title: Enzymatic oxidative biodegradation of nanoparticles: Mechanisms, significance and applications.
abstract: Biopersistence of carbon nanotubes, graphene oxide (GO) and several other types of carbonaceous nanomaterials is an essential determinant of their health effects. Successful biodegradation is one of the major factors defining the life span and biological responses to nanoparticles. Here, we review the role and contribution of different oxidative enzymes of inflammatory cells - myeloperoxidase, eosinophil peroxidase, lactoperoxidase, hemoglobin, and xanthine oxidase - to the reactions of nanoparticle biodegradation. We further focus on interactions of nanomaterials with hemoproteins dependent on the specific features of their physico-chemical and structural characteristics. Mechanistically, we highlight the significance of immobilized peroxidase reactive intermediates vs diffusible small molecule oxidants (hypochlorous and hypobromous acids) for the overall oxidative biodegradation process in neutrophils and eosinophils. We also accentuate the importance of peroxynitrite-driven pathways realized in macrophages via the engagement of NADPH oxidase- and NO synthase-triggered oxidative mechanisms. We consider possible involvement of oxidative machinery of other professional phagocytes such as microglial cells, myeloid-derived suppressor cells, in the context of biodegradation relevant to targeted drug delivery. We evaluate the importance of genetic factors and their manipulations for the enzymatic biodegradation in vivo. Finally, we emphasize a novel type of biodegradation realized via the activation of the "dormant" peroxidase activity of hemoproteins by the nano-surface. This is exemplified by the binding of GO to cyt c causing the unfolding and 'unmasking' of the peroxidase activity of the latter. We conclude with the strategies leading to safe by design carbonaceous nanoparticles with optimized characteristics for mechanism-based targeted delivery and regulatable life-span of drugs in circulation.
authors.affiliation: Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, United States; Research Institute for Physico-Chemical Medicine, Federal Medico-Biological Agency, Moscow 119453, Russia.
authors.forename: Irina I
authors.initials: II
authors.lastname: Vlasova
authors.affiliation: Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, United States.
authors.forename: Alexandr A
authors.initials: AA
authors.lastname: Kapralov
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States.
authors.forename: Zachary P
authors.initials: ZP
authors.lastname: Michael
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States.
authors.forename: Seth C
authors.initials: SC
authors.lastname: Burkert
authors.affiliation: Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, United States; Department of Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Shurin
authors.affiliation: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States.
authors.forename: Alexander
authors.initials: A
authors.lastname: Star
authors.affiliation: Pathology and Physiology Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH) and Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26505, United States. Electronic address: ats@cdc.gov.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Shvedova
authors.affiliation: Department of Environmental and Occupational Health, Center for Free Radical and Antioxidant Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15219, United States; Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, United States; Departments of Pharmacology and Chemical Biology and Radiation Oncology, University of Pittsburgh, Pittsburgh, PA 15260, United States. Electronic address: kagan@pitt.edu.
authors.forename: Valerian E
authors.initials: VE
authors.lastname: Kagan
mesh_terms: D000818:Animals; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D037742:Nanotubes, Carbon / Q000737:chemistry; D009504:Neutrophils / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D037742:Nanotubes, Carbon; D010544:Peroxidases
keywords: Carbon nanotubes; Free radicals; Graphene oxide; Oxidants; Peroxidase activity; Phagocytes