• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.1981-1984
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• 2006

Novel amphiphilic, thermo-responsive polyaspartamides which showed both LCST (lower critical solution temperature), and sol-gel transition were prepared and characterized. The polyaspartamide derivatives were synthesized from polysuccinimide, the polycondensate of aspartic acid monomer, via successive nucleophilic ring-opening reaction by using dodecylamine and N-isopropylethylenediamine (NIPEDA). At the intermediate composition ranges, the dilute aqueous solution exhibited a thermally responsive phase separation due to the presence of LCST. The phase transition temperature was controllable by changing the content of pendent groups. In addition, a physical gelation, i.e. the sol-gel transition was observed from the concentrated solutions, which was elucidated by dynamic viscoelastic measurements. These novel injectable and thermo-responsive hydrogels have potential for various biomedical applications such as tissue engineering and current drug delivery system.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.981-985
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• 2006

Novel copolymers consisting of poly(2-hydroxyethyl aspartamide-co-N,N'-dimethyl-1,3-propane aspartamide) (PHEA-DPA) were prepared from polysuccinimide (PSI), which is the thermal polycondensation product of aspartic acid, via a ring-opening reaction with N,N'-dimethyl-1,3-propane diamine (DPA) and ethanolamine. The prepared water-soluble copolymer was then crosslinked by reacting it with hexamethylene diisocyanate to provide the corresponding gel. The swelling behavior and morphology of the crosslinked hydrogels were investigated. The degree of swelling decreased with increasing crosslinking reagent due to the higher crosslinking density. It was also confirmed that the swelling property is affected by pH. At low pH (< pH 4), swelling is increased due to the ionization of DPA with a tertiary amine moiety. In addition, a reversible swelling and de-swelling behavior was demonstrated by adjusting the pH of the solution. The prepared hydrogels showed a well-interconnected microporous structure with regular 5-20 $\mu$m sized pores.

• Polymer(Korea)
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• v.38 no.1
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• pp.108-112
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• 2014

Novel adhesive polyaspartamides containing catechol and primary amine pendent groups were synthesized through successive ring-opening aminolysis reactions of dopamine (DOP) and ethylenediamine (EDA) with polysuccinimide (PSI). The oxidative gelation of aqueous dopamine-modified polyaspartamide was observed by adding $NaIO_4$ as the oxidizing reagent. FTIR, UV-vis and oscillatory rheometry was used to elucidate the oxidative cross-linking toward gel formation. The prepared gel was characterized by the swelling degree, thermogravimetric analysis (TGA), and by scanning electronic microscopy (SEM).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.4
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• pp.433-440
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• 2016

In this study, a poly (amino acid)s derivative grafted with retinoic acids, which could form self-assemblies in an aqueous solution, was successfully synthesized. The synthesized amphiphilic poly (amino acid)s were controlled with 5, 10, 30 mol% substitution of retinoic acid. Then, the amphiphilic poly (amino acid)s were self-assembled by inter/intra molecular stacking of retinoic acids in an aqueous solution. Also, the increasing the degree of substitution (DS) of retinoic acids decreased the size of self-assembled nanoparticles and induced structural transition to bilayer structure from spherical structure. The retinol was stably encapsulated into a core of self-assembled nanoparticle with 10 mol% of DS. This strategy to prepare the self-assemblies of amphiphilic polyaspartamide will serve to improve the efficiency of targeted delivery for a functional cosmetic with various biological modalities.

• Polymer(Korea)
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• v.29 no.1
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• pp.36-40
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• 2005

Poly(amino acid) derivatives have been widely investigated as a drug carrier in drug delivery system. Particularly,polysuccinimide (PSI) is one of the most promising drug carriers since it possesses suitable physicochemical characteristics for development of macromolecular prodrugs, due to biocompatibility and biodegradability. In this study, we deal with the synthesis of polyaspartamide having various functional groups such as methoxy-poly(ethylene glycol) (MPEG) via ring closing of PSI. PSI was synthesized by polyonensation polymerization of spartic acid. The variety of average molecular weight was confirmed with reacion time and catalyst content to observe the optimum condition of synthesis. MPEG, hydrophilic chain, was bonded to fabricate polymeric micell composed of hydrophilic and hydrophobic polymer. All materials were characterized by 1H-NMR, FT-IR and GPC. In addition, the formation of nanoparticle micelle as drug carrier were also examined. Micelle size was measured by ELS and AFM. The functionalized polysparamide formed nanoparticle micelle whose size ranged from 90 to 130 nm. In conclusion, we prepared polyaspartamide functionalized with PEG examined the possibility as drug carriers.

• Polymer(Korea)
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• v.36 no.5
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• pp.617-621
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• 2012

PHEAs [${\alpha}$,${\beta}$-poly(2-hydroxyethyl-DL-aspartamides)], a class of poly(amino acid), have been widely studied as biodegradable and biocompatible polymers for potential biomedical and pharmaceutical applications. In this study, we investigated a homogeneous blend of PHEA with poly(N-vinyl pyrrolidone) (PNVP) and its semi-IPN (semi-interpenetrating polymer network) gels. Blend films were prepared by a solution casting method. The resulting blends were totally transparent over the whole composition ranges and the single $T_g$, changing monotonously with composition, was observed by DSC to confirm the miscibility between these two polymers. FTIR was used to discuss the possible hydrogen-bonding interaction between polymers. In addition, semi-IPN type gels were prepared by chemical crosslinking of PHEA/PNVP blend solution using hexamethylene diisocyanate (HMDI) as a crosslinking reagent. The prepared gel was characterized by their swelling property and morphology.

• Polymer(Korea)
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• v.29 no.5
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• pp.518-521
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• 2005

Biodegradable polymers and hydrogels have been increasingly applied in a variety of biomedical applications including current drug delivery system and tissue engineering field. ${\alpha},\;{\beta}-Poly$(N-2-hydroxyethyl-DL-aspart-amide), PHEA. is one of poly(amino acids) with hydroxyethyl pendants, which is hewn to be biodegradable and potentially biocompatible. So that, the utilization and various chemical modifications of PHEA have been attempted for useful biomedical applications. In this wort chemical gels based on PHEA were prepared by crosslinking with diisocyanate compound in DMF in the presence of catalyst. Here, the PHEA was prepared from polysuccinimde, the thermal polycondensation product of aspartic acid, via ring-opening reaction with ethanolamine. The preparation of gels and their swelling behavior, depending on the different medium and pH, were investigated. Also the morphology by SEM and simple hydrolytic degradation were observed.