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The unique properties and morphology of liquid marbles (LMs) make them potentially useful for various applications. Non-edible hydrophobic organic polymer particles are widely used to prepare LMs. It is necessary to increase the variety of LM particles to extend their use into food and pharmaceuticals. Herein, we focus on hydrophobically modified gelatin (HMG) as a base material for the particles. The surface tension of HMG decreased as the length of alkyl chains incorporated into the gelatin and the degree of substitution (DS) of the alkyl chains increased. HMG with a surface tension of less than 37.5 mN/m (determined using equations based on the Young-Dupré equation and Kaelble-Uy theory) successfully formed LMs of water. The minimum surface tension of a liquid in which it was possible to form LMs using HMG particles was approximately 53 mN/m. We also showed that the liquid-over-solid spreading coefficient S_(L/S) is a potential new factor for predicting if particles can form LMs. The HMG particles and the new system for predicting LM formation could expand the use of LMs in food and pharmaceuticals.

This research reports the success of the fabrication of hydrophobically modified chitosan cryogel. Chitosan was modified with alkyl groups through reductive animation. By varying the alkyl chain length and the substitution degree, the resulting cryogel could be optimized for strength, and the adsorption and release of hydrophobic dye, a model for hydrophobic medicines. By optimizing these attributes, the hydrogel was found to have the potential as a biomedical material.

Drug delivery systems (DDS) are devices able to adsorb therapeutic drugs in vitro before being either injected or surgically implanted into the body before releasing the drugs in vivo. Hydrogels are interesting for DDS researchers as they mimic soft tissue and can absorb large quantities of liquid. This research reported the successful fabrication of hydrophobically modified agarose (HMA) as well as the creation of a novel approach to the formation of hydrophobically modified agarose cryogels. By activating the hydroxyl groups in agarose, hydrophobic modification could occur through the bonding of the activated hydroxyl groups and the amines in fatty aldehydes. It was found that HMA was insoluble in water, and as such a new method of cryogel creation was produced using dimethyl sulfoxide. Further testing of HMA cryogels showed that cell adhesiveness and cytotoxicity were low. Adsorption tests showed that HMA cryogels had the ability to adsorb larger amounts of hydrophobic dye than unmodified agarose cryogels and that the release of the hydrophobic dye from HMA cryogels could be controlled. These results showed that the HMA cryogels made using this novel approach have the potential to be used as drug delivery systems.

Hypothesis In our previous study, we prepared millimeter-sized spherical hard capsules by solidifying droplets of liquid monomer or polymer solution placed on superamphiphobic surface. Application of liquid marbles in place of the naked droplets for capsule preparation has a great potential to increase encapsulation efficiency of high volatile ingredients. Further, interfacial thermodynamic prediction of internal configuration of capsules from spreading coefficients may be effective to prepare core/shell capsule. Experiments Droplets of liquid monomer containing a volatile ingredient were rolled on superamphiphobic powders to prepare liquid marbles and solidified by photopolymerization. For preparation of core/shell capsules, the liquid marbles injected with an immiscible water droplet were also solidified. Findings A volatile ingredient could be encapsulated with higher efficiency than our previous method. Interfacial thermodynamic prediction of internal configuration of capsules from spreading coefficients indicated successful formation of core/shell capsules. However, photopolymerization of the liquid marbles in a static condition resulted in formation of not only core/shell capsules but also acorn-type capsules. Furthermore, the core/shell capsules were distorted and the shell thickness was not uniform. Rolling of the liquid marbles, which generated centrifugal force inside of the liquid marbles, was effective to prepare spherical capsules with highly uniform shell thickness.

Hydrogels have become popular as drug carriers. Controlled release of the drugs from hydrogels can reduce dosage, inducing prevention of side effects. However, the hydrophilicity of hydrogels interferes with controlled release of hydrophobic drugs such as anticancer agents or antibiotics. In this study, we developed hydrophobically-modified gelatin (HMG) hydrogel, which was cross-linked only by hydrophobic interaction. HMG does not require toxic chemical cross-linkers to form hydrogel. In addition, the HMG hydrogel has hydrophobic chambers in its structure which hydrophobic drugs can adsorb to and desorb from. In order to control the amount of hydrophobic drugs adsorbed into the hydrogel, hydrophobic alkyl chains with different lengths (C4-C12) were incorporated into gelatin molecules. Uranine was used as a model for hydrophobic drugs. The adsorption test exhibited that the amount of uranine adsorbed in HMG hydrogels could be controlled by varying hydrophobic alkyl chain length and that the drug could be released in a controlled manner. These results show that HMG hydrogels are promising carriers of hydrophobic drugs.

