Young Sil Jeon

Preparation and Properties of Alginate/Polyaspartate Composite Hydrogels

This study examined the swelling behavior andin vitro release of a model drug, tetracycline-HCl, from alginate and alginate-polyaspartate (Alg-PASP) composite gel beads. The alginate and Alg-PASP composite beads were prepared using an ionic crosslinking method with aqueous Ca2+. Their microporous morphology was observed by scanning electron microscopy. The swelling ratio of the beads in different media varied according to their composition, cross-linking density (Ca2+ concentration), and pH of the aqueous medium. Thein vitro release experiment of the tetracycline-HCl encapsulated beads in different media suggests that the release of the drug is governed mainly by the swelling properties of the polymer network. The presence of PASP was found to significantly influence the swelling properties and drug release profile.

Drug release characteristics of modified PHEMA hydrogel containing tethered PEG sulfonate

ConclusionsThe modified PHEMA hydrogel containing sulfonated PEG tether was prepared and the drug incorporation and release behavior was investigated to elucidate the effect of swelling and the ionic sulfonate groups on the PEG chain end. By using the model drugs including biphenyl acetic acid (BPAA), cationic methylene blue (MB), and anionic methyl orange (MO), it was found that the drug release behavior was significantly influenced by the electrostatic interactions between drug molecules and the inner surface nature of gel matrix to modulate the capacity and release rate of drugs.

Self-healable mussel-mimetic nanocomposite hydrogel based on catechol-containing polyaspartamide and graphene oxide.

Stimuli-responsive and self-healing materials have a wide range of potential uses, and some significant research has focused on cross-linking of hydrogel materials by means of reversible coordination bonding. The resulting materials, however, tend to have poor mechanical properties with pronounced weakness and brittleness. In this work, we present a novel mussel-inspired graphene oxide(GO)-containing hydrogel based on modified polyaspartamide with γ-amino butyric acid (GABA), 3.4-dihydroxyphenethylamine (DOPA), and ethanolamine (EA), termed PolyAspAm(GABA/DOPA/EA). Here both GO nanosheets and boric acid (H3BO3) act as cross-linkers, interacting with polar functional groups of the PolyAspAm(GABA/DOPA/EA). Compared to PolyAspAm(GABA/DOPA/EA)/B(3+) gel without GO, the same containing 5wt% of GO yielded a 10-fold increase in both the storage and loss moduli, as well as 134% and 104% increases in the tensile and compressive strengths, respectively. In addition, the GO-containing polyaspartamide hydrogel exhibited rapid and autonomous self-healing property. Two types of bonding, boron-catechol coordination and strong hydrogen bonding interactions between PolyAspAm side chains and GO nanosheets, would impart the enhanced mechanical strength and good reversible gelation behavior upon pH stimulation to the hydrogel, making this biocompatible hydrogel a promising soft matter for biomedical applications.

Preparation and Properties of Modified PHEMA Hydrogels Containing Thermo-responsive Pluronic Component

To modify and strengthen the properties of PHEMA hydrogel, composite hydrogels containing varying amounts of a Pluronic (PEO-PPO-PEO) component were synthesized by bulk polymerization of HEMA in the presence of Pluronic dimethacrylate under mild photoinitiating conditions. The effects of the Pluronic component on gel properties were investigated by measuring the degree of swelling with its temperature responsive behavior, the mechanical properties, and the morphology of the composite hydrogels. With increased Pluronic content, the modified PHEMA hydrogels exhibited an increase in the degree of swelling, and the swelling showed an enhanced thermo-responsive behavior that was completely reversible. In addition, improved mechanical strength and the development of a microporous gel morphology were observed in hydrogels containing Pluronic.

Bioinspired self-adhesive polymer for surface modification to improve antifouling property

The catechol functional group of dopamine (3,4-dihydroxyphenethylamine) forms a strong coordinate bond with both inorganic and organic substrates in a wet environment. The nonfouling surfaces required for this process are typically prepared through the immobilization of poly(ethylene glycol), so-called, PEGylation. In this work, polyaspartamides containing adhesive catechol and methoxy PEG pendants were synthesized from polysuccinimide through successive aminolysis reactions. The adhesion and crosslinking of the polyaspartamide derivatives in pH-controlled aqueous media was successfully utilized to modify a glass surface using a simple immersion method. Contact angle, α-step profiler, SEM and EDS, XPS, and AFM were used to characterize and verify the surface coating. In addition, the biocompatibility and antifouling properties of the modified surface were elucidated with a cell viability test, and a protein adsorption experiment, respectively. This biocompatible polymer system has biomedical application potential for use in adhesives and the surface coating of various biomaterials.

