• Nuclear Engineering and Technology
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• v.52 no.10
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• pp.2320-2327
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• 2020

The extreme hydrophobicity of expanded polytetrafluoroethylene (ePTFE) hinders bone-tissue integration, thus limiting the use of ePTFE in medical implant applications. To improve the potential of ePTFE as a biomaterial, 2-hydroxyethyl methacrylate (HEMA) was grafted onto the ePTFE surface using the gamma irradiation technique. The characteristics of the grafted ePTFE were successfully evaluated using attenuated total reflectance Fourier transform infrared (ATR-FTIR), field-emission scanning electron microscopy (FESEM)/energy dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). Under the tensile test, the modified ePTFE was found to be more brittle and rigid than the untreated sample. In addition, the grafted ePTFE was less hydrophobic with a higher percentage of water uptake compared to the untreated ePTFE. The protein adsorption test showed that grafted ePTFE could adsorb protein, which was denoted by the presence of N peaks in the XPS analysis. Moreover, the formation of the globular mineral on the grafted ePTFE surface was successfully visualized using the FESEM analysis, with a ratio of 1.94 for Ca:P minerals by the EDX. To summarize, the capability of the modified ePTFE to show protein adsorption and mineralization indicates the improvement of the polymer properties, and it can potentially be used as a biomaterial for implant application.

• Journal of Dairy Science and Biotechnology
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• v.40 no.4
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• pp.143-150
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• 2022

Maillard conjugates are formed by covalent bonds between proteins and polysaccharides. Understanding the functional properties of Maillard conjugates, including emulsifying and antioxidant properties, can be crucial when Maillard conjugates are used in processed foods. This study aimed to manufacture whey protein isolate (WPI)/Inulin Maillard conjugates and investigate how manufacturing variables including heating temperature and pH affect the functional properties of Maillard conjugates. The surface properties, emulsifying properties, and antioxidant properties of Maillard conjugates were assessed by varying heating temperature and pH. The grafting degree of WPI/Inulin Maillard conjugates increased with increasing pH and heating temperature, indicating enhanced conjugation efficiency. Surface hydrophobicity, emulsifying properties (including emulsifying activity index and emulsifying stability index), and ABTS radical scavenging ability of WPI/Inulin Maillard conjugates increased as pH and heating temperature were increased. In conclusion, WPI/Inulin Maillard conjugates were successfully manufactured, and pH and heating temperature were critical factors in enhancing Maillard conjugate functional properties.

• Journal of Environmental Health Sciences
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• v.38 no.4
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• pp.351-359
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• 2012

Objectives: This study was conducted in order to investigate the specific correlation between physicochemical properties and bioactivity in ecdysteroids found in living organisms. Methods: The examined steroidal compounds were classified into three groups according to their relevance to ecdysone activity. Each compound molecule was completely drawn to automatically calculate its physicochemical parameters and docked against 20-hydroxyecdysone to calculate the total distance. Electronic charge distribution was also observed for each molecule. All procedures were conducted using a computational chemistry program. Results: Ecdysone agonists showed different ranges of parameter values, such as log P, hydrophilic-lipophilic balance (HLB), solubility parameter (SP), hydrophilic surface (HPS), hydrogen bond (HB) and Kappa 2, when compared with antagonists and steroids without ecdysone activity. They also showed a similar electronic charge distribution that is significantly different from the electron charge distribution of antagonists and steroids without ecdysone activity. The total distance values of agonists, estimated by docking them with 20-hydroxyecdysone, were relatively small but showed no correlation with binding affinity with receptor ligand. Conclusions: These results suggest that physicochemical properties such as steric and electronic effects, hydrophobicity and hydrogen bonding may operate in combination to determine the binding activity of ecdysteroids to the receptor protein.

