Wrinkled Nanoporous Gold Films with Ultrahigh Surface-Enhanced Raman Scattering Enhancement
WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.ACS Nano (Impact Factor: 12.88). 06/2011; 5(6):4407-13. DOI: 10.1021/nn201443p
Amplified by plasomonic nanostructured metals, Raman intensity of organic molecules and biomolecules can be dramatically improved, particularly at "hot spots" where intense electromagnetic fields are produced in the vicinity of narrow nanogaps between metallic nanostructures. Therefore, developing new substrates with a high density of "hot spots" has been the recent topic of intense study. Here we report wrinkled nanoporous gold films that contain abundant Raman-active nanogaps produced by deformation and fracture of nanowire-like gold ligaments. This novel nanostructure yields ultrahigh surface enhanced Raman scattering for molecule detection.
Applied Surface Science 08/2015; DOI:10.1016/j.apsusc.2015.08.168 · 2.71 Impact Factor
- "The dependence of the enhancement effect on the detailed preparation procedure is supported by further contributions   . Zhang et al.  for example, found a 100 times higher enhancement effect on wrinkled nanoporous gold films. Also, the enhancement effect on np-Au films obtained after dealloying of Au–Ag alloys is strongly affected by residual Ag . "
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- "However, their in-plane structural features and smooth ligament surfaces resulted from chemical etching constrain the local electromagnetic field strength below the limit for SERS-based single molecule detection212223. The SERS performances of nanoporous metal films can be further improved by introducing 3D quasi-periodic wrinkles through thermal contraction of pre-strained polymer substrates (Fig. 1a)242526. Using this procedure detailed in the Method section, rich SERS-active nanostructures at the ridges of the wrinkles, such as nanogaps and nanotips, are produced by deformation and failure of metal ligaments during film shrinking. "
ABSTRACT: Detecting and identifying single molecules are the ultimate goal of analytic sensitivity. Single molecule detection by surface-enhanced Raman scattering (SM-SERS) depends predominantly on SERS-active metal substrates that are usually colloidal silver fractal clusters. However, the high chemical reactivity of silver and the low reproducibility of its complicated synthesis with fractal clusters have been serious obstacles to practical applications of SERS, particularly for probing single biomolecules in extensive physiological environments. Here we report a large-scale, free standing and chemically stable SERS substrate for both resonant and nonresonant single molecule detection. Our robust substrate is made from wrinkled nanoporous Au₇₉Ag₂₁ films that contain a high number of electromagnetic "hot spots" with a local SERS enhancement larger than 10⁹. This biocompatible gold-based SERS substrate with superior reproducibility, excellent chemical stability and facile synthesis promises to be an ideal candidate for a wide range of applications in life science and environment protection.Scientific Reports 10/2011; 1:112. DOI:10.1038/srep00112 · 5.58 Impact Factor
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ABSTRACT: Nanoporous gold films containing various amounts of residual silver have been synthesized by controllable dealloying and subsequent annealing for surface-enhanced Raman scattering (SERS). It was found that the residual Ag plays an important role in the SERS effect of dealloyed nanoporous gold. More residual Ag gives rise to better SERS effects when nanopore sizes are nearly identical. Moreover, homogenization of the residual silver by annealing can further improve the SERS enhancement of nanoporous Au–Ag alloys.The Journal of Physical Chemistry C 09/2011; DOI:10.1021/jp205892n · 4.77 Impact Factor
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