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形態: カラー図版あり, Physical characteristics: Original contains color illustrations, Accepted: 2021-06-23, 資料番号: PA2210035000

Self-assembling polymer micelle (NanoVPA) composed of PEG-b-poly(vinyl valproate) was developed. IP administration of NanoVPA extended the bioavailability of VPA, which increased its therapeutic effect against epilepsy, reducing its adverse effects.

Combustion instabilities were investigated experimentally for a hydrogen-rich combustion in a model afterburner installed at the end of a high-enthalpy wind tunnel. Air was supplied at 0.3 MPa and 950 K. The combustion instabilities were studied with the time-resolved measurements of a near-infrared (NIR) emission from water molecules over 780 nm using a high-speed video camera. Pressure was also measured in the combustor. The pressure and the NIR images were analyzed by data-driven approach, which include the fast Fourier transform (FFT), the wavelet transform, the dynamic mode decomposition (DMD) and the Gaussian process latent variable methods (GP-LVM). Thermoacoustic instability was observed under a rich condition, and the amplitude of the pressure oscillation was the maximum at the overall equivalence ratio of approximately 2.4 or 2.7 as a result of the FFT. The combustion dynamics were investigated in detail for an experimental run at the equivalence ratio of 2.4. A pressure spectrogram indicated a flame–vortex interaction with a Strouhal number of 0.5 (2300 Hz), thermoacoustic instability (560 Hz), and their transitions with the wavelet transform. For NIR images, the same tendency was also observed in the spectrogram of the modes obtained by the Gabor-filtered DMD, which could clearly resolve the high-order harmonic modes of the flame–vortex interaction and the thermoacoustic instability. Furthermore, NIR images were analyzed with GP-LVM to study the evolution of the combustion dynamics in a three-dimensional latent space. Recurrence plots with the Euclidean distance function were used to visualize the evolutions of the combustion dynamics. A limit cycle behavior of the flame–vortex interaction was clearly observed, whereas the limit cycle of the thermoacoustic instability showed more complicated behaviors. The transition behaviors of the instabilities were observed in the recurrence plots in detail, indicating that the flame–vortex interaction excited the fourth harmonic mode of the thermoacoustic instability, followed by the basic mode.

Electrical power recovery from waste heat released during active cooling of 100–200 °C solids is of great importance because such situations are common in our world. However, the concept of simultaneous liquid cooling and electric power generation has been barely explored, apart from a few preliminary studies that showed power generation densities of only 0.05–0.5 W m−2. Here, we report a realistically useful power generation density of 10 W m−2 during liquid forced convection cooling of a 170 °C surface, thus demonstrating the feasibility of such a concept, based on thermogalvanic conversion with a redox couple. This was achieved by exploiting the fluid dynamics based on a microchannel concept, where a thin thermal boundary layer is formed on the hot surface, enabling both high cooling efficiency and large interelectrode temperature difference (>100 K). A new γ-butyrolactone-based high density electrolyte with sufficient stability against flame contact was used. Our combined cooling and thermogalvanic cell was able to continuously light LEDs and run air fans despite the small electrode area. Large values of heat transfer coefficient, up to 1160 W m−2 K−1, were achieved. At all flow rates tested, the electrical power obtained was 10 to 1000 times larger than the hydrodynamic pumping work required to force the liquid through the cell, that is, gain ≫1. Thus, this technological concept has been shown, for the first time, to be a feasible option to recover electrical power from the waste heat released during cooling of 100–200 °C surfaces, which are widespread in our world.

Maintenance of the pluripotent state of mesenchymal stem cells (MSCs) during in vitro expansion is an important factor for the successful proliferation of MSCs possessing high differentiation capacity. However, the differentiation potential of MSCs can easily be lost during in vitro expansion, particularly at late passages. Reactive oxygen species (ROS) are signaling molecules that help to maintain MSC function; however, excessive ROS generation can induce senescence and impair both the differentiation capacity and proliferation of MSCs. In this study, we have designed an amphiphilic block copolymer (redox copolymer), which possesses ROS scavenging capacity in the hydrophobic site. When this redox copolymer was coated on cell culture dishes coupled with human E-cadherin chimeric antibody (hE-cad-Fc), it had an antioxidative effect on cultured MSCs. We also confirmed that the redox polymer construct poly(ethylene glycol) tethered chain on the surface prevented nonspecific cell binding, whereas the co-immobilized surface allowed high adhesion of E-cadherin-positive MSCs. Interestingly, the intracellular ROS level was significantly decreased by the prepared cell culture dish, despite ROS being scavenged only on the surface of the dish, on the cell exterior. Consequently, the cultured MSCs retained high expression levels of pluripotency-associated genes, including SOX2.

