AVS 53rd International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS+BI-ThM

Paper NS+BI-ThM6
Characterization of Silver Nanoparticles Films for the Development of TPB Biosensors

Thursday, November 16, 2006, 9:40 am, Room 2016

Session: Biological and Molecular Applications of Nanoscale Structures
Presenter: J. Wolstenholme, Thermo Electron Corporation, UK
Authors: J. Wolstenholme, Thermo Electron Corporation, UK
K. Bonroy, IMEC, Belgium
G. Borghs, IMEC, Belgium
F. Frederix, IMEC, Belgium
R.G. White, Thermo Electron Corporation, UK
Correspondent: Click to Email
Metal nanoparticle films have been subject of much research, primarily due to their interesting optical and electronic properties and due to their high surface-to-volume ratio. According to numerous studies, nanoparticle films are promising as precursors for metallic films, as catalysts and especially as sensing substrates for the development of novel biosensors such as the Transmission Plasmon Biosensor (TPB). This type of biosensor is based upon the optical properties of silver and gold nanoparticles which are used to sense the specific target molecules in a complex matrix. Hereby, the nanoparticles are to be functionalized with self-assembled monolayers (SAMs) of thiols or disulfide molecules. These monolayers form a covalent bond with the gold or silver surface and can have appropriate functional groups to allow the attachment of specific bioreceptors. For surface plasmon based biosensors such as TPB, gold nanoparticles are most frequently used due to their chemical stability and their relatively simple preparation. Nevertheless, various studies and models predict a much higher sensitivity using silver nanoparticles as TPB sensing substrate. However, at this moment the drawbacks for using silver films as sensing substrates are their instability due to the formation of an oxide layer. The latter will negatively influence the formation of well-organized SAMs of thiols and the subsequent functionalization of the particles with specific bioreceptors. In this paper, we describe the FTIR, the XPS and angle resolved XPS characterization of the multilayered TPB sensing substrates, comprising quartz, silanes, silver nanoparticles and thiol molecules. In this study, we compared the thickness of the silane layer, the oxidation ratio of the silver films and the density of the thiol SAM for both silver nanoparticle films and continuous silver films. Our study indicates that the deposition of SAMs decreases the formation of oxides on the silver nanoparticle films.