Fabrication of a Au Nanoporous Film by Self-Organization of Networked Ultrathin Nanowires and Its Application as a Surface-Enhanced Raman Scattering Substrate for Single-Molecule Detection

State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Analytical Chemistry (Impact Factor: 5.64). 12/2011; 83(23):9131-7. DOI: 10.1021/ac2022647
Source: PubMed


Due to its demonstrated usefulness in fields such as trace analysis, biodiagnosis, and in vivo study, surface-enhanced Raman scattering (SERS) has received renewed interest in recent years. Development of SERS substrates is of great importance as the SERS intensity and reproducibility depend strongly on the SERS substrates. In this paper we report the fabrication of Au nanoporous film (NPFs) by self-organization of networked ultrathin Au nanowires for use as SERS substrates. The acquired Au NPFs display controllable thickness, low relative density, and considerable specific surface area. Furthermore, this self-organization of nanowires not only provides abundant junctions between nanowires, 5-20 nm nanopores, and three-dimensional nanowells, but also makes nanopores/nanogaps down to 1-2 nm. These nanoscale characteristics result in a high spatial density of hotspots with Raman enhancement factors up to 10(9). Combined with the uniformity and high purity, our Au NPF provides high-quality substrates for SERS sensing.

Download full-text


Available from: Mengtao Sun, Jul 03, 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: In pH 5.5 2-(N-morpholino)-ethanosulfonic acid buffer solution containing 0.25 M NaCl at 80 °C, the single-stranded substrate DNA hybridizes with the enzyme DNA to form double-stranded DNA (dsDNA). The substrate chain of dsDNA could be cracked catalytically by UO22+ to produce a short single-stranded DNA (ssDNA) that adsorbed on the nanogold (NG) surface to form a stable nanogold–ssDNA conjugate and then further combine with rhodamine 6G (RhG) to form a NG–ssDNA–RhG conjugate that can be monitored by the surface-enhanced resonance Raman scattering (SERRS) spectral technique at 1,360 cm−1. Under the selected conditions, the increased SERRS intensity ΔI 1360 was linear to UO22+ concentration in the range of 5–125 nmol/L, with a detection limit of 1.6 nmol/L. Using a 0.5-μmol/L Hg2+ as enhancer, a 2.5–100-nmol/L UO22+ can be determined.
    No preview · Article · Jun 2012 · Plasmonics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a facile production approach to highly efficient SERS test strips by physical vapor deposition of silver on paper, which contains natural wrinkle and fibril structures. The SERS test strips open the door to highly sensitive (e.g., 10(-10) M) SERS detection in a convenient fashion.
    Full-text · Article · May 2012 · Chemical Communications
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Highly branched Au flowers (AuFs) with sharp tips have been synthesized in high yield by controlling the kinetics of nanocrystal growth via galvanic replacement reaction. Controlled galvanic replacement takes place on appropriately chosen commercially available polystyrene bead supported Cu nanoparticles with HAuCl4. Such a reaction is thermodynamically driven through the exploitation of a Cu(II)/Cu(0) redox couple during nanocrystal formation. The hierarchical morphology of the resulting naked Au flowers (AuFs) depends on the galvanic exchange rate, which increases with increasing HAuCl4 concentration but over a specific concentration range. The formation of AuF is carefully studied, and a spontaneous assembly mechanism is proposed The time course experimental results show that the influence of electrostatic field force (EFF) of the charged resin beads is held responsible for prickly tipped AuF formation. Then the fabrication of AuF morphology becomes a large-scale free-standing synthetic protocol for a chemically stable substrate for surface-enhanced Raman scattering (SERS) studies down to the single molecular level. The SERS results guarantee that the as-prepared naked AuF is an excellent and stable SERS substrate. The prickly tips of the gold bearing enhanced field with a large number of embedded "hot spots" hidden within the oriented petals and absence of surfactant or capping agent invites a probe molecule to show the enhancement even for a concentration of 4-mercaptopyridine (4-MPy) down to 10(-12) mol dm(-3). The electric field distribution around the hot spot has been estimated from 3D-FDTD simulation studies. The selective enhancements of SER bands of the 4-MPy molecule have been unveiled from the view of Herzberg-Teller (HT) charge transfer (CT) mechanism.
    Full-text · Article · Nov 2012 · The Journal of Physical Chemistry C
Show more