• KSBB Journal
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• v.14 no.6
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• pp.651-654
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• 1999

Using recombinant human growth hormone as a model protein, we carried out unfolding by adding a denaturant such as urea, guanidine HCl, or SDS followed by refolding by dilution and dialysis. The objectives were to monitor the structural changes during in vitro refolding process and, based on the results, to develop a quantitative method of refolding progress assessment. The changes in surface hydrophobicity were measured by fluorescence tagging of 1-anilinonaphthalene-8-sulfonate(1,8-ANS) to the hydrophobic portions, and those in the secondary structure were monitored by using far UV-CD(circular dichroism) spectroscopy. Also, we used RP-HPLC to separate and quantify the folded and unfolded proteins to correlate the result with the structure analysis. Our results indicate the surface hydrophobicity are well correlated with the formations of the secondary structure, primarily ${\alpha}$-helices, as well as the disulfide bridges. We expect this monitoring technique can be applied in industrial fields as a means to quantitatively assess the progress of in-vitro refolding of recombinant proteins.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.71-76
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• 2012

Biofouling by marine organisms such as algae and barnacles causes lots of significant problems in marine systems such as a rise of the maintenance-repair cost for the ship and the marine structures. In this work, a fluoropolymer, perfluoropolyether (PFPE), was applied as an anti-biofouling coating material that prevents the adhesion of marine organisms and facilitates the removal of them. Water contact angles of various surfaces were tested to examine the hydrophobicity of the PFPE-modified surface. The PFPE-modified surface showed the water contact angle of $64.5^{\circ}$ which is a remarkable rise from $46.7^{\circ}$ of amine-treated surface. When the substrate was treated with PFPE, the adhesion on the of the barnacle and other marine organisms were repressed around 15% by the enhanced hydrophobicity. In addition, the removal the of the adhered marine organisms were better comparing to that of the surface prepared by PDMS. Surfaces of the substrate treated by PFPE were characterized through physical and chemical methods to analyze the biofouling results. Degree of biomolecular adhesion to the substrate was quantified by the measurement the fluorescence intensity of marine organisms dyed with green fluorescence. PFPE is expected to be applicable not only to anti-biofouling systems but also to medical devices where the prevention of protein adhesion is required.

• Macromolecular Research
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• v.8 no.6
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• pp.276-284
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• 2000

A wettability chemogradient on poly(L-lactide-co-glycolide) (PLGA) films was prepared by treating the films in air with corona from a knife-type electrode whose power increases gradually along the sample length. The PLGA surfaces oxidized gradually with the increasing corona power, and the wettability chemogradient was created on the surfaces as evidenced by the measurement of water contact angles and electron spectroscopy for chemical analysis. The wettability chemogradient PLGA surfaces were used to investigate the interaction of four different types of cells such as hepatoma (Hep G2), osteoblast (MG 63), bovine aortic endothelial (CPAE), and fibroblast (NIH/3T3) cells in terms of the surface hydrophilicity/hydrophobicity of PLGA. The cells adhered and grown on the chemogradient surface along the sample length were counted and observed by scanning electron microscopy. It was observed that the cells were adhered, spread, and grown more onto the positions with moderate hydrophilicity of the wettability chemogradient PLGA surface than the more hydrophobic or hydrophillic positions, regardless of the cell types used. The maximum adhesion and growth of the cells appeared at around water contact angles of 53～55°. This result seems closely related with the serum protein adsorption on the surface; the serum proteins were also adsorbed more onto the positions with moderate hydrophilicity of the wettability chemogradient surface. It seems that the wettability plays important roles for cell adhesion, spreading and growth on the PLGA surface. The surface modification technique used in this study may be applicable tothe area of tissue engineering for the improvement of tissue compatibility of films- or scaffold-type substrates.

• Food Science and Biotechnology
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• v.15 no.3
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• pp.418-423
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• 2006

Egg white powders (EWPs) were produced after pH adjustment (PH 6-9) of fresh egg white, followed by spray-drying, and foaming and gelling properties of EWPs were examined. EWP produced after pH adjustment to 6.5 (EWP-6.5) resulted in significantly higher foaming ability and gel hardness than control and other pH-adjusted EWP. Significant increases in surface -SH content and surface hydrophobicity of EWP-6.5 coincided with improved foaming ability and gel hardness. Significantly higher consistency index for reconstituted EWP-6.5 indicates unfolding of egg white protein was substantially increased in EWP-6.5. Decreased a-helix content in EWP-6.5 was confirmed by circular dichroism spectral analysis. These results indicate pH adjustment prior to spray-drying leads to structural changes in egg white proteins, significantly affecting major functionalities of EWP.

