Visible-light-driven organic transformations are of great interest in synthesizing valuable fine chemicals under mild conditions. The merger of heterogeneous photocatalysts and transition metal catalysts has recently drawn much attention due...
Precise
identification of protein–protein interactions is required
to improve our understanding of biochemical pathways for biology and
medicine. In physiology, how proteins interact with other proteins
or small molecules is crucial for maintaining biological functions.
For instance, multivalent protein binding (MPB), in which a ligand
concurrently interacts with two or more receptors, plays a key role
in regulating complex but accurate biological functions, and its interference
is related to many diseases. Therefore, determining MPB and its kinetics
has long been sought, which currently requires complicated procedures
and instruments to distinguish multivalent binding from monovalent
binding. Here, we show a method for quickly evaluating the MPB over
monovalent binding and its kinetic parameters in a label-free manner.
Engaging pNIPAm-co-AAc nanogels with MPB-capable
moieties (e.g., PD-1 antigen and biocytin) permits a surface plasmon
resonance (SPR) instrument to evaluate the MPB events by amplifying
signals from the specific target molecules. Using our MPB-based method,
PD-1 antibody that forms a type of MPB by complexing with two PD-1
proteins, which are currently used for cancer immunotherapy, is detectable
down to a level of 10 nM. In addition, small multivalent cations (e.g.,
Ca2+, Fe2+, and Fe3+) are distinguishably
measurable over monovalent cations (e.g., Na+ and K+) with the pNIPAm-co-AAc nanogels.
Ceria (CeO 2 )-supported metal catalysts have been widely utilized for various single-step chemical transformations. However, using such catalysts for a multistep organic reaction in one reaction system has rarely been achieved. Here, we investigate multiple active sites on PdÀ CeO 2 catalysts and optimize them for a multistep reaction of CÀ C cross-coupling and alcohol oxidation. Atomic-level imaging and spectroscopic studies reveal that metallic Pd 0 and PdÀ CeO 2 interface are active sites on PdÀ CeO 2 for CÀ C cross-coupling and oxidation, respectively. These active sites are controlled under the structural evolution of PdÀ CeO 2 during reductive heat-treatments. Accordingly, we found that optimally reduced PdÀ CeO 2 catalysts containing ~1.5 nm-sized Pd nanoclusters with both sites in balance are ideal for multistep chemical transformations in one reaction system. Our strategy to design supported metal catalysts leads to one-pot sequential synthetic protocols for pharmaceutical building blocks.
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