title: Diatomite biosilica nanocarriers for siRNA transport inside cancer cells.
abstract: BACKGROUND
  Diatomite is a natural porous biomaterial of sedimentary origin, formed by fragments of diatom siliceous skeletons, called "frustules". Due to large availability in many areas of the world, chemical stability, and non-toxicity, these fossil structures have been widespread used in lot of industrial applications, such as food production, water extracting agent, production of cosmetics and pharmaceutics. However, diatomite is surprisingly still rarely used in biomedical applications. In this work, we exploit diatomite nanoparticles for small interfering ribonucleic acid (siRNA) transport inside human epidermoid cancer cells (H1355).
  
  
  METHODS
  Morphology and composition of diatomite microfrustules (average size lower than 40μm) are investigated by scanning electron microscopy equipped by energy dispersive X-ray spectroscopy, Fourier transform infrared analysis, and photoluminescence measurements. Nanometric porous particles (average size lower than 450nm) are obtained by mechanical crushing, sonication, and filtering of micrometric frustules. siRNA bioconjugation is performed on both micrometric and nanometric fragments by silanization.
  
  
  RESULTS
  In-vitro experiments show very low toxicity on exposure of the cells to diatomite nanoparticle concentration up to 300μg/ml for 72h. Confocal microscopy imaging performed on cancer cells incubated with siRNA conjugated nanoparticles demonstrates a cytoplasmatic localization of vectors. Gene silencing by delivered siRNA is also demonstrated.
  
  
  CONCLUSIONS
  Our studies endorse diatomite nanoparticles as non-toxic nanocarriers for siRNA transport in cancer cells.
  
  
  CONCLUSIONS
  siRNA is a powerful molecular tool for cancer treatment but its delivery is inefficient due to the difficulty to penetrate the cell membrane. siRNA-diatomite nanoconjugate may be well suited for delivery of therapeutic to cancer cells.
authors.affiliation: Institute for Microelectronics and Microsystems, National Council of Research, Naples, Italy. Electronic address: ilaria.rea@na.imm.cnr.it.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Rea
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Nicola M
authors.initials: NM
authors.lastname: Martucci
authors.affiliation: Institute for Microelectronics and Microsystems, National Council of Research, Naples, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: De Stefano
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Immacolata
authors.initials: I
authors.lastname: Ruggiero
authors.affiliation: Institute for Microelectronics and Microsystems, National Council of Research, Naples, Italy; Department of Pharmacy, University of Naples Federico II, Naples, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Terracciano
authors.affiliation: Institute for Microelectronics and Microsystems, National Council of Research, Naples, Italy.
authors.forename: Principia
authors.initials: P
authors.lastname: Dardano
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Nunzia
authors.initials: N
authors.lastname: Migliaccio
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Arcari
authors.affiliation: Institute of Genetics and Biophysics, National Council of Research, Naples, Italy.
authors.forename: Rosarita
authors.initials: R
authors.lastname: Taté
authors.affiliation: Institute for Microelectronics and Microsystems, National Council of Research, Naples, Italy.
authors.forename: Ivo
authors.initials: I
authors.lastname: Rendina
authors.affiliation: Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Naples, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Lamberti
keywords: Diatomite; Drug delivery; Nanovector; Photoluminescence; Porous material; Surface modification