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1.
Proc Natl Acad Sci U S A ; 120(45): e2309156120, 2023 Nov 07.
Article in English | MEDLINE | ID: mdl-37903261

ABSTRACT

Cobalt-containing alloys are useful for orthopedic applications due to their low volumetric wear rates, corrosion resistance, high mechanical strength, hardness, and fatigue resistance. Unfortunately, these prosthetics release significant levels of cobalt ions, which was only discovered after their widespread implantation into patients requiring hip replacements. These cobalt ions can result in local toxic effects-including peri-implant toxicity, aseptic loosening, and pseudotumor-as well as systemic toxic effects-including neurological, cardiovascular, and endocrine disorders. Failing metal-on-metal (MoM) implants usually necessitate painful, risky, and costly revision surgeries. To treat metallosis arising from failing MoM implants, a synovial fluid-mimicking chelator was designed to remove these metal ions. Hyaluronic acid (HA), the major chemical component of synovial fluid, was functionalized with British anti-Lewisite (BAL) to create a chelator (BAL-HA). BAL-HA effectively binds cobalt and rescues in vitro cell vitality (up to 370% of cells exposed to IC50 levels of cobalt) and enhances the rate of clearance of cobalt in vivo (t1/2 from 48 h to 6 h). A metallosis model was also created to investigate our therapy. Results demonstrate that BAL-HA chelator system is biocompatible and capable of capturing significant amounts of cobalt ions from the hip joint within 30 min, with no risk of kidney failure. This chelation therapy has the potential to mitigate cobalt toxicity from failing MoM implants through noninvasive injections into the joint.


Subject(s)
Arthroplasty, Replacement, Hip , Hip Prosthesis , Humans , Hip Prosthesis/adverse effects , Hyaluronic Acid , Dimercaprol , Chelation Therapy , Prosthesis Failure , Arthroplasty, Replacement, Hip/adverse effects , Metals , Cobalt , Chelating Agents/therapeutic use , Ions
2.
Sci Rep ; 12(1): 6960, 2022 04 28.
Article in English | MEDLINE | ID: mdl-35484292

ABSTRACT

Bone regenerative engineering could replace autografts; however, no synthetic material fulfills all design criteria. Nanocarbons incorporated into three-dimensional printed (3DP) matrices can improve properties, but incorporation is constrained to low wt%. Further, unmodified nanocarbons have limited osteogenic potential. Functionalization to calcium phosphate graphene (CaPG) imparts osteoinductivity and osteoconductivity, but loading into matrices remained limited. This work presents ultra-high content (90%), 3DP-CaPG matrices. 3DP-CaPG matrices are highly porous (95%), moderately stiff (3 MPa), and mechanically robust. In vitro, they are cytocompatible and induce osteogenic differentiation of human mesenchymal stem cells (hMSCs), indicated by alkaline phosphatase, mineralization, and COL1α1 expression. In vivo, bone regeneration was studied using a transgenic fluorescent-reporter mouse non-union calvarial defect model. 3DP-CaPG stimulates cellular ingrowth, retains donor cells, and induces osteogenic differentiation. Histology shows TRAP staining around struts, suggesting potential osteoclast activity. Apparent resorption of 3DP-CaPG was observed and presented no toxicity. 3DP-CaPG represents an advancement towards a synthetic bone regeneration matrix.


Subject(s)
Graphite , Mesenchymal Stem Cells , Animals , Mice , Calcium Phosphates , Graphite/pharmacology , Osteogenesis , Printing, Three-Dimensional , Tissue Scaffolds
3.
Adv Healthc Mater ; 10(7): e2001761, 2021 04.
Article in English | MEDLINE | ID: mdl-33645004

ABSTRACT

Extensive cytocompatibility testing of 2D nanocarbon materials including graphene oxide (GO) has been performed, but results remain contradictory. Literature has yet to account for settling-although sedimentation is visible to the eye and physics suggests that even individual graphenic flakes will settle. To investigate settling, a series of functional graphenic materials (FGMs) with differing oxidation levels, functionalities, and physical dimensions are synthesized. Though zeta potential indicates colloidal stability, significant gravitational settling of the FGMs is theoretically and experimentally demonstrated. By creating a setup to culture cells in traditional and inverted orientations in the same well, a "blanket effect" is demonstrated in which FGMs settle out of solution and cover cells at the bottom of the well, ultimately reducing viability. Inverted cells protected from the blanket effect are unaffected. Therefore, these results demonstrate that settling is a crucial factor that must be considered for FGM cytocompatibility experiments.


