3 research outputs found
Aptamer-Based Surface-Enhanced Raman Scattering-Microfluidic Sensor for Sensitive and Selective Polychlorinated Biphenyls Detection
A surface-enhanced Raman scattering
(SERS) measurement of 3,3′,4,4′-tetrachlorobiphenyl
(PCB77) with aptamer capturing in a microfluidic device was demonstrated.
To construct the microfluidic chip, an ordered Ag nanocrown array
was fabricated over a patterned polydimethylsiloxane (PDMS) that was
achieved by replicating an anodic aluminum oxide (AAO) template. The
patterned PDMS sheet was covered with another PDMS sheet having two
input channel grooves to form a close chip. The Ag nanocrown array
was used for the SERS enhancement area and the detection zone. PCB
77 aptamers were injected into one channel and the other allows for
analytes (PCBs). The mercapto aptamers captured the targets in the
mixed zone and were immobilized to the SERS detection zone via S–Ag
bonds so as to further improve both the SERS sensitivity and selectivity
of PCB77. Such an aptamer-based microfluidic chip realized a rapid
SERS detection. The lowest detectable concentration of 1.0 Ă—
10<sup>–8</sup> M was achieved for PCB77. This work demonstrates
that the aptamer-modified SERS microfluidic sensor can be utilized
for selective detections of organic pollutants in the environment
DNAzyme-Based Plasmonic Nanomachine for Ultrasensitive Selective Surface-Enhanced Raman Scattering Detection of Lead Ions via a Particle-on-a-Film Hot Spot Construction
We
propose a highly sensitive and selective surface-enhanced Raman
scattering (SERS) method for determining lead ions based on a DNAzyme-linked
plasmonic nanomachine. A metallic nanoparticle-on-a-film structure
was built through a rigid double-stranded bridge linker composed of
a DNAzyme and its substrate. This DNAzyme could be activated by lead
ions and catalyze a fracture action of the substrate. Thus, the double
chain structure of DNA would turn into a flexible single strand, making
the metal nanoparticles that connected to the terminal of DNAzyme
fall to the surface of the metal film. Hereby, a narrow gap close
to 2 nm generated between metal nanoparticles and the metal film,
exhibiting a similar effect of a “hot spot” and remarkably
enhancing the signal of randomly dispersed Raman-active molecules
on the surface of metal film. By measuring the improvement of SERS
intensity of the Raman-active molecules, we realized the lowest detection
concentration of Pb<sup>2+</sup> ions to 1.0 nM. This SERS analytical
method is highly selective and can be extended universally to other
targets via the accurate programming of corresponding DNA sequences
DataSheet1_Direct preparation of solid carbon dots by pyrolysis of collagen waste and their applications in fluorescent sensing and imaging.DOCX
The fluorescent carbon dots (CDs) have found their extensive applications in sensing, bioimaging, and photoelectronic devices. In general terms, the synthesis of CDs is straight-forward, though their subsequent purification can be laborious. Therefore, there is a need for easier ways to generate solid CDs with a high conversion yield. Herein, we used collagen waste as a carbon source in producing solid CDs through a calcination procedure without additional chemical decomposition treatment of the raw material. Considering a mass of acid has destroyed the original protein macromolecules into the assembled structure with amino acids and peptide chains in the commercial extraction procedure of collagen product. The residual tissues were assembled with weak intermolecular interactions, which would easily undergo dehydration, polymerization, and carbonization during the heat treatment to produce solid CDs directly. The calcination parameters were surveyed to give the highest conversion yield at 78%, which occurred at 300°C for 2 h. N and S atomic doping CDs (N-CDs and S-CDs) were synthesized at a similar process except for immersion of the collagen waste in sulfuric acid or nitric acid in advance. Further experiments suggested the prepared CDs can serve as an excellent sensor platform for Fe3+ in an acid medium with high anti-interference. The cytotoxicity assays confirmed the biosafety and biocompatibility of the CDs, suggesting potential applications in bioimaging. This work provides a new avenue for preparing solid CDs with high conversion yield.</p