29 results on '"Kihak Gwon"'
Search Results
2. Intracellular NO Delivery by Si-Based Ni Composite Nanoflowers
- Author
-
Do Nam Lee, Kihak Gwon, Jeong-Hoon Yu, Yeong Rim Kim, Gisang Park, Ihn Han, Su Jung Lee, Jae Ho Shin, and Jong-Sung Yu
- Subjects
General Materials Science - Published
- 2022
3. Bioactive hydrogel microcapsules for guiding stem cell fate decisions by release and reloading of growth factors
- Author
-
Kihak Gwon, Hye Jin Hong, Alan M. Gonzalez-Suarez, Michael Q. Slama, Daheui Choi, Jinkee Hong, Harihara Baskaran, Gulnaz Stybayeva, Quinn P. Peterson, and Alexander Revzin
- Subjects
Biomaterials ,Biomedical Engineering ,Biotechnology - Abstract
Human pluripotent stem cells (hPSC) hold considerable promise as a source of adult cells for treatment of diseases ranging from diabetes to liver failure. Some of the challenges that limit the clinical/translational impact of hPSCs are high cost and difficulty in scaling-up of existing differentiation protocols. In this paper, we sought to address these challenges through the development of bioactive microcapsules. A co-axial flow focusing microfluidic device was used to encapsulate hPSCs in microcapsules comprised of an aqueous core and a hydrogel shell. Importantly, the shell contained heparin moieties for growth factor (GF) binding and release. The aqueous core enabled rapid aggregation of hPSCs into 3D spheroids while the bioactive hydrogel shell was used to load inductive cues driving pluripotency maintenance and endodermal differentiation. Specifically, we demonstrated that one-time, 1 h long loading of pluripotency signals, fibroblast growth factor (FGF)-2 and transforming growth factor (TGF)-β1, into bioactive microcapsules was sufficient to induce and maintain pluripotency of hPSCs over the course of 5 days at levels similar to or better than a standard protocol with soluble GFs. Furthermore, stem cell-carrying microcapsules that previously contained pluripotency signals could be reloaded with an endodermal cue, Nodal, resulting in higher levels of endodermal markers compared to stem cells differentiated in a standard protocol. Overall, bioactive heparin-containing core-shell microcapsules decreased GF usage five-fold while improving stem cell phenotype and are well suited for 3D cultivation of hPSCs.
- Published
- 2022
4. Injectable bioactive copper-based metal organic framework embedded dual-crosslinked alginate hydrogel for potential antimicrobial applications
- Author
-
Kihak Gwon, Seonhwa Lee, Youngmee Kim, Jun Choi, Sujin Kim, Sung-Jin Kim, Hye Jin Hong, Youngmin Hwang, Munemasa Mori, and Do Nam Lee
- Abstract
Background: The antibiotic resistance of pathogenic microbes due to the overuse of antibiotics is a growing threat to the public health and can eventually reduce the therapeutic effects of antibiotics. Hydrogel-based systems for local delivery of antibiotics can be a solution to this problem. Metal-organic frameworks (MOFs) have received considerable interest for use as antimicrobial materials due to their high porosity, large surface area to volume, diverse structures, and tunable topologies. Methods: In this study, we developed MOF-encapsulated and dual (photo & chemical)-crosslinkable alginate hydrogel as an antimicrobial scaffold. We synthesized antimicrobial Cu(AZPY)-MOF using solvothermal reaction and encapsulated them in an alginate-based hydrogel via visible light photo-crosslinking and calcium ion-induced chemical-crosslinking processes. Results: Powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy confirmed the successful fabrication of Cu(AZPY)-MOF encapsulated alginate hydrogel. The mechanical strength of the dual-crosslinked hydrogels was better than that of the photo-crosslinked hydrogel. Encapsulation of Cu(AZPY)-MOF in an alginate hydrogel resulted in a further increase in the mechanical strength of the hydrogel owing to the additional interaction of alginate with Cu-MOF. Moreover, the Cu(AZPY)-MOF encapsulated alginate hydrogel exhibited excellent antibacterial and antifungal properties against two bacterial strains (i.e., MRSA and S. mutans) and one fungal strain (C. albicans) as well as negligible cytotoxicity toward MEFs. Conclusions: The antimicrobial agents encapsulated dual-crosslinkable alginate hydrogel developed in this study is a promising candidate for use in tissue engineering and biomedical field.
