Graphene-based contrast agents for photoacoustic and thermoacoustic tomography

Photoacoustics (Impact Factor: 4.6). 12/2013; 1(3-4):62-67. DOI: 10.1016/j.pacs.2013.10.001

ABSTRACT In this work, graphene nanoribbons and nanoplatelets were investigated as contrast agents for photoacoustic and thermoacoustic tomography (PAT and TAT). We show that oxidized single- and multi-walled graphene oxide nanoribbons (O-SWGNRs, O-MWGNRs) exhibit approximately 5–10 fold signal enhancement for PAT in comparison to blood at the wavelength of 755 nm, and approximately 10–28% signal enhancement for TAT in comparison to deionized (DI) water at 3 GHz. Oxidized graphite microparticles (O-GMPs) and exfoliated graphene oxide nanoplatelets (O-GNPs) show no significant signal enhancement for PAT, and approximately 12–29% signal enhancement for TAT. These results indicate that O-GNRs show promise as multi-modal PAT and TAT contrast agents, and that O-GNPs are suitable contrast agents for TAT.

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Available from: Gaurav Lalwani, Sep 28, 2015
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    • "GNPs could also be intercalated or covalently functionalized with important elements (e.g. manganese, iodine) in medicine to develop highly efficacious contrast agents for magnetic resonance imaging (MRI) [8] [9], computed tomography (CT) [10], and their intrinsic electromagnetic properties could be harnessed towards the development of probes for fluorescence [4], photoacoustic and thermoacoustic imaging [11]. There is now a wide body of research documenting the toxicology and pharmacology of fullerenes, metallofullerenes and carbon nanotubes (CNTs) [1e3,12]. "
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    ABSTRACT: Graphene nanoparticle dispersions show immense potential as multifunctional agents for in vivo biomedical applications. Herein, we follow regulatory guidelines for pharmaceuticals that recommend safety pharmacology assessment at least 10 – 100 times higher than the projected therapeutic dose, and present comprehensive single dose response, expanded acute toxicology, toxicokinetics, and respiratory/cardiovascular safety pharmacology results for intravenously administered dextran-coated graphene oxide nanoplatelet (GNP-Dex) formulations to rats at doses between 1 and 500 mg/kg. Our results indicate that the maximum tolerable dose (MTD) of GNP-Dex is between 50 mg/kg ≤ MTD < 125 mg/kg, blood half-life < 30 min, and majority of nanoparticles excreted within 24 h through feces. Histopathology changes were noted at ≥250 mg/kg in the heart, liver, lung, spleen, and kidney; we found no changes in the brain and no GNP-Dex related effects in the cardiovascular parameters or hematological factors (blood, lipid, and metabolic panels) at doses < 125 mg/kg. The results open avenues for pivotal preclinical single and repeat dose safety studies following good laboratory practices (GLP) as required by regulatory agencies for investigational new drug (IND) application.
    Biomaterials 05/2014; 35(25). DOI:10.1016/j.biomaterials.2014.04.066 · 8.56 Impact Factor
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    ABSTRACT: The potential of graphene as a mesenchymal stem cell (MSC) culture substrate to promote cardiomyogenic differentiation is demonstrated. Graphene exhibits no sign of cytotoxicity for stem cell culture. MSCs are committed toward cardiomyogenic lineage by simply culturing them on graphene. This may be attributed, at least partially, to the regulation of expression levels of extracellular matrix and signaling molecules.
    02/2014; 3(2). DOI:10.1002/adhm.201300177
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    ABSTRACT: Graphene nanoplatelets (GNPs), synthesized by potassium permanganate-based oxidation and exfoliation followed by reduction with hydroiodic acid (rGNP–HI), intercalated with manganese ions within the graphene sheets, and covalently functionalized with iodine, exhibit excellent potential as biomodal contrast agents for magnetic resonance imaging (MRI) and computed tomography (CT). Structural characterization of rGNP–HI nanoparticles with low-and high-resolution transmission electron microscopy (TEM) showed disc-shaped nanoparticles (average diameter, 200 nm and average thickness, 3 nm). Energy dispersive X-ray spectroscopy (EDX) analysis confirmed the presence of intercalated manganese. Raman spectroscopy and X-ray diffraction (XRD) analysis of rGNP–HI confirmed the reduction of oxidized GNPs (O-GNPs), the absence of molecular and physically-adsorbed iodine, and the functionalization of graphene with iodine as polyiodide complexes (I 3 À and I 5 À). Manganese and iodine contents were quantified to be 5.1 AE 0.5 and 10.54 AE 0.87 wt% by inductively coupled plasma optical emission spectroscopy and ion-selective electrode measurements, respectively. In vitro cytotoxicity analysis, using absorbance (LDH assay) and fluorescence (calcein AM) assays, performed on NIH3T3 mouse fibroblasts and A498 human kidney epithelial cells, indicated CD 50 values of rGNP–HI between 179 and 301 mg ml À1 , depending on the cell line and the cytotoxicity assay. CT and MRI phantom imaging of rGNP–HI displayed high CT (approximately 3200% greater than that of HI at equimolar iodine concentration) and MRI (approximately 59% greater than that of an equimolar Mn 2+ solution) contrast. These results open avenues for further in vivo safety and efficacy studies towards the development of carbon nanostructure-based multimodal MRI-CT contrast agents.
    Journal of Materials Chemistry 03/2014; 2(22). DOI:10.1039/c4tb00326h · 7.44 Impact Factor
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