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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

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Growth and surface-enhanced Raman scattering of Ag nanoparticle assembly in agarose gel

Keating, M. and Chen, Y. and Larmour, I. A. and Faulds, K. and Graham, D. (2012) Growth and surface-enhanced Raman scattering of Ag nanoparticle assembly in agarose gel. Measurement Science and Technology, 23 (8). -. ISSN 0957-0233

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Abstract

Agarose gel loaded with silver nanoparticles has attracted a lot of attention recently due to its excellent molecular trapping capabilities and strong surface-enhanced Raman scattering (SERS). Despite its potential, the influence of the growth condition on the gel structure and resultant SERS intensity and reproducibility is not clear. In this work, we examine the effect of silver nitrate feed solution concentration, the precursor to neutral silver nanoparticles, on the resultant nanoparticle morphology, gel homogeneity, SERS signal intensity and reproducibility. SERS of trans-1,2-bis-(4-pyridyl) ethylene, a non-resonant molecule, was conducted. A substantial rise in SERS signal strength with increasing feed concentration was observed, accompanied by a modest increase in average particle size as disclosed by TEM analysis. At higher concentrations, gels possessed larger particles from broader size distributions which had a higher tendency to aggregate. This created a higher density of SERS 'hotspots', regions of intense electromagnetic field crucial for maximal enhancement of the Raman signal, but also led to increased spot-to-spot signal variation due to a marked change in nanoparticle morphology and gel homogeneity. Beyond an optimal feed concentration, no further increase in overall signal strength was evident, correlating with no appreciable rise in the number of larger particles.