Sensitive and Fast Detection of Fructose in Complex
Media via Symmetry Breaking and Signal Amplification Using Surface-Enhanced
Raman Spectroscopy
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Abstract
A new
strategy is proposed to sensitively and rapidly detect analytes
with weak Raman signals in complex media using surface-enhanced Raman
spectroscopy (SERS) via detecting the SERS signal changes of the immobilized
probe molecules on SERS-active substrates upon binding of the analytes.
In this work, 4-mercaptophenylboronic acid (4-MPBA) was selected as
the probe molecule which was immobilized on the gold surface of a
quasi-three-dimensional plasmonic nanostructure array (Q3D-PNA) SERS
substrate to detect fructose. The molecule of 4-MPBA possesses three
key functions: molecule recognition and reversible binding of the
analyte via the boronic acid group, amplification of SERS signals
by the phenyl group and thus shielding of the background noise of
complex media, and immobilization on the surface of SERS-active substrates
via the thiol group. Most importantly, the symmetry breaking of the
4-MPBA molecule upon fructose binding leads to the change of area
ratio between totally symmetric 8a ring mode and nontotally symmetric
8b ring mode, which enables the detection. The detection curves were
obtained in phosphate-buffered saline (PBS) and in undiluted artificial
urine at clinically relevant concentrations, and the limit of detection
of 0.05 mM was achieved