A SERS-Active System Based on Silver Nanoparticles Tethered to a Deposited Silver Film

Abstract

A series of SERS-active nanostructures were produced by exposing a freshly deposited silver film (fabricated to be as free from roughness as practicable) to a solution containing a mixture of 1-decanethiol (m) and 1,9-nonanedithiol (d) of varying concentrations of m to d, then allowing colloidal silver nanoparticles to interact with the surface. Silver nanoparticles were found to bind exclusively to films which were prepared from solutions with a nonzero concentration of the dithiol implying that the nanoparticles were tethered to the silver surface by the dithiol with one of the thiolate groups bound to the nanoparticle and the other to the silver film. Intense SERS spectra were observed even from samples in which the m/d concentration ratio was so large that the adsorbed molecules in the vicinity of only approximately 8 +/- 3 nanoparticles were illuminated by the diffraction-limited focused laser beam. At such high dilution, the molecules (numbering at most approximately 330) residing in the SERS "hot spots" associated with the approximately 8 nanoparticles consisted primarily of m (although, of course, for each nanoparticle, at least one molecule in the hot spot had to be d to serve as the linker). This was corroborated by the SERS spectra. An analysis is presented, which accounts for the fact that as the concentration ratio of m/d increases, the SERS intensity associated with bands belonging to m first increases to a maximum then decreases. The nanoparticle-metal film system presented here is a simple embodiment of a more general range of SERS-active sensing platforms in which a molecular tether is used to create a SERS hot spot that (although nanosized) is large enough to accommodate analyte molecules that cannot themselves function as linkers, which are subsequently detected by SERS at the few-molecule level.

Antibacterial Activity of Biogenic Platinum Nanoparticles: An In vitro Study

“…Currently a variety of metallic and nonmetallic nanoparticles such as gold, alginate, silver, copper, zinc, titanium, magnesium, platinum and silica etc., are emerged. These nanoparticles are used in various fields such as optical devices (Anderson and Moskovits, 2006), catalytic (Jiang et al, 2005), bactericidal (Sekar et al, 2011), antibiofouling (Agarwal et al, 2014), dye degradation (Priyaragini et al, 2014), electronic (Rao et al, 2000), sensor technology (Sharpe and Andreescu, 2015), treatment of some cancers (Praetorius and Mandal, 2007) and malaria (Karthik et al, 2013). This wide range of application justifies the research and development inputs required in the field of nanotechnology.…”

Thermal decomposition as route for silver nanoparticles

“…Synthesis of silver nanoparticles is a significant area of research, because Ag nanoparticles have potential applications in various fields such as biochemistry, environment, medicine, catalysis, electronics and optics [1][2][3][4]. Particularly, the recent finding revealed that Ag nanoparticles can bind to the HIV [5].…”

RAPD Molecular Marker Based Genetic Diversity among Oriental Pickling Melon (Cucumis melo var. conomon) Genotypes in Karnataka

“…Most recently, there is a global interest among the scientists to develop, improve, employ and use nanoparticles for solving various problems encountered by mankind. In recent past, a variety of metallic and non-metallic nanoparticles are extensively used in various fields such as pharmaceuticals, optical devices, catalyst, bioremediation, electronic and sensor technology (Praetorius et al, 2007;Karthik et al, 2013;Anderson et al, 2006;Jiang et al, 2005;Agarwal et al, 2014;Sharpe et al, 2014).…”