Fusion and fission of molecular assemblies of amphiphilic polypeptides generating small vesicles from nanotubes

Abstract

Three amphiphilic block polypeptides, (sarcosine) -b-(l- or d-Leu-Aib) (L16, D16, D14), having different helical chain lengths or helicity are synthesized. A mixture of L16, D16, and D14 generates vesicles of diameters more than ca. 130 nm by injecting the ethanol solution into water and heating at 90°C for 1 h. On the other hand, when nanotubes composed of L16 and D14 having ca. 50 nm diameter are mixed with nanosheets composed of D16, smaller and homogeneous vesicles of ca. 60 nm diameter are obtained with the heat treatment. The time lapse TEM image analysis of the mixtures revealed some transient structures of nanotubes sticking a nanosheet or a vesicle at the open end of nanotubes. The precise size control of vesicles is therefore attainable by using nanotubes as a structural template regulating the size of vesicles near to the nanotube diameter upon the membrane fission processes.

Modulation of immunogenicity of poly(sarcosine) displayed on various nanoparticle surfaces due to different physical properties

“…We prepared six kinds of amphiphilic block polypeptides (Figure ). We synthesized helical polypeptides of Boc‐( l ‐Leu‐Aib) 6 ‐OMe, Boc‐( d ‐Leu‐Aib) 6 ‐OMe, Boc‐( d ‐Val‐Aib) 6 ‐OMe, Boc‐( d ‐Leu‐Aib) 7 ‐OMe, Boc‐( l ‐Leu‐Aib) 8 ‐OMe, and Boc‐( d ‐Leu‐Aib) 8 ‐OMe, followed by polymerization of sarcosine‐NCA from the N terminal to yield six kinds of amphiphilic block polypeptides of LL (poly(sarcosine) 21 ‐ b ‐( l ‐Leu‐Aib) 6 ), DL (poly(sarcosine) 27 ‐ b ‐( d ‐Leu‐Aib) 6 ), DV (poly(sarcosine) 25 ‐ b ‐( d ‐Val‐Aib) 6 ), D14 (poly(sarcosine) 21 ‐ b ‐( d ‐Leu‐Aib) 7 ), L16 (poly(sarcosine) 21 ‐ b ‐( l ‐Leu‐Aib) 8 ), and D16 (poly(sarcosine) 26 ‐ b ‐( d ‐Leu‐Aib) 8 ) as reported previously …”

“…The amphiphilic block polypeptide solutions was injected into a saline (1 mL) with stirring at 4 °C for 1 h to become to concentration of 1 mg/mL. All self‐assemblies were prepared by heated at 90 °C for 48 h. Only group 4 vesicles ( G4 ) were prepared by a two‐step method . In detail, the dispersion of a mixture of L16 and D14 (1:1, w /w) prepared by the described method previously with heating at 90 °C for 72 h to obtain nanotube structure.…”

“…We synthesized helical polypeptides of Boc-(L-Leu-Aib) 6 -OMe, Boc-(D-Leu-Aib) 6 -OMe, Boc-(D-Val-Aib) 6 -OMe, Boc-(D-Leu-Aib) 7 -OMe, Boc-(L-Leu-Aib) 8 -OMe, and Boc-(D-Leu-Aib) 8 -OMe, followed by polymerization of sarcosine-NCA from the N terminal to yield six kinds of amphiphilic block polypeptides of LL (poly(sarcosine) 21 -b-(L-Leu-Aib) 6 ), DL (poly(sarcosine) 27 -b-(D-Leu-Aib) 6 ), DV (poly(sarcosine) 25 8 ), and D16 (poly(sarcosine) 26 -b-(D-Leu-Aib) 8 ) as reported previously. [41][42][43]…”

“…All self-assemblies were prepared by heated at 90°C for 48 h. Only group 4 vesicles (G4) were prepared by a two-step method. [42] In detail, the dispersion of a mixture of L16 and D14 (1:1, w/w) prepared by the described method previously with heating at 90°C for 72 h to obtain nanotube structure. To this self-assembly of the nanotube, a specified amount of ethanol solution of D16 was injected, and heat treatment was carried out at 90°C.…”

“…[46] A small vesicle with an average diameter of 85 nm (PDI = 0.002) (G4) was obtained by a combination of a nanotube of a mixture of poly(sarcosine)-b-(L-Leu-Aib) 8 (PSar21-b-(L-Leu-Aib) 8 ; the most frequent residue number of the poly(sarcosine) block is 21) and polysarcosine-b-(D-Leu-Aib) 7 (PSar21-b-(D-Leu-Aib) 7 ; the most frequent residue number of the poly(sarcosine) block is 21) with a nanosheet of poly(sarcosine)-b-(D-Leu-Aib) 8 (PSar26-b-(D-Leu-Aib) 8; the most frequent residue number of the poly(sarcosine) block is 26). [42] TEM images and DLS data of three kinds of vesicles, G2 to G4, are shown in Figure 2, and the characteristics of the molecular assemblies are summarized in Table 1.…”