Article

Two-Dimensional Nanostructure-Reinforced Biodegradable Polymeric Nanocomposites for Bone Tissue Engineering

Department of Biomedical Engineering, Stony Brook University , Stony Brook, New York 11794-5281, United States.
Biomacromolecules (Impact Factor: 5.75). 02/2013; 14(3). DOI: 10.1021/bm301995s
Source: PubMed

ABSTRACT

This study investigates the efficacy of two-dimensional (2D) carbon and inorganic nanostructures as reinforcing agents for cross-linked composites of the biodegradable and biocompatible polymer polypropylene fumarate (PPF) as a function of nanostructure concentration. PPF composites were reinforced using various 2D nanostructures: single- and multiwalled graphene oxide nanoribbons (SWGONRs, MWGONRs), graphene oxide nanoplatelets (GONPs), and molybdenum disulfide nanoplatelets (MSNPs) at 0.01-0.2 weight% concentrations. Cross-linked PPF was used as the baseline control, and PPF composites reinforced with single- or multiwalled carbon nanotubes (SWCNTs, MWCNTs) were used as positive controls. Compression and flexural testing show a significant enhancement (i.e., compressive modulus = 35-108%, compressive yield strength = 26-93%, flexural modulus = 15-53%, and flexural yield strength = 101-262% greater than the baseline control) in the mechanical properties of the 2D-reinforced PPF nanocomposites. MSNP nanocomposites consistently showed the highest values among the experimental or control groups in all the mechanical measurements. In general, the inorganic nanoparticle MSNP showed a better or equivalent mechanical reinforcement compared to carbon nanomaterials, and 2D nanostructures (GONPs, MSNPs) are better reinforcing agents compared to one-dimensional (1D) nanostructures (e.g., SWCNTs). The results also indicated that the extent of mechanical reinforcement is closely dependent on the nanostructure morphology and follows the trend nanoplatelets > nanoribbons > nanotubes. Transmission electron microscopy of the cross-linked nanocomposites indicated good dispersion of nanomaterials in the polymer matrix without the use of a surfactant. The sol-fraction analysis showed significant changes in the polymer cross-linking in the presence of MSNP (0.01-0.2 wt %) and higher loading concentrations of GONP and MWGONR (0.1-0.2 wt %). The analysis of surface area and aspect ratio of the nanostructures taken together with the above results indicated differences in nanostructure architecture (2D vs 1D nanostructures), and the chemical compositions (inorganic vs carbon nanostructures), number of functional groups, and structural defects for the 2D nanostructures may be key properties that affect the mechanical properties of 2D nanostructure-reinforced PPF nanocomposites and the reason for the enhanced mechanical properties compared to the controls.

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    • "Carbon nanoparticles such as zero dimensional (0D) fullerenes, one dimensional (1D) carbon nanotubes, and recently two dimensional (2D) graphene [1] have been investigated for applications in therapeutics [2e5], bioimaging [6e8], and regenerative medicine [9]. Mesenchymal stem cells (MSCs) are an important class of adult or somatic stem cells, found in various tissues including bone marrow and adipose tissue. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the effects of two-dimensional graphene nanostructures; graphene nano-onions (GNOs), graphene oxide nanoribbons (GONRs), and graphene oxide nanoplatelets (GONPs) on viability, and differentiation of human mesenchymal stem cells (MSCs). Cytotoxicity of GNOs, GONRs, and GONPs dispersed in distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)] (DSPE-PEG), on adipose derived mesenchymal stem cells (adMSCs), and bone marrow-derived mesenchymal stem cells (bmMSCs) was assessed by AlamarBlue and Calcein AM viability assays at concentrations ranging from 5 to 300 μg/ml for 24 or 72 h. Cytotoxicity of the 2D graphene nanostructures was found to be dose dependent, not time dependent, with concentrations less than 50 μg/ml showing no significant differences compared to untreated controls. Differentiation potential of adMSCs to adipocytes and osteoblasts, - characterized by Oil Red O staining and elution, alkaline phosphatase activity, calcium matrix deposition and Alizarin Red S staining - did not change significantly when treated with the three graphene nanoparticles at a low (10 μg/ml) and high (50 μg/ml) concentration for 24 h. Transmission electron microscopy (TEM) and confocal Raman spectroscopy indicated cellular uptake of only GNOs and GONPs. The results lay the foundation for the use of these nanoparticles at potentially safe doses as ex vivo labels for MSC-based imaging and therapy.
    Full-text · Article · Jun 2014 · Biomaterials
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    • "were used as received. O-SWGNRs, O-MWGNRs, O-GMPs, and O-GNPs were synthesized and characterized as reported previously [22] [23] [24]. "
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    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.
    Full-text · Article · Dec 2013 · Photoacoustics
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    • "Graphene, a two-dimensional carbon nanostructure, due to its unique physiochemical properties, has shown potential for a variety of materials, electronic and biomedical applications123. Specifically, graphene nanoparticles called graphene nanoplatelets, that can be synthesized in macroscopic amounts using the modified Hummer's method have shown promise as multifunctional nanoparticle for imaging45, targeted drug delivery4678, gene delivery9, tissue engineering1011, and photodynamic/photothermal therapy121314. Development of graphene nanoparticles for any in vivo application requires thorough assessment of their toxicity and biocompatibility. "
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    ABSTRACT: The intravenous, intramuscular or intraperitoneal administration of water solubilized graphene nanoparticles for biomedical applications will result in their interaction with the hematological components and vasculature. Herein, we have investigated the effects of dextran functionalized graphene nanoplatelets (GNP-Dex) on histamine release, platelet activation, immune activation, blood cell hemolysis in vitro, and vasoactivity in vivo. The results indicate that GNP-Dex formulations prevented histamine release from activated RBL-2H3 rat mast cells, and at concentrations ≥ 7 mg/ml, showed a 12-20% increase in levels of complement proteins. Cytokine (TNF-Alpha and IL-10) levels remained within normal range. GNP-Dex formulations did not cause platelet activation or blood cell hemolysis. Using the hamster cheek pouch in vivo model, the initial vasoactivity of GNP-Dex at concentrations (1-50 mg/ml) equivalent to the first pass of a bolus injection was a brief concentration-dependent dilation in arcade and terminal arterioles. However, they did not induce a pro-inflammatory endothelial dysfunction effect.
    Full-text · Article · Sep 2013 · Scientific Reports
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Questions & Answers about this publication

