2 research outputs found
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Rapid Enrichment and Sensitive Detection of Multiple Metal Ions Enabled by Macroporous Graphene Foam
Nanomaterials
have shown great promise in advancing biomedical
and environmental analysis because of the unique properties originated
from their ultrafine dimensions. In general, nanomaterials are separately
applied to either enhance detection by producing strong signals upon
target recognition or to specifically extract analytes taking advantage
of their high specific surface area. Herein, we report a dual-functional
nanomaterial-based platform that can simultaneously enrich and enable
sensitive detection of multiple metal ions. The macroporous graphene
foam (GF) we prepared displays abundant phosphate groups on the surface
and can extract divalent metal ions via metal-phosphate coordination.
The enriched metal ions then activate the metal-responsive DNAzymes
and produce the fluorescently labeled single-stranded DNAs that are
adsorbed and quenched by the GF. The resultant fluorescence reduction
can be used for metal quantitation. The present work demonstrated
duplexed detection of Pb<sup>2+</sup> and Cu<sup>2+</sup> using the
Pb- and Cu-responsive DNAzymes, achieving a low detection limit of
50 pM and 0.6 nM, respectively. Successful quantification of Pb<sup>2+</sup> and Cu<sup>2+</sup> in human serum and river water were
achieved with high metal recovery. Since the phosphate-decorated GF
can enrich diverse types of divalent metal cations, this dual-functional
GF-DNAzyme platform can serve as a simple and cost-effective tool
for rapid and accurate metal quantification in determination of human
metal exposure and inspection of environmental contamination
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Enhancement of the Intrinsic Peroxidase-Like Activity of Graphitic Carbon Nitride Nanosheets by ssDNAs and Its Application for Detection of Exosomes
The
present work investigates the capability of single-stranded
DNA (ssDNA) in enhancing the intrinsic peroxidase-like activity of
the g-C<sub>3</sub>N<sub>4</sub> nanosheets (NSs). We found that ssDNA
adsorbed on g-C<sub>3</sub>N<sub>4</sub> NSs could improve the catalytic
activity of the nanosheets. The maximum reaction rate of the H<sub>2</sub>O<sub>2</sub>-mediated TMB oxidation catalyzed by the ssDNA-NSs
hybrid was at least 4 times faster than that obtained with unmodified
NSs. The activity enhancement could be attributed to the strong interaction
between TMB and ssDNA mediated by electrostatic attraction and aromatic
stacking and by both the length and base composition of the ssDNA.
The high catalytic activity of the ssDNA-NSs hybrid permitted sensitive
colorimetric detection of exosomes if the aptamer against CD63, a
surface marker of exosome, was employed in hybrid construction. The
sensor recognized the differential expression of CD63 between the
exosomes produced by a breast cancer cell line (MCF-7) and a control
cell line (MCF-10A). Moreover, a similar trend was detected in the
circulating exosomes isolated from the sera samples collected from
breast cancer patients and healthy controls. Our work sheds lights
on the possibility of using ssDNA to enhance the peroxidase-like activity
of nanomaterials and demonstrates the high potential of the ssDNA-NSs
hybrid in clinical diagnosis using liquid biopsy