction: Electronic cigarettes (ECIGs) heat a nicotine-containing solution; the resulting aerosol is inhaled by the user. Nicotine delivery may be affected by users' puffing behavior (puff topography), and little is known about the puff topography of ECIG users. Puff topography can be measured using mouthpiece-based computerized systems. However, the extent to which a mouthpiece influences nicotine delivery and subjective effects in ECIG users is unknown. Methods: Plasma nicotine concentration, heart rate, and subjective effects were measured in 13 experienced ECIG users who used their preferred ECIG and liquid (≥12 mg/ml nicotine) during 2 sessions (with or without a mouthpiece). In both sessions, participants completed an ECIG use session in which they were instructed to take 10 puffs with 30-second inter-puff intervals. Puff topography was recorded in the mouthpiece condition. Results: Almost all measures of the effects of ECIG use were independent of topography measurement. Collapsed across session, mean plasma nicotine concentration increased by 16.8 ng/ml, and mean heart rate increased by 8.5 bpm (ps < .05). Withdrawal symptoms decreased significantly after ECIG use. Participants reported that the mouthpiece affected awareness and made ECIG use more difficult. Relative to previously reported data for tobacco cigarette smokers using similar topography measurement equipment, ECIG-using participants took larger and longer puffs with lower flow rates. Conclusions: In experienced ECIG users, measuring ECIG topography did not influence ECIGassociated nicotine delivery or most measures of withdrawal suppression. Topography measurement systems will need to account for the low flow rates observed for ECIG users. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved
