Preparation of Amylose-Oligo[(R)-3-hydroxybutyrate] Inclusion Complex by Vine-Twining Polymerization.

In this study, we attempted to prepare an amylose-oligo[(R)-3-hydroxybutyrate] (ORHB) inclusion complex using a vine-twining polymerization approach. Our previous studies indicated that glucan phosphorylase (GP)-catalyzed enzymatic polymerization in the presence of appropriate hydrophobic guest polymers produces the corresponding amylose-polymer inclusion complexes, a process named vine-twining polymerization. When vine-twining polymerization was conducted in the presence of ORHB under general enzymatic polymerization conditions (45 °C), the enzymatically produced amylose did not undergo complexation with ORHB. However, using a maltotriose primer in the same polymerization system at 70 °C for 48 h to obtain water-soluble amylose, called single amylose, followed by cooling the system over 7 h to 45 °C, successfully induced the formation of the inclusion complex. Furthermore, enzymatic polymerization initiated from a longer primer under the same conditions induced the partial formation of the inclusion complex. The structures of the different products were analyzed by X-ray diffraction, 1H-NMR, and IR measurements. The mechanism of formation of the inclusion complexes discussed in the study is proposed based on the additional experimental results.

Microwave treatment of breast milk for prevention of cytomegalovirus infection.

BACKGROUND: Breast milk (BM) is the best nutrition for very preterm infants (VPI), except when provided by human cytomegalovirus (HCMV)-seropositive mothers. Given that VPI are at high risk of developing a sepsis-like syndrome or cholestasis, methods for prevention of HCMV infection via BM have been investigated. Although Holder pasteurization (HP) is the gold standard, HP needs special instruments. Microwave (MW) is available anywhere, therefore, we performed this study to determine whether MW can be used for HCMV prevention. METHODS: Human cytomegalovirus Towne strain was added to formula, followed by heating procedure using HP or MW (at 500 W for 20, 30, 40, or 60 s). HFL-III cells were seeded in culture dishes. Aliquots of HCMV-milk samples after heating were inoculated onto susceptible cell monolayers. The number of plaques was counted to determine the viral titer. The determination of HCMV-DNA copies was also performed. RESULTS: Addition of HCMV for a viral load of 5.0 × 103 plaque-forming units (p.f.u.)/mL achieved 772 p.f.u./mL at baseline, with a decrease to 257 p.f.u./mL after MW radiation for 20 s. No plaque was detected after HP or MW for 30, 40, and 60 s. The temperature of the breast milk reached 60°C after MW radiation for 40 s. The number of HCMV-DNA copies did not change with MW. CONCLUSIONS: Microwave at 500 W for 40 s can be used as a prevention strategy for HCMV transmission. Further research including the loss of bioactive properties in BM is required prior to clinical application.

Chemoenzymatic Preparation of Amylose-Grafted Chitin Nanofiber Network Materials.

We previously found that the methanol-treatment of a chitin ion gel with an ionic liquid, 1-allyl-3-methylimidazolium bromide, for regeneration and subsequent filtration of a resulting self-assembled chitin nanofiber (CNF) dispersion gave a CNF film. In this study, we investigated a chemoenzymatic approach including enzymatic polymerization catalyzed by phosphorylase for the preparation of amylose-grafted CNF network materials. Maltoheptaose (Glc7) as the primer for the enzymatic polymerization was immobilized on the CNF film by reductive amination with amino groups, generated by the partial deacetylation of chitin molecules. The enzymatic polymerization of α-d-glucose 1-phosphate as a monomer catalyzed by phosphorylase was then conducted from the Glc7 chain ends on the CNFs dispersed in a sodium acetate aqueous buffer. The elongated amylose graft chains spontaneously constructed double helixes for cross-linking among CNFs to produce networks, resulting in a hydrogel. A robust cryogel was obtained by lyophilization of the hydrogel by the reaction at 80 °C, while the same procedure from the hydrogel produced by the reaction at 45 °C gave a flimsy cryogel. The scanning electron microscopic images of the former and latter samples observed uniform and nonuniform network morphologies, respectively. We revealed that dispersion behaviors of the Glc7-grafted CNFs in a sodium acetate aqueous buffer were different depending on temperatures, which affected the morphologies of the resulting networks formed in the enzymatic polymerization.

