22 results on '"Amber L. Doiron"'
Search Results
2. Differential effect of gold nanoparticles on cerebrovascular function and biomechanical properties
- Author
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Ryan D. Hunt, Omid Sedighi, Wayne M. Clark, Amber L. Doiron, and Marilyn J. Cipolla
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blood–brain barrier ,cerebrovasculature ,gold nanoparticles ,ischemia ,stroke ,Physiology ,QP1-981 - Abstract
Abstract Human stroke serum (HSS) has been shown to impair cerebrovascular function, likely by factors released into the circulation after ischemia. 20 nm gold nanoparticles (GNPs) have demonstrated anti‐inflammatory properties, with evidence that they decrease pathologic markers of ischemic severity. Whether GNPs affect cerebrovascular function, and potentially protect against the damaging effects of HSS on the cerebral circulation remains unclear. HSS obtained 24 h poststroke was perfused through the lumen of isolated and pressurized third‐order posterior cerebral arteries (PCAs) from male Wistar rats with and without GNPs (~2 × 109 GNP/ml), or GNPs in vehicle, in an arteriograph chamber (n = 8/group). All vessels were myogenically reactive ≥60 mmHg intravascular pressure; however, vessels containing GNPs had significantly less myogenic tone. GNPs increased vasoreactivity to small and intermediate conductance calcium activated potassium channel activation via NS309; however, reduced vasoconstriction to nitric oxide synthase inhibition. Hydraulic conductivity and transvascular filtration, were decreased by GNPs, suggesting a protective effect on the blood–brain barrier. The stress–strain curves of PCAs exposed to GNPs were shifted leftward, indicating increased vessel stiffness. This study provides the first evidence that GNPs affect the structure and function of the cerebrovasculature, which may be important for their development and use in biomedical applications.
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- 2023
- Full Text
- View/download PDF
3. Surface characterization of nanoparticles using near-field light scattering
- Author
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Eunsoo Yoo, Yizhong Liu, Chukwuazam A. Nwasike, Sebastian R. Freeman, Brian C. DiPaolo, Bernardo Cordovez, and Amber L. Doiron
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nanoparticle surface properties ,nanoparticles ,nanophotonic force microscopy ,near-field light scattering ,superparamagnetic iron oxide ,Technology ,Chemical technology ,TP1-1185 ,Science ,Physics ,QC1-999 - 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.
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- 2018
- Full Text
- View/download PDF
4. Non-ionising UV light increases the optical density of hygroscopic self assembled DNA crystal films
- Author
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Alexandria E. Gasperini, Susy Sanchez, Amber L. Doiron, Mark Lyles, and Guy K. German
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Medicine ,Science - 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.
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- 2017
- Full Text
- View/download PDF
5. Activatable Nanoparticles: Recent Advances in Redox-Sensitive Magnetic Resonance Contrast Agent Candidates Capable of Detecting Inflammation
- Author
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Chukwuazam Nwasike, Erin Purr, Eunsoo Yoo, Jaspreet Singh Nagi, and Amber L. Doiron
- Subjects
MR contrast agents ,responsive ,relaxation ,redox-activatable ,Medicine ,Pharmacy and materia medica ,RS1-441 - 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.
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- 2021
- Full Text
- View/download PDF
6. A human cell model for dynamic testing of MR contrast agents
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Anne-Lise Aulanier, Amber L. Doiron, Robert D. Shepherd, Kristina D. Rinker, Richard Frayne, and Linda B. Andersen
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Atherosclerosis ,inflammatory reaction ,monocytes ,endothelial cells ,positive MR contrast agent ,molecular MR imaging ,Biology (General) ,QH301-705.5 - 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.