Over the last three decades, the protocols and procedures of the DNA amplification technique, polymerase chain reaction (PCR), have been optimized and well developed. However, there have been no significant innovations in processes for sample dispersion for PCR that have reduced the amount of single-use or unrecyclable plastic waste produced. To address the issue of plastic waste, this paper reports the synthesis and successful use of a core-shell bead microreactor using photopolymerization of a composite liquid marble as a dispersion process. This platform uses the core-shell bead as a simple and effective sample dispersion medium that significantly reduces plastic waste generated compared to conventional PCR processes. Other improvements over conventional PCR processes of the novel dispersion platform include increasing the throughput capability, enhancing the performance and portability of the thermal cycler, and allowing for the contamination-free storage of samples after thermal cycling.

Pancreatic cancer is one of the tumors with the worst prognosis, with the 5-year survival rate reported to be 6%. The number of patients suffering from pancreatic cancer in recent years has continued to increase dramatically. Carbohydrate antigen 19-9 is an established biomarker of pancreatic cancer, but it does not have sufficient ability to detect pancreatic cancer at an early stage. We focused on angiopoietin-like protein 2 (ANGPTL2), which has been reported to be related to chronic inflammation and Type 2 diabetes mellitus. In this study, whether ANGPTL2 can detect early pancreatic cancer was evaluated. It was found that the concentration of serum ANGPTL2 was significantly higher in pancreatic cancer patients and tumor stage 0-I patients than in healthy individuals (5.84 ± 1.82 ng/mL vs 3.61 ± 0.64 ng/mL; P < 0.001) (5.68 ± 0.79 ng/mL vs 3.61 ± 0.64 ng/mL; P = 0.010). In addition, the diagnostic capability of serum ANGPTL2 levels for pancreatic cancer was evaluated using receiver operating characteristic (ROC) curve analysis. The area under the ROC curve (AUC) for ANGPTL2 was 0.906 (95% confidence interval (CI): 0.815-0.997; P < 0.001). To identify the risk factors for pancreatic cancer, multivariate regression models were used. Ten factors were included, and increasing age (odds ratio (OR), 1.318, 95% CI, 1.058-1.642; P = 0.014) and high ANGPTL2 levels (OR, 22.219, 95% CI, 1.962-251.659, P = 0.012) were found to be independent risk factors for pancreatic cancer, with ANGPTL2 having the strongest relationship. In addition, serum ANGPTL2 levels were strongly correlated with inflammatory markers, with blood sugar levels showing the strongest correlation with serum ANGPTL2 levels. In conclusion, this study suggested that an elevated serum ANGPTL2 level has the potential to be a biomarker capable of early detection of pancreatic cancer, and it was correlated with inflammation of the pancreas and the risk of developing diabetes mellitus.

Moist wounds were known to heal more rapidly than dry wounds. Hydrogel wound dressings were suitable for the moist wound healing because of their hyperhydrous structure. Chitosan was a strong candidate as a base material for hydrogel wound dressings because the polymer had excellent biological properties that promoted wound healing. We previously developed physically-crosslinked chitosan cryogels, which were prepared solely by freeze-thawing of a chitosan-gluconic acid conjugate (CG) aqueous solution, for wound treatment. The CG cryogels were disinfected by immersing in 70% ethanol before applying to wounds in our previous study. In the present study, we examined the influence of autoclave sterilization (121°C, 20 min) on the characteristics of CG cryogel because complete sterilization was one of the fundamental requirements for medical devices. We found that optimum value of gluconic acid content of CG, defined as the number of the incorporated gluconic acid units per 100 glucosamine units of chitosan, was 11 for autoclaving. An increased crosslinking level of CG cryogel on autoclaving enhanced resistance of the gels to enzymatic degradation. Furthermore, the autoclaved CG cryogels retained favorable biological properties of the pre-autoclaved CG cryogels in that they showed the same hemostatic activity and efficacy in repairing full-thickness skin wounds as the pre-autoclaved CG cryogels. These results showed the great potential of autoclavable CG cryogels as a practical wound dressing.

