2 research outputs found
Photocatalytic Cleavage of C–C Bond in Lignin Models under Visible Light on Mesoporous Graphitic Carbon Nitride through π–π Stacking Interaction
Photocatalysis is
a potentially promising approach to harvest aromatic
compounds from lignin. However, the development of an active and selective
solid photocatalyst is still challenging for lignin transformation
under ambient conditions. We herein report a mild photocatalytic oxidative
strategy for C–C bond cleavage of lignin β-O-4 and β-1
linkages using a mesoporous graphitic carbon nitride catalyst. Identifications
by solid-state NMR techniques and density functional theory (DFT)
calculations indicate that π–π stacking interactions
are most likely present between the flexible carbon nitride surface
and lignin model molecule. Besides, low charge recombination efficiency
and high specific surface area (206.5 m<sup>2</sup> g<sup>–1</sup>) of the catalyst also contribute to its high catalytic activity.
Mechanistic investigations reveal that photogenerated holes, as the
main active species, trigger the oxidation and C–C bond cleavage
of lignin models. This study sheds light on the interaction between
complex lignin structures and the catalyst surface and provides a
new strategy of photocatalytic cleavage of lignin models with heterogeneous
photocatalysts
Self-Assembled DNA Hydrogel Based on Enzymatically Polymerized DNA for Protein Encapsulation and Enzyme/DNAzyme Hybrid Cascade Reaction
DNA hydrogel is a promising biomaterial
for biological and medical applications due to its native biocompatibility
and biodegradability. Herein, we provide a novel, versatile, and cost-effective
approach for self-assembly of DNA hydrogel using the enzymatically
polymerized DNA building blocks. The X-shaped DNA motif was elongated
by terminal deoxynucleotidyl transferase (TdT) to form the building
blocks, and hybridization between dual building blocks via their complementary
TdT-polymerized DNA tails led to gel formation. TdT polymerization
dramatically reduced the required amount of original DNA motifs, and
the hybridization-mediated cross-linking of building blocks endows
the gel with high mechanical strength. The DNA hydrogel can be applied
for encapsulation and controllable release of protein cargos (for
instance, green fluorescent protein) due to its enzymatic responsive
properties. Moreover, this versatile strategy was extended to construct
a functional DNAzyme hydrogel by integrating the peroxidase-mimicking
DNAzyme into DNA motifs. Furthermore, a hybrid cascade enzymatic reaction
system was constructed by coencapsulating glucose oxidase and β-galactosidase
into DNAzyme hydrogel. This efficient cascade reaction provides not
only a potential method for glucose/lactose detection by naked eye
but also a promising modular platform for constructing a multiple
enzyme or enzyme/DNAzyme hybrid system