Kwangsok Kim
Stony Brook University
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Featured researches published by Kwangsok Kim.
Polymer | 2002
Xinhua Zong; Kwangsok Kim; Dufei Fang; Shaofeng Ran; Benjamin S. Hsiao; Benjamin Chu
Abstract An electrospinning method was used to fabricate bioabsorbable amorphous poly( d , l -lactic acid) (PDLA) and semi-crystalline poly( l -lactic acid) (PLLA) nanofiber non-woven membranes for biomedical applications. The structure and morphology of electrospun membranes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and synchrotron wide-angle X-ray diffraction/small angle X-ray scattering. SEM images showed that the fiber diameter and the nanostructured morphology depended on processing parameters such as solution viscosity (e.g. concentration and polymer molecular weight), applied electric field strength, solution feeding rate and ionic salt addition. The combination of different materials and processing parameters could be used to fabricate bead-free nanofiber non-woven membranes. Concentration and salt addition were found to have relatively larger effects on the fiber diameter than the other parameters. DSC and X-ray results indicated that the electrospun PLLA nanofibers were completely non-crystalline but had highly oriented chains and a lower glass transition temperature than the cast film.
Journal of Controlled Release | 2003
Yen Kim Luu; Kwangsok Kim; Benjamin S. Hsiao; Benjamin Chu; Michael Hadjiargyrou
The present work utilizes electrospinning to fabricate synthetic polymer/DNA composite scaffolds for therapeutic application in gene delivery for tissue engineering. The scaffolds are non-woven, nano-fibered, membranous structures composed predominantly of poly(lactide-co-glycolide) (PLGA) random copolymer and a poly(D,L-lactide)-poly(ethylene glycol) (PLA-PEG) block copolymer. Release of plasmid DNA from the scaffolds was sustained over a 20-day study period, with maximum release occurring at approximately 2 h. Cumulative release profiles indicated amounts released were approximately 68-80% of the initially loaded DNA. Variations in the PLGA to PLA-PEG block copolymer ratio vastly affected the overall structural morphology, as well as both the rate and efficiency of DNA release. Results indicated that DNA released directly from these electrospun scaffolds was indeed intact, capable of cellular transfection, and successfully encoded the protein beta-galactosidase. When tested under tensile loads, the electrospun polymer/DNA composite scaffolds exhibited tensile moduli of approximately 35 MPa, with approximately 45% strain initially. These values approximate those of skin and cartilage. Taken together, this work represents the first successful demonstration of plasmid DNA incorporation into a polymer scaffold using electrospinning.
Biomaterials | 2003
Kwangsok Kim; Meiki Yu; Xinhua Zong; Jonathan B. Chiu; Dufei Fang; Young-Soo Seo; Benjamin S. Hsiao; Benjamin Chu; Michael Hadjiargyrou
Typical properties of poly(D,L-lactide) (PLA)-based scaffolds (films and foams), such as long degradation time, mechanical stiffness and hydrophobicity, are sometimes not suitable for biomedical applications. These properties can be substantially altered by electrospinning of PLA blends with miscible poly(lactide-co-glycolide) (PLGA) random copolymers, poly(lactide-b-ethylene glycol-b-lactide) (PLA-b-PEG-b-PLA) triblock copolymers, and a lactide (used as a hydrolytic catalyst). Electrospun scaffolds based on the multi-component PLA blends, comprised of randomly interconnected webs of sub-micron sized fibers, have a bulk density of 0.3-0.4 g/cm3. In this study, the concentration effects of PLA-b-PEG-b-PLA triblock copolymer and lactide on the cell proliferation and the hydrophilicity of electrospun scaffolds were investigated. Based on in vitro degradation study, we found that the electrospun scaffold having PLA (40 wt%), PLGA (LA/GA=50/50, 25 wt%), PLA-b-PEG-b-PLA (20 wt%), and lactide (15 wt%) underwent a rapid weight loss of approximately 65% in 7 weeks. The hydrophobicity of this membrane, as determined by contact angle measurements in a cell buffer solution, decreased by approximately 50% from 105 degrees (of an electrospun PLA scaffold) to 50 degrees. The selection of suitable chemical compositions in conjunction with the non-invasive electrospinning process is useful in the production of a new kind of biodegradable scaffolds suitable for different biomedical applications such as cell storage and delivery as well as prevention of post-surgical adhesion because of their porosity, mechanical flexibility and tunable biodegradability.
