• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1597-1604
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• 2020

In this study, a synthesized poly(amino acid) self-assembly grafted with valine molecules was investigated on the skin activity of skin growth factors. The amphiphilic grafted poly(amino acid) derivatives were successfully synthesized by varying of degree of substitution(DS) and polymerization (DP) with valine molecules forming a β-sheet structure. Then, the pro-collagen biosynthesis of EGF(epidermal growth factor) was improved by 20%, and the inhibitory ability of tyrosinase activity was increased by 6.5 times by self-assembling of EGF with the poly(amino acid)s having β-sheet structures. This strategy of preparing protein self-assembly with poly(amino acid) derivatives will help improve the stability of protein growth factors and use it in medicals as well as cosmeceuticals through skin improvement.

• Journal of Adhesion and Interface
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• v.21 no.4
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• pp.156-161
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• 2020

Waterborne pressure sensitive adhesives (PSA) has been received much attentions from both academia and industries as an environmental friendly-technology because it can significantly reduce use of hazardous organic volatile solvents. However, in the process of the mass production of waterborne PSAs, hazardous phenol type amphiphilic compounds have essentially been used as surfactants for the emulsion polymerization. For the reason, tremendous research efforts have been made to develop environment-friendly organic surfactant which can replace the phenol type surfactants. In this study, we verify the potential of a new class of surfactants based on the styrenated phenol derivatives as an alternative to the phenol type surfactants.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.121-125
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• 2023

Casein is a milk protein and one of the most important nutrients in milk. The composition is over 80% in cow's milk and about 20~45% in human's milk. Casein is highly biocompatible and biodegradable, so it has been studied for various biomedical materials applications as well as drug delivery systems. It is widely known that casein can be prepared as nanoparticles in the presence of the Ca²⁺ metal ion. Because casein is amphiphilic, hydrophobic drugs could be loaded inside to form a protein-based drug delivery system. In this study, we studied the optimum conditions for casein nanoparticle formation using natural metal ions present in the body, such as calcium, magnesium, zinc, and iron. It was confirmed that nanoparticles have a uniform size of around 150 nm and negative zeta potential values. In addition, it was demonstrated that casein nanoparticles have a cell viability of more than 80% and efficient intracellular uptake properties using confocal microscopy. From the results, it was also shown that the casein nanoparticles prepared using various metal ions have the potential to be biocompatible drug delivery carriers.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.247-251
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• 2023

Lecithin can self-assemble into reverse spherical micelles in organic solvents due to its amphiphilic properties. With additives such as D-sorbitol and water, the reverse spherical micelles are transformed into reverse cylindrical micelles by the morphology change of lecithin molecules. In this study, the rheological properties of lecithin/D-sorbitol/water mixtures were investigated. In addition, the small angle X-ray scattering (SAXS) technique was used to examine the shape and size of the formed nanostructures related to their rheological properties. Such mixtures are expected to be used in drug delivery and oleogels because of their high viscosity and viscoelastic behavior.

• Korean Journal of Microbiology
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• v.46 no.1
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• pp.15-20
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• 2010

Xenotransplantation of pig organs is complicated by the existence of polytropic replication-competent porcine endogenous retroviruses (PERV) capable of infecting human cells. Two classes of infectious human-tropic replication-competent PERVs (PERV-A and PERV-B) and one class of ecotropic PERV-C are known. The potential for recombination between ecotropic PERV-C and human-tropic PERVs adds another level of infectious risk. A recombinant PERV-A/C (PERV-A14/220) virus is 500-fold more infectious than PERV-A. Two determinants of this high infectivity was identified; one was isoleucine-to-valine substitution at position 140 in RBD (receptor binding domain), and the other lies within the PRR (proline rich region) of the envelope protein. To examine whether the effects of the cytoplasmic tail of the PERV-C Env on fusogenesity also influences infectivity, we constructed a pseudotype retroviral vectors containing MoMLV core protein and PERV envelopes. Pseudotyping experiments with the PERV envelope glycoproteins indicated that recombinant PERV-A/C virus is 10-fold more infectious than PERV-A by lacZ staining. This result supports the suggestion that viral transduction of PERV-A/C is enhanced by a membrane-proximal cytoplasmic amphiphilic ${\alpha}$-helix in PERV-C Env tail.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.64.1-64.1
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• 2010

The morphology of mesoporous $TiO_2$ films plays an important role in the operation of a DSSC. For example, the energy conversion efficiency of DSSCs with well-organized mesoporous $TiO_2$ films is much higher than those with traditional films possessing a random morphology. In previous research, well-organized mesoporous $TiO_2$ films have mainly been synthesized using an amphiphilic block copolymer, e.g., a poly(ethylene oxide) (PEO)-based template. A graft copolymer is more attractive than a block copolymer due to its low cost and the ease with which it can be synthesized. In this work, we provide the first report on the successful synthesis of well-organized mesoporous $TiO_2$ films templated by an organized graft copolymer as a structure directing agent. Well-organized mesoporous $TiO_2$ films with excellent channel connectivities were developed via the sol gel processusing an organized PVC-g-POEM graft copolymer synthesized by one-pot ATRP. The careful adjustment of copolymer composition and solvent affinity using a THF/$H_2O$/HCl mixture was used to systematically vary the material structure. The influence of the material structure on solar cell performance was then investigated. A solid-state DSSC employing both the graft copolymer templated organized 700 nm-thick $TiO_2$ films and graft copolymer electrolytes exhibited a solar conversion efficiency of 2.2% at 100 $mW/cm^2$. This value was approximately two-fold higher than that attained from a DSSC employing a random mesoporous $TiO_2$ film. The solar cell performance was maximized at 4.6% when the film thickness was increased to $2.5{\mu}m$. We believe that this graft copolymer-directed approach introduces a new and simple route toward the synthesis of well-organized metal oxide films as an alternative to a conventional block copolymer-based template.

