Cover Picture: Expanding the Toolbox of Target Directed Bio-Orthogonal Synthesis: In Situ Direct Macrocyclization by DNA Templates (Angew. Chem. Int. Ed. 7/2023)

Herein, we demonstrate for the first time that noncanonical DNA can direct macrocyclization-like challenging reactions to synthesize gene modulators. The planar G-quartets present in DNA G-quadruplexes (G4s) provide a size complementary reaction platform for the bio-orthogonal macrocyclization of bifunctional azide and alkyne fragments over oligo- and polymerization. G4s immobilized on gold-coated magnetic nanoparticles have been used as target templates to enable easy identification of a selective peptidomimetic macrocycle. Structurally similar macrocycles have been synthesized to understand their functional role in the modulation of gene function. The innate fluorescence of the in situ formed macrocycle has been utilized to monitor its cellular localization using a G4 antibody and its in cell formation from the corresponding azide and alkyne fragments. The successful execution of in situ macrocyclization in vitro and in cells would open up a new dimension for target-directed therapeutic applications.     

Programming Super DNA-Enzyme Molecules for On-Demand Enzyme Activity Modulation**

Dynamic interactions of enzymes, including programmable configuration and cycling of enzymes, play important roles in the regulation of cellular metabolism. Here, we constructed a super DNA-enzymes molecule (SDEM) that comprises at least two cascade enzymes and multiple linked DNA strands to control and detect metabolism. We found that the programmable SDEM, which comprises glucose oxidase (GOx) and horseradish peroxidase (HRP), has a 20-fold lower detection limit and a 1.6-fold higher reaction rate than free enzymes. An SDEM can be assembled and disassembled using a hairpin structure and a displacement DNA strand to complete multiple cycles. An entropically driven catalytic assembly (catassembly) enables different SDEMs to switch from an SDEM with GOx and HRP cascades to an SDEM with sarcosine oxidase (SOX) and HRP cascades in over six orders of magnitude less time than without the catassembly to detect different metabolisms (GO and sarcosine) on demand.     

Unveiling One-to-One Correspondence Between Excited Triplet States and Determinate Interactions by Temperature-Controllable Blue-Green-Yellow Afterglow

Phosphorescence of organic materials is highly dependent on intermolecular interactions, for the sensitive triplet excitons toward environment and aggregated structures. However, until now, relationship between phosphorescence and intermolecular interactions is still unclear for complicated influence factors and uncontrollable aggregated behaviors. Herein, taking temperature as the controlled variable, the afterglow can continuously change from blue to green, then to yellow, even achieve the white emission with deuteration process. It is mainly due to the hierarchical architectures of molecular aggregates with rational distribution of intermolecular interactions, as well as gradually unlocking process of interactions with different energies. Accordingly, the one-to-one correspondence between the determinate interactions and excited triplet states have been established, guiding accurate design of desirable phosphorescence materials by hierarchical control of aggregated structures.