The effect of cooling condition on the intergranular corrosion resistance of UNS S32506 duplex stainless steel was investigated by means of Huey test and microstructural observation. It was found that quenching at a temperature below 800 °C after air cooling at a fixed rate from solutionization temperature enhances the intergranular corrosion rate. No precipitation has been found at all cooling conditions. Formation of Cr-depletion zone on the γ phase side of the α/γ interface due to local chemical change accompanying α-γ phase transformation during air cooling is responsible for the intergranular corrosion degradation of the UNS S32506 duplex stainless steel.

Immobilization of microbial cells in hydrophobic resin capsules for various bioprocesses such as metabolite production allows for greater efficiency than use of free cells. Conventional emulsion solvent evaporation (ESE) technique can seriously damage microbial cells in capsules by organic solvents. To overcome this issue, we applied an air drying technique on superamphiphobic surfaces for encapsulating microbial cells. Amphiphobic surface means water- and oil-repellent surface. Our data show that air drying allows capsules to be prepared without using water, and reduces cell contact with organic solvents. These features of air drying contribute to significant reduction of cell damage caused by solvents compared with ESE. Our results show that air drying is a promising technique for immobilization of living microbial cells in hydrophobic resin capsules.

Gelatin molecules have been chemically crosslinked using potentially cytotoxic reagents to prepare stable hydrogels. Hydrophobic interaction is a means of forming physical crosslinks that is a good candidate for enhancing the stability of gelatin hydrogels without using cytotoxic chemicals. In this study, we proposed a new method to fabricate hydrogels from hydrophobically-modified gelatin (HMG) with high content of hydrophobic segments. HMG was first dissolved in dimethyl sulfoxide and poured into a vial with the desired shape. After the solution was freeze-dried, the solid construct was hydrated. The HMG hydrogel containing basic fibroblast growth factor promoted angiogenesis in vivo, indicating that the positively charged hydrophilic growth factor formed an electrostatic complex with negatively charged HMG hydrogel and was gradually released in vivo with the degradation of the hydrogel. In addition, we showed that the hydrophobic segments of HMG enhanced the adsorption of fluorescein sodium, a model for hydrophobic therapeutic agents, to the hydrogel through hydrophobic interaction. Furthermore, in vitro experiments indicated that the hydrophobic agents would be released from the hydrogel in a controlled manner in vivo. These results show that the HMG hydrogel has significant potential as a carrier for both charged hydrophilic drugs and hydrophobic drugs.

Microcapsules and porous polymer particles containing extractants, which are functional molecules to extract target ions or molecules by specific interaction using in solvent extraction process, are expected to be an effective separation medium of various substances from aqueous solution in hydrometallurgical process of harmful or valuable metals and in environmental protection processes from various pollutants. The preparation method, encapsulating materials and application area of these materials has been developed and extended in recent years. Recent topics of this field was been presented. The research on the polymeric particles for separation medium investigated by authors was introduced and showed the structural effect of the polymeric particles containing extractant on the separation performance of metal ion and chiral separation of amino acids by porous particles impregnated with phospholipids.

Novel organic-inorganic hybrid materials were developed as LED sealants. Polysilsesquioxane with an -SH group (PSQ-SH) and acrylic monomer were selected as the inorganic and organic components, respectively. Trimethylolpropane trimethacrylate (TRIM), which is a trifunctional monomer, was selected as an acrylic monomer, and curing of the material was performed by the thiol-ene reaction. The LED was sealed using the prepared PSQ-SH/TRIM hybrid material (PTH), and a light emission test was performed. However, cracks occurred in the hybrid material during lighting. Therefore, ditrimethylol propane tetraacrylate (DTMPTA), which is a tetrafunctional monomer, was selected for the first time to prepare a PSQ-SH/DTMPA hybrid material (PDH) in order to enhance the strength and heat resistance of the material. The characteristics of the novel PDH were evaluated and compared with those of PTH. Specifically, the heat resistance was evaluated by confirming the onset temperature of weight reduction using thermogravimetry-differential thermal analyzer (TG-DTA) analysis, and the mechanical strength was also evaluated by bonding the glass substrates with a hybrid material and measuring the sealing strength. In conclusion, it was possible to suppress crack generation during lighting by using PDH instead of PTH in the light emission test.