• Polymer(Korea)
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• v.24 no.4
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• pp.488-498
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• 2000

Molecular bottle-brush was prepared by hydrogen-bonding between poly(4-vinylpyridine)(P4VP) as main chain and 3-pentadecylphenol (PDP) as amphiphilic side chain. Variation of long period ( $L_{p}$), order-disorder transition temperature ( $T_{ODT}$) and mesomorphic structure of bottle-brush were investigated by changing various mole ratio (x) of pyridine group in P4VP and PDP and molecular weight of P4VP. Upper critical solution temperature (UCST) behaviour was observed. For x 0.8-0.9, maximum critical temperature was found. As molecular weight of P4VP was increased, phase transition occurred at higher temperature. It was found that phase behaviour of the bottle-brush was affected by mobility of P4VP as well as size and regularity of lamellar structure. The $L_{p}$ determined from analysis of crystal structure was in the range of 35 $\AA$ and 40 $\AA$ and was more affected by the molecular weight of P4VP than by mole ratio (x). However, if the molecular weight of P4VP was high, LP value was little affected.ted.d.

• Polymer(Korea)
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• v.34 no.3
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• pp.274-281
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• 2010

In this study, PEG-PLA(or PLGA) amphiphilic di-block copolymers were synthesized by ring opening polymerization of D,L-lactide(or glycolide) and applied to polymeric micelle system for solubilization of a rosiglitazone as diabetes drug. The drug could be efficiently loaded into the polymer micelle by solid dispersion technique, and the drug-loaded micelles were characterized and evaluated as a drug delivery carrier by fluorescence spectrometer, DSC, and DLS measurements. The colloidal stability of drug loaded micelles in aqueous media could be enhanced by addition of 2-hydroxy-N-picolylnitinamide as a hydrotropic agent. The polymer micelles also showed biocompatible and nontoxic properties in vitro cell viability using MTT assay, and the drug loaded micelles were observed to be more effective than free drug for decreasing glucose in blood of rats.

• Membrane Journal
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• v.21 no.2
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• pp.193-200
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• 2011

An amphiphilic graft copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymerization (ATRP). Mesoporous titanium dioxide $(TiO_2)$ films with crystalline anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA graft copolymer. Titanium isopropoxide (TTIP), a $TiO_2$ precursor was selectively incorporated into the hydrophilic PSSA domains of the graft copolymer and grew to form mesoporous $TiO_2$ films, as confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amounts of P25 nanoparticies. The energy conversion efficiency reached up to 2.7% at 100 mW/$cm^2$ upon using quasi-solid-state polymer electrolyte.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.301-310
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• 2010

Bacillus subtilis strains produce a broad spectrum of bioactive peptides. The lipopeptide surfactin belongs to one well-known class, which includes amphiphilic membrane-active biosurfactants and peptide antibiotics. Both the srfA promoter and the ComP-ComA signal transduction system are an important part of the factor that results in the production of surfactin. Bs-M49, obtained by means of low-energy ion implantation in wild-type Bs-916, produced significantly lower levels of surfactin, and had no obvious effects against R. solani. Occasionally, we found strain Bs-M49 decreased spore formation and the development of competence. Blast comparison of the sequences from Bs-916 and M49 indicate that there is no difference in the srfA operon promoter PsrfA, but there are differences in the coding sequence of the comA gene. These differences result in three missense mutations within the M49 ComA protein. RT-PCR analyses results showed that the expression levels of selected genes involved in competence and sporulation in both the wild-type Bs-916 and mutant M49 strains were significantly different. When we integrated the comA ORF into the chromosome of M49 at the amyE locus, M49 restored hemolytic activity and antifungal activity. Then, HPLC analyses results also showed the comA-complemented strain had a similar ability to produce surf actin with wild-type strain Bs-916. These data suggested that the mutation of three key amino acids in ComA greatly affected the biological activity of Bacillus subtilis. ComA protein 3D structure prediction and motif search prediction indicated that ComA has two obvious motifs common to response regulator proteins, which are the N-terminal response regulator receiver motif and the C-terminal helix-turn-helix motif. The three residues in the ComA N-terminal portion may be involved in phosphorylation activation mechanism. These structural prediction results implicate that three mutated residues in the ComA protein may play an important role in the formation of a salt-bridge to the phosphoryl group keeping active conformation to subsequent regulation of the expression of downstream genes.