13 research outputs found
Design and synthesis of thermoresponsive aliphatic polyethers with a tunable phase transition temperature
This paper describes a comprehensive study of the lower critical solution temperature (LCST)-type thermoresponsive properties of various poly(glycidyl ether) homopolymers with a varying side chain structure, molecular weight, and main chain tacticity, as well as their copolymers with a varying monomer composition and monomer sequence. For the initial screening, we prepared nine kinds of poly(glycidyl ether)s by the phosphazene base-catalyzed ring-opening polymerization of glycidyl methyl ether (MeGE), ethyl glycidyl ether (EtGE), glycidyl isopropyl ether (iPrGE), 2-methoxyethyl glycidyl ether (MeEOGE), 2-ethoxyethyl glycidyl ether (EtEOGE), 2-propoxyethyl glycidyl ether (PrEOGE), 2-(2- methoxyethoxy) ethyl glycidyl ether (MeEO(2)GE), 2-(2-ethoxyethyl) ethyl glycidyl ether (EtEO(2)GE), and 2-(2-(2-methoxyethoxy) ethoxy) ethyl glycidyl ether (MeEO(3)GE). Among them, poly(MeGE), poly(EtGE), poly(MeEOGE), poly(EtEOGE), and poly(MeEO(2)GE) (M-n = ca. 5000 g mol(-1)) were found to exhibit a LCST-type phase transition in water at 65.5 degrees C, 10.3 degrees C, 91.6 degrees C, 41.3 degrees C, and 58.2 degrees C, respectively. Although the molecular weight and main chain tacticity had little impact on the phase transition temperature, the side chain structure, i.e., the number of oxyethylene units and terminal alkyl groups, significantly affected the transition temperature. The statistical copolymers composed of MeEOGE and EtEOGE revealed that the transition temperature of the polymer can be desirably customized in between those of the homopolymers by varying the monomer composition. On the other hand, we found that the block copolymer composed of MeEOGE and EtEOGE exhibited a complex thermoresponsive behavior due to its ability to form a micellar aggregate
Self-Assembly of Maltoheptaose- block -polycaprolactone Copolymers: Carbohydrate-Decorated Nanoparticles with Tunable Morphology and Size in Aqueous Media
International audienc
Synthesis, Thermal Properties, and Morphologies of Amphiphilic Brush Block Copolymers with Tacticity-Controlled Polyether Main Chain
A series of brush
block copolymers (BBCPs) consisting of poly(decyl
glycidyl ether) (PDGE) and poly(10-hydroxyldecyl glycidyl ether) (PHDGE)
blocks, having four different types of chain tacticities, i.e., [<i>at</i>-PDGE]-<i>b</i>-[<i>at</i>-PDEGE],
[<i>at</i>-PDGE]-<i>b</i>-[<i>it</i>-PDEGE], [<i>it</i>-PDGE]-<i>b</i>-[<i>at</i>-PDEGE], and [<i>it</i>-PDGE]-<i>b</i>-[<i>it</i>-PDEGE], where the <i>it</i> and <i>at</i> represent the isotactic and atactic chains, respectively, were prepared
by <i>t</i>-Bu-P<sub>4</sub>-catalyzed sequential anionic
ring-opening polymerization of glycidyl ethers followed by side-chain
modification. The corresponding homopolymers, i.e., <i>at</i>-PDGE, <i>it</i>-PDGE, <i>at</i>-PHDGE, and <i>it</i>-PHDGE, were also prepared for comparison with the BBCPs.
The PDGE homopolymers were significantly promoted in the phase transitions
and morphological structure formation by the isotacticity formation.
In particular, <i>it</i>-PDGE was found to form only a horizontal
multibilayer structure with a monoclinic lattice in thin films, which
was driven by the bristles’ self-assembling ability and enhanced
by the isotacticity. However, the PHDGE homopolymers were found to
reveal somewhat different behaviors in the phase transitions and morphological
structure formation by the tacticity control due to the additional
presence of a hydroxyl group in the bristle end as an H-bonding interaction
site. The H-bonding interaction could be enhanced by the isotacticity
formation. The <i>it</i>-PHDGE homopolymer formed only the
horizontal multibilayer structure, which was different from the formation
of a mixture of horizontal and tilted multibilayer structures in <i>at</i>-PHDGE. The structural characteristics were further significantly
influenced by the diblock formation and the tacticity of the counterpart
block. Because of the strong self-assembling characteristics of the
individual block components, all the BBCPs formed separate crystals
rather than cocrystals. The isotacticity always promoted the formation
of better quality morphological structures in terms of their lateral
ordering and orientation
MANTA, an integrative database and analysis platform that relates microbiome and phenotypic data.
