3 research outputs found
Histidineâdialkoxyanthracene dyad for selective and sensitive detection of mercury ions
<p>Histidine-dialkoxyanthracene (HDA) was synthesised as a turn off type fluorescent sensor for fast and sensitive detection of mercury ions (Hg<sup>2+</sup>) in aqueous media. The two histidine moieties act as âclawsâ to selectively complex Hg<sup>2+</sup>. The binding ratio of HDA to Hg<sup>2+</sup> was 1:1 (metal-to-ligand ratio). The association constant for Hg<sup>2+</sup> towards the receptor HDA obtained from BenesiâHildebrand plot was found to be 3.22Â ĂÂ 10<sup>4</sup>Â M<sup>â1</sup> with detection limit as low as 4.7Â nM (0.94Â ÎŒg/L).</p
Tunable and Linker Free Nanogaps in CoreâShell Plasmonic Nanorods for Selective and Quantitative Detection of Circulating Tumor Cells by SERS
Controlling
the size, number, and shape of nanogaps in plasmonic nanostructures
is of significant importance for the development of novel quantum
plasmonic devices and quantitative sensing techniques such as surface-enhanced
Raman scattering (SERS). Here, we introduce a new synthetic method
based on coordination interactions and galvanic replacement to prepare
coreâshell plasmonic nanorods with tunable enclosed nanogaps.
Decorating Au nanorods with Raman reporters that strongly coordinate
Ag<sup>+</sup> ions (e.g., 4-mercaptopyridine) afforded uniform nucleation
sites to form a sacrificial Ag shell. Galvanic replacement of the
Ag shell by HAuCl<sub>4</sub> resulted in AuâAgAu coreâshell
structure with a uniform intra-nanoparticle gap. The size (length
and width) and morphology of the coreâshell plasmonic nanorods
as well as the nanogap size depend on the concentration of the coordination
complexes formed between Ag<sup>+</sup> ions and 4-mercaptopyridine.
Moreover, encapsulating Raman reporters within the nanogaps afforded
an internal standard for sensitive and quantitative SERS analysis.
To test the applicability, coreâshell plasmonic nanorods were
functionalized with aptamers specific to circulating tumor cells such
as MCF-7 (Michigan Cancer Foundation-7, breast cancer cell line).
This system could selectively detect as low as 20 MCF-7 cells in a
blood mimicking fluid employing SERS. The linking DNA duplex on coreâshell
plasmonic nanorods can also intercalate hydrophobic drug molecules
such as Doxorubicin, thereby increasing the versatility of this sensing
platform to include drug delivery. Our synthetic method offers the
possibility of developing multifunctional SERS-active materials with
a wide range of applications including biosensing, imaging, and therapy
Impact of PoreâWalls Ligand Assembly on the Biodegradation of Mesoporous Organosilica Nanoparticles for Controlled Drug Delivery
Porous materials with molecular-scale
ordering have attracted major
attention mainly because of the possibility to engineer their pores
for selective applications. Periodic mesoporous organosilica is a
class of hybrid materials where self-assembly of the organic linkers
provides a crystal-like pore wall. However, unlike metal coordination,
specific geometries cannot be predicted because of the competitive
and dynamic nature of noncovalent interactions. Herein, we study the
influence of competing noncovalent interactions in the pore walls
on the biodegradation of organosilica frameworks for drug delivery
application. These results support the importance of studying self-assembly
patterns in hybrid frameworks to better engineer the next generation
of dynamic or âsoftâ porous materials