Cholinesterase levels predict exercise capacity in cardiac recipients early after transplantation.

PURPOSE: Although cardiac rehabilitation is recommended for patients early after heart transplantation (HTx), adequate exercise effect cannot always be obtained, partly because in patients with chronic heart failure, exercise capacity is reduced due to malnutrition while waiting for HTx. This study aimed to investigate the relationships between exercise capacity and clinical variables, including nutritional indicators, early after HTx. PATIENTS AND METHODS: Forty-three HTx recipients were studied. The mean age at HTx was 38 ± 14 years, and 86% were male. We assessed the relationships between peak oxygen uptake (VO2 ) and clinical variables, including plasma B-type natriuretic peptide (BNP), isometric knee extensor muscle strength (KEMS), and nutritional indicators within 1 week of their respective discharges. RESULTS: Peak VO2 correlated positively with isometric KEMS (r = .63, P < .0001) and negatively with BNP level (r = -.37, P = .015). Of the nutritional indicators, only cholinesterase levels had a significant relationship with peak VO2 (r = .34, P = .028), whereas the Geriatric Nutritional Risk Index and the Controlling Nutritional Status scores did not. In multiple linear regression analysis, cholinesterase levels and isometric KEMS were independent predictors of peak VO2 . CONCLUSION: Cholinesterase levels predicted exercise capacity early after HTx.

Understanding dissolution process of chitin crystal in ionic liquids: theoretical study.

Chitin is a promising biomass resource and has high potential for industrial applications owing to its huge annual production in nature. However, it exhibits poor processability and solubility due to its very stable and crystalline character. Recently, ionic liquids (ILs) have attracted attention as solvents for structural polysaccharides - for example, 1-allyl-3-methylimidazolium bromide (AMIMBr) has been found to dissolve chitin. As few ILs are known to dissolve chitin, little research has been conducted on the dissolution mechanism involved. In this study, we have adopted a molecular dynamics (MD) approach to study the dissolution of chitin crystals in imidazolium-based ILs. The MD simulation in AMIMBr has demonstrated that the dissolution process involved peeling of chitin chains from the crystal surface, with Br- cleaving the chitin hydrogen bonds, and AMIM+ preventing a return to the crystalline phase after the peeling. By contrast, in imidazolium acetates, which has also been reported to dissolve chitin, although the molecular chains are peeled off, the peeled chains occasionally return to the crystalline phase. Furthermore, the MD trajectory analysis has revealed that the solubility of chitin is well correlated with the number of intermolecular hydrogen bonds by acetamido groups in the chitin crystal. It has been experimentally proven that mixing a small amount of 2-bromoethyl acetate, as a bromide generator, with 1-allyl-3-methylimidazolium chloride can enhance chitin solubility, which supports the dissolution mechanism indicated by the above theoretical results.

Predictors of improvements in exercise capacity during cardiac rehabilitation in the recovery phase after coronary artery bypass graft surgery versus acute myocardial infarction.

This study aimed to elucidate the predictors of improvements in exercise capacity during cardiac rehabilitation (CR) in the recovery phase after coronary artery bypass graft surgery (CABG) versus acute myocardial infarction (AMI). We studied 152 patients (91 after AMI and 61 after CABG) who participated in a 3-month CR program. All patients underwent a cardiopulmonary exercise test, blood tests, maximal quadriceps isometric strength (QIS) measurement, and bioelectrical impedance body composition measurement at the beginning and end of the 3-month CR program. At baseline, the percentage of predicted peak oxygen uptake (%pred-PVO2), maximal QIS, and hemoglobin (Hb) were significantly lower, while C-reactive protein (CRP) was significantly higher, in the CABG than the AMI group. After the 3-month CR, %change in PVO2 (%ΔPVO2) was significantly greater in the CABG than the AMI group (18 ± 15% vs 11 ± 12%, P < 0.01). At univariate analysis, baseline plasma brain natriuretic peptide (BNP), %change in maximal QIS after CR (%Δ maximal QIS), and change in plasma hemoglobin (ΔHb) significantly correlated with %ΔPVO2 in the CABG group, whereas only baseline %pred-PVO2 did so in the AMI group. Multiple regression analysis revealed that the same factors were independent and significant predictors of %ΔPVO2 in the CABG and AMI groups. The predictors of improvements in exercise capacity after CR differed between patients after CABG or AMI. Specifically, in CABG patients both enhancing QIS and correcting anemia may contribute to greater improvements in exercise capacity after CR, while a more effective CR program should be designed for CABG patients with high baseline BNP.

