title: Reversible gating of smart plasmonic molecular traps using thermoresponsive polymers for single-molecule detection.
abstract: Single-molecule surface-enhanced Raman spectroscopy (SERS) has attracted increasing interest for chemical and biochemical sensing. Many conventional substrates have a broad distribution of SERS enhancements, which compromise reproducibility and result in slow response times for single-molecule detection. Here we report a smart plasmonic sensor that can reversibly trap a single molecule at hotspots for rapid single-molecule detection. The sensor was fabricated through electrostatic self-assembly of gold nanoparticles onto a gold/silica-coated silicon substrate, producing a high yield of uniformly distributed hotspots on the surface. The hotspots were isolated with a monolayer of a thermoresponsive polymer (poly(N-isopropylacrylamide)), which act as gates for molecular trapping at the hotspots. The sensor shows not only a good SERS reproducibility but also a capability to repetitively trap and release molecules for single-molecular sensing. The single-molecule sensitivity is experimentally verified using SERS spectral blinking and bianalyte methods.
authors.affiliation: School of Chemistry, The University of New South Wales, Sydney, New South Wales 2052, Australia.|Australian Centre for NanoMedicine, The University of New South Wales, Sydney, New South Wales 2052, Australia.|ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Yuanhui
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: School of Chemistry, The University of New South Wales, Sydney, New South Wales 2052, Australia.|Australian Centre for NanoMedicine, The University of New South Wales, Sydney, New South Wales 2052, Australia.|ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Soeriyadi
authors.affiliation: Centre for Micro-Photonics (H34), Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122, Australia.|Department of Information Engineering, University of Parma, V.le G.P. Usberti 181/A, I-43124 Parma, Italy.
authors.forename: Lorenzo
authors.identifier: http://orcid.org/0000-0002-9210-5680
authors.initials: L
authors.lastname: Rosa
authors.affiliation: Department of Materials Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.|The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria 3168, Australia.
authors.forename: Soon Hock
authors.initials: SH
authors.lastname: Ng
authors.affiliation: Department of Materials Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.|The Melbourne Centre for Nanofabrication, 151 Wellington Road, Clayton, Victoria 3168, Australia.
authors.forename: Udo
authors.initials: U
authors.lastname: Bach
authors.affiliation: School of Chemistry, The University of New South Wales, Sydney, New South Wales 2052, Australia.|Australian Centre for NanoMedicine, The University of New South Wales, Sydney, New South Wales 2052, Australia.|ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, New South Wales 2052, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Justin Gooding