title: Enzyme-catalyzed oxidation facilitates the return of fluorescence for single-walled carbon nanotubes.
abstract: In this work, we studied enzyme-catalyzed oxidation of single-walled carbon nanotubes (SWCNTs) produced by the high-pressure carbon monoxide (HiPco) method. While oxidation via strong acids introduced defect sites on SWCNTs and suppressed their near-infrared (NIR) fluorescence, our results indicated that the fluorescence of SWCNTs was restored upon enzymatic oxidation, providing new evidence that the reaction catalyzed by horseradish peroxidase (HRP) in the presence of H2O2 is mainly a defect-consuming step. These results were further supported by both UV-vis-NIR and Raman spectroscopy. Therefore, when acid oxidation followed by HRP-catalyzed enzyme oxidation was employed, shortened (<300 nm in length) and NIR-fluorescent SWCNTs were produced. In contrast, upon treatment with myeloperoxidase, H2O2, and NaCl, the oxidized HiPco SWCNTs underwent complete oxidation (i.e., degradation). The shortened, NIR-fluorescent SWCNTs resulting from HRP-catalyzed oxidation of acid-cut HiPco SWCNTs may find applications in cellular NIR imaging and drug delivery systems.
authors.affiliation: Department of Chemistry, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Cheuk Fai
authors.initials: CF
authors.lastname: Chiu
authors.forename: Brian A
authors.initials: BA
authors.lastname: Barth
authors.forename: Gregg P
authors.initials: GP
authors.lastname: Kotchey
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhao
authors.forename: Kristy A
authors.initials: KA
authors.lastname: Gogick
authors.forename: Wissam A
authors.initials: WA
authors.lastname: Saidi
authors.forename: Stéphane
authors.initials: S
authors.lastname: Petoud
authors.forename: Alexander
authors.initials: A
authors.lastname: Star
mesh_terms: D055162:Biocatalysis; D005453:Fluorescence; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010316:Particle Size; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D006735:Horseradish Peroxidase