Chemoenzymatic synthesis and pH-responsive properties of amphoteric block polysaccharides.

Here, we investigated the chemoenzymatic synthesis of α(1→4)-linked amphoteric block polysaccharides. Amylouronic acid as an acidic block was first synthesized by 2,2,6,6-tetramethylpiperidine 1-oxyl-mediated oxidation of a water-soluble amylose (chemical reaction). A short maltooligosaccharide chain, serving as an initiating site for the following enzymatic polymerization, was then introduced at the nonreducing end of the product by thermostable α-glucan phosphorylase-catalyzed enzymatic oligomerization of α-d-glucose 1-phosphate. Finally, thermostable α-glucan phosphorylase-catalyzed enzymatic polymerization of α-d-glucosamine 1-phosphate from the produced primer provided a basic block at the nonreducing end, leading to the desired amphoteric block polysaccharides. The structures of the products at each step were determined by (1)H NMR analysis. Furthermore, amphoteric products exhibited specific inherent isoelectric points (pIs). When the pH-responsive properties in aqueous solutions were evaluated using a divalent acid and base, similar hierarchical assembling/disassembling processes were observed by shifting the pH values from the pI to both the acidic and basic pH.

Synthesis of Non-Natural Heteroaminopolysaccharides by α-Glucan Phosphorylase-Catalyzed Enzymatic Copolymerization: α(1→4)-Linked Glucosaminoglucans.

Thermostable α-glucan phosphorylase-catalyzed enzymatic copolymerization of α-d-glucose 1-phosphate (Glc-1-P) with its analogue monomer, α-d-glucosamine 1-phosphate (GlcN-1-P), from a maltotriose primer was performed to produce non-natural heteroaminopolysaccharides composed of Glc/GlcN units, that is, α(1→4)-linked glucosaminoglucans. The GlcN units in the products were further converted to N-acetyl-d-glucosamine (GlcNAc) units by N-acetylation. The structures of the products were evaluated by the MALDI-TOF MS, (1)H NMR, and (1)H-(1)H COSY NMR measurements, which were completely different from those of the natural glycosaminoglycans. The degrees of polymerization and Glc/GlcN compositional ratios of the products were relatively dependent on the Glc-1-P/Glc-1-P/Glc3 feed ratios. The noncrystalline natures of the present materials were supported by the X-ray diffraction measurement.

Synthesis of chitin and chitosan stereoisomers by thermostable α-glucan phosphorylase-catalyzed enzymatic polymerization of α-D-glucosamine 1-phosphate.

The relationship between two aminopolysaccharide stereoisomers, namely α-(1→4)- and ß-(1→4)-linked (N-acetyl)-D-glucosamine polymers, is of significant interest within the field of polysaccharide science, as they correspond to amino analogs of the representative abundant natural polysaccharides, viz. amylose and cellulose. While the latter glucosamine polymer is the basis of well-known natural polysaccharides, chitin and chitosan (linear polysaccharides composed of ß-(1→4)-linked N-acetyl-D-glucosamine and D-glucosamine), to the best of our knowledge, the former (α-(1→4)-linked) has not been observed in nature. For the purpose of these studies, the synthesis of such non-natural aminopolysaccharides was performed by the thermostable α-glucan phosphorylase (from Aquifex aeolicus VF5)-catalyzed enzymatic polymerization of α-D-glucosamine 1-phosphate (GlcN-1-P), via successive α-glucosaminylations, in ammonia buffer containing Mg(2+) ions, resulting in the production of the α-(1→4)-linked D-glucosamine polymers, corresponding to the structure of the chitosan stereoisomer. Subsequent N-acetylation of the products gave the aminopolysaccharides, corresponding to the chitin stereoisomer.