We present the case of a 75-year-old woman who received CapeOX plus Bmab therapy(capecitabine, oxaliplatin, and bevacizumab)after primary excision for an unresectable advanced sigmoid colon cancer with remote metastasis. Pneumatosis intestinalis(i.e., the presence of isolated gas in the abdominal cavity)was revealed accidentally during a periodical imaging examination in the small intestine and transverse colon, albeit no subjective symptoms were reported. Owing to the absence of definitive evidence of pneumatosis intestinalis and gastrointestinal perforation, the patient was diagnosed with idiopathic pneumatosis intestinalis. Bmab was discontinued, and CapeOX therapy alone was continued after follow-up. Approximately 4 months later, pneumatosis intestinalis had completely disappeared. Bmab is a vascular endothelial growth factor antibody with well-known side effect of gastrointestinal-perforation. However, there have been few reports on pneumatosis intestinalis; to our knowledge, there have been no reports on pneumatosis intestinalis associated with colorectal cancer in Japan. Further, the report suggests the need for appropriate and immediate management of pneumatosis intestinalis following diagnosis.

Acute inflammatory conditions such as sepsis lead to fatal conditions, including multiple organ failure. Several treatments such as steroidal anti-inflammatory drugs are currently being investigated in order to decrease the blood cytokine level, which increases remarkably. However, any of these therapeutic treatments are not always reliable and effective; none have drastically improved survival rates, and some have mostly ended with failure. Reactive oxygen species (ROS) are signaling molecules responsible for the production of cytokines and chemokines that can mediate hyperactivation of the immune response called cytokine storm. In addition to the above-mentioned agents, various antioxidants have been explored for the removal of excess ROS during inflammation. However, the development of low-molecular-weight (LMW) antioxidants as therapeutic agents has been hampered by several issues associated with toxicity, poor pharmacokinetics, low bioavailability, and rapid metabolism. In the present study, we aimed to overcome these limitations through the use of antioxidative nanoparticles possessing 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) which are covalently conjugated to polymer. Although treatment with antioxidative nanoparticles alone did not eliminate bacteria, combined treatment with an antibacterial agent was found to significantly improve survival rate of the treated mice as compared to the control group. More importantly, the antioxidative nanoparticles reduced oxidative tissue injury caused by the bacterial infection. Thus, our findings highlighted the effectiveness of combination treatment with antioxidative nanoparticles and an antibacterial agent to prevent severe inflammation caused by bacterial infection.

Background MicroRNAs (miRNAs) encapsulated in the exosomes of plasma is of interest as stable and minimally invasive biomarkers for recurrence and prognosis in cancer patients. The aim of this study was to clarify the predictive and prognostic value of plasma exosomal microRNA-451a (miR-451a) in patients with pancreatic ductal adenocarcinoma (PDAC). Methods Microarray-based expression profiling of miRNAs derived from exosomes in the plasma of six PDAC patients with UICC stage II was employed to identify a biomarker to distinguish between patients with and without recurrence. For validation analysis, plasma exosome samples of other 50 PDAC patients were measured by TaqMan MicroRNA assays. Results In the miRNA microarray analyses, miR-451a showed the highest upregulation in the stage II patients who showed recurrence after surgery. In the relationship to pathological factors, exosomal miR-451a showed a significant association with tumor size and stage. The overall survival (OS) and disease-free survival rates (DFS) of the high exosomal miR-451a patients were significantly worse than those of the low miR-451a patients. In Cox proportional hazards model analysis, exsomal miR-451a showed significance to OS and DFS. Conclusions Plasma exosomal miR-451a levels may be a useful minimally invasive biomarker for the prediction of recurrence and prognosis in PDAC patients.

