2 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