Design and fabrication of random silver films as substrate for SERS based nano-stress sensing of proteins

Design and fabrication of random silver films as substrate for SERS based nano-stress sensing of proteins
Title:
Design and fabrication of random silver films as substrate for SERS based nano-stress sensing of proteins
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RSC Advances
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Publication Date:
23 January 2014
Citation:
Abstract:
We report a simple and easy to fabricate random silver film (RSF) as a highly sensitive Surface Enhanced Raman Scattering (SERS) substrate which can be fabricated directly onto a dielectric substrate such as glass. An electron beam evaporation system was used for substrate fabrication. The SERS activity is attributed to the formation of electromagnetic ‘hot-spots’ on the film. Substrate performance is analyzed by studying the reproducibility and signal enhancement from the Raman active molecule, 2-naphthalenethiol (NT), which is covalently anchored to the substrate. The metal thickness is optimized to achieve the highest SERS enhancement. Based on this study we found that a 7 nm RSF substrate gave the best SERS activity. The SERS signal intensity exhibited by 7 nm RSF is found to be at least 3 orders of magnitude higher than that of a commercial substrate. The SERS enhancement factor is estimated to be ~1 X107 with a point-to-point intensity variation of about 12% and it reaches a maximum of 15% for batch-tobatch comparison. The efficacy of this substrate for biosensing is demonstrated by detecting H1 influenza protein, and the detection limit is found to be 10 pM when it is used along with a recently established nano-stress SERS sensor, 4-ATP (4-amino-thiophenol), as linker molecule. This detection limit shows a performance superior to conventional ELISA (which has a nM detection limit). These results show promise for the development of a biosensing platform based on the marriage of RSF with nanostress snsors.
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PublisherCopyrights
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ISSN:
2046-2069
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