title: Dual-Enzyme Characteristics of Polyvinylpyrrolidone-Capped Iridium Nanoparticles and Their Cellular Protective Effect against H2O2-Induced Oxidative Damage.
abstract: Polyvinylpyrrolidone-stabilized iridium nanoparticles (PVP-IrNPs), synthesized by the facile alcoholic reduction method using abundantly available PVP as protecting agents, were first reported as enzyme mimics showing intrinsic catalase- and peroxidase-like activities. The preparation procedure was much easier and more importantly, kinetic studies found that the catalytic activity of PVP-IrNPs was comparable to previously reported platinum nanoparticles. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterization indicated that PVP-IrNPs had the average size of approximately 1.5 nm and mainly consisted of Ir(0) chemical state. The mechanism of PVP-IrNPs' dual-enzyme activities was investigated using XPS, Electron spin resonance (ESR) and cytochrome C-based electron transfer methods. The catalase-like activity was related to the formation of oxidized species Ir(0)@IrO2 upon reaction with H2O2. The peroxidase-like activity originated from their ability acting as electron transfer mediators during the catalysis cycle, without the production of hydroxyl radicals. Interestingly, the protective effect of PVP-IrNPs against H2O2-induced cellular oxidative damage was investigated in an A549 lung cancer cell model and PVP-IrNPs displayed excellent biocompatibility and antioxidant activity. Upon pretreatment of cells with PVP-IrNPs, the intracellular reactive oxygen species (ROS) level in response to H2O2 was decreased and the cell viability increased. This work will facilitate studies on the mechanism and biomedical application of nanomaterials-based enzyme mimic.
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Hua
authors.initials: H
authors.lastname: Su
authors.affiliation: ‡Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642, P. R. China.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Liu
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhao
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Wei-Liang
authors.initials: WL
authors.lastname: Hu
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Xue
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Cao
authors.affiliation: ‡Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642, P. R. China.
authors.forename: Xue-Yi
authors.initials: XY
authors.lastname: Le
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
authors.forename: Liang-Nian
authors.initials: LN
authors.lastname: Ji
authors.affiliation: †MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.|‡Department of Applied Chemistry, South China Agricultural University, Guangzhou 510642, P. R. China.
authors.forename: Zong-Wan
authors.initials: ZW
authors.lastname: Mao
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000494:pharmacology; D002374:Catalase / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis; D019610:Cytoprotection / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007495:Iridium / Q000008:administration & dosage* / Q000737:chemistry; D008175:Lung Neoplasms / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D018384:Oxidative Stress / Q000187:drug effects*; D010544:Peroxidases / Q000737:chemistry / Q000494:pharmacology; D011205:Povidone / Q000008:administration & dosage* / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D020099:Coated Materials, Biocompatible; D017382:Reactive Oxygen Species; D007495:Iridium; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase; D011205:Povidone
keywords: H2O2-induced cytotoxicity reduction; antioxidants; catalase- and peroxidase-like activity; catalytic mechanism; iridium nanoparticles; polyvinylpyrrolidone