4 research outputs found
Ultrasensitive Surface-Enhanced Raman Scattering Sensor of Gaseous Aldehydes as Biomarkers of Lung Cancer on Dendritic Ag Nanocrystals
Surface-enhanced
Raman scattering (SERS) is expected as a technique
that even theoretically detected chemicals at the single molecule
level by surface plasmon phenomena of noble metal nanostructures.
Insensitivity of detecting Raman weak-intensity molecules and low
adsorptivity of gaseous molecules on solid substrates are two main
factors hindering the application of SERS in gas detectors. In this
manuscript, we demonstrated an operational SERS strategy to detect
gaseous Raman weak-intensity aldehydes that have been considered as
a biomarker of lung cancer for abnormal content was measured in volatile
organic compounds (VOCs) of lung cancer patients. To enhance the adsorption
of gaseous molecules, dendritic Ag nanocrystals mimicking the structural
feature (dendritic) of moth’s antennae were formed, wherein
the existence of numerous cavity traps in Ag dendritic nanocrystals
prolonged reaction time of the gaseous molecules on the surface of
solid surface through the “cavity-vortex” effect. By
the nucleophilic addition reaction with the Raman-active probe molecule <i>p</i>-aminothiophenol (4-ATP) pregrafted on dendritic Ag nanocrystals,
the gaseous aldehyde molecules were sensitively captured to detect
at the ppb (parts per billion) level. Additionally, the sensitivity
of this operational SERS strategy to detection of lung cancer biomarkers
was not affected by the humidity, which represented a great potential
in fast, easy, cost-effective, and noninvasive recognition of lung
malignancies
Understanding the Selective Detection of Fe<sup>3+</sup> Based on Graphene Quantum Dots as Fluorescent Probes: The <i>K</i><sub>sp</sub> of a Metal Hydroxide-Assisted Mechanism
Graphene quantum
dots (GQDs) have been widely used as fluorescence
probes to detect metal ions with satisfactory selectivity. However,
the diverse chemical structures of GQDs lead to selectivity for multiple
metal ions, and this can lead to trouble in the interpretation of
selectivity due to the lack of an in depth and systematic analysis.
Herein, bare GQDs were synthesized by oxidizing carbon black with
nitric acid and used as fluorescent probes to detect metal ions. We
found that the specific ability of GQDs to recognize ferric ions relates
to the acidity of the medium. Specifically, we demonstrated that the
coordination between GQDs and Fe<sup>3+</sup> is regulated by the
pH of the aqueous GQDs solution. Dissociative Fe<sup>3+</sup> can
coordinate with the hydroxyl groups on the surface of the GQDs to
form aggregates (such as iron hydroxide), which induces fluorescence
quenching. A satisfactory selectivity for Fe<sup>3+</sup> ions was
achieved under relatively acidic conditions; this is because of the
extremely small <i>K</i><sub>sp</sub> of ferric hydroxide
compared to those of other common metal hydroxides. To directly survey
the key parameter for Fe<sup>3+</sup> ion specificity, we performed
the detection experiment in an environment free of interference from
the buffer solution, noninherent groups, and other complex factors.
This study will help researchers understand the selectivity mechanisms
of GQDs as fluorescence probes for metal ions, which could guide the
design of other GQD-based sensor platforms
Economical, Green Synthesis of Fluorescent Carbon Nanoparticles and Their Use as Probes for Sensitive and Selective Detection of Mercury(II) Ions
The present article reports on a simple, economical,
and green preparative strategy toward water-soluble, fluorescent carbon
nanoparticles (CPs) with a quantum yield of approximately 6.9% by
hydrothermal process using low cost wastes of pomelo peel as a carbon
source for the first time. We further explore the use of such CPs
as probes for a fluorescent Hg<sup>2+</sup> detection application,
which is based on Hg<sup>2+</sup>-induced fluorescence quenching of
CPs. This sensing system exhibits excellent sensitivity and selectivity
toward Hg<sup>2+</sup>, and a detection limit as low as 0.23 nM is
achieved. The practical use of this system for Hg<sup>2+</sup> determination
in lake water samples is also demonstrated successfully
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