- Published
- 2022
5. Immobilization of antibacterial copper metal-organic framework containing glutarate and 1,2-bis(4-pyridyl)ethylene ligands on polydimethylsiloxane and its low cytotoxicity
- Author
-
Hyunjun Cho, Seonhwa Lee, Kihak Gwon, Youngmee Kim, and Do Nam Lee
- Subjects
chemistry.chemical_compound ,Ethylene ,Polydimethylsiloxane ,Chemistry ,Hydrosilylation ,General Chemical Engineering ,Metal ions in aqueous solution ,fungi ,Drug delivery ,Cytotoxicity ,Combinatorial chemistry ,Controlled release ,Bond cleavage - Abstract
Metal-organic frameworks (MOFs) that include bioactive metals may exhibit activity against various microbes through metal–ligand bond cleavage to release metal ions or ligands into the media. However, controlled release over an extended time is required to avoid toxicity due to excess metal ions for successful clinical applications. Recently, copper-based MOFs (Cu-MOFs), which showed sustained release capability, porosity, and structural flexibility, exhibited antibacterial properties. Herein, toward the development of regenerative biomedical applications, we immobilized a robust Cu-MOF containing glutarate and 1,2-bis(4-pyridyl)ethylene ligands within biocompatible polydimethylsiloxane (PDMS) via simple hydrosilylation at 25 °C. The PDMS-immobilized Cu-MOF (PDMS@Cu-MOF) exhibited concentration-dependent antibacterial activities against five bacterial strains: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus. Furthermore, PDMS@Cu-MOF maintained the physical and thermal properties of PDMS and showed low cytotoxicity toward mouse embryonic fibroblasts. Owing to its antibacterial properties and low cytotoxicity, PDMS@Cu-MOF exhibited potential for medicinal applications, such as implants, skin disease treatment, wound healing, and drug delivery.
- Published
- 2021
6. Construction of a bioactive copper-based metal organic framework-embedded dual-crosslinked alginate hydrogel for antimicrobial applications
- Author
-
Kihak Gwon, Seonhwa Lee, Youngmee Kim, Jun Choi, Sujin Kim, Sung-Jin Kim, Hye Jin Hong, Youngmin Hwang, Munemasa Mori, and Do Nam Lee
- Subjects
Structural Biology ,General Medicine ,Molecular Biology ,Biochemistry - Published
- 2023
7. Highly bioactive and low cytotoxic Si-based NiOOH nanoflowers targeted against various bacteria, including MRSA, and their potential antibacterial mechanism
- Author
-
Jong-Deok Park, Ihn Han, Jong-Sung Yu, Seonhwa Lee, Do Nam Lee, and Kihak Gwon
- Subjects
biology ,Chemistry ,General Chemical Engineering ,02 engineering and technology ,Nanoflower ,010402 general chemistry ,021001 nanoscience & nanotechnology ,medicine.disease_cause ,biology.organism_classification ,Antimicrobial ,Ascorbic acid ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Staphylococcus aureus ,medicine ,0210 nano-technology ,Antibacterial activity ,Cytotoxicity ,Bacteria ,Chemical bath deposition - Abstract
With the emergence of new drug-resistant microorganisms, the development of effective antimicrobial agents is urgently required. Core-shell-structured nanomaterials have received considerable attention as antibacterial agents. We prepared a bioactive core-shell-structured silicon-based NiOOH nanoflower (Si@NiOOH) targeted against various bacteria using a modified chemical bath deposition method. Further, we investigated its potential antibacterial mechanism by evaluating electrochemical properties in a redox reaction with ascorbic acid, measuring metal ion release, and analyzing the surface area. The bactericidal rate of Si@NiOOH at 200 μg/mL towards Pseudomonas aeruginosa, Klebsiella pneumoniae, and methicillin-resistant Staphylococcus aureus was as high as 99.9%. Si@NiOOH maintained its original morphology after killing the bacteria and exhibited negligible cytotoxicity towards mouse embryonic fibroblasts. The excellent antibacterial activities of Si@NiOOH are possibly derived from its high surface area, providing a wide active site attached to the cell wall, and the high oxidative potency of the Ni(III) cations existing on its surface. The high antibacterial activity and low cytotoxicity of the nanoflower make it a promising tool for promoting wound healing and for use with medical devices and implants.
