TNT residues from land mine explosion and military activities are a major pollution concern on soil and groundwater environments. In this presentation we will discuss our recent effort on development of cysteine modified gold nanoparticle based nonlinear optical (NLO) assay for the detection of trace amounts of TNT from environmental samples. Our assay demonstrates for the first time a label-free, highly selective and ultra sensitive probe for TNT recognition in nano-molar level in aqueous solution. Due to the formation of Meisenheimer complex between TNT and cysteine, gold nanoparticles undergo aggregation in the presence of TNT via electrostatic interaction between Meisenheimer complex bound gold nanoparticle and cysteine modified gold nanoparticle. The mechanism for HRS intensity change has been discussed in detail using particle size-dependent NLO properties as well as a two-state model. Our experimental results show that TNT can be detected quickly in nM level with excellent discrimination against other nitro compounds and heavy metals. Keywords: Two-Photon, Meisenheimer Complex, TNT.

Label-free, ultrasensitive and selective detection of Trinitrotoluene (TNT) using NLO properties of L-Cysteine modified gold nanoparticle

240th National Meeting (2010)

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