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- 2011
- Full Text
- View/download PDF
7. Incorporation of Targeting Biomolecule Improves Interpolymer Complex-Superparamagnetic Iron Oxide Nanoparticles Attachment to and Activation of T2 MR Signals in M2 Macrophages
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Chukwuazam Nwasike, Erin Purr, Jaspreet Singh Nagi, Gretchen J Mahler, and Amber L Doiron
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Biomaterials ,International Journal of Nanomedicine ,Organic Chemistry ,Drug Discovery ,Biophysics ,Pharmaceutical Science ,Bioengineering ,General Medicine - Abstract
Chukwuazam Nwasike,1 Erin Purr,1 Jaspreet Singh Nagi,2 Gretchen J Mahler,1 Amber L Doiron2 1Department of Biomedical Engineering, Binghamton University (SUNY), Binghamton, NY, USA; 2Department of Electrical and Biomedical Engineering, University of Vermont, Burlington, VT, USACorrespondence: Amber L Doiron, Email amber.doiron@uvm.eduIntroduction: Inflammatory diseases are the leading cause of death in the world, accounting for 3 out of 5 deaths. Despite the abundance of diagnostic tools for detection, most screening and diagnostic methods are indirect and insufficient as they are unable to reliably discriminate between high-risk or low-risk stages of inflammatory diseases. Previously, we showed that the selective activation of interpolymer complexed superparamagnetic iron oxide nanoparticles (IPC-SPIOs) under oxidative conditions can be detected by a change in T2 magnetic resonance (MR) contrast. In this work, IPC-SPIOs were further modified by incorporating mannose as a targeting biomolecule to enhance nanoparticle delivery to M2 macrophages at inflammatory sites.Methods: Uncoated SPIOs were synthesized via coprecipitation from a mixture of FeCl2 and FeCl3, PEGylated by adsorbing PEG 300 kDa (40 mg/mL in water) to SPIOs (3 mg/mL in water) over 24 hours, and complexed by mixing 0.25 mg/mL aqueous poly(gallol) with 2 mg/mL PEG-SPIOs and adding 1 M of phosphate buffer in a 9:9:2 ratio. Mannose-PEG attachment was accomplished conducting a second complexation of mannose-PEG to IPC-SPIOs. M2 macrophages were treated with 150, 100, and 75 μg/mL of IPC-SPIOs and mannose-IPC-SPIOs to investigate activation of T2 MRI signals.Results and Discussion: Surface modification resulted in a slight reduction in ROS scavenging capacity; however, nanoparticle uptake by M2 macrophages increased by over 50%. The higher uptake did not cause a reduction in cellular viability. In fact, mannose-IPC-SPIOs induced significant T2 MR contrast in M2 macrophages compared to IPC-SPIOs and nanoparticles exposed to M1 macrophages. M2 macrophages activated over 30% of mannose-IPC-SPIOs after 6 hours of exposure compared to M1 macrophages and untargeted M2 macrophages. These findings demonstrated that mannose-IPC-SPIOs specifically targeted M2 macrophages and scavenged cellular ROS to activate T2 MR signal, which can be used to detect inflammation.Graphical Abstract: Keywords: targeted nanoparticles, inflammatory diseases, MRI, contrast agents, mannose biomolecules
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- 2023
8. Design of core–shell gold‐coated superparamagnetic nanoparticles as a theranostic for targeted magnetic resonance imaging and photoablation therapy
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Chendong Han, Daniel Goldstein, Amber L. Doiron, and Matthew M. Mahan
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Materials science ,Biocompatibility ,Biomedical Engineering ,Nanoparticle ,Bioengineering ,Nanotechnology ,Photoablation ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Dark field microscopy ,0104 chemical sciences ,Magnetic nanoparticles ,Nanomedicine ,General Materials Science ,Surface plasmon resonance ,0210 nano-technology ,Superparamagnetism - Abstract
A theranostic refers to the concept of integrating diagnostic and therapeutic capabilities into a single platform. In this work, a layer of gold was reduced around superparamagnetic iron oxide (SPIO) nanoparticles to be used as a theranostic for magnetic resonance imaging and photoablation. In addition, a gold shell was included in the particle design to improve biocompatibility, stabilise nanoparticles in suspension, and allow robust surface functionalisation. Gold-coated SPIO nanoparticles of 8 nm in diameter exhibited surface plasmon resonance while also maintaining their superparamagnetic nature. Energy dispersive spectroscopy confirmed the existence of gold at the surface of the nanoparticles, the thickness of which was 0.5 nm based on transmission electron microscopy measurements. To demonstrate their potential for targeted therapies, nanoparticles were targeted to VCAM-1 on human umbilical vein endothelial cells and detected via darkfield microscopy.
