• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1303-1307
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• 2003

The low molecular water-soluble chitosan nanoparticles (LMWSC-NPs) were prepared, which was modified with hydrophilic and hydrophobic moieties to evaluate the potential for pharmaceutics application. The synthesis of LMWSC-NPs was identified by FT-IR and $^1H$-NMR spectra. Also, we measured the photon correlation spectroscopy (PCS), transmission electron microscope (TEM) and atomic force microscope (AFM) to investigate the characteristics and morphology of the LMWSC-NPs. At the PCS measurement, the more increase the number of substitutive group, the more decrease the positive charge of LMWSC-NP surface. From the results of TEM and AFM, spherical morphologies were observed, and their sizes were 30-150 nm. Resultantly, LMWSC-NPs prepared in this experiment will be expected as a suitable device for the drug targeting system.

• Polymer(Korea)
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• v.31 no.6
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• pp.555-561
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• 2007

To obtain low molecular weight water soluble chitosan (LMWSC) with various molecular weights, chitosan oligosaccharides (COS) with lactic acid was separated by using ultrafilteration technique and LMWSC with a free amine group was prepared by the novel salts-removal method. The characterization of LMWSC removed the lactic acid and degree of deacetylation (DDA) were identified by FT-IR and $^1H-NMR$ spectra. Polydispersity index (PDI) was $1.278{\sim}1.499$, which indicates a relatively molecular weight distribution. To identify the potential as a gene carrier, we confirmed the transfection efficiency of COS fractioned according to molecular weight successfully and the salt-removed LMWSC using 293T cell. Also, LMWSC derivatives prepared for improvement transfection efficiency were evaluated using Balb/C mice.

• Polymer(Korea)
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• v.30 no.4
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• pp.279-285
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• 2006

Non-viral gene carriers continue to attract a great deal of interest due to advantageous safety profile. Among the non-viral gene carriers, cationic liposomes or synthetic gene carriers are efficient DNA carriers in vitro. but their in vivo applications are greatly hampered because of low biocompatibility. On the other hand, chitosan, a natural cationic polysaccharide, is a candidate non-viral vector for gene delivery because of its low cytotoxicity and high positive charges. In this work, targeted gene carrier was synthesized to target artery wall cells using low molecular water-soluble chitosan (LMWSC). The molecular weight $(M_W)$ and degree of de acetylation (DDA) of LMWSC were measured by relative viscometer and Kina titration. respectively. The structure of LMWSC was analyzed by measuring FTIR, $^1H-NMR,\;and\;^{13}C-NMR$. AWBP-PEG-g-LMWSC was synthesized by conjugation of the artery wall binding peptide (AWBP), a specific targeting peptide, to the end of pegylated LMWSC as a gene carrier to target artery wall cells. The synthesized AWBP-PEG-g-LMWSC were analyzed by measuring FTIR, $^1H-NMR$, zeta -potentiometer, and atomic force microscopy (AFM).

• Macromolecular Research
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• v.14 no.1
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• pp.66-72
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• 2006

The purpose of this study is to develop novel nanoparticles based on polyion complex formation between low molecular weight water-soluble chitosan (LMWSC) and all-trans retinoic acid (atRA). LMWSC nanoparticles encapsulating atRA based on polyion complex were prepared by mixing of atRA into LMWSC aqueous solution using ultrasonication. In FTIR spectra, the carbonyl group of atRA at 1690 $cm^{-1}$ disappeared or decreased when ion complexes were formed between LMWSC and atRA. In ${1}^H$ NMR spectra, specific peaks of atRA disappeared when atRA-encapsulated LMWSC (RAC) nanoparticles were reconstituted into $D_{2}O$ while specific peaks both of atRA and LMWSC appeared in $D_{2}O$/DMSO (1/3, v/v) mixture. XRD patterns also showed that the crystal peaks of atRA were disappeared by encapsulation into LMWSC nanoparticles. LMWSC nanoparticles encapsulating atRA have spherical shapes with particle size below 200 nm. The mechanism of encapsulation of atRA into LMWSC nanoparticles was thought to be an ion complex formation between LMWSC and atRA. LMWSC nanoparticles showed high atRA loading efficiency over 90$\%$ (w/w). AtRA was continuously released from nanoparticles over 10 days. In in vitro cell cytotoxicity test, free atRA showed higher cytotoxic effect against CT 26 colon carcinoma cell line on 1 day. However, RAC nanoparticles showed similar cytotoxicity against CT 26 cells on 2 day. These results suggest the potential for the introduction of LMWSC nanoparticles into various biomedical fields such as drug delivery.

• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.607-611
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• 2007

To improve transfection efficiency, we prepared histidine-low molecular weight water-soluble chitosan (LMWSC) having the potential to form complex with DNA as a cationic polymer. Histidine-LMWSC was synthesized by the esterification reaction and removing phthaloyl group. The histidine-LMWSC was characterized using FT-IR, $^1H$ NMR spectra. Histidine-LMWSC was complexed with plasmid DNA (pDNA) in various polymer/DNA (N/P) weight ratios, and the complex was identified using gel retardation assay. The particle sizes of the hisitidine-LMWSC/DNA complexes were measured on a DLS instrument by fixing the histidine-LMWSC/DNA weight ratio of 10/1. Owing to the utilization of a large excess amount of cationic LMWSC against anionic DNA, the particle size of histidine-LMWSC/DNA complexes was in the range of 100~200 nm. Therefore, histidine-LMWSC will be useful in the development of gene carriers.