This cross-sectional study aimed to examine the oral hygiene behaviors in the general population and identify factors affecting oral hygiene behaviors and plaque removal efficacy. A survey was distributed to patients through 11 dental practices in Japan, and each patient’s plaque index score (PIS) was recorded. In total, 1184 patients participated (521 women and 660 men), with 84.04% using manual toothbrushes (MTBs) and 15.96% using electric toothbrushes (ETBs). ETB users had a significantly lower PIS compared to MTB users (p = 0.0017). In addition, a statistically significant difference in the PIS was detected in relation to the frequency of brushing per day (≥2 times) and time spent on brushing (≥1 min). Some MTB users spent less than 1 min brushing, while all ETB users spent at least 1 min brushing, and extended brushing periods significantly improved the PIS for the MTB users. MTB users tend to replace brush heads more frequently than ETB users, and the frequency of replacement affected the PIS significantly (p < 0.01) for the MTB users. The status of dental treatment (first visit, in treatment versus recall) also significantly affected the PIS (p < 0.01). The ETB was more effective than the MTB in terms of better plaque removal and reduced frequency of brush head replacement.

Background Surgical results of patients with resected distal cholangiocarcinoma (DCC) were evaluated to elucidate prognostic impact of the type of preoperative biliary drainage (PBD). Methods Eighty-eight patients with resected DCC were stratified into two groups according to the type of PBD: the percutaneous transhepatic biliary drainage (PTBD) group (n = 25) and the endoscopic biliary drainage (EBD) group (n = 63). Results Overall 5-year survival rate of the patients in the PTBD group was poorer than in the EBD group (24% vs. 52%, P = 0.020). On univariate analysis, PTBD, pancreatic invasion, perineural invasion, and lymph node involvement were significant prognostic factors for poor overall survival. On multivariate analysis, PTBD was the only significantly independent prognostic factor for poor overall survival. The incidence of liver metastasis was significantly higher in the PTBD group than in the EBD group (32.0% vs. 13.3%, P = 0.034). Conclusions PTBD should be avoided as much as possible in patients with DCC since the patients who underwent PTBD had poorer overall survival and higher incidence of liver metastasis than those who underwent EBD.

Forced convection cooling is important in numerous technologies ranging from microprocessors in data centers to turbines and engines; active cooling is essential in these situations. However, active transfer of heat or thermal energy under a large temperature difference promptly destroys the exergy, which is the free-energy component of thermal energy, and this issue has remained unaddressed. Herein, we describe a thermoelectrochemical conversion to partially recover presently lost exergy in forced convection cooling. We design a test cell in which an electrolyte liquid is forced through a channel formed between two parallel electrodes and the hot-side electrode simulates an object to be cooled. Our investigations show that the narrower interelectrode channels afford higher cooling and power generation performances. The mass transfer resistance is the most dominant type of resistance for all the conditions tested and the charge transfer kinetics is likely to be controlled by viscosity. The dependence of the generated power on the flow rate is caused by the change in the diffusion coefficient of redox species with temperature. As an evaluation measure for such forced-flow thermocells, the gain (\Lambda) --defined as the ratio of the generated power to the hydrodynamic pumping work required to force the liquid through the cell-- is introduced. \Lambda is above unity in a certain flow rate region. This demonstrates that such a system can generate more electric power than the pump work required to drive the liquid through the cell, suggesting its potential to partly recover presently lost exergy of thermal energy as electricity., Comment: 35 pages of main body + 20 pages of supplementary information

Tumor hypoxia, which is associated with poor prognosis in cancer, is known to lead to resistance to radiotherapy and anticancer chemotherapy. Impaired drug penetration in hypoxic regions has been recognized as an essential barrier to drug development in solid tumors. Here, we propose novel hypoxia-activated prodrugs, which drastically improved the penetration property of commonly used anticancer drugs in the hypoxic region. In this design, conventional anticancer drugs were modified with 2-nitroimidazole derivatives. The most important point of this study was that the prodrug designed formed a 6-membered cyclic structure to allow liberation of the active drug in the hypoxic region. This design markedly increased the selectivity of the hypoxia-targeted prodrug, resulting in significant reduction of adverse effects in the normoxic region. In vitro studies confirmed the selective activation under hypoxic conditions. In vivo studies showed drastic reduction of adverse effects associated with conventional anticancer drugs and improvement of the survival rate of mice. Immunofluorescence analyses confirmed that the designed prodrug had a tendency to localize at the hypoxic region, in contrast to conventional anticancer drugs, which localize only at the normoxic region.