With the recent advances in medical technologies, gastric cancer can often be removed with minimally invasive surgical techniques when identified early. Surgery must remove all gastric cancer, since residual cancerous tissue may lead to recurrence. Resected cancerous tissues are pathologically evaluated to determine whether all cancerous areas have been removed, but such assessments are rarely straightforward, and cancer markers could inform such pathological evaluations of cancer. An ideal marker would be identifiable in formalin-fixed paraffin-embedded (FFPE) tumor tissue. The first objective of the present study was to compare levels of angiopoietin-like protein 2 (ANGPTL2) in cancerous and noncancerous areas of FFPE tissues to determine whether ANGPTL2 is a marker relevant to the pathological diagnosis of cancer. The second objective was to evaluate whether ANGPTL2 mRNA is useful as a marker of the extent of vascular invasion of gastric cancer. Out of the 15 patients studied, 12 had a higher ANGPTL2 mRNA levels in cancerous areas compared with noncancerous areas. This finding indicated that ANGPTL2 mRNA is useful as a biomarker for identifying cancerous areas in FFPE tissues, at least for male patients. Spearman's rank correlation analysis showed a significant correlation between the ANGPTL2 mRNA level and the degree of vascular invasion of cancer (r=0.66; P=0.01). In receiver operating characteristic curve analysis of the association between the ANGPTL2 mRNA level and the degree of vascular invasion, the area under the curve was 0.92 (95% confidence interval, 0.78-1.00; P=0.01), indicating a significant association. The present study demonstrates that ANGPTL2 mRNA in FFPE tissues is a potential biomarker that informs the pathological diagnosis of gastric cancer and that ANGPTL2 mRNA may be predictive of vascular invasion, which is an indicator of metastasis in gastric cancer.

Magnetic manipulation of paramagnetic particles had great potential for efficient bioprocessing. In this study, we stirred microliter-volume water droplets formed on a superhydrophobic surface as micro-bioreactors by using paramagnetic magnetite microparticles manipulated by an external magnetic field. We showed that magnetite microparticles in the droplets spontaneously formed rod-like aggregates, which were like commercial stir bars, in an external magnetic field and spun with rotating of magnetic field. Increasing the rotating rate of the magnetic field and increasing the concentration of the microparticles caused the microparticles to fixate at the air/water interface of the droplets and their rotation at the interface with rotating of magnetic field. The active mixing enhanced the enzyme reaction and microorganism proliferation in the droplets. These results demonstrated that manipulating the magnetite microparticles by an external magnetic field efficiently mixed the small droplets as micro-bioreactors.

Design of porous scaffolds in tissue engineering field was challenging. Uniform immobilization of cells in the scaffolds with high porosity was essential for homogeneous tissue formation. The present study was aimed at fabricating uniformly cell-laden porous scaffolds with porosity >74% using the gas-in-liquid foam templating technique. To this end, we used gelatin, microbial transglutaminase and argon gas as a scaffold material, cross-linker of the protein and porogen of scaffold, respectively. We confirmed that a porosity of >74% could be achieved by increasing the gas volume delivered to a gelatin solution. Pore size in the scaffold could be controlled by stirring speed, stirring time and the pore size of the filter through which the gas passed. The foaming technique enabled us to uniformly immobilize a human hepatoblastoma cell line in scaffold. Engraftment efficiency of the cell line entrapped within the scaffold in nude mice was higher than that of cells in free-form. These results showed that the uniformly cell-laden porous scaffolds were promising for tissue engineering.

Spherical capsules have been used in various fields because of their many advantages. In many industrial applications, hydrophobic hard resins (e.g., polyacrylate, epoxy and polystyrene) are used as a shell material for stable packaging of ingredients within capsules. However, it is difficult to encapsulate ingredients in such capsules without loss by conventional techniques. The purpose of this study was to encapsulate hydrophobic ingredients within polyacrylate resin capsules with ultrahigh efficiency. In our methodology, a small volume of resin monomer solution containing the ingredients was first placed on a superoleophobic material and the resulting spherical droplets were then solidified by polymerization of the monomer. Doxorubicin (an anticancer drug), α-tocopherol (an antioxidant) and tetradecane (a phase change material used for heat storage) could be encapsulated in spherical hard capsules with almost no loss by heat and photopolymerization. We showed that tetradecane in the capsules had almost identical thermal properties to pure tetradecane. These results demonstrate that our technique is promising for encapsulation of hydrophobic ingredients in hard resin capsules.