Subject(s)
Graphite , Oxidation-Reduction
4.
Adv Healthc Mater ; 10(2): e2001189, 2021 01.
Article in English | MEDLINE | ID: mdl-33326158

ABSTRACT

Graphene oxide and functionalized graphenic materials (FGMs) have promise as platforms for imparting programmable bioactivity to poly(methyl methacrylate) (PMMA)-based bone cement. To date, however, graphenic fillers have only been feasible in PMMA cements at extremely low loadings, limiting the bioactive effects. At higher loadings, graphenic fillers decrease cement strength by aggregating and interfering with curing process. Here, these challenges are addressed by combining bioactive FGM fillers with a custom cement formulation. These cements contain an order of magnitude more graphenic filler than previous reports. Even at 1 wt% FGM, these cements have compressive strengths of 78- 88 MPa, flexural strengths of 74-81 MPa, and flexural stiffnesses of 1.8-1.9 GPa, surpassing the ASTM requirements for bone cement and competing with traditional PMMA cement. Further, by utilizing designer FGMs with programmed bioactivity, these cements demonstrate controlled release of osteogenic calcium ions (releasing a total of 5 ± 2 µmol of Ca2+ per gram of cement over 28 d) and stimulate a 290% increase in expression of alkaline phosphatase in human mesenchymal stem cells in vitro. Also, design criteria are described to guide creation of future generations of bone cements that utilize FGMs as platforms to achieve dynamic biological activity.


Subject(s)
Bone Cements , Polymethyl Methacrylate , Compressive Strength , Humans , Materials Testing
5.
RSC Adv ; 10(14): 8548-8557, 2020 Feb 24.
Article in English | MEDLINE | ID: mdl-35497868

ABSTRACT

Traditional metal implants such as titanium, cobalt, and chromium have found wide utility in medicine; however, these come with a risk of toxicity. To overcome metal-related toxicity and enable degradability, polyesters including polycaprolactone (PCL), polylactic acid (PLA), and polyglycolic acid (PGA) show promise for the replacement of various biomedical applications of metals due to their accepted biocompatibility and FDA approval. However, polyesters are less stiff than their metallic counterparts, limiting their application to non-load bearing injury sites, such as fixation hardware for fingers. To improve mechanical properties, graphene oxide (GO)-polyester composites are a promising class of biodegradable scaffolds. Initial reports of these composites are encouraging, but mechanical properties still fall short. Traditional composites rely on non-covalent association between GO and the polyesters, which often leads to failure at the interface and weakens the overall strength of the material. Herein, we present a strategy for attachment of these FDA-approved polyesters onto a derivative of GO using a robust covalent bond. By covalently functionalizing the graphenic backbone with polyesters and without metal catalysts, we create functional graphenic materials (FGMs) to not only simultaneously retain biodegradability and compatibility, but also mechanically strengthen PCL, PLA, and PGA; we observed an average increase in the Young's modulus of over 140% compared to the graphenic backbone. These polyester-functionalized FGMs are a promising platform technology for tissue implants.

6.
Biomater Sci ; 7(9): 3876-3885, 2019 Aug 20.
Article in English | MEDLINE | ID: mdl-31309944

ABSTRACT

Graphene is a valuable material in biomedical implant applications due to its mechanical integrity, long-range order, and conductivity; but graphene must be chemically modified to increase biocompatibility and maximize functionality in the body. Here, we developed a foundational synthetic method for covalently functionalizing a reduced GO with bioactive molecules, focusing on synthetic peptides that have shown osteogenic or neurogenic capability as a prototypical example. X-ray photoelectron spectroscopy provides evidence that the peptide is covalently linked to the graphenic backbone. These peptide-graphene (Pep-G) conjugate materials can be processed into mechanically robust, three-dimensional constructs. Differences in their electrostatic charges allow the Pep-G conjugates to form self-assembled, layer-by-layer coatings. Further, the Pep-G conjugates are cytocompatible and electrically conductive, leading us to investigate their potential as regenerative scaffolds, as conductive surfaces can stimulate bone and nerve regeneration. Notably, PC12 cells grown on an electrically stimulated Pep-G scaffold demonstrated enhanced adhesion and neurite outgrowth compared to the control. The functionalization strategy developed here can be used to conjugate a wide variety of bioactive molecules to graphene oxide to create cell-instructive surfaces for biomedical scaffold materials.


