Separated Coil and Chain Aggregation Behaviors on the Miscibility and Helical Peptide Secondary Structure of Poly(tyrosine) with Poly(4-vinylpyridine)

Abstract

In this study, we synthesized a low-molecular-weight polytyrosine (PTyr) through living ring-opening polymerization of the α-amino acid-N-carboxyanhydride and then blended it with poly(4-vinylpyridine) (P4VP) homopolymer in N,N-dimethylformamide (DMF) and MeOH solutions, thereby controlling the miscibility behavior and secondary structures of the PTyr. Infrared spectroscopy revealed that the PTyr/P4VP mixture featured strong hydrogen bonds between the OH groups of PTyr and the pyridyl groups of P4VP. Differential scanning calorimetry revealed that the glass transition temperatures of the PTyr/P4VP complexes formed from MeOH solutions were higher than those of the corresponding PTyr/P4VP miscible blends obtained from DMF solutions. The behavior of the PTyr/P4VP blends obtained after evaporation of the DMF solutions was consistent with separated random coils of the PTyr chains. The increased degree of hydrogen bonding within the PTyr/P4VP complexes formed from MeOH solutions resulted in interpolymer complex aggregates; the corresponding enhanced intermolecular hydrogen bonding of PTyr with P4VP resulted in β-sheet conformations for PTyr, as evidenced from Fourier transform infrared spectroscopy, solid state nuclear magnetic resonance spectroscopy, and wide-angle X-ray diffraction analyses. This model, which takes advantage of the well-defined secondary structures (α-helices, β-sheets) of PTyr, can, therefore, be used to identity the behavior of separated coils and aggregated chains in polymer blend and complex systems.

Combined atom-transfer radical polymerization and ring-opening polymerization to design polymer-polypeptide copolymer conjugates toward self-aggregated hybrid micro/nanospheres for dye encapsulation

“…As the Ptyr segment length is comparatively higher in the cases of PMMA‐ b ‐Ptyr‐II and PMMA‐ b ‐Ptyr‐III conjugates, they assembled to a greater extent probably through hydrogen bonds between the OH groups of Ptyr block and the carbonyl groups of PMMA block that led to flake‐like morphology. Similar types of interaction were also highlighted in the case of blend of Ptyr and poly(4‐vinylpyridine), leading to the β‐sheet type of secondary structures reported by Lu et al Furthermore, at the optimum pH of ∼12.5, PMMA‐ b ‐Ptyr‐II and PMMA‐ b ‐Ptyr‐III conjugates were soluble in water owing to the presence of tyrosinate ion in the Ptyr moiety, but remain strongly aggregated and exhibit indistinguishable aggregated morphology (Supporting Information Figs. S9A and S9B).…”

“…However, we were unable to calculate M n s of PMMA‐ b ‐Ptyr‐II and PMMA‐ b ‐Ptyr‐III, where the Ptyr block lengths are comparatively higher than that in PMMA‐ b ‐Ptyr‐I. This difficulty may arise owing to the increase of interaction among Ptyr block of PMMA‐ b ‐Ptyr conjugate . Therefore, instead of M n , GPC, we provided their molecular weights as the measurement from 1 H‐NMR analysis (Table ).…”

“…Thus, several different techniques have been employed to synthesize polypeptide/peptide–polymer conjugates of various polymers and peptides and investigated their self‐aggregation behavior in different solvents . Nagai et al used di‐ tert ‐butyltricarbonate to prepare NCAs and synthesized poly(α‐amino acid)s. Lu et al synthesized polytyrosine by ROP using propargyl amine as initiator and blended the polypeptide with poly(4‐vinylpyridine) in dimethylformamide (DMF) and MeOH solutions. Klok et al synthesized (styrene) 10 ‐ b ‐poly(γ‐benzyl‐ l ‐glutamate) conjugates via ROP of γ‐benzyl‐ l ‐glutamate NCA using primary amine‐terminated oligo(styrene) as the initiator and studied the self‐assembly of diblock copolymers.…”

Synthesis and evaluation of interaction parameters of synthetic elastin‐derived polypentapeptide with poly(vinylpyrrolidone) in solution and solid phase

“…Thus the better miscibility between poly(GVGVP) and PVP is observed when the polypeptide content is greater than 60% in the blends. While there is a nonlinear and small deviation in slopes of Huggins's plots when the poly(GVGVP) content is less than 60%, specifies the existence of the immiscibility gap and this may be because of repulsive interactions between the poly(GVGVP) and PVP …”

“…Recently, few groups have explored the miscibility among the synthetic polypeptide–poly(γ‐benzyl l ‐glutamate) with synthetic polymers such as poly(ethylene glycol), poly(butyl acrylate‐ co ‐methylmethacrylate), poly(vinyl alcohol) (PVA), phenolic resin, and polystyrene (PS) . Similarly, Lu et al . have examined the miscibility behaviors of polytyrosine (PTyr)/poly(4‐vinylpyridine) (P4VP).…”