Showing papers by "Nikhil R. Jana published in 2007"

Synthesis of water-soluble and functionalized nanoparticles by silica coating

Abstract: Synthetic methods for high-quality near-monodispersed nanoparticles of metals, metal oxides, and quantum dots in organic solvents are well-developed, but their applications are restricted due to the lack of water solubility and tailored surface chemistry. In this work, we report the silica-coating procedure for various hydrophobic nanoparticles, including Au, Ag, Fe3O4, and ZnS−CdSe to derive water-soluble and functionalized nanoparticles. We have developed a silica-coating method in toluene using commercially available silanes. This approach is applicable to hydrophobic nanoparticles in the size range of 2−20 nm. Silica-coated nanoparticles are 10−30 nm in size, water-soluble, buffer-stable, and have a positive or negative surface charge depending on the surface functional group and solution pH. The coated particles have primary amine groups on the outer surface and are further functionalized with biotin and antibody.

Detection of protein molecules by surface‐enhanced Raman spectroscopy‐based immunoassay using 2–5 nm gold nanoparticle lables

Abstract: Here we report the synthesis of 2–5 nm size gold nanoparticle labels for surface-enhanced Raman Spectroscopy (SERS) based immunoassay to detect protein molecules. The Au nanoparticles were conjugated with fluorescein isothiocyanate (FITC) and goat anti-h-IgG (immunoglobin) and the resultant particles were used for the detection of h-IgG. Commercially available nitrocellulose strip and silver enhancement method were used for SERS-based immunoassays. The FITC acts as a Raman probe, and vibrational fingerprint of this molecule was used for the detection of h-IgG in concentration ranging from 1 to 100 ng/µl. Our Raman probe is robust and small in size and has high water solubility with minimum steric effect during antigen–antibody binding. Copyright © 2007 John Wiley & Sons, Ltd.