With an ever-increasing interest in understanding the relationships between the microbiota and the host, more tools to map, analyze and interpret these relationships have been developed. Most of these tools, however, focus on taxonomic profiling and comparative analysis among groups, with very few analytical tools designed to correlate microbiota and the host phenotypic data. We have developed a software program for creating a web-based integrative database and analysis platform called MANTA (Microbiota And pheNoType correlation Analysis platform). In addition to storing the data, MANTA is equipped with an intuitive user interface that can be used to correlate the microbial composition with phenotypic parameters. Using a case study, we demonstrated that MANTA was able to quickly identify the significant correlations between microbial abundances and phenotypes that are supported by previous studies. Moreover, MANTA enabled the users to quick access locally stored data that can help interpret microbiota-phenotype relations. MANTA is available at https://mizuguchilab.org/manta/ for download and the source code can be found at https://github.com/chenyian-nibio/manta
Synthesis of Linear, Cyclic, Figure-Eight-Shaped, and Tadpole-Shaped Amphiphilic Block Copolyethers via <i>t</i>‑Bu‑P<sub>4</sub>‑Catalyzed Ring-Opening Polymerization of Hydrophilic and Hydrophobic Glycidyl Ethers
This paper describes the synthesis
of systematic sets of figure-eight-
and tadpole-shaped amphiphilic block copolyethers (BCPs) consisting
of poly(decyl glycidyl ether) and poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl
glycidyl ether], together with the corresponding cyclic counterparts,
via combination of the <i>t</i>-Bu-P<sub>4</sub>-catalyzed
ring-opening polymerization (ROP) and click cyclization. The clickable
linear BCP precursors, with precisely controlled azido and ethynyl
group placements as well as a fixed molecular weight and monomer composition
(degree of polymerization for each block was adjusted to be around
50), were prepared by the <i>t</i>-Bu-P<sub>4</sub>-catalyzed
ROP with the aid of functional initiators and terminators. The click
cyclization of the precursors under highly diluted conditions produced
a series of cyclic, figure-eight-, and tadpole-shaped BCPs with narrow
molecular weight distributions of less than 1.06. Preliminary studies
of the BCPs self-assembly in water revealed the significant variation
in their cloud points depending on the BCP architecture, though there
were small architectural effects on their critical micelle concentration
and morphology of the aggregates
Self-Assembly of Maltoheptaose-<i>block</i>-polycaprolactone Copolymers: Carbohydrate-Decorated Nanoparticles with Tunable Morphology and Size in Aqueous Media
This paper describes the systematic
investigation into the aqueous
self-assembly of a series of block copolymers (BCPs) consisting of
maltoheptaose (MH; as the A block) and poly(ε-caprolactone)
(PCL; as the B block), i.e., linear AB-type diblock copolymers with
varied PCL molecular weights (MH-<i>b</i>-PCL<sub>(2.5k,3.3k,5k,10k)</sub>), AB<sub><i>y</i></sub>-type (<i>y</i> = 2,
MH-<i>b</i>-(PCL<sub>5k</sub>)<sub>2</sub>; <i>y</i> = 3, MH-<i>b</i>-(PCL<sub>3.3k</sub>)<sub>3</sub>), A<sub>2</sub>B<sub>2</sub>-type ((MH)<sub>2</sub>-<i>b</i>-(PCL<sub>5k</sub>)<sub>2</sub>), and A<sub><i>x</i></sub>B-type
miktoarm star polymers (<i>x</i> = 2, (MH)<sub>2</sub>-<i>b</i>-PCL<sub>10k</sub>; <i>x</i> = 3, (MH)<sub>3</sub>-<i>b</i>-PCL<sub>10k</sub>), which had been precisely
synthesized via the combination of the living ring-opening polymerization
and click reaction. Under similar conditions, the nanoprecipitation
method was employed to self-assemble them in an aqueous medium. Imaging
and dynamic light scattering techniques indicated the successful formation
of the carbohydrate-decorated nanoparticles via self-assembly. The
MH-<i>b</i>-PCLs formed regular core–shell micellar
nanoparticles with the hydrodynamic radius (<i>R</i><sub>h</sub>) of 17–43 nm. MH-<i>b</i>-(PCL<sub>5k</sub>)<sub>2</sub> and MH-<i>b</i>-(PCL<sub>3.3k</sub>)<sub>3</sub>, which have an <i>N</i><sub>PCL</sub> comparable
to MH-<i>b</i>-PCL<sub>10k</sub>, were found to form large
compound micelles with relatively large radii (<i>R</i><sub>h</sub> of 49 and 56 nm, respectively). On the other hand, (MH)<sub>2</sub>-<i>b</i>-(PCL<sub>5k</sub>)<sub>2</sub>, (MH)<sub>2</sub>-<i>b</i>-PCL<sub>10k</sub>, and (MH)<sub>3</sub>-<i>b</i>-PCL<sub>10k</sub> predominantly formed the regular
core–shell micellar nanoparticles (<i>R</i><sub>h</sub> = 29–39 nm) with a size smaller than that of MH-<i>b</i>-PCL<sub>10k</sub> (<i>R</i><sub>h</sub> = 43 nm)
Dietary Vitamin B1 Intake Influences Gut Microbial Community and the Consequent Production of Short-Chain Fatty Acids
The gut microbiota is closely related to good health; thus, there have been extensive efforts dedicated to improving health by controlling the gut microbial environment. Probiotics and prebiotics are being developed to support a healthier intestinal environment. However, much work remains to be performed to provide effective solutions to overcome individual differences in the gut microbial community. This study examined the importance of nutrients, other than dietary fiber, on the survival of gut bacteria in high-health-conscious populations. We found that vitamin B1, which is an essential nutrient for humans, had a significant effect on the survival and competition of bacteria in the symbiotic gut microbiota. In particular, sufficient dietary vitamin B1 intake affects the relative abundance of Ruminococcaceae, and these bacteria have proven to require dietary vitamin B1 because they lack the de novo vitamin B1 synthetic pathway. Moreover, we demonstrated that vitamin B1 is involved in the production of butyrate, along with the amount of acetate in the intestinal environment. We established the causality of possible associations and obtained mechanical insight, through in vivo murine experiments and in silico pathway analyses. These findings serve as a reference to support the development of methods to establish optimal intestinal environment conditions for healthy lifestyles