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We show that self-assembled vertically aligned gold nanorod (VA-GNRs) superlattices can serve as probes or substrates for ultra-high sensitive detection of various molecules. D-glucose and 2, 4, 6-trinitrotoluene (TNT) have been chosen as model systems due to their very low Raman cross-sections (5.6 × 10-30 cm2·molecule-1·sr-1 for D-glucose and 4.9 × 10-31 cm2·molecule-1·sr-1 for TNT) to show that the VA-GNR superlattice assembly offers as low as yoctomole sensitivity. Our experiment on mixed samples of bovine serum albumin (BSA) and D-glucose solutions demonstrate sensitivity for the latter, and the possible extension to real samples. Self-assembled superlattices of VA-GNRs were achieved on a silicon wafer by depositing a drop of solvent containing the GNRs and subsequent solvent evaporation in ambient conditions. An additional advantage of the VA-GNR monolayers is their extremely high reproducible morphology accompanied by ultrahigh sensitivity which will be useful in many fields where a very small amount of analyte is available. Moreover the assembly can be reused a number of times after removing the already present molecules. The method of obtaining VA-GNRs is simple, inexpensive and reproducible. With the help of simulations of monolayers and multilayers it has been shown that superlattices can achieve better sensitivity than monolayer assembly of VA-GNRs.

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Publication history

Received: 05 May 2013
Revised: 25 August 2014
Accepted: 26 August 2014
Published: 11 October 2014
Issue date: March 2015

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© Tsinghua University Press and Springer-Verlag Heidelberg 2014

Acknowledgements

Acknowledgements

We thank the Department of Science and Technology (DST), India Nano-Mission Initiative Project SR/NM/NS-42/2009. S.C. thanks DST, India Grant No SR/WOS/-A/PS50/2012(G). S.K. thanks UGC, India for constant support. The authors thank Anil Prathamshetti, IISER Pune, for technical assistance. P.P. acknowledges DST project DST/INT/ISR/P-8/2011.

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Email: nanores@tup.tsinghua.edu.cn

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