Superlattice Structure from Self-Assembly of High‑χ Block Copolymers via Chain Interdigitation

Flexible and shape-tunable features of block copolymers (BCPs) with high Flory–Huggins interaction parameters (high χ value) have drawn intensive attention due to their rich phase behaviors. Herein, this work aims to examine a fascinating superlattice structure obtained from the self-assembly of high-χ BCP, polystyrene-block-polydimethyl­siloxane (PS-b-PDMS), as evidenced by reciprocal-space imaging from small-angle X-ray scattering (SAXS) and by real-space imaging from transmission electron microscopy (TEM). Surprisingly, an interesting reversible order–order transition from superlattice structure with chain interdigitation to typical lamellae with bilayer texture can be identified by in situ temperature-resolved SAXS. In contrast to the diblock (PS-b-PDMS)n (n = 1), the forming superlattice structure will be greatly impeded in star-block (PS-b-PDMS)n (n = 3 and 4) with equivalent arm length, suggesting a topological effect on self-assembly due to their star-shaped architecture. Accordingly, a lamellae-forming PS-b-PDMS with chain interdigitation (wet-brush-like chain packing) was proposed to be the origin of the forming superlattice structure. This finding provides an insight for the possible model with ladder-like structure and corresponding transformation mechanisms of high-χ BCPs. Also, the topological effect from star-block architecture may play an important role to justify the formation of such a unique self-assembled texture. These results implicitly explore the feasibility to acquire a superlattice structure from a simple coil–coil diblock copolymer

Location and sequence of the PCR primers used in the present study.

<p>DNA sequences (upper: sense strand; lower: anti-sense strand) encoding a glycine-extended version of the mature Sco-CHH (accession No. AAQ75760) are given. Forward (blue) and reverse (red) primers are placed above the sense strand and below the anti-sense strand, respectively. Nucleotide sequences of the primers identical to those of the Sco-CHH sequence are indicated by bold dash line (- - - -), with the alanine-encoding codons in the forward primers (GCC, GCT, GCA, or GCG) and in the reverse primers (GGC, AGC, or TGC) shown in italics. <i>NdeI</i> recognition sequence (CATATG) containing a methionine-encoding start codon (ATG, shown in green) was included in the forward primers STPPF, I2APF, F3APF, D4APF; <i>XhoI</i> recognition sequence (CTCGAG) was included in the reverse primers SGPR, I69APR, V72APR, followed by a stop codon (TTA shown in red) and a glycine-encoding codon GCC. Amino acid sequence of the glycine-extended Sco-CHH is also shown. CHH motifs as defined by Lacombe et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134983#pone.0134983.ref030" target="_blank">30</a>] are boxed. Residues for which alanine was substituted in the present study are pointed by arrows and the residue numbers given.</p

The <i>p</i>-values derived from statistical analyses in early stage of diseases when SARA scores were below 10 unit points.

<p>Comparison of MRS ratios in the cerebellum between subgroups of SCAs.</p

The <i>p</i>-values derived from statistical analyses in early stage of diseases when SARA scores were below 10 unit points.

<p>Comparison of MRS ratios in the cerebellum between patients with subtypes of SCA and MSA-C.</p

Identification and characterization of wild-type and alanine-substituted rSco-CHH peptides.

<p>^a Data of % α-helix were calculated from the CD spectral data of peptides not yet amidated.</p><p>^b Percentage of acetonitrile at which each peptide was eluted.</p><p>^c Monoisotopic values are given.</p><p>Identification and characterization of wild-type and alanine-substituted rSco-CHH peptides.</p

Circular dichroism spectra of wild-type and alanine-substituted rSco-CHH-Gly.

<p>CD spectral data of each recombinant peptide, dissolved in 10 mM PBS (150 mM NaCl, pH 6.8), were collected from 260 nm to 200 nm at 25°C using an AVIV 202 spectropolarimeter.</p

The MR spectroscopy features of the study participants.

*<p>Mann-Whitney test, <i>p</i><0.05, compared with the healthy controls.</p

Demographic features of the subjects.

#<p>Kruskal-Wallis test, <i>p</i><0.05.</p>§<p>Patients with SCA2 or SCA3 had a longer disease duration than those with SCA17, <i>p</i><0.05.</p>§§<p>Patients with SCA3 had a longer disease duration than those with MSA-C.</p>*<p>Patients with SCA2 or SCA3 were younger than those with SCA6.</p>**<p>Patients with SCA were younger than those with MSA-C.</p

Four recombinant Sco-CHH mutants exhibit hyperglycemic activities significantly different from those elicited by wild-type Sco-CHH.

<p>Eyestalk-ablated animals (<i>S</i>. <i>olivacea</i>) received a 50-μl injection of (A) I2A rSco-CHH (▼: 10 pmol/animal), (B) F3A rSco-CHH (▼: 10 pmol/animal), (C) D12A rSco-CHH (▼: 10 pmol/animal), (D) D60A rSco-CHH (▼: 10 pmol/animal), (A-D) wild-type rSco-CHH (○: 10 pmol/animal) or saline (●). Hemolymph was withdrawn at designated time points and processed for determination of glucose levels. Data are given as mean ± S.E.M. For the sake of clarity, one-sided SEM bars are given. Sample size (n) is 8 for each time point. *,** indicate significant differences from corresponding zero time controls at 5% and 1% levels, respectively. Parenthesized * indicates significant differences between the wild-type and mutants at the same time-point at 5%. No significant change over time was observed in saline-treated animals.</p

Representative MR spectra.

<p>(A) The MR spectroscopy in the cerebellar hemispheres (upper row) and vermis (lower row) in healthy controls and patients with SCA6, SCA3, SCA17, SCA1, SCA2 or MSA-C. (B) Group comparisons of NAA/Cr, Cho/Cr and NAA/Cho between the patients and controls.</p