During cell cultivation, excessively generated reactive oxygen species (ROS) affect cellular properties and functions. Although cell cultivation media contain several types of low-molecular-weight antioxidants, these small antioxidants are internalized into the mitochondria and they disrupt regulated redox balance. Here, we developed a novel biointerface that effectively eliminates ROS on a cell culture surface. Poly(ethylene glycol)-b-poly[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)aminomethylstyrene] (PEG-b-PMNT) was synthesized and covalently coated on a carboxyl group-activated culture dish using sec-amino groups on a PMNT segment followed by immobilization of anti-CD34 antibodies. CD34-positive hematopoietic stem progenitor cells (HSPCs) were separated from mice fetal liver cells using our polymer-coated cell culture dish. The separated HSPCs possessed intact mitochondrial membrane potential compared with those in the conventional cell cultivation system. In addition, the expression level of CD34 was maintained for an extended period on our culture dish with the antioxidative biointerface. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2080-2085, 2016.

Transdermal vaccination with cancer antigens is expected to become a useful anti-cancer therapy. However, it is difficult to accumulate enough antigen in the epidermis for effective exposure to Langerhans cells because of diffusion into the skin and muscle. Carriers, such as liposomes and nanoparticles, may be useful for the prevention of antigen diffusion. Iontophoresis, via application of a small electric current, is a noninvasive and efficient technology for transdermal drug delivery. Previously, we succeeded in the iontophoretic transdermal delivery of liposomes encapsulating insulin, and accumulation of polymer-based nanoparticle nanogels in the stratum corneum of the skin. Therefore, in the present study, we examined the use of iontophoresis with cancer antigen gp-100 peptide KVPRNQDWL-loaded nanogels for anti-cancer vaccination. Iontophoresis resulted in the accumulation of gp-100 peptide and nanogels in the epidermis, and subsequent increase in the number of Langerhans cells in the epidermis. Moreover, tumor growth was significantly suppressed by iontophoresis of the antigen peptide-loaded nanogels. Thus, iontophoresis of the antigen peptide-loaded nanogels may serve as an effective transdermal delivery system for anti-cancer vaccination.

During cell cultivation on conventional culture dishes, various events results in strong stresses that lead to the production of bioactive species such as reactive oxygen species (ROS) and nitric oxide. These reactive species cause variable damage to cells and stimulate cellular responses. Here, we report the design of a novel biocompatible surface that decreases stress by not only morphologically modifying the dish surface by using poly(ethylene glycol) tethered chains, but also actively scavenging oxidative stress by using our novel nitroxide radical-containing polymer. A block copolymer, poly(ethylene glycol)-b-poly[(2,2,6,6-tetramethylpiperidine-N-oxyl)aminomethylstyrene] (PEG-b-PMNT) was used to coat the surface of a dish. Differentiation of undifferentiated human leukemia (HL-60) cells was found to be suppressed on the polymer-coated dish. Notably, HL-60 cell cultivation caused apoptosis under high-density conditions, while spontaneous apoptosis was suppressed in cells plated on the PEG-b-PMNT-modified surface, because a healthy mitochondrial membrane potential was maintained. In contrast, low molecular weight antioxidants did not have apparent effects on the maintenance of mitochondria. We attribute this to the lack of cellular internalization of our immobilized polymer and selective scavenging of excessive ROS generated outside of cells. These results demonstrate the utility of our novel biocompatible material for actively scavenging ROS and thus maintaining cellular morphology.

Toponogov's triangle comparison theorem and its generalizations are important tools for studying the topology of Riemannian manifolds. In these theorems, one assumes that the curvature of a given manifold is bounded from below by the curvature of a model surface. The models are either of constant curvature, or, in the generalizations, rotationally symmetric about some point. One concludes that geodesic triangles in the manifold correspond to geodesic triangles in the model surface which have the same corresponding side lengths, but smaller corresponding angles. In addition, a certain rigidity holds: Whenever there is equality in one of the corresponding angles, the geodesic triangle in the surface embeds totally geodesically and isometrically in the manifold. ¶ In this paper, we discuss a condition relating the geometry of a Riemannian manifold to that of a model surface which is weaker than the usual curvature hypothesis in the generalized Toponogov theorems, but yet is strong enough to ensure that a geodesic triangle in the manifold has a corresponding triangle in the model with the same corresponding side lengths, but smaller corresponding angles. In contrast, it is interesting that rigidity fails in this setting.

