Spatiotemporal Resolved Live Cell Membrane Tracking through Photo-click Reactions Enriched in Lipid Phase

Light-intersecting Photoclick Reactions for Bioorthogonal Labeling on Single Cells: Dibenzo[b,f][1,4,5]thiadiazepine-11,11-dioxide as a Photoswitchable Reporter

The advancement of ring-strain preloaded dipolaro-/dienophiles plays a crucial role in bioorthogonal chemistry, enabling multiple high-precision conjugations toward biomolecules simultaneously. However, durability of these ring-strain preloaded reagents in vivo is a concern, as the ring-strain is not reloadable once released during delivery process. In situ conversion of light-energy into ring-strain is a promising approach to ensure both biostability and spatiotemporal control endowed by light. Herein, we advance a seven-membered cyclic azobenzene photoswitch, dibenzo[b,f][1,4,5]thiadiazepine-11,11-dioxide (DBTDD), bridged by a sulphone moiety. The photoisomerization from Z-DBTDD to ring-strain-loaded E-DBTDD enables an accelerated cycloaddition with various photogenerated dipoles to establish novel photoclick reactions, featuring a dual-λ (405 nm+445 nm) synergistic control. In reactions with monoarylsydnones, a higher photo-stationary ratio of E-DBTDD, achieved by varying the power density of 445 nm laser, presented an ultrafast cycloaddition rate (kE=6.6×107 M-1 s-1) with a 13.8-fold acceleration compared with Z-DBTDD, which is superior to established ring-strain reporters (e.g., BCN-OH, sTCO-OH, DBTD). Then, bioorthogonal photoclick labeling of DBTDD tagged artificial phospholipid on living cell membranes was realized at subcellular resolution via an essential dual-λ intersecting lithography with an elevated efficiency by adjusting the 445 nm power density.

Photo-activatable Reagents for Bioorthogonal Ligation Reactions

Light-induced bioorthogonal reactions offer spatiotemporal control over selective biomolecular labeling. This review covers the recent advances in the design of photo-activatable reagents for bioorthogonal conjugation reactions in living systems. These reagents are stable in the absence of light, but transformed into reactive species upon light illumination, which then undergo rapid ligation reactions. The light wavelength has been tuned from ultraviolet to near infrared to enable efficient photo-activation in reactions in deep tissues. The most prominent photo-activatable reagents are presented, including tetrazoles, tetrazines, 9,10-phenanthrenequinone, diarylsydnones, and others. A particular focus is on the strategies for improving reaction kinetics and biocompatibility accomplished through careful molecular engineering. The utilities of these photo-activatable reagents are illustrated through a broad range of biological applications, including in vivo protein labeling, positron emission tomography (PET) imaging, responsive hydrogels, and fluorescence microscopy. The further development and optimization of these biocompatible photo-activatable reagents should lead to new chemical biology strategies for studying biomolecular structure and function in living systems.

A facile and light-controllable drug combination for enhanced photopharmacology

We investigated the feasibility of creating cyclic azobenzene/azobenzene-based photo-switchable drugs that can fine-tune antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with light dependence. Furthermore, a "light-controlled drug combination" of these obtained drugs could be reversibly controlled to efficiently improve the antibiotic effect so as to reduce the minimum inhibitory concentrations (MICs) with different wavelength light illumination. Importantly, their antimicrobial activity could be easily manipulated by using light in bacterial patterning studies with high spatiotemporal precision, which might allow for localized activation of drugs and provide an alternative solution for practical clinical application in photopharmacology.