Yoshie Fujimori

Investigation of the antiviral properties of copper iodide nanoparticles against feline calicivirus

This study demonstrated the antiviral properties of copper iodide (CuI) nanoparticles against the non-enveloped virus feline calicivirus (FCV) as a surrogate for human norovirus. The effect of CuI nanoparticles on FCV infectivity to Crandell-Rees feline kidney (CRFK) cells was elucidated. The infectivity of FCV to CRFK cells was greatly reduced by 7 orders of magnitude at 1000μgml(-1) CuI nanoparticles. At the conditions, electron spin resonance (ESR) analysis proved hydroxyl radical production in CuI nanoparticle suspension. Furthermore, amino acid oxidation in the viral capsid protein of FCV was determined by nanoflow liquid chromatography-mass spectrometric (nano LC-MS) analysis. The use of CuI nanoparticles showed extremely high antiviral activity against FCV. The high antiviral property of CuI nanoparticles was attributed to Cu(+), followed by ROS generation and subsequent capsid protein oxidation. CuI nanoparticles could be proposed as useful sources of a continuous supply of Cu(+) ions for efficient virus inactivation. Furthermore, this study brings new insights into toxic actions of copper iodide nanoparticles against viruses.

Novel antiviral characteristics of nanosized copper(I) iodide particles showing inactivation activity against 2009 pandemic H1N1 influenza virus.

ABSTRACT We investigated the antiviral activity of nanosized copper(I) iodide (CuI) particles having an average size of 160 nm. CuI particles showed aqueous stability and generated hydroxyl radicals, which were probably derived from monovalent copper (Cu+). We confirmed that CuI particles showed antiviral activity against an influenza A virus of swine origin (pandemic [H1N1] 2009) by plaque titration assay. The virus titer decreased in a dose-dependent manner upon incubation with CuI particles, with the 50% effective concentration being approximately 17 μg/ml after exposure for 60 min. SDS-PAGE analysis confirmed the inactivation of the virus due to the degradation of viral proteins such as hemagglutinin and neuraminidase by CuI. Electron spin resonance (ESR) spectroscopy revealed that CuI generates hydroxyl radicals in aqueous solution, and radical production was found to be blocked by the radical scavenger N-acetylcysteine. Taken together, these findings indicate that CuI particles exert antiviral activity by generating hydroxyl radicals. Thus, CuI may be a useful material for protecting against viral attacks and may be suitable for applications such as filters, face masks, protective clothing, and kitchen cloths.

Introduction of copper iodide fine particles into a poly(acrylic acid) matrix via a complex of polymer–polyiodide ions

In this study, an organic–inorganic nanocomposite material of cross-linked poly(acrylic acid) (PAA) doped with fine particles of copper iodide (CuI) was prepared. The preparation method of the composite involved the complexing of PAA film with polyiodide ions such as I3− and I5− by immersion in an iodine–potassium iodide (I2–KI) aqueous solution, and then reaction with CuCl in aqueous hydrochloric acid, resulting in the in-situ formation of CuI fine particles within the PAA matrix. The crystal form of CuI in the composite was identified as γ-CuI using X-ray diffraction, and the amount of CuI could be varied by changing both the concentration of the I2–KI solution and the frequency of performing the doping procedure to introduce CuI into the matrix. This preparation method, using polyiodide ions as a precursor, has an advantage in that a large amount of metal iodide, such as CuI, can be easily formed, and it is regarded as a unique method for the preparation of organic–inorganic composites.