• Food Science and Preservation
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• v.10 no.1
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• pp.80-88
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• 2003

In order to establish the enzymatic hydrolysis system improving of taste and flavor in the preparation of soy protein hydrolysates using the enzymes with excellent hydrolytic ability and different hydrolysis pattern of soy protein, Degree of hydrolysis(DH) and surface hydrophobicity under the optimal conditions of enzyme reaction, hydrolysis patterns by the SDS electrophoresis and sensory evaluation of soy protein hydrolysates by enzyme reactions were investigated. Four enzyme reactions were highly activated at pH 7.0, 45$^{\circ}C$ under the optimal conditions. As result of changes on the pattern of soy-protein hydrolysates by SDS-electrophoresis, high molecular peptides of hydrolysates by No. 5(Mucor circinelloides M5) and No. 16(Bacillus megaterium B16) enzymes were slowly decrease and 66KD band of these were remained after 3hours reaction. Production of low molecular peptides of hydrolysates by No. 4(Aspergillus oryzae M4) and No. 95(Bacillus subtilis YG 95) enzymes were remarkably detected during the proceeding reactions. As results of HPLC analysis, low molecular peptides of 15∼70KD were mainly appeared during the proceeding enzyme reactions. And, the more DH was increased, the more SDS-surface hydrophobicity was decreased. Hydrolysates by No. 4 enzyme was not only the highest DH of all hydrolysates, but the strongest bitter taste in a sensory evaluation. Sweat taste among the hydrolysates showed little difference. But, when combinative enzymes were treated, combinative enzyme of No. 4(Aspergillus oryzae M4)and No. 16(Bacillus megaterium B16) showed the strongest sweat taste. In conclusion, we assumed that it will be possible to prepare the hydrolysates having functionality when soy-protein were hydrolyzed by these specific enzymes.

• Membrane Journal
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• v.31 no.5
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• pp.293-303
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• 2021

Separation membranes used in water filtration, protein purification or biomedical filtration device frequently undergo membrane fouling for several reasons. The formation of biofilm on the membrane surface by bacteria causes a severe problem for durability of the membrane. For the protein separation, the membrane pores get blocked due to surface hydrophobicity of the membrane. There are several approaches controlling the membrane fouling and one of them is the incorporation of silver nanoparticles. Antibacterial properties of silver nanoparticles are well known and thus widely used in several applications. In this review, we have focused on the membranes where silver nanoparticles or its derivatives are either incorporated in the active layer of thin film composite membranes or uniformly distributed throughout the whole membranes.

• Food Science of Animal Resources
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• v.38 no.1
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• pp.14-25
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• 2018

Chemical compositions, trypsin inhibitory activity, and gelling properties of albumen from duck egg during salting of 30 days were studied. As the salting time increased, moisture content decreased, the salt content and surface hydrophobicity increased (p<0.05). Trypsin inhibitory activity and specific activity were continuously decreased throughout the salting time of 30 days (p<0.05). This coincided with the decrease in band intensity of inhibitor with molecular weight of 44 kDa as examined by inhibitory activity staining. Nevertheless, no differences in protein patterns were observed in albumen during the salting of 30 days. Based on texture profile analysis, hardness, springiness, gumminess, chewiness, and resilience of albumen gel decreased with increasing salting time. Conversely, salted albumen gels exhibited higher cohesiveness and adhesiveness, compared to those of fresh albumen. Scanning electron microscopic study revealed that gel of salted albumen showed the larger voids and less compactness. In general, salting lowered trypsin inhibitory activity and gelling property of albumen from duck egg to some extent. Nevertheless, the salted albumen with the remaining inhibitor could be an alternative additive for surimi or other meat products to prevent proteolysis.