Science & Technology

Silver Nanoparticles Take Raman Spectroscopy to a New Dimension

Detection of a low focus analyte molecule utilizing silicon nanowires adorned with silver nanoparticles and floor enhanced Raman scattering measurements. Credit score: V.S. Vendamani

As medication and pharmacology examine nanoscale processes, it has change into more and more essential to determine and characterize completely different molecules. Raman spectroscopy, a method that leverages the scattering of laser mild to determine molecules, has a restricted capability to detect molecules in diluted samples due to low sign yield.

A crew of researchers from the College of Hyderabad in India has improved molecular detection at low focus ranges by arranging nanoparticles on nanowires to improve Raman spectroscopy. Floor-enhanced Raman spectroscopy (SERS) makes use of electromagnetic fields to enhance Raman scattering and increase sensitivity in customary dyes akin to R6G by a couple of billionfold.

The crew adorned vertically aligned silicon nanowires with various densities of silver nanoparticles, using and enhancing the construction’s 3-D form. Their outcomes, revealed within the Journal of Utilized Physics, from AIP Publishing, present that their system was in a position to improve the Raman indicators for cytosine protein and ammonium perchlorate by a issue of 100,000.

“The wonder is that we are able to enhance the density of those nanowires utilizing easy chemistry,” stated Soma Venugopal Rao, one of many paper’s authors. “You probably have a giant density of nanowires, you may put extra silver nanoparticles into the substrate and may enhance the sensitivity of the substrate.”

Making use of the mandatory nanostructures to SERS units stays a problem for the sector. Constructing these buildings in three dimensions with silicon nanowires has garnered consideration for his or her larger floor space and superior efficiency, however silicon nanowires are nonetheless costly to produce.

As an alternative, the crew was in a position to discover a cheaper method to make silicon nanowires and used a method known as electroless etching to make a big selection of nanowires. They “adorned” these wires with silver nanoparticles with variable and managed densities, which elevated the nanowires’ floor space.

“Optimizing these vertically aligned buildings took a lot of time at first,” stated Nageswara Rao, one other of the paper’s authors. “We elevated the floor space and to do that we wanted to change the side ratio.”

After optimizing their system to detect Rhodamine dye on a nanomolar degree, these new substrates the crew constructed enhanced Raman sensitivity by a issue of 10,000 to 100,000. The substrates detected concentrations of cytosine, a nucleotide present in DNA, and ammonium perchlorate, a molecule with potential for detecting explosives, in as dilute concentrations as 50 and 10 micromolar, respectively.

The outcomes have given the crew purpose to imagine that it’d quickly be doable to detect compounds in concentrations on the dimensions of nanomolar and even picomolar, Nageswara Rao stated. The crew’s work has opened a number of avenues for future analysis, from experimenting with completely different nanoparticles akin to gold, rising the sharpness of the nanowires or testing these units throughout a number of kinds of molecules.

Publication: V. S. Vendamani, et al., “Three-dimensional hybrid silicon nanostructures for floor enhanced Raman spectroscopy based mostly molecular detection,” Journal of Utilized Physics 123, 014301 (2018); doi:10.1063/1.5000994

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