Surface-Enhanced Raman Scattering (SERS) Characterization of Trace Organoarsenic Antimicrobials Using Silver/Polydimethylsiloxane Nanocomposites

Abstract

Organoarsenic drugs such as roxarsone and 4-arsanilic acid are poultry feed additives widely used in US broilers to prevent coccidosis and to enhance growth and pigmentation. Despite their veterinary benefits there has been growing concern about their use because over 90% of these drugs are released intact into litter, which is often sold as a fertilizing supplement. The biochemical degradation of these antimicrobials in the litter matrix can release significant amounts of soluble As(III) and As(V) to the environment, representing a potential environmental risk. Silver/polydimethylsiloxane (Ag/PDMS) nanocomposites are a class of surfaceenhanced Raman scattering (SERS) substrates that have proven effective for the sensitive, reproducible, and field-adaptable detection of aromatic acids in water. The work presented herein uses for the first time Ag/PDMS nanocomposites as substrates for the detection and characterization of trace amounts of roxarsone, 4-arsanilic acid, and acetarsone in water. The results gathered in this study show that organoarsenic species are distributed into the PDMS surface where the arsonic acid binds onto the embedded silver nanoparticles, enhancing its characteristic 792 cm(-1) stretching band. The chemisorption of the drugs to the metal facilitates its detection and characterization in the parts per million to parts per billion range. An extensive analysis of the distinct spectroscopic features of each drug is presented with emphasis on the interactions of the arsonic acid, amino, and nitro groups with the metal surface. The benefits of SERS based methods for the study of arsenic drugs are also discussed.

On-line sensitive detection of aromatic vapor through PDMS/C3H7S-assisted SERS amplification

“…Till now, various identication techniques have been explored for detection of pollutants diffused in the atmosphere. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] An excellent strategy for SERS detection of aromatic vapor is to modify a hydrophobic thiol or alkylsilane monolayer on the metallic surface. 5 Surface enhanced Raman spectroscopy (SERS) has emerged as a powerful analytical tool for identication of molecules.…”

“…As such, the detection limit of SERS could be down to the single molecule level. [25][26][27][28][29][30][31][32] Despite advance in enhanced SERS detection of weakly adsorbed molecules, most of the molecules captured by PDMS are still located far away from the hot spots of plasmonic substrates. thio, amino, nitrile, and nitro) that strongly chemisorb on the plasmonic metal surface.…”

In Situ Arsenic Speciation using Surface-enhanced Raman Spectroscopy

“…In the past several decades, many studies have been carried out for the applications of SERS in arsenic analysis and speciation with an emphasis on improvement of the substrates for strong SERS signal production. Metallic colloidal suspensions [127][128][129][130] and metallic nanofilms [131][132][133][134][135][136][137][138] are two common substrates for SERS measurement while some indirect SERS methods employing nanoparticles for arsenite analysis [127,129,130] has also been reported.…”

“…Metallic nanofilm is the other popular SERS substrate for arsenic speciation, and it is easy to obtain arsenic SERS signals from nanofilms because of evaporation of droplets or diffusion of arsenicals on the nanofilm. Currently, different strategies are employed for nanofilm fabrication to study arsenic species, such as the modified mirror reaction for silver nanofilm deposition [137,138,142], coffee-ring evaporation [131], through the Langmuir-Blodgett assembly [132], electrothermal deposition [134,135]. Overall the surface morphology of the nanofilm is critical for the sensitivity and reproducibility of arsenic analysis.…”

“…Until now, SERS application for arsenic analysis has been mainly limited to inorganic arsenic species, such as As III or As V and environmental samples, such as well water or underground water. Comparing to inorganic arsenic compounds, analysis of organic arsenicals using SERS was much less reported [134,135,143]. Furthermore, the SERS application of arsenic speciation in biological matrices has not been explored to the best of our knowledge.…”