RESUMO
The improvements in Raman instrumentation have led to the development of -portable, simple to operate, Raman instruments that can be used for on-site analysis of substances relevant for homeland security purposes such as chemical and biological warfare and explosives materials.Raman spectroscopy, however, suffers from limited sensitivity which can be overcome by Surface-Enhanced Raman Spectroscopy (SERS). SERS can enhance the Raman signal of a target molecule by 6-10 orders of magnitude. The increased sensitivity, together with Raman's molecular recognition capabilities and the availability of portable Raman instruments make SERS a powerful analytical tool for on site detection.In this work we studied the effect of target molecules and SERS-active substrate properties on the obtained SERS, using a field portable Raman spectrometer. Also reported herein is the SERS detection of the chemical warfare agent sulfur mustard (HD, 2,2 dichloroethyl sulfide). This study may serve as a basis for the development of SERS platform for homeland security purposes.
Assuntos
Nanopartículas Metálicas/química , Compostos Orgânicos/química , Análise Espectral Raman/métodos , Adsorção , Ácido Benzoico/química , Compostos de Benzil/química , Substâncias para a Guerra Química/química , Citratos/química , Coloides , Ouro/química , Gás de Mostarda/química , Prata/química , Citrato de Sódio , Propriedades de SuperfícieRESUMO
A new sensitive surface-enhanced Raman scattering (SERS) assay for detection of cholinesterase inhibitors such as organophosphorous pesticides using silver colloidal nanoparticles was developed and optimized. Acetylcholinesterase (AChE) mediated the hydrolysis of acetylthiocholine to produce thiocholine, which interacted with the silver nanoparticles to give a specific SERS spectrum. Variation in enzyme activity due to inhibition was measured from changes in intensity of a characteristic peak (772 cm(-1)) of the SERS spectrum that was directly correlated with the concentration of produced thiocholine. The method was demonstrated for the detection of paraoxon as reference AChE inhibitor. Limit of detection of paraoxon for 5 min incubation at 25 °C was 1.8×10(-8) M. This assay can be utilized for the detection of trace amounts of any AChE inhibitor.