Direct evidence of spatially selective iron mineralization using an immobilized ferritin protein cage.

(Apo)ferritins are cage-shaped proteins which have recently received a great deal of attention because the inner cavity of the protein shell can be used as a size-restricted reaction field for the synthesis of nanomaterials. The biomineralization behavior and inorganic nanoparticle (NP) synthesis mechanism of (apo)ferritin in solution systems have been studied but the mineralization behavior of (apo)ferritin on the substrates has not yet been well studied. Here, we conducted quantitative and kinetic analyses of the mineralization behavior of immobilized (apo)ferritin on a polyelectrolyte multilayer (PEM) using quartz crystal microbalance (QCM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. We demonstrated that the (apo)ferritin immobilized on a substrate synthesizes a ferrihydrite core within the confines of the protein cage; similar to a solution dispersed system. In addition, we applied a ferritin/apoferritin blended monolayer to the study of iron mineralization and revealed that biomineralization in this system is spatially selective. It is important to understand the mineralization mechanisms for the synthesis of other functional NPs as this approach has potential for a broad range of magnetic, catalytic, and biomedical sensing applications.

Association Between Adherence to a 3-Month Cardiac Rehabilitation Program and Long-Term Clinical Outcomes in Japanese Patients With Cardiac Implantable Electronic Devices.

PURPOSE: The objective of this study was to evaluate the association between comprehensive cardiac rehabilitation (CCR) completion and long-term clinical outcomes in patients with cardiac implantable electronic devices (CIED). METHODS: This retrospective cohort study included 834 patients with CIED who participated in CCR, which included a cardiopulmonary exercise test or 6-min walk test. Patients with a left ventricular ejection fraction ≤40%, predicted peak oxygen uptake ≤80%, or B-type natriuretic peptide level ≥80 pg/mL were eligible. The primary outcome was all-cause mortality. RESULTS: After excluding 241 patients with duplicate records and 69 who underwent CCR in the outpatient department, the data of 524 patients were analyzed. Mean age was 64 ± 15 yr, 389 (74%) patients were men, left ventricular ejection fraction was 31 ± 15%, and 282 (54%) patients had a history of hospitalization for worsening heart failure. Of the patients referred for CCR, 294 (56%) completed the program, and an additional 230 patients started but did not complete CCR. Over a 3.7-yr median follow-up period, all-cause mortality occurred in 156 (30%) patients. Completers had lower all-cause mortality rates than non-completers (log-rank 15.77, P < .001). After adjusting for prognostic baseline characteristics, completers had 58% lower all-cause mortality risks than non-completers (HR = 0.42; 95% CI, 0.27-0.64, P < .001). CONCLUSIONS: Three-mo CCR program completion was associated with lower mortality risks in patients with CIED. New programs or management methods are needed to decrease mortality risks, especially for those who cannot complete CCR programs.

Analysis of the Effects of Known Sleep-Support Supplements in Relation to Life Habits, Sleep Conditions, and Sleep Problems.