- Published
- 2021
8. Disposable Strip-Type Biosensors for Amperometric Determination of Galactose
- Author
-
Jae Ho Shin, Seonhwa Lee, Hakhyun Nam, and Kihak Gwon
- Subjects
chemistry.chemical_compound ,Chromatography ,Chemistry ,Galactose ,Electrochemistry ,Biosensor ,Amperometry - Published
- 2020
9. Delivery of nitric oxide-releasing silica nanoparticles for
- Author
-
Jung Il, Lee, Ji Hun, Park, Yeong-Rim, Kim, Kihak, Gwon, Hae Won, Hwang, Gayoung, Jung, Joo-Yup, Lee, Jeong-Yun, Sun, Jong Woong, Park, Jae Ho, Shin, and Myoung-Ryul, Ok
- Abstract
Nitric oxide (NO) has been shown to promote revascularization and nerve regeneration after peripheral nerve injury. However, in vivo application of NO remains challenging due to the lack of stable carrier materials capable of storing large amounts of NO molecules and releasing them on a clinically meaningful time scale. Recently, a silica nanoparticle system capable of reversible NO storage and release at a controlled and sustained rate was introduced. In this study, NO-releasing silica nanoparticles (NO-SNs) were delivered to the peripheral nerves in rats after acute crush injury, mixed with natural hydrogel, to ensure the effective application of NO to the lesion. Microangiography using a polymer dye and immunohistochemical staining for the detection of CD34 (a marker for revascularization) results showed that NO-releasing silica nanoparticles increased revascularization at the crush site of the sciatic nerve. The sciatic functional index revealed that there was a significant improvement in sciatic nerve function in NO-treated animals. Histological and anatomical analyses showed that the number of myelinated axons in the crushed sciatic nerve and wet muscle weight excised from NO-treated rats were increased. Moreover, muscle function recovery was improved in rats treated with NO-SNs. Taken together, our results suggest that NO delivered to the injured sciatic nerve triggers enhanced revascularization at the lesion in the early phase after crushing injury, thereby promoting axonal regeneration and improving functional recovery.
