Fabrication of Gold Nanoparticle-Embedded Metal–Organic Framework for Highly
Sensitive Surface-Enhanced Raman Scattering Detection
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Abstract
Surface-enhanced Raman scattering
(SERS) signals strongly rely
on the interactions and distance between analyte molecules and metallic
nanostructures. In this work, the use of a gold nanoparticle (AuNP)-embedded metal–organic
framework was introduced for the highly sensitive SERS detection.
The AuNPs were in situ grown and encapsulated within the host matrix
of MIL-101 by a solution impregnation strategy. The as-synthesized
AuNPs/MIL-101 nanocomposites combined the localized surface plasmon
resonance properties of the gold nanoparticles and the high adsorption
capability of metal–organic framework, making them highly sensitive
SERS substrates by effectively preconcentrating analytes in close
proximity to the electromagnetic fields at the SERS-active metal surface.
We discussed the fabrication, physical characterization, and SERS
activity of our novel substrates by measuring the Raman signals of
a variety of model analytes. The SERS substrate was found to be highly
sensitive, robust, and amiable to several different target analytes.
A SERS detection limit of 41.75 and 0.54 fmol for Rhodamine 6G and
benzadine, respectively, was demonstrated. The substrate also showed
high stability and reproducibility, as well as molecular sieving effect
thanks to the protective shell of the metal–organic framework.
Subsequently, the potential practical application of the novel SERS
substrate was evaluated by quantitative analysis of organic pollutant <i>p</i>-phenylenediamine in environmental water and tumor marker
alpha-fetoprotein in human serum. The method showed good linearity
between 1.0 and 100.0 ng/mL for <i>p</i>-phenylenediamine
and 1.0–130.0 ng/mL for alpha-fetoprotein with the correlation
coefficients of 0.9950 and −0.9938, respectively. The recoveries
ranged from 80.5% to 114.7% for <i>p</i>-phenylenediamine
in environmental water and 79.3% to 107.3% for alpha-fetoprotein in
human serum. These results foresee promising application of the novel
metal–organic framework based composites as sensitive SERS-active
substrates in both environmental and clinical samples