Sleep is a crucial component of health, and insomnia is among the most common and vexing of life-habit-related disorders. While dietary sleep-support supplements can improve sleep, choosing an effective dietary supplement can be challenging for users due to the wide variety of options available and the varying effects experienced by different individuals. In this study, to identify new criteria for estimating the effects of dietary supplements, we examined the relationships among the dietary supplements, the pre-conditions (PCs; defined as the life habits and sleep conditions before supplementation), and the sleep problems of subjects before supplementation. An open, randomized, cross-over intervention trial enrolling 160 subjects was conducted to test the efficacy of each dietary supplement (Analysis 1) and the relationships among dietary supplements, the PCs, and sleep problems (Analysis 2). To this end, l-theanine (200 mg/day), γ-aminobutyric acid (GABA) (111.1 mg/day), Apocynum venetum leaf extract (AVLE) (50 mg/day), and l-serine (300 mg/day) were administered to subjects. Before the first intervention period, life habits and sleep conditions were surveyed to identify each subject's PCs. For each combination of supplements and sleep problems, PCs were compared between subjects whose sleep problems were improved and subjects whose sleep problems were not improved via supplementation. All the tested supplements were found to ameliorate sleep problems significantly (Analysis 1). In Analysis 2, the PCs specific to improved subjects were found to differ depending on the dietary supplements and sleep problems. In addition, subjects who consumed dairy products often showed improvement in their sleep problems with all the tested supplements. This study suggests the possibility of personalizing sleep-support supplementation based on personal life habits, sleep conditions, and sleep problems, in addition to the known efficacy of dietary supplements.

Pre-existing sarcopenia and swallowing outcomes in acute stroke patients.

BACKGROUND & AIMS: This study aimed to investigate the associations of pre-existing sarcopenia with swallowing function, oral intake level, and aspiration pneumonia in patients with acute stroke. METHODS: This observational study included patients (≥60 years of age) with acute ischemic stroke or intracerebral hemorrhage within 7 days of onset who were screened for sarcopenia, malnutrition, and swallowing difficulties in a stroke-care unit within 48 h of admission. Sarcopenia was defined by the Asian Working Group on Sarcopenia 2019 as having a low calf circumference, handgrip strength, and appendicular muscle mass index. The primary outcome was impaired oral intake (functional oral intake scale <5 points) at 3, 7, and 14 days after admission, and the secondary outcome was aspiration pneumonia during hospitalization. RESULTS: We enrolled 350 patients (median age of 77 years; 63% males) who underwent the aforementioned screening. Sarcopenia was diagnosed in 34% of patients, and malnutrition was found in 66% of patients with sarcopenia. When compared with the comparison group (defined as patients with either or both normal calf circumference and handgrip strength), the sarcopenia group had significantly lower tongue pressure and a higher prevalence of dysphagia. Sarcopenia was associated with functional oral intake scale <5 at 7 days (adjusted odds ratio [OR], 4.72; 95% confidence interval [CI], 1.91-11.71); p = 0.002) and 14 days (adjusted OR, 3.93; 95% CI, 1.47-10.53; p = 0.006) and with aspiration pneumonia during hospitalization (adjusted OR, 6.12; 95% CI, 1.63-22.94; p = 0.007). CONCLUSION: Acute stroke patients with sarcopenia may have weakness of the swallowing-related muscles which may lead to impaired oral intake and aspiration pneumonia.

Efficacy and Safety of Esaxerenone in Hypertensive Patients with Diabetes Mellitus Undergoing Treatment with Sodium-Glucose Cotransporter 2 Inhibitors (EAGLE-DH).

INTRODUCTION: The EAGLE-DH study assessed the efficacy and safety of esaxerenone in hypertensive patients with diabetes mellitus receiving sodium-glucose cotransporter 2 (SGLT2) inhibitors. METHODS: In this multicenter, open-label, prospective, interventional study, esaxerenone was started at 1.25 or 2.5 mg/day and could be gradually increased to 5 mg/day on the basis of blood pressure (BP) and serum potassium levels. Oral hypoglycemic or antihypertensive medications prior to obtaining consent was continued. Data were evaluated in the total population and creatinine-based estimated glomerular filtration rate (eGFR) subcohorts (eGFR ≥ 60 mL/min/1.73 m2 [G1-G2 subcohort] and 30 to < 60 mL/min/1.73 m2 [G3 subcohort]). RESULTS: In total, 93 patients were evaluated (G1-G2, n = 49; G3, n = 44). Morning home systolic/diastolic BP values (SBP/DBP) were significantly reduced from baseline to week 12 (- 11.8 ± 10.8/- 5.1 ± 6.3 mmHg, both P < 0.001) and week 24 (- 12.9 ± 10.5/- 5.7 ± 6.3 mmHg, both P < 0.001). Similar results were observed in both eGFR subcohorts. The urinary albumin-to-creatinine ratio significantly decreased from baseline to week 24 in the total population (geometric percentage change, - 49.1%, P < 0.001) and in both eGFR subcohorts. The incidences of treatment-emergent adverse events (TEAEs) and drug-related TEAEs were 45.2% and 12.9%, respectively; most were mild or moderate. Serum potassium levels increased over the first 2 weeks of esaxerenone treatment, gradually decreased by week 12, and remained constant to week 24. One patient in the G1-G2 subcohort had serum potassium levels ≥ 5.5 mEq/L. No patients had serum potassium ≥ 6.0 mEq/L. CONCLUSION: Esaxerenone effectively lowered BP, was safe, and showed renoprotective effects in hypertensive patients with diabetes mellitus receiving treatment with SGLT2 inhibitors. Esaxerenone and SGLT2 inhibitors did not interfere with either drug's efficacy and may reduce the frequency of serum potassium elevations, suggesting they are a compatible combination. CLINICAL TRIAL REGISTRATION: jRCTs031200273.

