The effect of hydration and dehydration on the conformation, assembling behavior and photoluminescence of PBLG

Multiple Levels of Organization in Amphiphilic Diblock Copolymers Based on Poly(γ-benzyl-l-glutamate) Produced by Aqueous ROPISA

A recent method for producing amphiphilic block copolymers and nano-objects based on the ring-opening polymerization-induced self-assembly (ROPISA) in aqueous buffer is explored with respect to the tunability toward nanostructures. ROPISA gives rise to polypeptide copolymers with unprecedented levels of organization. By employing amphiphilic block copolymers of poly(ethylene glycol) (PEG) with the synthetic polypeptide poly(γ-benzyl-l-glutamate) (PBLG) and a combination of static (13C NMR, X-ray scattering, polarizing optical microscopy), thermodynamic (differential scanning calorimetry), and dynamic (dielectric spectroscopy) probes, we demonstrate a record of six levels of organization only found before in natural materials. These levels of organization could not be obtained in earlier morphology investigations of copolymers based on PEG and PBLG prepared by different methods. Furthermore, the type of NCA monomer (BLG-NCA vs Leu-NCA) and the solvent treatment method had an influence on the degree of segregation, the α-helical content, and the order-to-disorder transition temperature in the PEG-b-PBLG and PEG-b-PLeu copolymers.

Biomimetic Capsid-Like Nanoshells Self-Assembled from Homopolypeptides

The preparation of capsid-like nanoshells and the elucidation of their formation pathways are crucial for the application potential of capsid-like nanomaterials. In this study, we have prepared biomimetic capsid-like nanoshells (CLNs) through the solution self-assembly of poly (β-phenethyl-L-aspartate) homopolypeptide (PPLA). The formation of CLNs is governed by an aggregation-fusion mechanism. Initially, PPLA molecules self-assemble into small spherical assemblies as subunits and the initial nuclei are formed through fusing some subunits. Subsequently, additional subunits rapidly fuse onto these nuclei, leading to the growth of full or partial CLNs during the growth phase. Moreover, the suitable condition benefiting CLNs formation is clarified by a morphological phase diagram based on the initial PPLA concentration against water content. Molecular-level measurements suggest that the molecular flexibility of PPLA is a key factor in the arrangement and fusion of subunits for the formation of CLNs. These findings offer new perspectives for a deeper understanding of the formation pathways of capsid-like nanoshells derived from synthetic polymers.