Au Film–Au@Ag Core–Shell Nanoparticle Structured Surface-Enhanced Raman Spectroscopy Aptasensor for Accurate Ochratoxin A Detection
2020
As
a powerful toxin that could cause fatal death, the detection
of ochratoxin A (OTA) has gained much attention in the fields of environmental
and food sciences. In this study, an internal standard (IS) aptasensor
was synthesized through a facile and scalable method to enhance the
sensitivity and quantativity of OTA detection. The substrates were
formed through hybridization of modified aptamers on Au@Ag core–shell
nanoparticles (NPs) and Au films at a silicon surface. Incorporated
with 4-ATP and 4-NTP as an internal standard, OTA recognition of such
aptamers could cause NP release and signal losses. Utilizing the strong
peaks at 1078 and 1335 cm–1, which represent 4-ATP
and 4-NTP, respectively, the intensity ratio of I1078/I1335 could delegate
the OTA concentration in a ratiometric manner. Therefore, the highest
ratio of I1078/I1335 represents the lowest concentration of OTA, and a lower
ratio means a higher OTA concentration. Quantitatively, the high consistency
for OTA detection was achieved through correction of signal losses
by IS references with an R2 of 0.993 and
RSD of 0.94%, and the OTA detection limit of 5 pM was achieved. Herein,
such an IS aptasensor provides a reliable and scalable detection platform
for various molecules in a continuous and high-throughput manner and
holds great promise in future quantitative SERS measurements.
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