Control over Multiple Nano‐ and Secondary Structures in Peptide Self‐Assembly

Abstract

Herein, we report the rich morphological and conformational versatility of ab iologically active peptide (PEP-1), whichf ollows diverse self-assembly pathwayst o form up to six distinct nanostructures and up to four different secondary structures through subtle modulation in pH, concentration and temperature. PEP-1 forms twisted b-sheet secondary structures and nanofibers at pH 7.4, which transform into fractal-like structures with strong b-sheet conformations at pH 13.0 or short disorganized elliptical aggregates at pH 5.5. Upon dilution at pH 7.4, the nanofibers with twisted bsheet secondary structural elements convert into nanoparticles with random coil conformations.I nterestingly,t hese two selfassembled states at pH 7.4 and room temperature are kinetically controlled and undergo af urther transformation into thermodynamically stable states upon thermal annealing: whereas the twisted b-sheet structures and corresponding nanofibers transform into 2D sheets with well-defined b-sheet domains,the nanoparticles with random coil structures convert into short nanorods with a-helix conformations.N otably, PEP-1 also showed high biocompatibility,l ow hemolytic activity and marked antibacterial activity,rendering our system apromising candidate for multiple bio-applications.