Preparation and characterization of imogolite/DNA hybrid hydrogels.

Imogolite is one of the clay minerals contained in volcanic ash soils. The novel hybrid hydrogels were prepared from imogolite nanofibers and DNA by utilizing strong interaction between the aluminol groups on imogolite surface and phosphate groups of DNA. The hybrid hydrogels of imogolite and DNA were prepared in various feed ratios, and their physicochemical properties and molecular aggregation states were investigated in both dispersion and gel states. The maximum DNA content in the hybrid gels was shown in equivalent molar ratio of imogolite and DNA. The physical properties of the hybrid gels were changed by varying DNA blend ratios. In the dispersion state, the hybrid gels showed a fibrous structure of imogolite, whereas a continuous network structure was observed in pure imogolite, indicating that the hybrid with DNA enhanced the dispersion of imogolite. In the gel state, DNA and imogolite nanofibers formed a 3D network structure.

Hemodialysis-induced P-wave signal-averaged electrocardiogram alterations are indicative of vulnerability to atrial arrhythmias.

BACKGROUND: Atrial fibrillation (AF) is the most common supraventricular arrhythmia, often occurring during hemodialysis (HD). Prolongation of the total filtered P-wave duration (PWD) and reduction of the root mean square voltages for the last 20 ms of the P wave (RMS20) on a P-wave signal-averaged electrocardiogram (P-SAECG) are predictors of AF. We investigated whether HD induces alterations of P-SAECG, and determined the influential factors. METHODS AND RESULTS: Thirty-three end-stage kidney disease patients (66.7 ± 12.6 years, 23 males) undergoing maintenance HD were enrolled in this study. Digital ambulatory P-SAECG monitoring and laboratory examination of serum proteins and ions were carried out before, during, and after the HD sessions. Data were analyzed by multiple regression analysis. PWD was significantly prolonged, and RMS20 significantly reduced, during HD. These values recovered after completion of HD. Multiple regression analysis showed that prolongation of PWD significantly correlated with HD duration and the rate of removal of body fluid. On the other hand, RMS20 significantly correlated with HD duration and blood urea nitrogen variation. CONCLUSIONS: HD resulted in prolongation of PWD and reduction of RMS20, indicating the vulnerability of HD patients to AF. These P-SAECG changes correlated with HD duration and the rate of removal of the body fluid. These findings underline the importance of the control of dialysis variables in the prevention of atrial arrhythmias following HD.

Synthesis of thermoplastic chitin hexanoate-graft-poly(ε-caprolactone).