Colorectal cancer (CRC) is the third most common malignancy worldwide. Disease progression leads to its spread to other organs, such as the liver, and is associated with higher mortality rates. Early CRC detection is therefore crucial for maximizing the chances of complete cure. The measurement of serum-based tumor biomarkers has shown great potential for the detection of CRC. In this study, we investigated the feasibility of using angiopoietin-like protein 2 (ANGPTL2) as a candidate biomarker for CRC. We first investigated ANGPTL2 expression in 7 CRC cell lines, among which Colo320, NCC-CoCK-115P, Caco-2 and Colo205 exhibited comparatively high ANGPTL2 expression. The serum levels of ANGPTL2 in CRC patients (3.45±1.30 ng/ml) were higher compared with those in healthy controls (2.74±0.64 ng/ml) (P

Globally, gastric cancer is one of the most common types of cancer and is the second leading cause of cancer‑induced mortality. Early detection of gastric cancer is able to contribute to a reduction of its mortality. For early detection, more specific and sensitive biomarkers than the classic biomarkers, including carcinoembryonic antigen, carbohydrate antigen 19‑9 and C‑reactive protein, are required. The present study focused on the evaluation of the potential of angiopoietin‑like protein 2 (ANGPTL2) as a novel biomarker for gastric cancer. The expression levels of ANGPTL2 in undifferentiated and differentiated gastric cancer cell lines (HGC‑27 and MKN7, respectively) were therefore investigated. Additionally, ANGPTL2 levels in the serum of gastric cancer patients were compared with those of healthy individuals to evaluate the possibility of the protein as a predictive biomarker for gastric cancer. It was established that the expression levels of ANGPTL2 mRNA and protein were higher in undifferentiated HGC‑27 cells than those in differentiated MKN7 cells. In a patient study, it was indicated that the levels of ANGPTL2 in the serum of gastric cancer patients were higher than those in healthy controls. The diagnostic performance of ANGPTL2 was assessed by constructing a receiver operating characteristic (ROC) curve and was evaluated by calculating the area under each ROC curve (AUC). For the discrimination of patients with gastric cancer from healthy individuals, the AUC for ANGPTL2 was 0.774 (P=0.005) (95% confidence interval, 0.615‑0.933). These results suggested that ANGPTL2 was a potential biomarker for gastric cancer.

Microscopic, fiber-shaped cell aggregates, have been used as building blocks for fabricating macroscopic three-dimensional tissue architectures, in the field of tissue engineering. In this study, we examined the occurrence of necrotic regions in the most widely used, fiber-shaped cell aggregates, approximately 100 μm in diameter. Alginate hydrogel hollow microfibers were used as templates for the cell aggregates. We demonstrated negligible necrotic region formation occurred in the cell aggregates formed in the hollow microfibers. Furthermore, we improved on previously-reported methods for preparing the hollow microfibers to avoid common microfiber tangling during the fiber preparation process.

Agarose gels were superior to calcium-alginate gels for immobilizing Rhodococcus erythropolis CS98 strain to remove cesium from water. Suitable incubation time of the immobilized cells in cesium solutions, cell number in the gels and volume ratio of the cesium solution to the gels for efficient cesium removal were identified.

Collagen extracted from tissues by alkaline treatment has a di erent isoelectric point (pI≈5) than the commonly-used acidor pepsin-treated collagen (pI≈9). In this study, the feasibility of using the alkali-treated collagen (AC) as a carrier of basic broblast growth factor (bFGF) for enhancement of angiogenesis was examined. AC hydrogels were prepared by chemically crosslinking AC molecules using glutaraldehyde (GA). We investigated the e ects of GA concentration in AC gels on the degree of swelling of the gels in an aqueous environment and on the in vivo degradation rate of the gels. Horse cytochrome c (pI: 9.6), a model for bFGF (pI: 9.6), electrostatically adsorbed to the AC gels. Subcutaneously-implanted AC gels incorporating bFGF led to enhanced angiogenesis compared with bFGF-free gels. Thus, AC gels incorporating bFGF appear to be useful materials for (i) the enhancement of angiogenesis and (ii) tissue engineering sca olds.

