BIOCHEMICALLY FUNCTIONALIZED SILICA NANOMATERIALS

Tarek H Afifi Mahmoud^1*, Pamela Shapiro², Steve M. Nelson³, Deborah L. Stenkamp³, Miles Beaux II⁴, David N. McIlroy⁴.

¹ Department of Chemistry, College of Science, Hail University, P. O. Box: 2440 Hail

² Department of Chemistry, ³ Department of Biological Sciences, Neuroscience Graduate Program, ⁴ Department of Physics, University of Idaho, Moscow, ID, USA.

Abstract

Fluorescent dye-doped silica nanoparticles facilitate unique applications in bioanalytical and drug delivery systems. We have prepared both pure and dye-doped silica nanoparticles encapsulated with Rhodamine-B isothiocyanate, Fluorescein isothiocyanate, Alexa fluor 514 and IR dye 800CW NHS-Ester using a modified stober and/or a water-in-oil microemulsion method. The procedure consists of the coupling of the fluorphore to a silane coupling agent such as (3-amino propyl) triethoxy Silane, and the controllable incorporation of the reaction product into the silica sphere. Silica nanoparticles were analyzed using Transmission Electron Microscopy (TEM) and the size ranged from 50 to 200nm. Bioconjugation of these silica nanoparticles adds unique biofunctions with various molecules such as peptides, antibodies and DNA molecules. Nanoparticles were also imaged on a Zeiss LSM 5 PASCAL confocal system mounted on an Axiovert 200M microscope. The system was equipped with an argon laser that emits at 458nm, 488nm and 514nm and a HeNe laser that emits at 633nm and a plan Apo 63X oil Immersion objective lens. The IR dye-doped silica nanoparticles were imaged using 633nm excitation and a long pass emission filter of 650nm. Rhodamine fluorphore was imaged using 514nm excitation and a long pass emission filter at 560nm. Using these settings allowed visualization of both the encapsulated IR dye conjugated and peptide labeled Rhodamine-B dye. Silica nanowires were also functionalized with fluorphore moieties following the same methodology of silica nanoparticles. We use the embryonic zebrafish to model silica nanomaterial exposure to human embryos immediately following implantation. Silica nanomaterials with aspect ratios >1 were highly toxic (LD 50= 1.5ng/g embryo) and caused embryo deformities, whereas silica nanomaterials with an aspect ratio =1, were not toxic or teratogenic. Large aspect ratio silica nanowires selectively interfered with neurulation and disrupted expression of the developmental gene.

^* Presenting Author and Correspondence to:

Tarek H Afifi Mahmoud

Hail University

College of Science

Department of Chemistry

P.O.Box 2440 Hail

Cell: 0541678869

E-mail: tarek@uoh.edu.sa and/or afifith@yahoo.com