[Aba5-14] BTD-2

Hypochlorite is an important active oxygen species formed in living organisms, and rapid and highly sensitive detection of trace hypochlorite is of great significance for understanding the mechanism of diseases caused by abnormal hypochlorite concentrations at an early stage. Although aggregation-induced emission (AIE) probes are highly important for analyte de-tection in living organisms, there is a lack of AIE probes for hypochlorite detection. In this study, two AIE probes based on benzothiazole derivatives (BTD-1 and BTD-2) were designed and synthesized. Both probes exhibited good AIE charac-teristics and allowed different visual detection for hypochlorite. Additionally, the two probes could be used to detect endogenous hypochlorite in mitochondria and were successfully applied for in vivo hypochlorite imaging in zebrafish.

Enantiomeric forms of BTD-2, PG-1, and PM-1 were synthesized to delineate the structure and function of these β-sheet antimicrobial peptides. Activity and lipid-binding assays confirm that these peptides act via a receptor-independent mechanism involving membrane interaction. The racemic crystal structure of BTD-2 solved at 1.45 Å revealed a novel oligomeric form of β-sheet antimicrobial peptides within the unit cell: an antiparallel trimer, which we suggest might be related to its membrane-active form. The BTD-2 oligomer extends into a larger supramolecular state that spans the crystal lattice, featuring a steric-zipper motif that is common in structures of amyloid-forming peptides. The supramolecular structure of BTD-2 thus represents a new mode of fibril-like assembly not previously observed for antimicrobial peptides, providing structural evidence linking antimicrobial and amyloid peptides.