Injectable hydrogels have advantages over pre-formed hydrogels in biomedical applications. In our previous study, we showed usefulness of sugar beet pectin (SBP) as an injectable gel material. However, the in vivo biodegradability of the gels was low because animals lack suitable hydrolytic enzymes of SBP. In this study we developed SBP-based injectable gels with higher in vivo biodegradability than the previous SBP gels by incorporating biodegradable gelatin into the latter. An aqueous solution with dissolved SBP and gelatin rapidly (< 1 min) formed gels through a horseradish peroxidase-catalyzed oxidative coupling reaction between feruloyl moieties on the SBP molecules and phenolic moieties on the gelatin molecules. Gelation time and mechanical properties of the gels were tunable by adjusting the polymer concentrations. The gels containing doxorubicin, an anti-cancer drug, successfully suppressed the growth of a solid tumor created by subcutaneous injection of mouse melanoma B16F1 cells into nude mice. These results indicate that injectable and biodegradable SBP/gelatin gels are useful in biomedical applications.

Tissue engineering has great potential to create tissue and organ constructs of clinically relevant sizes. The main obstacle to creating volumetric tissue constructs was the lack of a technique for fabricating dense and perfusable vascular networks in vitro within the constructs. In significant efforts to develop such a technique, hydrogels have been used as materials for templates and support architectures of vascular-like networks because of their excellent properties, such as high biocompatibility, flexibility, and the rapid diffusion of oxygen and nutrients compared with solid materials. Herein, we reviewed current hydrogel-based strategies to fabricate vascular-like networks in vitro. The first strategy was based on the ability of vascular endothelial cells to form capillary-like tubes. The second was an engineering-based strategy that can be categorized into templating, modular assembly, microfabrication, rapid prototyping technique, and their hybrid model. Finally, we discussed future directions in tissue engineering for creating transplantable and volumetric constructs.

Growth factor (GF)-immobilizable materials were developed as a practical hepatocyte transplantation method for reconstructing a tissue-like structure in liver tissue engineering. Two GF-immobilizable scaffolds, namely single hepatocyte-embedded, heparin-immobilized, collagen-gel-filled polyurethane foam, and hepatocyte spheroid-embedded, heparin-immobilized, collagen-gel-filled polyurethane foam were developed by covalently incorporating heparin into collagen gel, using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide for hepatocyte transplantation. Seventy percent partial hepatectomy (PH) was performed at the same time after hepatocyte transplantation. Angiogenesis efficiency and viability of transplanted cells are discussed in terms of normalized hemoglobin content, nuclear density and histological observations after transplantation. In summary, the normalized hemoglobin content and viability of transplanted cells were higher in GF-immobilized scaffolds with PH pretreatment than in the other scaffolds with/without PH pretreatment. These materials have the potential for in vivo hepatocyte transplantation, as GFs released from remnant liver were easily incorporated into the heparin-immobilized collagen gel system. These GF–heparin complexes may promote the survival of embedded cells. Furthermore, the transplantation of spheroids promoted increased angiogenesis compared with hepatocytes, and resulted in sufficient vascularization for cell survival.

The construction of a functional liver-tissue equivalent using tissue engineering is a very important goal because the liver is a central organ in the body. However, the construction of functional organ-scale liver tissue is impossible because it requires a high-density blood vessel network. In this study, we focused on decellularization technology to solve this problem. Decellularized liver tissue with a fine vascular tree network template was obtained using Triton X-100. The distance between each vascular structure was less than 1 mm. Endothelialization of the blood vessel network with human umbilical vein endothelial cells (HUVECs) was successfully performed without any leakage of HUVECs to the outside of the vessel structure. Furthermore, hepatocytes/spheroids could be located around the blood vessel structure. This study indicates that decellularized liver tissue is a potential scaffold for creating a practical liver tissue using tissue engineering technology.

Poly(vinyl alcohol) (PVA) gel beads crosslinked with sodium phosphate or boric acid have been widely utilized for microorganism immobilization. We previously utilized sodium sulfate to induce crosslinking of PVA for preparing immobilized yeast cells in PVA beads. In this study, we compared the toxicities of sodium sulfate and conventional crosslinkers (sodium phosphate and boric acid) toward Pseudomonas putida F1 (PpF1) and the performance of the corresponding immobilized PpF1 in PVA beads. The toxicity of sodium sulfate to PpF1 was lower than those of the conventional crosslinkers. PVA–sodium sulfate beads showed a higher gel fraction of PVA and a lower swelling ratio in water than PVA–sodium phosphate beads, which indicates that the former had higher stability. PpF1 immobilized in the PVA–sodium sulfate beads completely degraded the pollutant trichloroethylene (TCE) with an initial concentration (0.42 mg/l) within the most common range of TCE concentration found in contaminated field sites.