- Published
- 2022
10. High-Performance Amperometric Carbon Monoxide Sensor Based on a Ptcr/C-Xerogel-Modified Microelectrode
- Author
-
Seonhwa Lee, Kihak Gwon, Heesu Kim, and Jae Ho Shin
- Subjects
History ,Polymers and Plastics ,Business and International Management ,Industrial and Manufacturing Engineering - Published
- 2022
11. Coating bioactive microcapsules with tannic acid enhances the phenotype of the encapsulated pluripotent stem cells
- Author
-
Daheui Choi, Kihak Gwon, Hye Jin Hong, Harihara Baskaran, Olalla Calvo-Lozano, Alan M. Gonzalez-Suarez, Kyungtae Park, Jose M. de Hoyos-Vega, Laura M. Lechuga, Jinkee Hong, Gulnaz Stybayeva, Alexander Revzin, Mayo Clinic, J. W. Kieckhefer Foundation, Khalifa Bin Zayed Al Nahyan Foundation, Regenerative Medicine Minnesota, and National Institutes of Health (US)
- Subjects
Tannic acid ,Controlled growth factor release ,Microfluidics ,3D stem cell cultures ,General Materials Science ,Nanofilm ,Heparin-based microcapsules - Abstract
Human pluripotent stem cells (hPSCs) may be differentiated into any adult cell type and therefore hold incredible promise for cell therapeutics and disease modeling. There is increasing interest in three-dimensional (3D) hPSC culture because of improved differentiation outcomes and potential for scale up. Our team has recently described bioactive heparin (Hep)-containing core-shell microcapsules that promote rapid aggregation of stem cells into spheroids and may also be loaded with growth factors for the local and sustained delivery to the encapsulated cells. In this study, we explored the possibility of further modulating bioactivity of microcapsules through the use of an ultrathin coating composed of tannic acid (TA). Deposition of the TA film onto model substrates functionalized with Hep and poly(ethylene glycol) was characterized by ellipsometry and atomic force microscopy. Furthermore, the presence of the TA coating was observed to increase the amount of basic fibroblast growth factor (bFGF) incorporation by up to twofold and to extend its release from 5 to 7 days. Most significantly, TA-microcapsules loaded with bFGF induced higher levels of pluripotency expression compared to uncoated microcapsules containing bFGF. Engineered microcapsules described here represent a new stem cell culture approach that enables 3D cultivation and relies on local delivery of inductive cues., This study was supported in part by the grants from the Mayo Clinic Center for Regenerative Medicine, J.W. Kieckhefer Foundation, Al Nahyan Foundation, Regenerative Medicine Minnesota (RMM 101617 TR 004), and NIH (DK107255). Additional support was provided by an NIH Grant EB021911 to H.B. Additional funding was provided by the Mayo Clinic Center for Cell Signaling in Gastroenterology (P30DK084567).
- Published
- 2022
12. Biocompatible Core-Shell-Structured Si-Based NiO Nanoflowers and Their Anticancer Activity
- Author
-
Kihak Gwon, Jong-Deok Park, Seonhwa Lee, Jong-Sung Yu, and Do Nam Lee
- Subjects
Pharmaceutical Science ,core–shell ,Ni composite ,nanoflowers ,biocompatibility ,anticancer activity - Abstract
Compared to most of nano-sized particles, core–shell-structured nanoflowers have received great attention as bioactive materials because of their high surface area with the flower-like structures. In this study, core–shell-structured Si-based NiO nanoflowers, Si@NiO, were prepared by a modified chemical bath deposition method followed by thermal reduction. The crystal morphology and basic structure of the composites were characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and porosity analysis (BJT), and inductively coupled plasma optical emission spectrometry (ICP-OES). The electrochemical properties of the Si@NiO nanoflowers were examined through the redox reaction of ascorbic acid with the metal ions present on the surface of the core–shell nanoflowers. This reaction favored the formation of reactive oxygen species. The Si@NiO nanoflowers showed excellent anticancer activity and low cytotoxicity toward the human breast cancer cell line (MCF-7) and mouse embryonic fibroblasts (MEFs), respectively, demonstrating that the anticancer activities of the Si@NiO nanoflowers were primarily derived from the oxidative capacity of the metal ions on the surface, rather than from the released metal ions. Thus, this proves that Si-based NiO nanoflowers can act as a promising candidate for therapeutic applications.
