A sensitive surface-enhanced Raman scattering (SERS) signal dependent double detection of mycotoxins is achieved for the first time, without the aid of nucleic acid amplification strategies. SERS labels embedded Ag@Au core-shell (CS) nanoparticles (NPs) as novel SERS tags are successfully prepared through a galvanic replacement-free deposition. SERS tags produce stable and quantitative SERS signal, emerging from the plasmonic coupling at the junction of Ag core and Au shell. SERS tags engineered Raman aptasensors are developed for the double detection of ochratoxin A (OTA) and aflatoxin B1 (AFB1) in maize meal. The limits of detection (LODs) are as low as 0.006 ng/mL for OTA and 0.03 ng/mL for AFB1. The developed protocol can be extended to a large set of different SERS tags for the sensitive detection of multiple targets that possess different lengths of aptamers.
Surface-enhanced Raman scattering (SERS)-active substrates assembled by two types of metallic nanoparticles (NPs) were fabricated. Aptamers driven Au nanoflower (Au NF)-Ag NP core-satellite assemblies exhibited amplified SERS signals and achieved the sensitive detection of microcystin-LR (MC-LR) in Tai lake water with the limit of detection (LOD) of 8.6 ± 0.4 pM.
Nanocatalysts depended
colorimetric assay possesses the advantage of fast detection and provides
a novel avenue for the detection of hydrogen sulfide (H2S). The exploration of nanocatalysts with superior catalytic activity
is challenging to achieve ultrasensitive colorimetric assay of H2S. Herein, 1.7 ± 0.2 nm ruthenium nanoparticles (Ru NPs)
were prepared and exhibited outstanding catalytic hydrogenation activity.
The degradation rate constants of orange I in the presence of Ru NPs
were 4-, 47- and 165-fold higher than those of platinum (Pt) NPs,
iridium (Ir) NPs and control groups without catalysts. H2S-induced deactivation of Ru NP catalysts was designed for the sensitive
colorimetric assay of H2S, attributing to the poor thiotolerance
of Ru NPs. A standard linear curve between the rate constants and
the concentration of H2S was established. The limit of
detection (LOD) was as low as 0.6 nM. A Ru NPs based colorimetric
principle was also used to fabricate colorimetric paper strips for
the on-site visual analysis of H2S. The proposed approach
shows potential prospective for the preparation of highly selective
colorimetric NP sensors for specific purposes.
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