- Published
- 2019
9. Pyruvate-depleting conditions induce biofilm dispersion and enhance the efficacy of antibiotics in killing biofilms in vitr o and in vivo
- Author
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Joel Gil, Karin Sauer, Michael Solis, Jose Valdes, James S Goodwine, Stephen C. Davis, Alex Higa, and Amber L. Doiron
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0301 basic medicine ,Staphylococcus aureus ,medicine.drug_class ,Swine ,Antibiotics ,lcsh:Medicine ,Article ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,In vivo ,Pyruvic Acid ,medicine ,Tobramycin ,Animals ,Humans ,Pseudomonas Infections ,lcsh:Science ,chemistry.chemical_classification ,Multidisciplinary ,lcsh:R ,Biofilm ,biochemical phenomena, metabolism, and nutrition ,In vitro ,Anti-Bacterial Agents ,Culture Media ,Disease Models, Animal ,030104 developmental biology ,Enzyme ,chemistry ,Biofilms ,Fermentation ,Pseudomonas aeruginosa ,lcsh:Q ,Pyruvic acid ,Burns ,030217 neurology & neurosurgery ,medicine.drug - Abstract
The formation of biofilms is a developmental process initiated by planktonic cells transitioning to the surface, which comes full circle when cells disperse from the biofilm and transition to the planktonic mode of growth. Considering that pyruvate has been previously demonstrated to be required for the formation of P. aeruginosa biofilms, we asked whether pyruvate likewise contributes to the maintenance of the biofilm structure, with depletion of pyruvate resulting in dispersion. Here, we demonstrate that the enzymatic depletion of pyruvate coincided with the dispersion of established biofilms by S. aureus and laboratory and clinical P. aeruginosa isolates. The dispersion response was dependent on pyruvate fermentation pathway components but independent of proteins previously described to contribute to P. aeruginosa biofilm dispersion. Using porcine second-degree burn wounds infected with P. aeruginosa biofilm cells, we furthermore demonstrated that pyruvate depletion resulted in a reduction of biofilm biomass in vivo. Pyruvate-depleting conditions enhanced the efficacy of tobramycin killing of the resident wound biofilms by up to 5-logs. Our findings strongly suggest the management of pyruvate availability to be a promising strategy to combat biofilm-related infections by two principal pathogens associated with wound and cystic fibrosis lung infections.
- Published
- 2019
10. Activatable Nanoparticles: Recent Advances in Redox-Sensitive Magnetic Resonance Contrast Agent Candidates Capable of Detecting Inflammation
- Author
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Amber L. Doiron, Erin Purr, Jaspreet Singh Nagi, Eunsoo Yoo, and Chukwuazam Nwasike
- Subjects
responsive ,media_common.quotation_subject ,lcsh:Medicine ,lcsh:RS1-441 ,Pharmaceutical Science ,Inflammation ,02 engineering and technology ,Disease ,Review ,010402 general chemistry ,01 natural sciences ,lcsh:Pharmacy and materia medica ,MR contrast agents ,relaxation ,Drug Discovery ,medicine ,redox-activatable ,Contrast (vision) ,media_common ,medicine.diagnostic_test ,Chemistry ,lcsh:R ,Mr contrast agent ,Magnetic resonance imaging ,021001 nanoscience & nanotechnology ,Mr imaging ,Redox sensitive ,0104 chemical sciences ,Cancer research ,Molecular Medicine ,Biomarker (medicine) ,medicine.symptom ,0210 nano-technology - 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.
