Publications by authors named "Seiichi Ohta"

Pancreatic islet transplantation is an effective treatment for type I diabetes mellitus. However, many problems associated with pancreatic islet engraftment remain unresolved. In this study, we developed a hydrogel microwell device for islet implantation, fabricated by crosslinking gelatin-methacryloyl (GelMA) and 2-hydroxyethyl methacrylate (HEMA) in appropriate proportions.

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Nanoparticles (NPs) are anticipated to be used for various biomedical applications in which their aggregation has been an important issue. However, concerns regarding slightly aggregated but apparently monodispersed NPs have been difficult to address because of a lack of appropriate evaluation methods. Here, we report centrifugal field-flow fractionation (CF3) as a powerful method for analyzing the slight aggregation of NPs, using antibody-modified gold NPs (Ab-AuNPs) prepared by a conventional protocol with centrifugal purification as a model.

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Biomedical applications of nanoparticles (NPs) have attracted much attention. With the advancement of personalized medicine, researchers are now proposing the concept that the design of NPs needs to be optimized according to the individual patient. To realize this concept, an important question is how precisely we can tailor the physicochemical properties of NPs, such as size, shape, and surface chemistry, using current technology.

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Article Synopsis
  • * Upon exposure to UV light, this solution quickly transforms into a gel, with the gelation time decreasing significantly as the concentration of HA-DAZ and DPI increases, indicating enhanced performance for medical applications.
  • * The resulting HA-DAZ/DPI hydrogel not only exhibits strong adhesion and self-healing properties but also outperforms traditional fibrin glue in reinforcing tissue, as demonstrated in tests on porcine esophageal mucosa.
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Endoscopic submucosal dissection (ESD) for the treatment of esophageal mucosal lesions often leads to postoperative stenosis, causing difficulty in swallowing, known as dysphagia. In this study, we developed an cross-linkable powder composed of alginate, gelatin, transglutaminase (TG), and calcium chloride ions (Ca), which can be administered through a 1.5 m-long and 3.

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We developed a new muco-adhesive hydrogel composed of cationic guar gum (CGG) and boric acid (BA). The CGG-BA precursor solution of 0.5-2% w/v concentration exhibited fluidity at low pH (3-5), while gelation occurred within 1 min at physiological pH (7-8) conditions.

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The focus of this brief review is to describe the application of nanoparticles, including endogenous nanoparticles (e.g., extracellular vesicles, EVs, and virus capsids) and exogenous nanoparticles (e.

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Diffuse large B-cell lymphoma (DLBCL) is the most common type of malignant lymphoma. Although the first-line treatment, R-CHOP treatment, shows efficacy in approximately 80% of patients with DLBCL, some patients have refractory disease or relapse after the initial response to therapy, resulting in a significantly poorer prognosis. In this study, we developed a microRNA (miRNA) signature-based companion diagnostic model to predict the response of patients with DLBCL to R-CHOP treatment by integrating two clinical study datasets.

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Stimuli-responsive star polymers are promising functional materials whose aggregation, adhesion, and interaction with cells can be altered by applying suitable stimuli. Among several stimuli assessed, the potassium ion (K), which is known to be captured by crown ethers, is of considerable interest because of the role it plays in the body. In this study, a K-responsive star copolymer was developed using a polyglycerol (PG) core and grafted copolymer arms consisting of a thermo-responsive poly(-isopropylacrylamide) unit, a metal ion-recognizing benzo-18-crown-6-acrylamide unit, and a photoluminescent fluorescein -methacrylate unit.

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Article Synopsis
  • * Compression during sponge fabrication significantly boosts mechanical strength and improves handling, with different thicknesses impacting their effectiveness for bleeding control and preventing adhesions.
  • * The findings reveal that a 100 μm sponge is optimal for hemostatic efficiency while a 200 μm sponge excels in preventing adhesions, marking a breakthrough in balancing these two critical surgical needs.
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Conjugated polymer nanoparticles (Pdots) are expected to be novel bioimaging and sensing probes. However, the size tuning required to control biological interactions has not been well established. Herein, we achieved a size-tunable synthesis of Pdots ranging from 30 to 200 nm by controlling the hydrolysis rate of the stabilising agent and evaluated their cellular imaging properties.

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The industrial use of living organisms for bioproduction of valued substances has been accomplished mostly using microorganisms. To produce high-value bioproducts such as antibodies that require glycosylation modification for better performance, animal cells have been recently gaining attention in bioengineering because microorganisms are unsuitable for producing such substances. Furthermore, animal cells are now classified as products because a large number of cells are required for use in regenerative medicine.

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Carboxymethyl cellulose (CMC) is a promising material for moist wound healing, and silver loading onto CMC has been examined for anti-bacterial activity. In this study, we developed silver-loaded CMC nonwoven sheets with different counterions, namely sodium CMC (CMC-Na/Ag) and partially protonated CMC (CMC-H/Ag), to examine their anti-bacterial and wound-healing properties. Owing to the presence of counter protons, CMC-H/Ag showed slower water adsorption, dissolution, and Ag release than CMC-Na/Ag.