Subject(s)
Biomedical Research , Graphite/pharmacology , Peptides/pharmacology , Animals , Cell Survival/drug effects , Dose-Response Relationship, Drug , Graphite/chemical synthesis , Graphite/chemistry , Molecular Structure , PC12 Cells , Peptides/chemical synthesis , Peptides/chemistry , Rats , Structure-Activity Relationship , Tumor Cells, Cultured
7.
ACS Appl Mater Interfaces ; 11(23): 20881-20887, 2019 Jun 12.
Article in English | MEDLINE | ID: mdl-31117460

ABSTRACT

Undesirable condenser tube leaks frequently occur in power plants, resulting in reduced power output, increased burden on downstream systems, and substantial revenue losses. Current techniques such as wood flour provide temporary in situ remediation but lack adhesive properties to form stable seals. Here, we report the development of in situ sealants for long-term defect repair. The carboxylic acids on graphene oxides and Claisen graphene were used as chemical handles to covalently install a bio-inspired, adhesive catechol, generating a class of functional graphenic material (FGM) sealants. FGM sealants outperformed unfunctionalized scaffolds with enhanced antimicrobial activity to prevent fouling (up to 55% reduction) and superior cohesive properties to promote stable seals. Further, FGM sealants were adhesive, effectively sealing defects in a model experiment, whereas unfunctionalized scaffolds did not display any sealant capacity.

8.
Proc Natl Acad Sci U S A ; 116(11): 4855-4860, 2019 03 12.
Article in English | MEDLINE | ID: mdl-30796184

ABSTRACT

Synthetic, resorbable scaffolds for bone regeneration have potential to transform the clinical standard of care. Here, we demonstrate that functional graphenic materials (FGMs) could serve as an osteoinductive scaffold: recruiting native cells to the site of injury and promoting differentiation into bone cells. By invoking a Lewis acid-catalyzed Arbuzov reaction, we are able to functionalize graphene oxide (GO) to produce phosphate graphenes (PGs) with unprecedented control of functional group density, mechanical properties, and counterion identity. In aqueous environments, PGs release inducerons, including Ca2+ and PO43- Calcium phosphate graphene (CaPG) intrinsically induces osteogenesis in vitro and in the presence of bone marrow stromal cells (BMSCs), can induce ectopic bone formation in vivo. Additionally, an FGM can be made by noncovalently loading GO with the growth factor recombinant human bone morphogenetic protein 2 (rhBMP-2), producing a scaffold that induces ectopic bone formation with or without BMSCs. The FGMs reported here are intrinsically inductive scaffolds with significant potential to revolutionize the regeneration of bone.


Subject(s)
Bone Regeneration/drug effects , Graphite/pharmacology , Mesenchymal Stem Cells/cytology , Osseointegration/drug effects , Phosphates/pharmacology , Tissue Scaffolds/chemistry , Animals , Bone Morphogenetic Protein 2/pharmacology , Cell Adhesion/drug effects , Cell Differentiation/drug effects , Graphite/chemical synthesis , Graphite/chemistry , Humans , Mesenchymal Stem Cells/drug effects , Mice , NIH 3T3 Cells , Osteogenesis/drug effects , Phosphates/chemical synthesis , Phosphates/chemistry , RAW 264.7 Cells , Recombinant Proteins/pharmacology , Transforming Growth Factor beta/pharmacology
9.
J Mater Chem B ; 7(15): 2442-2453, 2019 04 21.
Article in English | MEDLINE | ID: mdl-32255121