  • Gaurav Lalwani added an answer in Graphene Oxide:
    D/G ratio of graphene oxide and its relation with sp2/sp3 carbon ratio?

    Is the intensity ratio of D and G
    bands in Raman expresses the sp2/sp3 carbon ratio? or SP3/SP2

    Gaurav Lalwani

    Raman Spectroscopy is an excellent method to characterize carbon nanomaterials. Its fairly complex so I am going to try to explain this in a very simple language. The ratio of intensity of D/G bands is a measure of the defects present on graphene structure. The G band is a result of in-plane vibrations of SP2 bonded carbon atoms whereas the D band is due to out of plane vibrations attributed to the presence of structural defects. Now, when you compare the spectra of graphene and graphene oxide, GO will have a higher D band. This is due to the disruption of SP2 bonds of the carbon as GO has oxidative functional groups. 
    So, if the D band is higher, it means that the SP2 bonds are broken which in turn means that there are more SP3 bonds. However, D band can be present due to various other reasons. So if your D/G ratio is higher than pristine graphene, it means that there are defects. It does not mean that you have more SP3 than SP2 in the same sample. It shows that you have more SP3 in GO compared to pristine graphene.

    You can also try high resolution XPS which can give you elemental quantification and see what functional groups are present.

    The limitation of Raman and XPS both is that these are point - surface - techniques. This means that you are only measuring a very small region of the entire sample, precisely a point that is on the surface. However, this is an accepted limitation of these techniques and therefore I would be very careful before drawing any firm conclusions. Its better to do two types of chemical characterization than just doing one. That way you can be more sure of your data.

    We have described this in these articles:

    1. https://www.researchgate.net/publication/235619062_Two-Dimensional_Nanostructure-Reinforced_Biodegradable_Polymeric_Nanocomposites_for_Bone_Tissue_Engineering?ev=prf_pub

    2.. https://www.researchgate.net/publication/261183815_The_effects_of_graphene_nanostructures_on_mesenchymal_stem_cells?ev=prf_pub 

    3. https://www.researchgate.net/publication/264315709_Enzymatic_Degradation_of_Oxidized_and_Reduced_Graphene_Nanoribbons_by_Lignin_Peroxidase?ev=prf_pub

    • Source
      [Show abstract] [Hide abstract]
      ABSTRACT: This study investigates the efficacy of two-dimensional (2D) carbon and inorganic nanostructures as reinforcing agents for cross-linked composites of the biodegradable and biocompatible polymer polypropylene fumarate (PPF) as a function of nanostructure concentration. PPF composites were reinforced using various 2D nanostructures: single- and multiwalled graphene oxide nanoribbons (SWGONRs, MWGONRs), graphene oxide nanoplatelets (GONPs), and molybdenum disulfide nanoplatelets (MSNPs) at 0.01-0.2 weight% concentrations. Cross-linked PPF was used as the baseline control, and PPF composites reinforced with single- or multiwalled carbon nanotubes (SWCNTs, MWCNTs) were used as positive controls. Compression and flexural testing show a significant enhancement (i.e., compressive modulus = 35-108%, compressive yield strength = 26-93%, flexural modulus = 15-53%, and flexural yield strength = 101-262% greater than the baseline control) in the mechanical properties of the 2D-reinforced PPF nanocomposites. MSNP nanocomposites consistently showed the highest values among the experimental or control groups in all the mechanical measurements. In general, the inorganic nanoparticle MSNP showed a better or equivalent mechanical reinforcement compared to carbon nanomaterials, and 2D nanostructures (GONPs, MSNPs) are better reinforcing agents compared to one-dimensional (1D) nanostructures (e.g., SWCNTs). The results also indicated that the extent of mechanical reinforcement is closely dependent on the nanostructure morphology and follows the trend nanoplatelets > nanoribbons > nanotubes. Transmission electron microscopy of the cross-linked nanocomposites indicated good dispersion of nanomaterials in the polymer matrix without the use of a surfactant. The sol-fraction analysis showed significant changes in the polymer cross-linking in the presence of MSNP (0.01-0.2 wt %) and higher loading concentrations of GONP and MWGONR (0.1-0.2 wt %). The analysis of surface area and aspect ratio of the nanostructures taken together with the above results indicated differences in nanostructure architecture (2D vs 1D nanostructures), and the chemical compositions (inorganic vs carbon nanostructures), number of functional groups, and structural defects for the 2D nanostructures may be key properties that affect the mechanical properties of 2D nanostructure-reinforced PPF nanocomposites and the reason for the enhanced mechanical properties compared to the controls.
      Full-text · Article · Feb 2013 · Biomacromolecules

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