3 research outputs found
Core–Shell Gold Nanoparticles@Pd-Loaded Covalent Organic Framework for In Situ Surface-Enhanced Raman Spectroscopy Monitoring of Catalytic Reactions
A core–shell
nanostructure of gold nanoparticles@covalent
organic framework (COF) loaded with palladium nanoparticles (AuNPs@COF-PdNPs)
was designed for the rapid monitoring of catalytic reactions with
surface-enhanced Raman spectroscopy (SERS). The nanostructure was
prepared by coating the COF layer on AuNPs and then in situ synthesizing
PdNPs within the COF shell. With the respective SERS activity and
catalytic performance of the AuNP core and COF-PdNPs shell, the nanostructure
can be directly used in the SERS study of the catalytic reaction processes.
It was shown that the confinement effect of COF resulted in the high
dispersity of PdNPs and outstanding catalytic activity of AuNPs@COF-PdNPs,
thus improving the reaction rate constant of the AuNPs@COF-PdNPs-catalyzed
hydrogenation reduction by 10 times higher than that obtained with
Au/Pd NPs. In addition, the COF layer can serve as a protective shell
to make AuNPs@COF-PdNPs possess excellent reusability. Moreover, the
loading of PdNPs within the COF layer was found to be in favor of
avoiding intermediate products to achieve a high total conversion
rate. AuNPs@COF-PdNPs also showed great catalytic activities toward
the Suzuki–Miyaura coupling reaction. Taken together, the proposed
core–shell nanostructure has great potential in monitoring
and exploring catalytic processes and interfacial reactions
AuNPs-COFs Core–Shell Reversible SERS Nanosensor for Monitoring Intracellular Redox Dynamics
The
redox homeostasis in living cells is greatly crucial for maintaining
the redox biological function, whereas accurate and dynamic detection
of intracellular redox states still remains challenging. Herein, a
reversible surface-enhanced Raman scattering (SERS) nanosensor based
on covalent organic frameworks (COFs) was prepared to dynamically
monitor the redox processes in living cells. The nanosensor was fabricated
by modifying the redox-responsive Raman reporter molecule, 2-Mercaptobenzoquione
(2-MBQ), on the surface of gold nanoparticles (AuNPs), followed by
the in situ coating of COFs shell. 2-MBQ molecules can repeatedly
and quickly undergo reduction and oxidation when successively treated
with ascorbic acid (AA) and hypochlorite (ClO–)
(as models of reductive and oxidative species, respectively), which
resulted in the reciprocating changes of SERS spectra at 900 cm–1. The construction of the COFs shell provided the
nanosensor with great stability and anti-interference capability,
thus reliably visualizing the dynamics of intracellular redox species
like AA and ClO– by SERS nanosensor. Taken together,
the proposed SERS strategy opens up the prospects to investigate the
signal transduction pathways and pathological processes related with
redox dynamics
Dual-Modal Apoptosis Assay Enabling Dynamic Visualization of ATP and Reactive Oxygen Species in Living Cells
ATP and reactive oxygen species (ROS) are considered
significant
indicators of cell apoptosis. However, visualizing the interplay between
apoptosis-related ATP and ROS is challenging. Herein, we developed
a metal–organic framework (MOF)-based nanoprobe for an apoptosis
assay using duplex imaging of cellular ATP and ROS. The nanoprobe
was fabricated through controlled encapsulation of gold nanorods with
a thin zirconium-based MOF layer, followed by modification of the
ROS-responsive molecules 2-mercaptohydroquinone and 6-carboxyfluorescein-labeled
ATP aptamer. The nanoprobe enables ATP and ROS visualization via fluorescence
and surface-enhanced Raman spectroscopy, respectively, avoiding the
mutual interference that often occurs in single-mode methods. Moreover,
the dual-modal assay effectively showed dynamic imaging of ATP and
ROS in cancer cells treated with various drugs, revealing their apoptosis-related
pathways and interactions that differ from those under normal conditions.
This study provides a method for studying the relationship between
energy metabolism and redox homeostasis in cell apoptosis processes