ABSTRACT

Damaged cartilage does not readily heal and often requires surgical intervention that only modestly improves outcomes. A synthetic material that could be injected and covalently crosslinked in situ to form a bioactive, mechanically robust scaffold that promotes stem cell chondrogenic differentiation holds promise for next-generation treatment of cartilage lesions. Here, Johnson-Claisen rearrangement chemistry was performed on graphene oxide (GO) to enable functionalization with a primary amine covalently bound to the graphenic backbone through a chemically stable linker. The primary amines are used to form covalent crosslinks with chondroitin sulfate, an important component of cartilage that promotes regeneration, to form a hydrogel (EDAG-CS). The EDAG-CS system gels in situ within 10 min, and the graphenic component imparts improved mechanical properties, including stiffness (320% increase) and toughness (70% increase). EDAG-CS hydrogels are highly porous, resistant to degradation, and enable the growth of human mesenchymal stem cells and their deposition of collagen matrix. This system has potential to improve clinical outcomes of patients with cartilage damage.


Subject(s)
Amines/chemistry , Cartilage/drug effects , Chondroitin Sulfates/chemistry , Graphite/chemistry , Hydrogels/chemistry , Hydrogels/pharmacology , Regeneration/drug effects , Animals , Cartilage/physiology , Injections , Mechanical Phenomena , Mice , NIH 3T3 Cells , Stem Cells/cytology , Stem Cells/drug effects
10.
J Mater Chem B ; 5(2): 369-374, 2017 Jan 14.
Article in English | MEDLINE | ID: mdl-32263555

ABSTRACT

Mitochondria are the organelles of cells that generate a majority of the cell's energy through ATP and are involved in programmed cell death through apoptosis. An understanding of non-specific targeting of nanomaterials, including single wall carbon nanotubes (SWCNTs), to organelles is important in trying to modulate cell function or determine the cellular toxicity with long term exposure. Here, we examine the impact of SWCNTs dispersed with Pluronic F127 and protein on mitochondria using a battery of standard tests. Seahorse XF24 analysis suggests complete loss of mitochondiral function, but this data is artifactual due to SWCNTs adsorbing onto the Seahorse probes. Imaging using the mitochondrial functional dye JC-1 gives inconclusive results owing to fluorescence quenching by SWCNTs. We observe no co-localization or reorganization of mitochondria in the presence of SWCNTs, although the results could have been misinterpreted had we not been correcting for significant fluorescence quenching by SWCNTs. In sum, the surface activity and fluorescence quenching of SWCNTs alter many traditional cellular assays. However, light emitting (luciferase) assays show that ATP levels are not altered with SWCNT treatment suggesting that mitochondiral function is not impacted as well as that light-emitting assays are an essential complimentary approach for quantitative, unambiguous cellular study of nanomaterials.

11.
J Mater Chem B ; 5(37): 7743-7755, 2017 Oct 07.
Article in English | MEDLINE | ID: mdl-32264375

ABSTRACT

Medical cyanoacrylate adhesives have the potential to eliminate the need for sutures but face challenges to widespread implementation due to their brittleness and release of formaldehyde upon degradation. To overcome these limitations, we used molecular design to create therapeutic methacrylic (TMA) monomers to impart tunable mechanical properties, decreased formaldehyde release, and covalently-controlled bioactivity to commercial cyanoacrylate adhesives. The small molecule therapeutics ibuprofen, acetaminophen, and benzocaine were covalently tethered to the carbonyl of methacrylate using anhydride, ester, and amide bonds. When these TMAs were incorporated into n-butyl cyanoacrylate (BCA) tissue adhesives, the resulting TMA-BCA materials provided release of the therapeutics across a range of time scales according to the reactivity of the tether bond to hydrolysis. The anhydride-tether TMA-BCA adhesive delivered ibuprofen on the same order of magnitude and time scale as topical medications (12 ± 6 mg per g adhesive after 3.4 h). TMA-BCA adhesives also produced less formaldehyde than standard BCA adhesive, showed promising cytocompatibility, and adhered effectively to porcine skin. Further, the anhydride, ester, and amide tether TMA-BCA adhesives exhibited a range of shear moduli, with those containing rigid aromatic amide groups being stiffer, and those with flexible alkyl segments being less stiff, which could enable these adhesives to be tailored to match the mechanical properties of target tissues. The amide-tether TMA-BCA adhesive also showed a 219% increase in toughness compared to BCA. Overall, TMAs represent a platform technology that can be used to build adaptable and bioactive tissue adhesives.