Burkholderia cepacia lipase was immobilized in silicates forming from n -butyl-substituted precursors within a silica monolith from methyl-substituted precursors. The resultant preparation gave about 12 times higher rates of transesterification of ( R , S )-1-phenylethanol with vinyl acetate and an approximately two-fold increase in the enantioselectivity toward ( R )-1-phenylethanol, as compared to a non-immobilized counterpart. The highest enzymatic activity and enantioselectivity (reaching 250) were found at a low water activity of 0.11. The continuous-flow kinetic resolution of ( R , S )-1-phenylethanol was successfully conducted using lipase-immobilized silica monolith micro-bioreactors with various inside diameters ranging from 0.25 to 1.6 mm. The reactor performance during continuous operation was consistent with the prediction from the batch reactor. A steady state conversion of 40% and enantiomeric excess more than 98% were maintained over a time period of 15 days.

In situ gellable hydrogels are more attractive in many biomedical and biopharmaceutical applications than pre-formed hydrogels because they can be implanted simply by injection and allow homogeneous incorporation of bioactive materials. In this study, the potential suitability of in situ gellable sugar beet pectin (SBP) for biomedical and biopharmaceutical applications was investigated. SBP aqueous solution gelled within 1 min after addition of appropriate amounts of horseradish peroxidase (HRP) and H 2 O 2 via HRP-catalyzed oxidative coupling reaction of feruloyl groups on SBP molecules. The resultant gels gradually degraded under simulated physiological condition. L929 fibroblast cells encapsulated in the gels were scarcely damaged during the gelation process. A subcutaneously injected mixture of SBP, HRP and H 2 O 2 solutions successfully gelled, and the gel did not induce necrosis in the surrounding tissue 1 week after implantation. These results demonstrate that the in situ gellable SBP gels are useful for biomedical and biopharmaceutical applications.

Poly(vinyl alcohol) (PVA) hydrogel beads crosslinked with boric acid have been widely utilized for microorganism immobilization. However, a drawback of the method for preparing conventional PVA–boric acid beads is that microorganisms enclosed in the PVA matrix are drastically damaged by boric acid during the bead preparation process. In the present study, we utilized sodium sulfate as an inducer for crosslinkage of PVA for fabricating microorganism-enclosing PVA hydrogel beads to avoid the drastic decrease in cell viability caused by saturated boric acid solution. First, PVA was crosslinked by boric acid for a short time. Subsequently, the molecules were further crosslinked using sodium sulfate. X-ray diffraction analysis indicated that sodium sulfate promoted crystallization of PVA, which contributed to gelation of PVA solution. Moreover, the toxicity of sodium sulfate to Saccharomyces cerevisiae was lower than that of boric acid. The stability in water of the PVA–sodium sulfate beads was superior to the stability of PVA–boric acid beads. The ethanol fermentation rate of the PVA–sodium sulfate hydrogel beads enclosing the yeast cells was 2–3 times as fast as that of PVA–boric acid beads. The PVA–sodium sulfate beads could be reused 10 times in repeated ethanol fermentation tests.

We aimed to develop cell-embedded gel-filled macroporous scaffold (CGS) culture technology as a fundamental technology for the construction of large-scale tissue-like structures, which will be indispensable for practical liver tissue engineering. Tissue transglutaminase (tTGase) from guinea pig liver showed no cytotoxicity toward primary hepatocytes, and hepatocyte-embedded gelatin gel cultures could be realized. The albumin production activities in tTGase-mediated hepatocyte-embedded gelatin gel cultures were similar to those in collagen gel cultures, representing an established hepatocyte culture method for the expression of liver-specific functions. Therefore, it was expected that a hepatocyte-embedded gelatin gel culture system enabling high liver-specific function expression could be created. The CGS culture system was created by incubating a suspension of hepatocytes and tTGase-containing gelatin-filled hydrophilic-treated scaffolds at 37 °C. The albumin production activities in CGS with poly( l -lactic acid) macroporous scaffold (porosity = 68.4%) were inferior to those in tTGase–gelatin gel cultures because of a diffusion problem. However, the activities were similar between CGS with macroporous polyurethane foam (porosity = 98.8%) and tTGase–gelatin gel cultures, even under stationary conditions. On the other hand, further functional improvements of hepatocytes were achieved in HGF- or HGF/heparin-containing gel cultures. Based on these results, tTGase-mediated CGS cultures are expected to become a fundamental technology for the creation of engineered liver tissues.