Silica nanoparticles were synthesized via a sol-gel method in which tetraethyl orthosilicate was hydrolyzed by the alkaline core of the nitroxide radical-containing nanoparticle (RNP). The silica nanoparticles were successively captured in the RNP core to obtain silica/RNP nanocomposite (siRNP). Alternatively, siRNP was prepared using commercially available silica nanoparticles. The amount of elemental Si present in the siRNPs was controlled from 3 wt% to 12 wt%. Notably, the obtained siRNPs were stable in acidic media, whereas the starting RNP disintegrated immediately. Crosslinking of the RNP by the entrapped silica might improve stability of the siRNPs under such acidic conditions. Rebamipide was found to be stably encapsulated in the cores of the prepared siRNPs even under acidic conditions, probably due to the both basic environment of the cores and absorption tendencies of the entrapped silica. Under neutral to alkaline conditions, release of the rebamipide is accelerated, which is probably due to the repulsion between the anionic silica surface and the anionic rebamipide. Rebamipide-loaded siRNPs (rebamipide@siRNP) were orally administered to mice, and the plasma level of rebamipide was checked at predetermined time intervals, showing a significantly higher uptake of rebamipide in the plasma when compared to orally-administered free rebamipide. Because siRNP possesses nitroxide radicals in the core, it is confirmed that dextran sodium sulfate-induced colon inflammation was effectively suppressed by the oral administration of rebamipide@siRNP in mice.

The effects of the substrate temperature on the morphology of erbia films synthesized from a metal–ethylenediaminetetraacetic acid complex using flame spraying were evaluated. To begin with, we focused on the effect of substrate preheating on the thermal conductivity of the substrates. The morphology of the Er2O3 splats formed on various substrates (S50C and SUS304) preheated/precooled to different temperatures was investigated. The types of splats formed depended on the substrate used and its preheating/precooling temperature. The ratio of the disc-like splats on S50C (29–68%) and SUS304 (36–86%) increased with an increase in the preheating temperature between 0 and 100 °C. The wettabilities of different substrates (S50C, SUS304, Al–Mg alloy, and quartz) were also evaluated. Fourier transform infrared spectroscopy and thermogravimetry/differential thermal analysis measurements reveled that, ideally, deposition should be performed when no surface-adsorbed water is present on the substrate surface. Thus, it can be concluded that substrate preheating aids the deposition of erbia films synthesized from a metal–EDTA complex through flame spraying and that preheating is especially effective in the case of S50C substrates.

Several PEGylated proteins have been approved as therapeutic drugs. In many cases, PEGylated protein has been synthesized by the conjugation reaction between PEG possessing activated ester and amine(s) in the protein. This reaction, however, often causes inactivation of PEGylated proteins. In this report, we present a novel chemistry which enables the PEGylation of proteins under the mild reaction condition. PEGylated lysozyme prepared by the method developed increased the biological activity of the PEGylated lysozyme more than 20 times compared with the PEGylated lysozyme prepared by the conventional method.

A novel oligonucleotide delivery system that is based on oligonucleotide–nanoparticle conjugates has been described. Installed oligonucleotides were modified with the carbohydrate at the 3′ terminus, accordingly, constructed nanoparticles display clustered carbohydrates on their outer layer for the targeted delivery of oligonucleotides. The method for the construction of ligand-functionalized nanoparticle was simple and reproducible. The stability of the nanoparticles displaying clustered carbohydrates greatly increased in serum compared to nanoparticles without carbohydrates. In order to investigate the targetability of oligonucleotide–nanoparticle conjugates into primary hepatic parenchymal cells, freshly isolated rat hepatocytes were incubated with nanoparticles and the amount of internalized gold nanoparticles was evaluated by an inductively coupled plasma mass spectroscopy analysis. Nanoparticles displaying clustered carbohydrates internalized more efficiently than nanoparticles without carbohydrate modifications. In particular, the cellular uptakes of oligonucleotide-conjugated gold nanoparticle increased 1.7 ∼2.0-fold by galactose modification. Competition assay revealed that clustered galactose enhanced the internalization of the nanoparticle into primary hepatic parenchymal cells by a receptor-mediated process.