12.
Article in English | MEDLINE | ID: mdl-27781398

ABSTRACT

Graphene oxide (GO), the oxidized form of graphene, holds great potential as a component of biomedical devices, deriving utility from its ability to support a broad range of chemical functionalities and its exceptional mechanical, electronic, and thermal properties. GO composites can be tuned chemically to be biomimetic, and mechanically to be stiff yet strong. These unique properties make GO-based materials promising candidates as a scaffold for bone regeneration. However, questions still exist as to the compatibility and long-term toxicity of nanocarbon materials. Unlike other nanocarbons, GO is meta-stable, water dispersible, and autodegrades in water on the timescale of months to humic acid-like materials, the degradation products of all organic matter. Thus, GO offers better prospects for biological compatibility over other nanocarbons. Recently, many publications have demonstrated enhanced osteogenic performance of GO-containing composites. Ongoing work toward surface modification or coating strategies could be useful to minimize the inflammatory response and improve compatibility of GO as a component of medical devices. Furthermore, biomimetic modifications could offer mechanical and chemical environments that encourage osteogenesis. So long as care is given to assure their safety, GO-based materials may be poised to become the next generation scaffold for bone regeneration. WIREs Nanomed Nanobiotechnol 2017, 9:e1437. doi: 10.1002/wnan.1437 For further resources related to this article, please visit the WIREs website.


Subject(s)
Bone Regeneration , Bone and Bones/cytology , Graphite , Tissue Engineering/methods , Tissue Scaffolds , Animals , Cells, Cultured , Humans , Mice , Stem Cells/cytology
13.
Adv Healthc Mater ; 5(23): 3056-3066, 2016 12.
Article in English | MEDLINE | ID: mdl-27925461

ABSTRACT

Synthetic biomaterials are poised to transform medicine; however, current synthetic options have yet to ideally recapitulate the desirable properties of native tissue. Thus, the development of new synthetic biomaterials remains an active challenge. Due to its excellent properties, including electrical conductivity, water dispersibility, and capacity for functionalization, graphene oxide (GO) holds potential for myriads of applications, including biological devices. While many studies have evaluated the compatibility of freshly prepared GO, understanding the compatibility of GO as it ages in an aqueous environment is crucial for its safe implementation in long-term biological applications. This is a critical disconnect, as GO has been shown to undergo an autodegradation pathway in aqueous conditions, dynamically changing its composition and structure while producing degradation products. Thus, the long-term cytocompatibility of GO is investigated by "aging" GO over time in water and accelerating aging and decomposition via sonication. While age affects the composition and size of GO, it has no effect on cellular vitality and does not alter subcellular structures or DNA melting. Overall, GO is cytocompatible throughout the process of aging, beginning to demonstrate that GO may be utilized for long-term in vivo applications such as implanted tissue engineered scaffolds or biosensors.


Subject(s)
Biocompatible Materials/chemistry , Graphite/chemistry , Oxides/chemistry , Tissue Scaffolds/chemistry , Biosensing Techniques , Electric Conductivity , Organic Chemicals/chemistry , Sonication/methods , Tissue Engineering/methods
14.
ACS Appl Mater Interfaces ; 8(5): 3524-34, 2016 Feb 10.
Article in English | MEDLINE | ID: mdl-26783632

