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  1. Article ; Online: Activatable Nanoparticles

    Chukwuazam Nwasike / Erin Purr / Eunsoo Yoo / Jaspreet Singh Nagi / Amber L. Doiron

    Pharmaceuticals, Vol 14, Iss 1, p

    Recent Advances in Redox-Sensitive Magnetic Resonance Contrast Agent Candidates Capable of Detecting Inflammation

    2021  Volume 69

    Abstract: The emergence of activatable magnetic resonance (MR) contrast agents has prompted significant interest in the detection of functional markers of diseases, resulting in the creation of a plethora of nanoprobes capable of detecting these biomarkers. These ... ...

    Abstract The emergence of activatable magnetic resonance (MR) contrast agents has prompted significant interest in the detection of functional markers of diseases, resulting in the creation of a plethora of nanoprobes capable of detecting these biomarkers. These markers are commonly dysregulated in several chronic diseases, specifically select cancers and inflammatory diseases. Recently, the development of redox-sensitive nanoparticle-based contrast agents has gained momentum given advances in medicine linking several inflammatory diseases to redox imbalance. Researchers have pinpointed redox dysregulation as an opportunity to use activatable MR contrast agents to detect and stage several diseases as well as monitor the treatment of inflammatory diseases or conditions. These new classes of agents represent an advancement in the field of MR imaging as they elicit a response to stimuli, creating contrast while providing evidence of biomarker changes and commensurate disease state. Most redox-sensitive nanoparticle-based contrast agents are sensitive to reductive glutathione or oxidative reactive oxygen species. In this review, we will explore recent investigations into redox-activatable, nanoparticle-based MR contrast agent candidates.
    Keywords MR contrast agents ; responsive ; relaxation ; redox-activatable ; Medicine ; R ; Pharmacy and materia medica ; RS1-441
    Subject code 500
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Non-ionising UV light increases the optical density of hygroscopic self assembled DNA crystal films

    Alexandria E. Gasperini / Susy Sanchez / Amber L. Doiron / Mark Lyles / Guy K. German

    Scientific Reports, Vol 7, Iss 1, Pp 1-

    2017  Volume 10

    Abstract: Abstract We report on ultraviolet (UV) light induced increases in the UV optical density of thin and optically transparent crystalline DNA films formed through self assembly. The films are comprised of closely packed, multi-faceted and sub micron sized ... ...

    Abstract Abstract We report on ultraviolet (UV) light induced increases in the UV optical density of thin and optically transparent crystalline DNA films formed through self assembly. The films are comprised of closely packed, multi-faceted and sub micron sized crystals. UV-Vis spectrophotometry reveals that DNA films with surface densities up to 0.031 mg/mm2 can reduce the transmittance of incident UVC and UVB light by up to 90%, and UVA transmittance by up to 20%. Subsequent and independent film irradiation with either UVA or UVB dosages upwards of 80 J/cm2 both reduce UV transmittance, with reductions scaling monotonically with UV dosage. To date the induction of a hyperchromic effect has been demonstrated using heat, pH, high salt mediums, and high energy ionising radiation. Both hyperchromicity and increased light scattering could account for the increased film optical density after UV irradiation. Additional characterisation of the films reveal they are highly absorbent and hygroscopic. When coated on human skin, they are capable of slowing water evaporation and keeping the tissue hydrated for extended periods of time.
    Keywords Medicine ; R ; Science ; Q
    Subject code 535
    Language English
    Publishing date 2017-07-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Surface characterization of nanoparticles using near-field light scattering

    Eunsoo Yoo / Yizhong Liu / Chukwuazam A. Nwasike / Sebastian R. Freeman / Brian C. DiPaolo / Bernardo Cordovez / Amber L. Doiron

    Beilstein Journal of Nanotechnology, Vol 9, Iss 1, Pp 1228-

    2018  Volume 1238

    Abstract: The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the ... ...

    Abstract The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the surface of poly(ethylene glycol)-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity using near-field light scattering. The local scattering intensity is correlated with the distance between the particle and waveguide, which is affected by the size of the particle (coating thickness) as well as the interactions between the particle and waveguide (related to the zeta potential of the coating). Therefore, we report here the use of near-field light scattering using nanophotonic force microscopy (using a NanoTweezerTM instrument, Halo Labs) to determine the changes that occurred in hydrated particle characteristics, which is accompanied by an analytical model. Furthermore, we found that altering the salt concentration of the suspension solution affected the velocity of particles due to the change of dielectric constant and viscosity of the solution. These findings suggest that this technique is suitable for studying particle surface changes and perhaps can be used to dynamically study reaction kinetics at the particle surface.
    Keywords nanoparticle surface properties ; nanoparticles ; nanophotonic force microscopy ; near-field light scattering ; superparamagnetic iron oxide ; Technology ; T ; Chemical technology ; TP1-1185 ; Science ; Q ; Physics ; QC1-999
    Subject code 620
    Language English
    Publishing date 2018-04-01T00:00:00Z
    Publisher Beilstein-Institut
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Activatable interpolymer complex-superparamagnetic iron oxide nanoparticles as magnetic resonance contrast agents sensitive to oxidative stress

