2 research outputs found
Fabrication of SERS Swab for Direct Detection of Trace Explosives in Fingerprints
Swab sampling is of great importance
in surface contamination analysis. A cotton swab (cotton Q-tip) was
successfully transformed into surface-enhanced Raman scattering (SERS)
substrate (SERS Q-tip) through a bottom-up strategy, where Ag NPs
were first self-assembled onto the Q-tip followed by in situ growing.
The capability for direct swab detection of Raman probe Nile Blue
A (NBA) and a primary explosive marker 2,4-dinitrotoluene (2,4-DNT)
using the SERS Q-tip was explored. It was found that at optimum conditions,
a femotogram of NBA on glass surface could be swab-detected. The lowest
detectable amount for 2,4-DNT is only ∼1.2 ng/cm<sup>2</sup> (total amount of 5 ng) on glass surface, 2 orders of magnitude more
sensitive than similar surface analysis achieved with infrared technique,
and comparable even with that obtained by ion mobility spectrometry–mass
spectrometry. Finally, 2,4-DNT left on fingerprints was also analyzed.
It was found that SERS signal of 2,4-DNT from 27th fingerprint after
touching 2,4-DNT powder can still be clearly identified by swabbing
with the SERS Q-tip. We believe this is the first direct SERS swabbing
test of explosives on fingerprint on glass. Considering its relative
long shelf life (>30 d), the SERS Q-tip may find great potential
in future homeland security applications when combined with portable
Raman spectrometers
Novel Xylanase from a Holstein Cattle Rumen Metagenomic Library and Its Application in Xylooligosaccharide and Ferulic Acid Production from Wheat Straw
A novel gene fragment containing a xylanase was identified
from
a Holstein cattle rumen metagenomic library. The novel xylanase (Xyln-SH1)
belonged to the glycoside hydrolase family 10 (GH10) and exhibited
a maximum of 44% identity to the glycoside hydrolase from Clostridium thermocellum ATCC 27405. Xyln-SH1 was
heterologously expressed, purified, and characterized. A high level
of activity was obtained under the optimum conditions of pH 6.5 and
40 °C. A substrate utilization study indicated that Xyln-SH1
was cellulase-free and strictly specific to xylan from softwood. The
synergistic effects of Xyln-SH1 and feruloyl esterase (FAE-SH1) were
observed for the release of xylooligosaccharides (XOS) and ferulic
acid (FA) from wheat straw. In addition, a high dose of Xyln-SH1 alone
was observed to improve the release of FA from wheat straw. These
features suggest that this enzyme has substantial potential to improve
biomass degradation and industrial applications