Directive Effect of Chain Length in Modulating Peptide Nano-assemblies

Cysteine Redox Chemistry in Peptide Self-Assembly to Modulate Hydrogelation

Cysteine redox chemistry is widely used in nature to direct protein assembly, and in recent years it has inspired chemists to design self-assembling peptides too. In this concise review, we describe the progress in the field focusing on the recent advancements that make use of Cys thiol-disulfide redox chemistry to modulate hydrogelation of various peptide classes.

Antibacterial hydrogels of aromatic tripeptides

Self-assembled peptide hydrogels have emerged as alternatives to the conventional approaches employed in controlled drug release, wound-healing, and drug delivery, and as anti-infective agents. However, peptide hydrogels possessing antibacterial properties are less explored. In this work, we have designed three ultrashort antibacterial peptide hydrogels: Fmoc-FFH-CONH₂, Fmoc-FHF-CONH₂, and Fmoc-HFF-CONH₂. The rheological study showed the higher storage modulus of Fmoc-FFH-CONH₂ (30.43 kPa) compared to Fmoc-FHF-CONH₂ and Fmoc-HFF-CONH₂, which may be attributed to the enhanced aromatic interaction in Fmoc-FFH-CONH₂ compared to the other two variants, resulting in more mechanical rigidity. Further, the prepared hydrogels were evaluated for their inherent antibacterial potency against Gram-positive (Staphylococcus aureus, strain MTCC 96) and Gram-negative (Pseudomonas aeruginosa, strain PA01) bacteria. Antibacterial experiments demonstrated the potency of the hydrogels in the order of Fmoc-FFH-CONH₂ > Fmoc-FHF-CONH₂ > Fmoc-HFF-CONH₂. The antibacterial effect of the hydrogels was predominantly due to the osmotic stress and membrane disruption, which was verified by reactive oxygen species (ROS) generation and outer membrane permeabilization assays. Our findings point to the scope of using the synthesized peptide hydrogels as agents for topical applications.