A new approach to the preparation of PEGylated [PEG: poly(ethylene glycol)] SiO 2 /Au hybrid nanoparticles was investigated. The synthesis of a PEGylated nanogel containing SiO 2 /Au hybrid nanoparticles was performed using matrix-catalyzed hydrolysis of tetraethyl orthosilicate, followed by the reduction of HAuCl 4 . UV–vis absorption of the prepared hybrid particles was obtained at 618 nm, which is a much longer wavelength than that of a nanogel containing only Au nanoparticles (523 nm). High-angle annular dark field images of the prepared particles observed using transmission electron microscopy and energy-dispersive X-ray spectroscopy confirmed the coexistence of Si and Au in the same particle. The presence of Si and Au in the prepared particles was also confirmed by inductively coupled plasma atomic emission spectroscopy. Dynamic light-scattering measurements of the particles in a highly ionic medium showed that they have high stability in both acidic and basic regions.

This study investigates the heat-shock properties of metal-oxide films synthesized from ethylenediamine tetraacetic acid (EDTA) complexes using conventional flame-spray equipment. An EDTA·Y·H powder was placed in the feed unit of the sprayer and transported by a flow of oxygen to the gun. The powder was sprayed using a mixture of H2 and O2 as the flame gas, producing a layer of yttrium oxide on a stainless steel substrate. XRD analysis was used to examine the crystal structure of the deposits and SEM imaging revealed the surface and cross-sectional microstructure. A cyclic thermal shock test was conducted and the deposited film was analyzed for the existence of cracks, deformation, and delamination. Although the number of cracks, crack lengths, and cracks per unit area increased due to heat shock, delaminations were not observed. The results show that the Y2O3 films have high thermal-shock resistance and are suitable for use as thermal barrier coatings.

The prevention of encapsulating peritoneal sclerosis (EPS) and the enhancement of dialysis efficiency are two important strategies that can improve the quality of life of patients undergoing peritoneal dialysis. We have thus far developed bionanoparticles that effectively scavenge reactive oxygen species (redox nanoparticles; RNPs). The objective of this study was to apply RNPs as a component of dialysate to reduce oxidative stress. Porous silica nanoparticles were combined with RNPs to enhance the effective adsorption capacity of low-molecular weight (LMW) compounds. The silica-containing RNPs (siRNPs) were confirmed to statistically decrease the level of creatinine and blood urea nitrogen in vivo. EPS model rats that underwent an intraperitoneal injection of chlorhexidine gluconate exhibited dysfunction of the peritoneal membrane. siRNP administration did not result in dysfunction of the peritoneal membrane. An LMW nitroxide compound, TEMPOL, also showed a weak peritoneal protective effect, although its efficiency was limited. No blood uptake of siRNPs was observed when they were administered into the peritoneal cavity. However, LMW-TEMPOL diffused into the blood stream, which might have decreased its effective concentration in the peritoneal cavity and led to adverse effects across the entire body. Considering these results, siRNPs are expected to be a new multi-functional nanomaterial for high performance peritoneal dialysis.

During cell cultivation, excessively generated reactive oxygen species (ROS) affect cellular properties and functions. Although cell cultivation media contain several types of low-molecular-weight antioxidants, these small antioxidants are internalized into the mitochondria and they disrupt regulated redox balance. Here, we developed a novel biointerface that effectively eliminates ROS on a cell culture surface. Poly(ethylene glycol)-b-poly[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)aminomethylstyrene] (PEG-b-PMNT) was synthesized and covalently coated on a carboxyl group-activated culture dish using sec-amino groups on a PMNT segment followed by immobilization of anti-CD34 antibodies. CD34-positive hematopoietic stem progenitor cells (HSPCs) were separated from mice fetal liver cells using our polymer-coated cell culture dish. The separated HSPCs possessed intact mitochondrial membrane potential compared with those in the conventional cell cultivation system. In addition, the expression level of CD34 was maintained for an extended period on our culture dish with the antioxidative biointerface. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2080-2085, 2016.

Two types of dithia[3.3]metacyclophanes having cofacial bisporphyrins were prepared. The flexible cyclophane having C2 methylene units as the spacer exhibits the large stability constant (108M-1) for binding of 1,4-diazabicyclo[2.2.2]octane (DABCO). Similar large affinity for DABCO is also observed for the rigid cyclophane having C10 methylene units.