- Published
- 2021
11. Activatable Superparamagnetic Iron Oxide Nanoparticles Scavenge Reactive Oxygen Species in Macrophages and Endothelial Cells
- Author
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Eunsoo Yoo, Amber L. Doiron, Chukwuazam Nwasike, and Erin Purr
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chemistry.chemical_classification ,0303 health sciences ,Reactive oxygen species ,Superoxide ,General Chemical Engineering ,Cell ,Inflammation ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,In vitro ,Cell biology ,03 medical and health sciences ,chemistry.chemical_compound ,Immune system ,medicine.anatomical_structure ,chemistry ,medicine ,Cytotoxic T cell ,medicine.symptom ,0210 nano-technology ,Ethylene glycol ,030304 developmental biology - Abstract
Reactive oxygen species (ROS) are key markers of inflammation, with varying levels of superoxide indicating the degree of inflammation. Inflammatory diseases remain the leading cause of death in the developed world. Previously, we showed that interpolymer complexed superparamagnetic iron oxide nanoparticles (IPC-SPIOs) are capable of decomplexing and activating T2 magnetic resonance (MR) contrast in superoxide-rich environments. Here, we investigate the ability of IPC-SPIOs to scavenge ROS in immune and endothelial cells which should activate the superparamagnetic core. In exogenously generated superoxide, ROS scavenging by the nanoparticles was concentration dependent and ranged from 5% to over 50% of available ROS. A statistically significant reduction in ROS was observed in the presence of IPCSPIOs compared to poly(ethylene glycol)-coated SPIOs (PEG-SPIOs). During in vitro cellular assays, a reduction in ROS was observed in macrophages, monocytes, and human endothelial cells. Macrophages and endothelial cells experienced significantly higher ROS reduction compared to monocytes. ROS scavenging peaked 12 hours post-exposure to IPC-SPIOs in most studies, with some cell samples experiencing extended scavenging with increasing IPC-SPIO concentration. At the tested concentrations, particles were not cytotoxic, and confocal imaging showed localization of particles within cells. These findings demonstrate the potential of IPC-SPIOs as activatable MR contrast agents capable of activating under inflammation-induced cellular redox conditions as reporters of inflammatory disease severity or staging.
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- 2020
12. Surface characterization of nanoparticles using near-field light scattering
- Author
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Brian DiPaolo, Amber L. Doiron, Sebastian R Freeman, Bernardo Cordovez, Yizhong Liu, Eunsoo Yoo, and Chukwuazam Nwasike
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Materials science ,General Physics and Astronomy ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,lcsh:Chemical technology ,01 natural sciences ,lcsh:Technology ,Light scattering ,Full Research Paper ,Zeta potential ,Nanotechnology ,General Materials Science ,lcsh:TP1-1185 ,Particle velocity ,nanoparticle surface properties ,Electrical and Electronic Engineering ,lcsh:Science ,nanophotonic force microscopy ,Scattering ,lcsh:T ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,0104 chemical sciences ,Surface coating ,Nanoscience ,Chemical physics ,near-field light scattering ,Particle ,superparamagnetic iron oxide ,lcsh:Q ,nanoparticles ,Particle size ,0210 nano-technology ,lcsh:Physics - 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.
- Published
- 2018
13. Recent developments in the use of nanoparticles for treatment of biofilms
- Author
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Chendong Han, Amber L. Doiron, Aaron Berger, Nicholas Romero, Stephen Fischer, and Julia Dookran
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0301 basic medicine ,Technology ,antibiotic resistance ,Physical and theoretical chemistry ,QD450-801 ,030106 microbiology ,Energy Engineering and Power Technology ,Medicine (miscellaneous) ,Nanoparticle ,Nanotechnology ,TP1-1185 ,02 engineering and technology ,biofilm ,Nanomaterials ,Biomaterials ,03 medical and health sciences ,Materials processing ,Chemistry ,Chemical technology ,Process Chemistry and Technology ,bacterial infection ,technology, industry, and agriculture ,Biofilm ,Industrial chemistry ,biochemical phenomena, metabolism, and nutrition ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,drug delivery ,Drug delivery ,nanoparticles ,0210 nano-technology ,Biotechnology - Abstract
Chronic infections have posed a tremendous burden on health care systems worldwide. Approximately 60% of chronic infections are estimated to be related to biofilms, in large part due to the extraordinary antibiotic resistance of biofilm bacteria. Nanoparticle (NP)-based therapies are viable approaches to treat biofilm-associated infections due to NPs’ unique chemical and physical properties, granted by their high surface area to volume ratio. The mechanism underlying the anti-biofilm activity of various types of NPs is actively under investigation. Simply comparing biofilm disruption or reduction rates is not adequate to describe the effectiveness of NPs; many other factors need to be taken into account, such as the NP type, bacterial strain, concentration of NPs, quantification methods, and the biofilm culture environment. This review focuses on recent research on the creation, characterization, and evaluation of NPs for the prevention or treatment of biofilm infections.
