• Macromolecular Research
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• v.10 no.2
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• pp.67-74
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• 2002

New immunoprotecting membranes were prepared by spin coating the amphiphilic random multiblock copolymers of poly(ethylene glycol) (PEG) and poly(tetramethylene ether glycol) (PTMEG) or poly(dimethyl siloxane) (PDMS) on porous Durapore(R) membrane. The copolymer coating was intended to make a biocompatible, immunoprotecting diffusional barrier and the supporting porous substrate was for mechanical stability and processability. By filling Durapore(R) membrane pores with water, the penetration of coating solution into the pores was minimized during the spin coating process. A single coating process produced a completely covered thin surface layer (~1 ${\mu}{\textrm}{m}$ in thickness) on the porous substrate membrane. The permselectivity of the coated layer was influenced by PEG block length, polymer composition, and thickness of the coating layer. A composite membrane with the coating layer prepared with PEG 2 K/PTMEG 2 K block copolymer showed that its molecular weight cut-of fat any 40 based on dextran was close to the molecular size of IgG (Mw = 150 kDa). However, IgG permeation was detected from protein permeation test, while glucose oxidase (Mw = 186 kDa) was not permeable through the coated membrane.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1424-1429
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• 2010

A poly(${\gamma}$-glutamic acid) (${\gamma}$PGA)-cholesterol conjugate was synthesized and its properties were then evaluated. The conjugate exhibited an amphiphilic nature derived from the hydrophilic ${\gamma}$PGA backbone and the hydrophobic cholesterol side chain. The conjugate spontaneously formed nanoparticles, becoming an aqueous solution when at low concentrations, and at high concentrations the result was the formation of a physical gel. By utilizing the self-aggregating properties of the conjugate in water, an artificial chaperone was developed. A complex of protein, with the nanoparticles of the conjugate, was formed and the protein was released upon the dissociation of the nanoparticles through the addition of ${\beta}$-cyclodextrin. For denatured carbonic anhydrase, the activity was recovered in the artificial chaperone of the nanoparticle conjugate.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3740-3744
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• 2010

A typically designed 'Peptide Lego' has two distinct surfaces: a hydrophilic side that contains the complete charge distribution and a hydrophobic side. In this article, we describe the fabrication of a unique lego-type peptide with the AEAEYAKAK sequence. The novel peptide with double amphiphilic surfaces is different from typical peptides due to special arrangement of the residues. The results of CD, FT-IR, AFM and DLS demonstrate that the peptide with the random coil characteristic was able to form stable nanostructures that were mediated by non-covalent interactions in an aqueous solution. The data further indicated that despite its different structure, the peptide was able to undergo self-assembly similar to a typical peptide. In addition, the use of hydrophobic pyrene as a model allowed the peptide to provide a new type of potential nanomaterial for drug delivery. These efforts collectively open up a new direction in the fabrication of nanomaterials that are more perfect and versatile.

• Polymer(Korea)
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• v.36 no.2
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• pp.149-154
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• 2012

The amphiphilic copolymer by the conjugation of biocompatible chitosan and antioxidant lipoic acid was studied as a drug delivery carrier. The amphiphilic copolymer was self-assembled to form nanoparticles in the aqueous solution. 5-Fluorouracil widely used as an anticancer drug was encapsulated inside the nanoparticles by a solid dispersion method. The degree of branching of lipoic acid on chitosan was controlled to obtain the optimal condition for the drug delivery carrier. The sizes of nanoparticles were about 250 nm by the dynamic light scattering. The encapsulation efficiency of nanoparticles were about 10%. The copolymer with 42% degree of branching showed the best performance as a drug delivery carrier.

• Macromolecular Research
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• v.16 no.2
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• pp.113-119
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• 2008

A series of amphiphilic dendrons n-18 (n: generation number, 18: octadecyl chain) based on an aliphatic polyether denderitic core and octadecyl peripheries were synthesized using a convergent dendron synthesis consisting of a Williamson etherification and hydroboration/oxidation reactions. This study investigated their thermal and self-assembling behavior in the solid state using differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) absorption spectroscopy, and small angle X-ray scattering (SAXS). DSC indicated that the melting transition and the corresponding heat of the fusion of the octadecyl chain decreased with each generation. FT-IR showed that the hydroxyl focal groups were hydrogen-bonded with one another in the solid state. DSC and FT-IR indicated microphase-separation between the hydrophilic dendritic cores and hydrophobic octadecyl peripheries. SAXS data analysis in the solid state suggested that the lower-generation dendrons 1-18 and 2-18 self-assemble into lamellar structures based upon a bilayered packing of octadecyl peripheries. In contrast, the analyzed data of higher-generation dendron 3-18 is consistent with 2-D oblique columnar structures, which presumably consist of elliptical cross sections. The data obtained could be rationalized by microphase-separation between the hydrophilic dendritic core and hydrophobic octadecyl peripheries, and the degree of interfacial curvature associated with dendron generation.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.461-469
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• 2019

In the present work, we present a new effective hydrophilicity modifier for polysulfone (PSf) membrane. Firstly, amphiphilic nanocellulose (ANC) with different substitution degrees (SD) was synthesized by esterification reaction with nanocellulose (NC) and dodecyl succinic anhydride (DDSA). The SD and morphology of ANC were characterized by titration method and transmission electron microscopy (TEM). Then, the polysulfone (PSf)/ANC blend membranes were prepared via an immersion phase inversion method. The influence of SD on the morphology, structure and performances of PSf/ANC blend membrane were carefully investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), mechanical property test, contact angle measuring instrument and filtration experiment. The results showed that the mechanical property, hydrophilicity and anti-fouling property of all the PSf/ANC blend membranes were higher than those of pure PSf membrane and PSf/NC membrane, and the membrane properties were increased with the increasing of SD values. As ANC-4 has the highest SD value, PSf/ANC-4 membrane exhibited the optimal membrane properties. In conclusion, the prepared ANC can be used as an additive to improve the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane.

• Proceedings of the Korean Fiber Society Conference
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• 1999.10a
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• pp.351-354
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• 1999

• Proceedings of the Korean Fiber Society Conference
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• 2001.04b
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• pp.351-354
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• 2001

• 한국전기화학회:학술대회논문집
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• 1999.04a
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• pp.12-12
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.11a
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• pp.103-103
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• 1998