ABSTRACT

Single-walled carbon nanotubes (SWCNTs) have great potential for cell-based therapies due to their unique intrinsic optical and physical characteristics. Consequently, broad classes of dispersants have been identified that individually suspend SWCNTs in water and cell media in addition to reducing nanotube toxicity to cells. Unambiguous control and verification of the localization and distribution of SWCNTs within cells, particularly to the nucleus, is needed to advance subcellular technologies utilizing nanotubes. Here we report delivery of SWCNTs to the nucleus by noncovalently attaching the tail domain of the nuclear protein lamin B1 (LB1), which we engineer from the full-length LMNB1 cDNA. More than half of this low molecular weight globular protein is intrinsically disordered but has an immunoglobulin-fold composed of a central hydrophobic core, which is highly suitable for associating with SWCNTs, stably suspending SWCNTs in water and cell media. In addition, LB1 has an exposed nuclear localization sequence to promote active nuclear import of SWCNTs. These SWCNTs-LB1 dispersions in water and cell media display near-infrared (NIR) absorption spectra with sharp van Hove peaks and an NIR fluorescence spectra, suggesting that LB1 individually disperses nanotubes. The dispersing capability of SWCNTs by LB1 is similar to that by albumin proteins. The SWCNTs-LB1 dispersions with concentrations ≥150 µg/mL (≥30 µg/mL) in water (cell media) remain stable for ≥75 days (≥3 days) at 4 °C (37 °C). Further, molecular dynamics modeling of association of LB1 with SWCNTs reveal that the exposure of the nuclear localization sequence is independent of LB1 binding conformation. Measurements from confocal Raman spectroscopy and microscopy, NIR fluorescence imaging of SWCNTs, and fluorescence lifetime imaging microscopy show that millions of these SWCNTs-LB1 complexes enter HeLa cells, localize to the nucleus of cells, and interact with DNA. We postulate that the modification of native cellular proteins as noncovalent dispersing agents to provide specific transport will open new possibilities to utilize both SWCNT and protein properties for multifunctional subcellular targeting applications. Specifically, nuclear targeting could allow delivery of anticancer therapies, genetic treatments, or DNA to the nucleus.


Subject(s)
Cell Nucleus/drug effects , Lamin Type B/chemistry , Nanotubes, Carbon/chemistry , Protein Engineering , Cell Nucleus/chemistry , Cell Nucleus/ultrastructure , HeLa Cells , Humans , Lamin Type B/genetics , Lamin Type B/metabolism , Microscopy, Fluorescence , Protein Binding , Protein Structure, Tertiary , Spectrum Analysis, Raman , Water/chemistry
15.
J Appl Toxicol ; 36(4): 568-78, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26510384

ABSTRACT

Single wall carbon nanotubes (SWCNTs) are advanced materials with the potential for a myriad of diverse applications, including biological technologies and large-scale usage with the potential for environmental impacts. SWCNTs have been exposed to developing organisms to determine their effects on embryogenesis, and results have been inconsistent arising, in part, from differing material quality, dispersion status, material size, impurity from catalysts and stability. For this study, we utilized highly purified SWCNT samples with short, uniform lengths (145 ± 17 nm) well dispersed in solution. To test high exposure doses, we microinjected > 500 µg ml(-1) SWCNT concentrations into the well-established embryogenesis model, Xenopus laevis, and determined embryo compatibility and subcellular localization during development. SWCNTs localized within cellular progeny of the microinjected cells, but were heterogeneously distributed throughout the target-injected tissue. Co-registering unique Raman spectral intensity of SWCNTs with images of fluorescently labeled subcellular compartments demonstrated that even at regions of highest SWCNT concentration, there were no gross alterations to subcellular microstructures, including filamentous actin, endoplasmic reticulum and vesicles. Furthermore, SWCNTs did not aggregate and localized to the perinuclear subcellular region. Combined, these results suggest that purified and dispersed SWCNTs are not toxic to X. laevis animal cap ectoderm and may be suitable candidate materials for biological applications.


Subject(s)
Embryo, Nonmammalian/drug effects , Microinjections , Nanotubes, Carbon/toxicity , Xenopus laevis/embryology , Animals , Embryo, Nonmammalian/metabolism , Microscopy, Confocal , Nanotubes, Carbon/chemistry , Serum Albumin/chemistry , Spectrum Analysis, Raman
16.
J Appl Toxicol ; 36(4): 579-85, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26153061

