Development of MWCNT/AuNP Nanostructures for Label-Free Localized SPR Based Biosensing

Metallic nanostructures exhibit charge density oscillations called localized surface plasmons when excited by an electromagnetic radiation. Consequently, localized electromagnetic field enhancement and selective photon absorption can be exploited using an inexpensive and simple technique of transmission spectroscopy in the UV range, unlike conventional SPR platforms which operate in total internal reflection mode. The intensity and surface plasmon absorption bands are specific to size, shape and dielectric properties of metallic nano-particles used. Well-defined and superior properties of LSPR and demand for high-throughput sensing assays have led to the development of three-dimensional sensor chips. We report the layer-by-layer assembly of a multi-walled carbon nanotube/gold nanoparticle (MWCNT/AuNP) based sensing platform for label free DNA sensing and nano-bioelectronic applications. Silicon/glass substrates were silanized using (3-aminopropyl) triethoxysilane (APTES). Initially, a monolayer of AuNP is developed by immersing the substrate in citrate stabilized AuNP solution (15 nm) for 12 hours. This is followed by immersing the substrate in a polymer solution of multi-walled carbon nanotube-polyethyleneimine (MWCNT-PEI) solution for 2 hours. Subsequently, the slides are immersed in AuNP solution for 2 hours and thus the layers are developed repeating the second and third steps Fig. 1. Presence of AuNP in the end-layer facilitates immobilization of a wide range of DNA scaffolds and enzymes for label-free biosensing.modified by 192.168.20.52 on 5-4-2010-->