• Polymer(Korea)
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• v.35 no.5
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• pp.419-423
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• 2011

Chitosan is a natural polymer derived from chitin that has been widely used as a dietary supplement and in a variety of pharmacological and biomedical applications. In addition, water-soluble chitosan has been used to enhance the stability of chitosan in water and reduce cytotoxic activity induced by acetic acid. In this study, the antibiotic activity and mechanism of low molecular weight water-soluble chitosan (LMWSC; MW1, MW3, MW5, and MW10) were examined in pathogenic bacteria cells and vesicles containing bacterial membrane lipids. MW10 displayed potent antibacterial activity against pathogenic bacteria strains and no cytotoxicity against mammalian cells. In addition, the degree of calcein leakage was examined as a function of lipid composition (PE/PG=7/3 w/w). The results of these experiments demonstrated that MW10 promoted leakage in negatively-charged membranes. Furthermore, confocal microscopy revealed that MW10 was located in the plasma membrane.

• Polymer(Korea)
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• v.31 no.5
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• pp.454-459
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• 2007

Gene therapy using low molecular weight water soluble chitosan (LMWSC) as polycationic polymer shows good biocompatibility, but low transfection efficiency. The mechanism of folic acid (FA) uptake in the cells to promote targeting and internalization could improve transfection rates. The objective of this study was to synthesize and characterize the WSCFA-DNA complex and evaluate their cytotoxicity, in vitro. In $^1H-NMR$ spectra, specific peaks appeared both of FA and LMWSC in $D_2O$. WSCFA nanoparticles have spherical shapes with particle size show below 110 nm. In the cell cytotoxicity test, the WSCFA-DNA complex showed high cell viability, in vitro. Gel electrophoresis showed condensed DNA within the carriers. hi vitro transfection efficiency was assayed by fluorescence spectroscopy WSCFA nanoparticles have less cytotoxicity, good DNA condensation and particle size around 110 nm, which makes them a promising candidate as a non-viral gene vector.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.593-602
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• 2010

Chitosan as a natural polymer has superior physicochemical properties such as biocompatibility, biodegradability and nontoxicity, but application of chitosan for therapy of cancer and gene related-disease has been limited by poor solubility in aqueous solution. Therefore, low molecular weight water-soluble chitosan (LMWSC) with high reactivity and strong positive charge can be applied as a delivery system having function to carry in the specific tissue the bioactive material like poor solubility drug, or therapeutic gene and developed as a therapeutic system having good therapeutic efficiency. The most important factor for therapy of various diseases is to reveal the antigen or receptor expressed in specific lesion tissue and the antibody and ligand which can bind with antigen is to introduce at the biomaterials for enhancement the therapeutic efficiency. The studies for cationic synthetic polymer as drug or gene delivery have been actively performed, but it has many problems such as toxicity in the body, therapeutic efficiency. From this point of view, this article demonstrated the introduction of functional groups to target the specific tissue and therapeutic strategy using the modification of LMWSC with free-amine group. The development of these delivery system will provide a positive vision for cancer therapy.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.457-465
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• 2008

Development of various medical systems was accomplished through the progress of biotechnological method for therapy of human diseases. Furthermore, drug delivery systems have been investigated to carry the bioactive materials such as drug or gene in the body effectively. The most important thing in this system is to develop biomedical polymers having biocompatibility, biodegradability, and non-toxicity. Chitosan, a natural polymer, has been importantly considered as biomedical materials due to its good biocompatibility and various bio-active characteristics. Since the property of chitosan is differently explained according to the crystalline structures of chitin, the study for structural analysis of chitin has to proceed to apply as a biomaterial. From this point of view, this article introduced the analysis of crystalline structural of chitin, general property of chitosan and potential characteristics of low molecular weight water-soluble chitosan (LMWSC) as a biomaterials. Furthermore, chemical modification of LMWSC using various functional groups was also performed to enhance its bioavailability and emphasize their potential as drug delivery carriers (DDS).

• Polymer(Korea)
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• v.33 no.4
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• pp.389-395
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• 2009

To develop the carrier of hydrophobic antifungal agents based on low molecular weight water-soluble chitosan (LMWSC), LMWSC was chemically modified with deoxycholic acid (DA) which is one of the bile acid as a hydrophobic group. The nanoparticles (WSCDA) using DA conjugated LMWSC were characterized using dynamic light scattering (DLS) and transmittance electron microscope (TEM). The particle size of WSCDA ranged from 250 to 350 nm and increased with the number of DA substitution. The loaded itraconazole as an antifungal agent WSCDA nanoparticles (WSCDA-ITCN) were prepared by solvent evaporation method. The drug content and the loading efficiency were investigated approximately $9{\sim}10%$ and $61{\sim}68%$ by UV spectrophotometer, respectively. The release of drug from nanoparticles was slow and showed sustained release characteristics. Based on the results of release study that the higher DA contents in WSCDA, the slower the releasing rate, the WSCDA-ITCN could be used as an excellent antifungal agent.