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Malignant pleural mesothelioma (MPM) is one of the intractable cancers that require a more effective therapeutic strategy for clinical practice. Hyaluronic acid (HA) nanogels were prepared by the chelation of cisplatin (CDDP) with different molecular weights of iminodiacetic acid-conjugated hyaluronic acid (HA-IDA). The sizes of the 100, 850, and 2000 kDa HA nanogels were 33, 43, and 44 nm, respectively.

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Intraperitoneal chemotherapy demonstrates potential applicability in the treatment of peritoneally disseminated ovarian cancer because the disseminated tumors can directly receive exposure to high concentrations of anticancer drugs. However, a considerable proportion of drugs, particularly micromolecular and hydrophilic drugs, such as cisplatin (CDDP), are often excreted through glomerular filtration for a short period. To effectively deliver CDDP into peritoneally disseminated ovarian cancer tissues, we developed an alginate (AL)-based hybrid system in which a CDDP-loaded AL nanogel (AL/CDDP-nanogel) was encapsulated in an injectable AL-hydrogel cross-linked with calcium ions.

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The blood-brain barrier (BBB) has hampered the efficiency of nanoparticle delivery into the brain via conventional strategies. The widening of BBB tight junctions via focused ultrasound (FUS) offers a promising approach for enhancing the delivery of nanoparticles into the brain. However, there is currently an insufficient understanding of how nanoparticles pass through the opened BBB gaps.

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Inorganic polyphosphate (PolyP) is a potential hemostatic material. However, the effect of PolyP chain length on the immune response and hemostatic function remains to be established. We have developed PolyP-conjugated hyaluronans (HA-PolyPs) with three different short-chain PolyPs ( = 13, 40, and 100 phosphate units).

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Postoperative peritoneal adhesions could cause pelvic pain, infertility, and bowel obstruction. In addition, adhesiolysis makes second surgery difficult. For the first time, we fabricated double-layered hydrogels in situ on the trauma surface via sequential double spray processes to prevent peritoneal adhesions.

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Pemetrexed (PMX) is a multi-targeted antifolate drug used for the treatment of malignant pleural mesothelioma (MPM) and non-small cell lung cancer. Hyaluronan (HA) in blood is well known as a disease marker of MPM. We synthesized PMX-conjugated hyaluronan (HA-ADH-PMX) for the first time to develop a novel anticancer chemotherapeutic agent.

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Background: Adhesion formation is a critical issue in surgery, particularly in hepatectomy. The present study aimed to develop a bilayer adhesion barrier comprising alginate (Alg) of different molecular weight (Mw). It was expected that a slowly dissolving layer remains on the cut surface, functioning as a physical barrier, whereas a rapidly dissolving layer widely distributes in the peritoneal cavity to prevent de novo adhesions.

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Thermoreversible gelation and liquid-liquid phase separation are theoretically studied for the gels of polyfunctional molecules (polymers) whose network junctions are formed by complexation of functional groups on the polymer chains with added metal ions. Phase diagrams on the polymer/ion/solvent concentration plane, including both sol-gel transition lines and liquid-liquid phase separation lines (spinodals), are derived as functions of the polymer functionality, molecular weight, maximum coordination number of ions, and temperature. Binding isotherms of ions are also calculated as functions of the ion concentration.

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Article Synopsis
  • The extracellular environment plays a crucial role in influencing how cells grow, develop, and function, especially during processes like embryo development, wound healing, and tumor growth.
  • Researchers created new alginate microcapsules that can attach thiol-containing peptides directly within the capsules when exposed to maleimide-modified alginate, even in lab conditions that mimic the body's serum.
  • This innovative method promotes faster cell growth and differentiation by specifically delivering functional peptides to encapsulated cells, offering a promising, cost-effective solution for tissue engineering and other biomedical applications in the future.
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We developed a facile fabrication method for preparing poly(ethylene glycol)(PEG)-coated poly (lactic-co-glycolic acid) (PLGA) microspheres with homogeneous size distribution via a combination of mPEG-b-PLGA and Shirasu Porous Glass membrane emulsification. Subsequently, extracellular matrix (ECM) degrading enzymes, collagenase (COLase) or hyaluronidase (HAse) were loaded into the microspheres. The obtained microspheres exhibited a sustained release of COLase or HAse over 10 days.

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Studies into the interactions of serum proteins with nanoparticles are typically performed using nanoparticles that are larger than the size of proteins. Due to this size discrepancy, adsorbed proteins are commonly depicted as a globular structure surrounding a nanoparticle. Here, we asked how we should view nanoparticle-protein complexes when the nanoparticles are of similar size or smaller than the proteins with which they interact.

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We have developed microsized perfluorocarbon (PFC) emulsions with different sizes as artificial oxygen carriers (OCs) via Shirasu porous glass membrane emulsification. Monodispersed PFC emulsions with narrow size distribution were obtained. By changing the membrane pore size, we were able to precisely control the size of emulsions and fabricate emulsions similar in size to human red blood cells.

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