ABSTRACT

Single wall carbon nanotubes are high aspect ratio nanomaterials being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties and chemical inertness. Because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single wall carbon nanotubes exposed to the widely studied model organism Xenopus laevis (African clawed frog). Microinjection of experimental substances into the Xenopus embryo is a standard technique for toxicology studies and cellular lineage tracing. Here we report the surprising finding that superficial (12.5 ± 7.5 µm below the membrane) microinjection of nanotubes dispersed with Pluronic F127 into one- to two-cell Xenopus embryos resulted in the formation and expulsion of compacted, nanotube-filled, punctate masses, at the blastula to mid-gastrula developmental stages, which we call "boluses." Such expulsion of microinjected materials by Xenopus embryos has not been reported before and is dramatically different from the typical distribution of the materials throughout the progeny of the microinjected cells. Previous studies of microinjections of nanomaterials such as nanodiamonds, quantum dots or spherical nanoparticles report that nanomaterials often induce toxicity and remain localized within the embryos. In contrast, our results demonstrate an active recovery pathway for embryos after exposure to Pluronic F127-coated nanotubes, which we speculate is due to a combined effect of the membrane activity of the dispersing agent, Pluronic F127, and the large aspect ratio of nanotubes.


Subject(s)
Embryonic Development/drug effects , Nanotubes, Carbon/toxicity , Xenopus laevis/embryology , Animals , Embryo, Nonmammalian/drug effects , Embryo, Nonmammalian/metabolism , Microinjections , Nanotubes, Carbon/chemistry , Spectrum Analysis, Raman
17.
ACS Appl Mater Interfaces ; 7(27): 14593-602, 2015 Jul 15.
Article in English | MEDLINE | ID: mdl-26098461

ABSTRACT

Magnetic resonance imaging (MRI) is of vast clinical utility, with tens of millions of scans performed annually. Chemical contrast agents (CAs) can greatly enhance the diagnostic potential of MRI, and ∼50% of MRI scans use CAs. However, CAs have significant limitations such as low contrast enhancement, lack of specificity, and potential toxicity. Recently developed, Gd3+-loaded ultrashort single-walled carbon nanotubes, also referred to as gadonanotubes or GNTs, exhibit ∼40 times the relaxivities of clinical CAs, representing a potential major advance in clinically relevant MRI CA materials. Although initial cytotoxicity and MRI studies have suggested great promise for GNTs, relatively little is known regarding their subcellular interactions, which are crucial for further, safe development of GNTs as CAs. In this work, we administered GNTs to a well-established human cell line (HeLa) and to murine macrophage-like cells (J774A.1). GNTs were not acutely cytotoxic and did not reduce proliferation, except for the highest exposure concentration of 27 µg/mL for J774A.1 macrophages, yet bulk uptake of GNTs occurred in minutes at picogram quantities, or millions of GNTs per cell. J774A.1 macrophages internalized substantially more GNTs than HeLa cells in a dose-dependent manner, and Raman imaging of the subcellular distribution of GNTs revealed perinuclear localization. Fluorescence intensity and lifetime imaging demonstrated that GNTs did not grossly alter subcellular compartments, including filamentous-actin structures. Together, these results provide subcellular evidence necessary to establish GNTs as a new MRI CA material.


Subject(s)
Gadolinium/chemistry , Magnetic Resonance Imaging/methods , Nanocapsules/chemistry , Nanotubes, Carbon/chemistry , Subcellular Fractions/chemistry , Subcellular Fractions/ultrastructure , Contrast Media/chemistry , Diffusion , HeLa Cells , Humans , Materials Testing , Nanocapsules/ultrastructure , Nanotubes, Carbon/ultrastructure , Particle Size , Tissue Distribution
18.
J Mater Chem B ; 3(30): 6274-6284, 2015 Aug 14.
Article in English | MEDLINE | ID: mdl-32262746

