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      Nano-Gold Corking and Enzymatic Uncorking of Carbon Nanotube Cups

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          Abstract

          Because of their unique stacked, cup-shaped, hollow compartments, nitrogen-doped carbon nanotube cups (NCNCs) have promising potential as nanoscale containers. Individual NCNCs are isolated from their stacked structure through acid oxidation and subsequent probe-tip sonication. The NCNCs are then effectively corked with gold nanoparticles (GNPs) by sodium citrate reduction with chloroauric acid, forming graphitic nanocapsules with significant surface-enhanced Raman signature. Mechanistically, the growth of the GNP corks starts from the nucleation and welding of gold seeds on the open rims of NCNCs enriched with nitrogen functionalities, as confirmed by density functional theory calculations. A potent oxidizing enzyme of neutrophils, myeloperoxidase (MPO), can effectively open the corked NCNCs through GNP detachment, with subsequent complete enzymatic degradation of the graphitic shells. This controlled opening and degradation was further carried out in vitro with human neutrophils. Furthermore, the GNP-corked NCNCs were demonstrated to function as novel drug delivery carriers, capable of effective (i) delivery of paclitaxel to tumor-associated myeloid-derived suppressor cells (MDSC), (ii) MPO-regulated release, and (iii) blockade of MDSC immunosuppressive potential.

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          Most cited references36

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          A new concept for macromolecular therapeutics in cancer chemotherapy: mechanism of tumoritropic accumulation of proteins and the antitumor agent smancs.

          We previously found that a polymer conjugated to the anticancer protein neocarzinostatin, named smancs, accumulated more in tumor tissues than did neocarzinostatin. To determine the general mechanism of this tumoritropic accumulation of smancs and other proteins, we used radioactive (51Cr-labeled) proteins of various molecular sizes (Mr 12,000 to 160,000) and other properties. In addition, we used dye-complexed serum albumin to visualize the accumulation in tumors of tumor-bearing mice. Many proteins progressively accumulated in the tumor tissues of these mice, and a ratio of the protein concentration in the tumor to that in the blood of 5 was obtained within 19 to 72 h. A large protein like immunoglobulin G required a longer time to reach this value of 5. The protein concentration ratio in the tumor to that in the blood of neither 1 nor 5 was achieved with neocarzinostatin, a representative of a small protein (Mr 12,000) in all time. We speculate that the tumoritropic accumulation of these proteins resulted because of the hypervasculature, an enhanced permeability to even macromolecules, and little recovery through either blood vessels or lymphatic vessels. This accumulation of macromolecules in the tumor was also found after i.v. injection of an albumin-dye complex (Mr 69,000), as well as after injection into normal and tumor tissues. The complex was retained only by tumor tissue for prolonged periods. There was little lymphatic recovery of macromolecules from tumor tissue. The present finding is of potential value in macromolecular tumor therapeutics and diagnosis.
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            Supramolecular chemistry on water-soluble carbon nanotubes for drug loading and delivery.

            We show that large surface areas exist for supramolecular chemistry on single-walled carbon nanotubes (SWNTs) prefunctionalized noncovalently or covalently by common surfactant or acid-oxidation routes. Water-soluble SWNTs with poly(ethylene glycol) (PEG) functionalization via these routes allow for surprisingly high degrees of pi-stacking of aromatic molecules, including a cancer drug (doxorubicin) with ultrahigh loading capacity, a widely used fluorescence molecule (fluorescein), and combinations of molecules. Binding of molecules to nanotubes and their release can be controlled by varying the pH. The strength of pi-stacking of aromatic molecules is dependent on nanotube diameter, leading to a method for controlling the release rate of molecules from SWNTs by using nanotube materials with suitable diameter. This work introduces the concept of "functionalization partitioning" of SWNTs, i.e., imparting multiple chemical species, such as PEG, drugs, and fluorescent tags, with different functionalities onto the surface of the same nanotube. Such chemical partitioning should open up new opportunities in chemical, biological, and medical applications of novel nanomaterials.
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              Arginine regulation by myeloid derived suppressor cells and tolerance in cancer: mechanisms and therapeutic perspectives.

              Patients with cancer have an impaired T-cell response that can decrease the potential therapeutic benefit of cancer vaccines and other forms of immunotherapy. L-arginine (L-Arg) is a conditionally essential amino acid that is fundamental for the function of T lymphocytes. Recent findings in tumor-bearing mice and cancer patients indicate that increased metabolism of L-Arg by myeloid derived suppressor cells (MDSCs) producing arginase I inhibits T-lymphocyte responses. Here we discuss some of the most recent concepts how MDSC expressing arginase I may regulate T-cell function in cancer and other chronic inflammatory diseases and suggest possible therapeutic interventions to overcome this inhibitory effect.
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                Author and article information

                Journal
                J Am Chem Soc
                J. Am. Chem. Soc
                ja
                jacsat
                Journal of the American Chemical Society
                American Chemical Society
                0002-7863
                1520-5126
                21 December 2015
                21 December 2014
                21 January 2015
                : 137
                : 2
                : 675-684
                Affiliations
                []Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
                []National Energy Technology Laboratory, U.S. Department of Energy , Pittsburgh, Pennsylvania 15263, United States
                [§ ]Department of Environmental and Occupational Health, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
                [4] Department of Pathology, and Department of Immunology, University of Pittsburgh Medical Center , Pittsburgh, Pennsylvania 15261, United States
                Author notes
                Article
                10.1021/ja511843w
                4308760
                25530234
                b25a31e9-3448-4097-a7f9-8e4fe4146460
                Copyright © 2014 American Chemical Society

                This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

                History
                : 02 April 2014
                Funding
                National Institutes of Health, United States
                Categories
                Article
                Custom metadata
                ja511843w
                ja-2014-11843w

                Chemistry
                Chemistry

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