Preparation and properties of PEG Modified PNVP hydrogel

Polymer hydrogel has attracted considerable interest as a soft material which is finding expanding applications in pharmaceutics and various biomedical fields. In this work, modified PNVP hydrogels were synthesized by crosslinking polymerization of NVP monomer in the presence of PEG macromer with a methoxy end. The effect of the tethered PEG chain on the properties of the hydrogel was investigated in terms of its swelling capacity, compression gel strength, and the morphology of the resulting hydrogels. These PEG-modified PNVP hydrogels possessed good biocompatibility and a decreased protein (fibrinogen) adsorption, thereby indicating their potential as novel drug delivery matrices and scaffold for tissue engineering.

Preparation and characterization of CO2-responsive poly(amino acid) derivatives with guanidine group

Polyaspartamides, which are termed to a variety of amide derivatives of poly(aspartic acid), one of the poly(amino acid)s or polypeptides, have been intensively investigated as biodegradable and biocompatible polymers with a broad range of potential biomedical applications as well as eco-friendly industrial uses. By discovering that polymers containing amidine or guanidine functionality have been shown to be reversibly responsive to carbon dioxide (CO2), we have developed two polyaspartamide systems: novel CO2-responsive hydrogel and amphiphilic polyaspartamide derivative containing l-arginine. In this work, poly(2-hydroxyethyl aspartamide) derivative was modified with l-arginine unit (PHEA-Larg), before cross-linked by hexamethylene diisocyanate in the presence of dibutyltin dilaurate catalyst to provide a hydrogel having not only good gel strength, but reversible CO2 absorption characteristics. On the other hand, amphiphilic polyaspartamide derivative containing hydrophobic long alkyl moiety (octyl) and l-arginine unit was synthesized, and the CO2-responsive solubility and molecular self-assembly behaviors of the systems were investigated. These new polyaspartamide systems have potential in several applications including CO2 capture, CO2-responsive and switchable surface, sensor, smart hydrogel for controlled drug delivery system, etc.

Adhesive and self-healing soft gel based on metal-coordinated imidazole-containing polyaspartamide

A supramolecular gel formed by coordination of Ni(II) with poly(2-hydroxyethyl-co-1-(3-imidazolyl)propyl aspartamide) (PHEA-API) is reported. Novel polyaspartamide copolymers, PHEA-API, were prepared from polysuccinimide, which is the thermal polycondensation product of aspartic acid, via a successive ring-opening reaction using 1-(3-aminopropyl imidazole) (API) and ethanolamine (EA). Ni(II)-mediated gels, cross-linked by metal–ligand coordination, showed self-healing viscoelastic behavior in rheological analysis, which was also well reflected in high bulk adhesion strength on various different substrates. The approach described here results in a promising self-healing adhesive hydrogel with potential for a variety of industrial and biomedical applications including tissue adhesive, sealant, and smart drug delivery systems.

Stabilized polymeric nanoparticle from amphiphilic mPEG-b-polyaspartamides containing ‘click’ functional groups

ABSTRACT The synthesis of a series of poly(ethylene glycol) and polyaspartamide-based block copolymers containing azide and alkyne function groups and its micelle formation in aqueous solution were described. The self-assembly behavior of these amphiphilic copolymers in aqueous media to form nanosized micelle and the core-crosslinking reaction to convert them to stable nanoparticle were investigated. The particle size distributions were measured by dynamic light scattering. The resulting nanogel, prepared by click reaction within the mixed micelle core, has been shown to exhibit stability upon dilution and also in the presence of SDS, a small-molecule surfactant, suggesting the potential use as carrier for current drug delivery system. GRAPHICAL ABSTRACT

Metal-ion Adsorption by Hybrid Gel based on Polyaspartamide and Alginate

폴리(2-히드록시에틸 아스팔트아미드)(PHEA)와 알지네이트(Alg) 유도체로부터 클릭반응에 의한 가교젤을 제조하고, 이 하이드로젤을 수용액상의 중금속이온 제거를 위한 흡착제로 사용하였다. PHEA/Alg 하이브리드젤은 중금속이온 Cu(II)와 Ni(II)에 대해 각각 75 mg/g과 60 mg/g의 높은 흡착능을 보였다. 하이드로젤은 이온함유 수용액에서 약 60~80 g/g의 수팽윤비를 나타내었다. 흡착 거동에 미치는 접촉시간, pH, 온도, 및 농도의 영향을 조사하였다. SEM과 FTIR을 통해 젤의 다공성 모폴로지 및 금속이온과 고분자 구조간의 상호작용을 고찰하였으며, 또한 농도에 따른 흡착량 데이터로부터 흡착등온선(isotherm)을 이론식에 적용하여 분석하였다. 그 결과로 Cu(II)와 Ni(II)의 흡착거동은 Freundlich보다는 Langmuir 모델에 잘 부합하였으며, 동력학적으로는 유사 2차 동역학적 모델(pseudosecond-order kinetic model)로 더 정확하게 묘사할 수 있음을 알았다.