Herein, we report that chitin hexanoate-graft-poly(ε-caprolactone) (ChHex-g-PCL) is thermoplastic, as confirmed by the formation of a melt-pressed film. Chitin hexanoates with degrees of substitution (DSs) of 1.4-1.8 and bearing free hydroxy groups were first prepared by the hexanoylation of chitin using adjusted feed equivalents of hexanoyl chloride in the presence of pyridine and N,N-dimethyl-4-aminopyridine in 1-allyl-3-methylimidazolium bromide, an ionic liquid. Surface-initiated ring-opening graft polymerization of ε-caprolactone from the hydroxy groups of the chitin hexanoates was conducted in the presence of tin(II) 2-ethylhexanoate as the catalyst at 100 °C to produce (ChHex-g-PCL)s. The feed equivalent of the catalyst, reaction time, and DS value were found to affect the molar substitution and degree of polymerization of the PCL graft chains. Longer PCL graft chains formed their crystalline structures and the (ChHex-g-PCL)s largely contained uncrystallized chitin chains. Accordingly, these (ChHex-g-PCL)s exhibited melting points associated with the PCL graft chains, leading to thermoplasticity.

Surface design with self-heating smart polymers for on-off switchable traps.

We have developed a novel self-heating, temperature-responsive chromatography system for the effective separation of biomolecules. Temperature-responsive poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide), poly(NIPAAm-co-HMAAm), was covalently grafted onto the surface of magnetite/silica composites as 'on-off' switchable surface traps. The lower critical solution temperature (LCST) of the poly(NIPAAm-co-HMAAm)s was controlled from 35 to 55 °C by varying the HMAAm content. Using the heat generated by magnetic particles in an alternating magnetic field (AMF) we were able to induce the hydrophilic to hydrophobic phase separation of the grafted temperature-responsive polymers. To assess the feasibility of the poly(NIPAAm-co-HMAAm)-grafted magnetite/silica particles as the stationary phase for chromatography, we packed the particles into the glass column of a liquid chromatography system and analyzed the elusion profiles for steroids. The retention time for hydrophobic steroids markedly increased in the AMF, because the hydrophobic interaction was enhanced via self-heating of the grafted magnetite/silica particles, and this effect could be controlled by changing the AMF irradiation time. Turning off the AMF shortened the total analysis time for steroids. The proposed system is useful for separating bioactive compounds because their elution profiles can be easily controlled by an AMF.

Fabrication of highly flexible nanochitin film and its composite film with anionic polysaccharide.

This study investigated the fabrication of a nanochitin film via the aggregation of scaled-down chitin nanofibers (SD-ChNFs). A self-assembled ChNF film, which was prepared by regeneration from a chitin/ionic liquid ion gel using methanol, followed by filtration, was treated with aqueous NaOH for deacetylation and subsequently disintegrated by cationization and electrostatic repulsion in 1.0 mol/L aqueous acetic acid with ultrasonication to give a SD-ChNF dispersion. Isolation of the SD-ChNFs via filtration of the dispersion resulted in a highly flexible self-assembled ChNF film that bent and twisted easily. The film exhibited superior mechanical properties compared to the parent self-assembled ChNF film, where the flexibility was further enhanced by the compositing the SD-ChNFs with an anionic polysaccharide, namely ι-carrageenan, via multi-point ionic cross-linking. These enhanced mechanical properties and efficient compositing properties were attributed to the scaling down of the ChNFs.

Preparation and gelation behaviors of poly(2-oxazoline)-grafted chitin nanofibers.

Based on our previous work on successful gelation of poly(2-methyl-2-oxazoline)-grafted chitin nanofibers (ChNFs) with high polar media, in this study, we investigated the preparation and gelation behaviors of the ChNFs having different poly(2-alkyl-2-oxazoline) graft chains, that is, poly(2-methyl-2-oxazoline), poly(2-isopropyl-2-oxazoline), and poly(2-butyl-2-oxazoline), with various disperse media. The grafting was carried out by reactions of living propagating ends of poly(2-alkyl-2-oxazoline)s with amino groups present on the self-assembled ChNFs, which were obtained from a chitin ion gel. The products formed gels in the reaction mixtures, which could be converted into hydrogels. All the products with the three poly(2-alkyl-2-oxazoline) graft chains formed gels with high polar media. Besides, gelation of the product with poly(2-butyl-2-oxazoline) was observed by immersing it in relatively non-polar media such as benzyl alcohol, ethyl acetate, and toluene. The formation process of network structures by the grafting of poly(2-alkyl-2-oxazoline)s on ChNFs is proposed to induce gelation of the products.