- Published
- 2017
14. Activatable interpolymer complex-superparamagnetic iron oxide nanoparticles as magnetic resonance contrast agents sensitive to oxidative stress
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Huaitzung A. Cheng, Omar Z. Fisher, David J. Beaman, Carmen Lee, Lauren E. Nardacci, Eunsoo Yoo, Richard G. Spencer, Charles T. Drinnan, Kenneth W. Fishbein, and Amber L. Doiron
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Contrast Media ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,medicine.disease_cause ,Ferric Compounds ,01 natural sciences ,Article ,Polyethylene Glycols ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Nuclear magnetic resonance ,PEG ratio ,medicine ,Physical and Theoretical Chemistry ,Magnetite Nanoparticles ,chemistry.chemical_classification ,Hydrogen bond ,Superoxide ,Surfaces and Interfaces ,General Medicine ,Polymer ,021001 nanoscience & nanotechnology ,Magnetic Resonance Imaging ,0104 chemical sciences ,Oxidative Stress ,chemistry ,Biophysics ,Nanoparticles ,0210 nano-technology ,Ethylene glycol ,Biosensor ,Oxidative stress ,Biotechnology - 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 ± 2 mM−1 s−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 ± 10 mM−1 s−1. These contrast agents show promise as effective sensors for diseases characterized in part by oxidative stress such as atherosclerosis, diabetes, and cancer.
- Published
- 2017
15. Near Infrared-Activated Dye-Linked ZnO Nanoparticles Release Reactive Oxygen Species for Potential Use in Photodynamic Therapy
- Author
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Amber L. Doiron, Kenneth H. Skorenko, Jaspreet Singh Nagi, William E. Bernier, and Wayne E. Jones
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Chemistry ,photosensitizer ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,0104 chemical sciences ,poly (ethylene glycol) ,chemistry.chemical_compound ,Cell killing ,PEG ratio ,Zeta potential ,Biophysics ,cardiovascular system ,Particle ,cytotoxicity ,General Materials Science ,Photosensitizer ,Viability assay ,0210 nano-technology ,Ethylene glycol ,surface modification ,cell viability - Abstract
Novel dye-linked zinc oxide nanoparticles (NPs) hold potential as photosensitizers for biomedical applications due to their excellent thermal- and photo-stability. The particles produced reactive oxygen species (ROS) upon irradiation with 850 nm near infrared (NIR) light in a concentration- and time-dependent manner. Upon irradiation, ROS detected in vitro in human umbilical vein endothelial cells (HUVEC) and human carcinoma MCF7 cells positively correlated with particle concentration and interestingly, ROS detected in MCF7 was higher than in HUVEC. Preferential cytotoxicity was also exhibited by the NPs as cell killing was higher in MCF7 than in HUVEC. In the absence of irradiation, dye-linked ZnO particles minimally affected the viability of cell (HUVEC) at low concentrations (<, 30 &mu, g/mL), but viability significantly decreased at higher particle concentrations, suggesting a need for particle surface modification with poly (ethylene glycol) (PEG) for improved biocompatibility. The presence of PEG on particles after dialysis was indicated by an increase in size, an increase in zeta potential towards neutral, and spectroscopy results. Cell viability was improved in the absence of irradiation when cells were exposed to PEG-coated, dye-linked ZnO particles compared to non-surface modified particles. The present study shows that there is potential for biological application of dye-linked ZnO particles in photodynamic therapy.