    Yoo, Eunsoo / Amber L. Doiron / Carmen Lee / Charles T. Drinnan / David J. Beaman / Huaitzung A. Cheng / Kenneth W. Fishbein / Lauren E. Nardacci / Omar Z. Fisher / Richard G. Spencer

    Elsevier B.V. Colloids and surfaces. 2017 Oct. 01, v. 158

    2017  

    Abstract: Magnetic resonance contrast agents that can be activated in response to specific triggers hold potential as molecular biosensors that may be of great utility in non-invasive disease diagnosis. We developed an activatable agent based on superparamagnetic ... ...

    Abstract Magnetic resonance contrast agents that can be activated in response to specific triggers hold potential as molecular biosensors that may be of great utility in non-invasive disease diagnosis. We developed an activatable agent based on superparamagnetic iron oxide nanoparticles (SPIOs) that is sensitive to oxidative stress, a factor in the pathophysiology of numerous diseases. SPIOs were coated with poly(ethylene glycol) (PEG) and complexed with poly(gallol), a synthetic tannin. Hydrogen bonding between PEG and poly(gallol) creates a complexed layer around the SPIO that decreases the interaction of solute water with the SPIO, attenuating its magnetic resonance relaxivity. The complexed interpolymer nanoparticle is in an OFF state (decreased T2 contrast), where the contrast agent has a low T2 relaxivity of 7±2mM−1s−1. In the presence of superoxides, the poly(gallol) is oxidized and the polymers decomplex, allowing solute water to again interact with the SPIO, representing an ON state (increased T2 contrast) with a T2 relaxivity of 70±10mM−1s−1. These contrast agents show promise as effective sensors for diseases characterized in part by oxidative stress such as atherosclerosis, diabetes, and cancer.
    Keywords atherosclerosis ; biosensors ; colloids ; diabetes ; disease diagnosis ; hydrogen bonding ; iron oxides ; nanoparticles ; neoplasms ; oxidative stress ; pathophysiology ; polyethylene glycol ; solutes ; superoxide anion
    Language English
    Dates of publication 2017-1001
    Size p. 578-588.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1500523-9
    ISSN 1873-4367 ; 0927-7765
    ISSN (online) 1873-4367
    ISSN 0927-7765
    DOI 10.1016/j.colsurfb.2017.07.025
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: A human cell model for dynamic testing of MR contrast agents

    Anne-Lise Aulanier / Amber L. Doiron / Robert D. Shepherd / Kristina D. Rinker / Richard Frayne / Linda B. Andersen

    BioTechniques, Vol 50, Iss 2, Pp 120-

    2011  Volume 123

    Abstract: To determine the initial feasibility of using magnetic resonance (MR) imaging to detect early atherosclerosis, we investigated inflammatory cells labeled with a positive contrast agent in an endothelial cell–based testing system. The human monocytic cell ...

    Abstract To determine the initial feasibility of using magnetic resonance (MR) imaging to detect early atherosclerosis, we investigated inflammatory cells labeled with a positive contrast agent in an endothelial cell–based testing system. The human monocytic cell line THP-1 was labeled by overnight incubation with a gadolinium colloid (Gado CELLTrack) prior to determination of the in vitro release profile from T1-weighted MR images. Next, MR signals arising from both a synthetic model of THP-1/human umbilical vein endothelial cell (HUVEC) accumulation and the dynamic adhesion of THP-1 cells to activated HUVECs under flow were obtained. THP-1 cells were found to be successfully—but not optimally—labeled with gadolinium colloid, and MR images demonstrated increased signal from labeled cells in both the synthetic and dynamic THP-1/HUVEC models. The observed THP-1 contrast release profile was rapid, suggesting the need for an agent that is optimized for retention in the target cells for use in further studies. Detection of labeled THP-1 cells was accomplished with no signal enhancement from unlabeled cells. These achievements demonstrate the feasibility of targeting early atherosclerosis with MR imaging, and suggest that using an in vitro system like the one described provides a rapid, efficient, and cost-effective way to support the development and evaluation of novel MR contrast agents.
    Keywords Atherosclerosis ; inflammatory reaction ; monocytes ; endothelial cells ; positive MR contrast agent ; molecular MR imaging ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2011-02-01T00:00:00Z
    Publisher Future Science Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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