The biocompatibility and body distribution of PEGylated polyamine nanogels composed of chemically cross-linked poly(2-N,N-(diethylamino)ethyl methacrylate) (PEAMA) gel cores surrounded by poly(ethylene glycol) (PEG) chains were investigated to evaluate their feasibility as drug nanocarriers for systemic administration. PEGylated nanogels with different cross-linking densities (1, 2, and 5 mol.%) were prepared to evaluate their biocompatibilities by in vitro cytotoxicity assay, hemolysis assay, and in vivo acute toxicity assay. The toxic effect of the PEGylated nanogels derived from polyamine gel cores was significantly reduced when the cross-linking density was increased, and those with a cross-linking density of 5 mol.% showed a remarkably high median lethal dose (LD50) value >200 mg kg−1,despite the abundance of amino groups in the core. One hour after intravenous injection the PEGylated nanogels were found to have been eliminated from the systemic circulation, and less than 1% of the injected dose (ID) remained in the bloodstream. To improve the blood circulation time by increasing the surface PEG density of the PEGylated nanogels post-PEGylation of the PEGylated nanogels (via the Menschutkin reaction between tertiary amines of the PEAMA gel core and bromobenzyl-terminated short PEG) was carried out. A biodistribution study of these post-PEGylated nanogels revealed that the blood circulation time of the nanogels was definitely prolonged as the PEG content was increased. Therefore, the precise design of PEGylated nanogels with increased cross-linking densities in their polyamine gel cores and increased surface PEG densities seems promising for systemic applications.

A novel oligonucleotide carrier which can scavenge ROS is described. The synthesized graft polymer is composed of a PEG segment and a TEMPO-containing hydrophobic segment for scavenging ROS. This graft polymer can form a PIC through electrostatic interaction with oligonucleotides such as siRNA. The amount of ROS was monitored by fluorescence measurements using H 2 DCFDA as a probe, and it was confirmed that the ROS level was effectively suppressed. The cellular uptake of PIC containing the fluorescence-labeled oligonucleotide was evaluated by fluorescence microscopy. Delivered siRNA suppressed the expression of the mRNA. The prepared graft copolymer is thus a promising candidate as a novel oligonucleotide carrier which also reduces ROS damage generated by cationic polymer carriers.

A novel synthesis method for oligonucleotides possessing a functional moiety at the 3'-terminus was established based on solid-phase synthesis. In order to install the functional group at the 3'-terminus of the oligonucleotide, a solid support possessing the functional group was prepared. A carbohydrate was employed in this study for the functionalization of the oligonucleotide. To prepare a glycosylated solid support, a novel glycosyl acceptor (2) was synthesized using 4,4-dihydroxymethyl-cyclopenta-1-ene as the starting compound. The glycosylation reaction proceeded smoothly (yield = 95%) to yield the suitable glycosylated compound (3). After 8 was immobilized on the solid support, it was subjected to solid-phase oligonucleotide synthesis by the standard phosphoramidite coupling method. An oligonucleotide possessing a sugar moiety at the 3'-terminus was obtained after the products were deprotected and cleaved from the solid support. The stability of the carbohydrate-modified oligonucleotide was greatly increased even in the serum buffer, indicating that the sugar moiety at the 3'-position improved the resistance against enzymatic degradation. This technique was also applied to RNA synthesis. Galactose-ended siRNA was prepared and was confirmed to possess enough ability, at a concentration of 10 nM, to regulate the expression of the target gene.

Oxidative stress caused by reactive oxygen species (ROS) occurs as events in which living tissues contact certain materials. These events include cell cultures and implantation of materials. Because of the high reactivity of ROS, they damage cells by oxidizing DNA, lipids, and proteins. Conversely, ROS also act as signaling molecules regulating cellular morphology. In particular, mitochondrial ROS are involved in the regulation of cellular physiology, including differentiation, autophagy, metabolic adaptation, apoptosis, and immunity. The balance between generation and elimination of ROS is essential for signaling pathways and proper cell function, and redox imbalance leads to cellular dysfunction and disturbs cellular homeostasis. To reduce oxidative stress, versatile antioxidants, including natural compounds, have been used; however, their poor bioavailability and pro-oxidant effects have limited the versatility of these antioxidants. Recent developments of antioxidative biointerfaces may represent a potent solution to this issue. Designed biointerfaces composed of polymer antioxidants eliminate excessive ROS at the interface between living tissues and materials, and do not disturb regulated redox balance inside cells, thus eliminating unexpected cell responses, such as inflammation and dysfunction.