- Published
- 2019
16. Endothelial barrier dysfunction induced by nanoparticle exposure through actin remodeling via caveolae/raft-regulated calcium signalling
- Author
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Yizhong Liu, Eunsoo Yoo, Chendong Han, Gretchen J. Mahler, and Amber L. Doiron
- Subjects
0301 basic medicine ,Myosin light-chain kinase ,Chemistry ,Materials Science (miscellaneous) ,Public Health, Environmental and Occupational Health ,Actin remodeling ,02 engineering and technology ,Raft ,021001 nanoscience & nanotechnology ,Endocytosis ,Calcium in biology ,Article ,03 medical and health sciences ,030104 developmental biology ,Caveolae ,Biophysics ,Viability assay ,0210 nano-technology ,Safety, Risk, Reliability and Quality ,Safety Research ,Calcium signaling - Abstract
The rapid development of modern nanotechnology has resulted in nanomaterial being use in nearly all applications of life, raising the potential risk of nanomaterial exposure alongside the need to design safe and effective materials. Previous work has demonstrated a specific effect of gold nanoparticles (GNPs) of approximately 20 nm on endothelial barrier function in vitro. To expand our understanding of this size-specific effect, titanium dioxide, silicon dioxide, and polystyrene nanoparticles (NPs) in this similar size range were studied. All tested nanoparticles were found to have minimal effects on cell viability, but exhibited a significant detrimental effect on endothelial barrier function. Nanoparticles in the size range of 20 to 30 nm were internalized by endothelial cells through caveolae/raft-mediated endocytosis, causing intracellular calcium elevation by approximately 30% at 2 h after administration, and triggering myosin light chain kinase (MLCK)-regulated actomyosin contraction. These effects culminated in an increase in endothelial monolayer permeability across all particle types within the 20–30 nm range. This nanoparticle exposure-induced endothelial barrier dysfunction may provide valuable information for designing safer nanomaterials or potential applications of this nanoparticle exposure-induced permeability effect in biomedicine.
- Published
- 2018
17. Gold Nanoparticles as X-Ray, CT, and Multimodal Imaging Contrast Agents: Formulation, Targeting, and Methodology
- Author
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Matthew M. Mahan and Amber L. Doiron
- Subjects
Multimodal imaging ,Materials science ,Rare earth ,X-ray ,02 engineering and technology ,Contrast (music) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Colloidal gold ,lcsh:Technology (General) ,Medical imaging ,Particle ,lcsh:T1-995 ,General Materials Science ,Circulation time ,0210 nano-technology ,Biomedical engineering - Abstract
Computed tomography (CT) is among the most popular medical imaging modalities due to its high resolution images, fast scan time, low cost, and compatibility with all patients. CT scans of soft tissues require the localization of imaging contrast agents (CA) to create contrast, revealing anatomic information. Gold nanoparticles (AuNP) have attracted interest recently for their use as CT CA due to their high X-ray attenuation, simple surface chemistry, and biocompatibility. Targeting molecules may be attached to the particles to allow for the targeting of specific cell types and disease states. AuNP can also be readily designed to incorporate other imaging contrast agents such as rare earth metals and dyes. This review summarizes the current state-of-the-art knowledge in the field of AuNP used as X-ray and multimodal contrast agents. Primary research is analyzed through the lens of structure-property-function to best explain the design of a particle for a given application. Design specification of particles includes size, shape, surface functionalization, composition, circulation time, and component synergy. Key considerations include delivery of a CA payload to the site of interest, nontoxicity of particle components, and contrast enhancement compared to the surrounding tissue. Examples from literature are included to illustrate the strategies used to address design considerations.