ABSTRACT

Strategies for cell-specific targeting and delivery of carbon nanotubes have made significant advancements over recent years. However, control of sub-cellular localization, an important criterion for many biomedical applications, remains largely unexplored. In this work, we experimentally demonstrate how different molecules that are used to non-covalently suspend hydrophobic SWCNTs in aqueous conditions also influence cellular processing and localization. We utilized complementary imaging modalities to show that SWCNTs dispersed using the membrane active tri-block copolymer Pluronic® F-127 (PF127) were endocytosed into cells by the millions but eventually escaped endosomes and altered F-actin structures. In contrast, SWCNTs dispersed with the protein bovine serum albumin (BSA) were endocytosed into cells at similarly high levels but remained in the endosomal pathway, ultimately co-registering with endoplasmic reticulum and vesicles. Interestingly, cellular exposure to SWCNTs-BSA in the presence of the endosome disrupter, chloroquine, led to altered F-actin structures that were similar to the alterations induced by cellular exposure to SWCNTs-PF127. These results suggest that PF127 facilitated endosome escape and that SWCNTs might have an energetically favorable interaction with stiff, filamentous structures inside the cell. Thus, our results provide a design principle for non-covalent surface modifications of SWCNTs that do not degrade the desirable, intrinsic SWCNT properties but provide differential trafficking to intracellular compartments for sub-cellular biomedical applications.

19.
ACS Nano ; 8(1): 188-97, 2014 Jan 28.
Article in English | MEDLINE | ID: mdl-24351114

ABSTRACT

Single-wall carbon nanotubes (SWCNTs) have been widely used for biological applications in recent years, and thus, it is critical to understand how these inert nanomaterials influence cell behavior. Recently, it has been observed that cellular phenotypes such as proliferation, force generation and growth change upon SWCNT treatment, and SWCNTs directly affect the organization and redistribution of the actin cytoskeleton. However, the interactions between SWCNTs and actin at the molecular level or how this interaction changes actin structure remain largely unknown. Here, we investigated direct interaction of actin with SWCNT using all-atom molecular dynamics simulations and NIR spectroscopy of actin-dispersed SWCNTs. Actin can stably bind to the SWCNT surfaces via hydrophobic interactions but still allows nanotubes to slide and rotate on the actin surface. Our results establish several nanoscale conformational changes for the actin-SWCNT complexes, and we suggest these changes likely induce reorganization of actin filaments observed at larger scales.


Subject(s)
Actins/chemistry , Nanotubes, Carbon , Models, Molecular , Molecular Dynamics Simulation
20.
Nanoscale ; 4(23): 7425-34, 2012 Dec 07.
Article in English | MEDLINE | ID: mdl-23086474

ABSTRACT

Single-wall carbon nanotubes (SWCNTs) have been dispersed with proteins to increase biocompatibility and specificity, but examinations of dispersion parameters on functional cellular uptake are required for utilization of SWCNTs in biological applications. Here we correlate conditions of SWCNT dispersion with various proteins to uptake these SWCNTs in NIH-3T3 fibroblasts and J774A.1 macrophage-like cells. We varied protein types (bovine serum albumin - BSA, lysozyme - LSZ, and γ-globulins - γG), protein : SWCNT ratio and sonication time. Each protein created stable, high yield (~25%) dispersions in water while preserving intrinsic SWCNT fluorescence, but SWCNT-LSZ flocculated in media and SWCNT-γG formed clusters in both water and media, drastically altering cellular internalization. Dispersion quality and yield improved with increased protein : SWCNT - without substantial effects from depletion attraction, even at 100 : 1 protein : SWCNT - and slightly increased internalized SWCNTs for both NIH-3T3 and J774A.1 cells. Longer sonication time (12 versus 2 h) improved the dispersion yield and quality but caused minor damage to SWCNTs and altered protein structure. Cell association of SWCNT-BSA was homogenous and unaltered by sonication time. Bulk assay showed that cell association of SWCNT-LSZ and SWCNT-γG was altered with 12 versus 2 h sonication, but imaging of individual cells showed that these differences are likely from precipitation of clusters of SWCNT-LSZ and SWCNT-γG in media onto cells. Hence, the quality of SWCNT-protein dispersions in water does not necessarily correlate with bulk cellular uptake, and quantification at the level of individual cells is required to determine delivery efficacy.


Subject(s)
Nanotubes, Carbon/chemistry , Serum Albumin, Bovine/chemistry , Animals , Cattle , Cell Line , Mice , Microscopy, Confocal , NIH 3T3 Cells , Protein Structure, Secondary , Serum Albumin, Bovine/metabolism , Sonication , Spectroscopy, Near-Infrared
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