Annals of Surgery | 2004
Xinhua Zong; Sean Li; Elliott Chen; Barbara Garlick; Kwangsok Kim; Dufei Fang; Jonathan B. Chiu; Tom Zimmerman; Collin E. M. Brathwaite; Benjamin S. Hsiao; Benjamin Chu
Objectives:The objective of this study was to evaluate the efficacy of nonwoven bioabsorbable nanofibrous membranes of poly(lactideco-glycolide) for prevention of postsurgery-induced abdominal adhesions. Summary Background Data:Recent reports indicated that current materials used for adhesion prevention have only limited success. Studies on other bioabsorbable materials using a new fabrication technique demonstrated the promising potential of generating an improved and inexpensive product that is suitable for a variety of surgical applications. Methods:All rats underwent a midline celiotomy. The cecum was identified and scored using an abrasive pad until serosal bleeding was noted on the anterior surface. A 1 × 1 cm2 of abdominal wall muscle was excised directly over the cecal wound. The celiotomy was then closed in 2 layers immediately (control) after a barrier was laid in between the cecum and the abdominal wall. All rats underwent a second celiotomy after 28 days to evaluate the extent of abdominal adhesions qualitatively and quantitatively. Results:Cecal adhesions were reduced from 78% in the control group to 50% in the group using biodegradable poly(lactide-co-glycolide) (PLGA) nonwoven nanofibrous membranes (n = 10, P = 0.2) and to 22% in the group using membranes containing PLGA and poly(ethylene glycol)/poly(D,L-lactide) (PEG-PLA) blends (n = 9, P = 0.03). Electrospinning method also enabled us to load an antibiotic drug Cefoxitin sodium (Mefoxin; Merck Inc., West Point, PA) with high efficacy. The electrospun PLGA/PEG-PLA membranes impregnated with 5 wt% cefoxitin sodium, which amounts to approximately 10% of the systemic daily dose typically taken after surgery in humans, completely prevented cecal adhesions (0%) in rats. Conclusions:Electrospun nonwoven bioabsorbable nanofibrous membranes of poly(lactide-co-glycolide) were effective to reduce adhesions at the site of injury using an objective rat model. The membrane acted as a physical barrier but with drug-delivery capability. The combined advantages of composition adjustment, drug-loading capability, and easy placement handling (relatively hydrophobic) make these membranes potentially successful candidates for further clinical evaluations.
Nucleic Acids Research | 2005
Dehai Liang; Yen Kim Luu; Kwangsok Kim; Benjamin S. Hsiao; Michael Hadjiargyrou; Benjamin Chu
Extracellular and intracellular barriers typically prevent non-viral gene vectors from having an effective transfection efficiency. Formulation of a gene delivery vehicle that can overcome the barriers is a key step for successful tissue regeneration. We have developed a novel core-shelled DNA nanoparticle by invoking solvent-induced condensation of plasmid DNA (β-galactosidase or GFP) in a solvent mixture [94% N,N-dimethylformamide (DMF) + 6% 1× TE buffer] and subsequent encapsulation of the condensed DNA globule in a triblock copolymer, polylactide-poly(ethylene glycol)-polylactide (L8E78L8), in the same solvent environment. The polylactide shell protects the encapsulated DNA from degradation during electrospinning of a mixture of encapsulated DNA nanoparticles and biodegradable PLGA (a random copolymer of lactide and glycolide) to form a nanofibrous non-woven scaffold using the same solution mixture. The bioactive plasmid DNA can then be released in an intact form from the scaffold with a controlled release rate and transfect cells in vitro.
Journal of Controlled Release | 2004
Kwangsok Kim; Yen Kim Luu; Charles Chang; Dufei Fang; Benjamin S. Hsiao; Benjamin Chu; Michael Hadjiargyrou
Polymer | 2006
Kyunghwan Yoon; Kwangsok Kim; Xuefen Wang; Dufei Fang; Benjamin S. Hsiao; Benjamin Chu
Biomacromolecules | 2003
Xinhua Zong; Shaofeng Ran; Kwangsok Kim; Dufei Fang; Benjamin S. Hsiao; Benjamin Chu
Archive | 2005
Benjamin Chu; Benjamin S. Hsiao; Dufei Fang; Kwangsok Kim
Archive | 2002
Benjamin Chu; Benjamin S. Hsiao; Michael Hadjiargyrou; Dufei Fang; Xinhua Zong; Kwangsok Kim