- Published
- 2018
18. Nanoparticle size-specific actin rearrangement and barrier dysfunction of endothelial cells
- Author
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Guy K. German, Kei Harada, Christopher H. Maiorana, Amber L. Doiron, Gretchen J. Mahler, Leigha Jarett, Noga Rogel, and Yizhong Liu
- Subjects
0301 basic medicine ,Cell Membrane Permeability ,Materials science ,Cell Survival ,Surface Properties ,Cell Culture Techniques ,Biomedical Engineering ,Metal Nanoparticles ,Nanoparticle ,Biocompatible Materials ,Nanotechnology ,02 engineering and technology ,Toxicology ,Microfilament ,Polyethylene Glycols ,03 medical and health sciences ,Human Umbilical Vein Endothelial Cells ,Humans ,Viability assay ,Particle Size ,Barrier function ,021001 nanoscience & nanotechnology ,Endothelial stem cell ,Actin Cytoskeleton ,030104 developmental biology ,Microscopy, Fluorescence ,Colloidal gold ,Paracellular transport ,Biophysics ,Gold ,Reactive Oxygen Species ,0210 nano-technology ,Intracellular - Abstract
In this work, we evaluated the impact of gold nanoparticles on endothelial cell behavior and function beyond the influence on cell viability. Five types of gold nanoparticles were studied: 5 nm and 20 nm bare gold nanoparticles, 5 nm and 20 nm gold nanoparticles with biocompatible polyethylene glycol (PEG) coating and 60 nm bare gold nanoparticles. We found that all tested gold nanoparticles did not affect cell viability significantly and reduced the reactive oxygen species (ROS) level in endothelial cells. Only 20 nm bare gold nanoparticles caused an over 50% increase in endothelial barrier permeability and slow recovery of barrier function was observed after the gold nanoparticles were removed. This impairment in endothelial barrier function was caused by unbalanced forces between intracellular tensions and paracellular forces, actin microfilament rearrangement, which occurred through a Rho/ROCK kinase-dependent pathway and broke the force balance between intracellular tensions and paracellular forces. The size-specific effect of gold nanoparticles on endothelial cells may have important implications regarding the behavior of nanoparticles in the biological system and provide valuable guidance in nanomaterial design and biomedical applications.
- Published
- 2017
- Full Text
- View/download PDF
19. A human cell model for dynamic testing of MR contrast agents
- Author
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Kristina D. Rinker, Anne-Lise Aulanier, Amber L. Doiron, Robert D. Shepherd, Linda B. Andersen, and Richard Frayne
- Subjects
Umbilical Veins ,Contrast Media ,Gadolinium ,Monocytes ,General Biochemistry, Genetics and Molecular Biology ,Cell Line ,Nuclear magnetic resonance ,Text mining ,Cell Line, Tumor ,Cell Adhesion ,medicine ,Humans ,medicine.diagnostic_test ,business.industry ,Chemistry ,Endothelial Cells ,Magnetic resonance imaging ,Equipment Design ,Mr contrast ,Human cell ,Atherosclerosis ,Magnetic Resonance Imaging ,Positive Contrast Agent ,business ,Biotechnology ,Dynamic testing - 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.
- Published
- 2011
20. Preparation and initial characterization of biodegradable particles containing gadolinium-DTPA contrast agent for enhanced MRI
- Author
-
Amber L. Doiron, Lisa Brannon-Peppas, Adeel Ali, and Kevin A. Chu
- Subjects
Gadolinium DTPA ,Materials science ,Gadolinium ,chemistry.chemical_element ,Contrast Media ,Nanotechnology ,macromolecular substances ,Cell Line ,chemistry.chemical_compound ,Polylactic Acid-Polyglycolic Acid Copolymer ,Microscopy ,PEG ratio ,medicine ,Humans ,Lactic Acid ,Particle Size ,Nanomaterials in Medicine Special Feature Sackler Colloquium ,Multidisciplinary ,medicine.diagnostic_test ,technology, industry, and agriculture ,Endothelial Cells ,Magnetic resonance imaging ,Atherosclerosis ,Magnetic Resonance Imaging ,PLGA ,chemistry ,Microscopy, Electron, Scanning ,Particle ,Particle size ,Ethylene glycol ,Polyglycolic Acid ,Biomedical engineering - Abstract
Accurate imaging of atherosclerosis is a growing necessity for timely treatment of the disease. Magnetic resonance imaging (MRI) is a promising technique for plaque imaging. The goal of this study was to create polymeric particles of a small size with high loading of diethylenetriaminepentaacetic acid gadolinium (III) (Gd-DTPA) and demonstrate their usefulness for MRI. A water-in-oil-in-oil double emulsion solvent evaporation technique was used to encapsulate the MRI agent in a poly(lactide-co-glycolide) (PLGA) or polylactide-poly(ethylene glycol) (PLA-PEG) particle for the purpose of concentrating the agent at an imaging site. PLGA particles with two separate average sizes of 1.83 μm and 920 nm, and PLA-PEG particles with a mean diameter of 952 nm were created. Loading of up to 30 wt % Gd-DTPA was achieved, and in vitro release occurred over 5 h. PLGA particles had highly negative zeta potentials, whereas the particles incorporating PEG had zeta potentials closer to neutral. Cytotoxicity of the particles on human umbilical vein endothelial cells (HUVEC) was shown to be minimal. The ability of the polymeric contrast agent formulation to create contrast was similar to that of Gd-DTPA alone. These results demonstrate the possible utility of the contrast agent-loaded polymeric particles for plaque detection with MRI.
- Published
- 2008
21. Poly(lactic-co-glycolic) acid as a carrier for imaging contrast agents
- Author
-
Kimberly A. Homan, Amber L. Doiron, Lisa Brannon-Peppas, and Stanislav Emelianov
- Subjects
Materials science ,Surface Properties ,Pharmaceutical Science ,Nanoparticle ,Contrast Media ,Nanotechnology ,Article ,chemistry.chemical_compound ,Molecular level ,Polylactic Acid-Polyglycolic Acid Copolymer ,Nano ,Organic chemistry ,Pharmacology (medical) ,Lactic Acid ,Glycolic acid ,Pharmacology ,Drug Carriers ,Organic Chemistry ,Magnetic Resonance Imaging ,Lactic acid ,PLGA ,Nanomedicine ,chemistry ,Microscopy, Fluorescence ,Microscopy, Electron, Scanning ,Molecular Medicine ,Nanoparticles ,Emulsions ,Drug carrier ,Polyglycolic Acid ,Biotechnology - Abstract
With the broadening field of nanomedicine poised for future molecular level therapeutics, nano- and microparticles intended for the augmentation of either single- or multimodal imaging are created with PLGA as the chief constituent and carrier.Emulsion techniques were used to encapsulate hydrophilic and hydrophobic imaging contrast agents in PLGA particles. The imaging contrast properties of these PLGA particles were further enhanced by reducing silver onto the PLGA surface, creating a silver cage around the polymeric core.The MRI contrast agent Gd-DTPA and the exogenous dye rhodamine 6G were both encapsulated in PLGA and shown to enhance MR and fluorescence contrast, respectively. The silver nanocage built around PLGA nanoparticles exhibited strong near infrared light absorbance properties, making it a suitable contrast agent for optical imaging strategies such as photoacoustic imaging.The biodegradable polymer PLGA is an extremely versatile nano- and micro-carrier for several imaging contrast agents with the possibility of targeting diseased states at a molecular level.
- Published
- 2008
22. Pharmacokinetics: Nanoparticle Accumulation in Angiogenic Tissues: Towards Predictable Pharmacokinetics (Small 18/2013)
- Author
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Aisling A. Clancy, Trinh Nguyen, John Walker, Kristina D. Rinker, Sarah J. Childs, Kristin Yaehne, Amber L. Doiron, Amy Tekrony, Xiao Yu Jiang, Kwin Dean, Yiota Gregoriou, and David T. Cramb
- Subjects
Biomaterials ,Pharmacokinetics ,Angiogenesis ,Chemistry ,Drug delivery ,Nanoparticle ,General Materials Science ,General Chemistry ,Pharmacology ,Biotechnology - Published
- 2013
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