- Published
- 2021
13. Biodegradable hyaluronic acid-based, nitric oxide-releasing nanofibers for potential wound healing applications
- Author
-
Jin Sil Lee, Won Il Choi, Jae Ho Shin, Seonhwa Lee, and Kihak Gwon
- Subjects
Wound Healing ,Chemistry ,Biomedical Engineering ,Nanofibers ,Biodegradation ,Methacrylate ,Nitric Oxide ,NONOate ,Electrospinning ,chemistry.chemical_compound ,Chemical engineering ,Nanofiber ,Hyaluronic acid ,General Materials Science ,Nitric Oxide Donors ,Fourier transform infrared spectroscopy ,Hyaluronic Acid ,Wound healing - Abstract
Nitric oxide (NO) is one of the smallest gas molecules with pharmaceutical and potential wound therapeutic effects due to its ability to regulate inflammation and eradicate bacterial infections. Recently, NO-releasing synthetic polymer-based nanofibers have become promising candidates for wound healing due to their facile functionalisation, tunable mechanical properties, and large effective surface areas. However, synthetic polymer-based nanofibers suffer from poor degradability in the physiological milieu, which restricts their use in in vivo applications. In this study, we developed biodegradable and nitric oxide-releasing nanofibers for potential wound healing applications. We synthesised dual-functionalised hyaluronic acid (HA) containing methacrylate groups and N-diazeniumdiolate (NONOate)-NO donor groups and capable of forming crosslinked, electrospun nanofibers, with an effective NO payload, through an electrospinning process and photoinitiated polymerisation. Nuclear magnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy confirmed the successful synthesis of the functionalised HA. Control over both the NO donor and HA concentrations allowed for the preparation of NO-releasing, HA-based nanofibers of varying diameters (240–490 nm), NO payloads (10–620 nmol mg−1), maximum amounts of NO released (160–8920 ppb mg−1), and NO release durations (1.5–20.2 h). Moreover, the NO-releasing nanofibers had good biodegradability and potential wound healing effects without any observed cytotoxicity. The biodegradable and NO-releasing HA-based nanofibers developed in this study have the potential application in wound healing.
- Published
- 2021
14. Microfluidic Fabrication of Core-Shell Microcapsules carrying Human Pluripotent Stem Cell Spheroids
- Author
-
Hye Jin Hong, Alan M. Gonzalez-Suarez, Gulnaz Stybayeva, Alexander Revzin, and Kihak Gwon
- Subjects
Pluripotent Stem Cells ,Aqueous solution ,General Immunology and Microbiology ,Chemistry ,General Chemical Engineering ,General Neuroscience ,Microfluidics ,technology, industry, and agriculture ,Spheroid ,Capsules ,Cell Differentiation ,Hydrogels ,Core (manufacturing) ,General Biochemistry, Genetics and Molecular Biology ,chemistry.chemical_compound ,Flow focusing ,Chemical engineering ,PEG ratio ,Click chemistry ,Humans ,Ethylene glycol - Abstract
Three-dimensional (3D) or spheroid cultures of human pluripotent stem cells (hPSCs) offer the benefits of improved differentiation outcomes and scalability. In this paper, we describe a strategy for the robust and reproducible formation of hPSC spheroids where a co-axial flow focusing device is utilized to entrap hPSCs inside core-shell microcapsules. The core solution contained single cell suspension of hPSCs and was made viscous by the incorporation of high molecular weight poly(ethylene glycol) (PEG) and density gradient media. The shell stream comprised of PEG-4 arm-maleimide or PEG-4-Mal and flowed alongside the core stream toward two consecutive oil junctions. Droplet formation occurred at the first oil junction with shell solution wrapping itself around the core. Chemical crosslinking of the shell occurred at the second oil junction by introducing a di-thiol crosslinker (1,4-dithiothreitol or DTT) to these droplets. The crosslinker reacts with maleimide functional groups via click chemistry, resulting in the formation of a hydrogel shell around the microcapsules. Our encapsulation technology produced 400 µm diameter capsules at a rate of 10 capsules per second. The resultant capsules had a hydrogel shell and an aqueous core that allowed single cells to rapidly assemble into aggregates and form spheroids. The process of encapsulation did not adversely affect the viability of hPSCs, with >95% viability observed 3 days post-encapsulation. For comparison, hPSCs encapsulated in solid gel microparticles (without an aqueous core) did not form spheroids and had
- Published
- 2021
15. Injectable hyaluronic acid hydrogel encapsulated with Si-based NiO nanoflower by visible light cross-linking: Its antibacterial applications
- Author
-
Kihak Gwon, Jong-Deok Park, Seonhwa Lee, Won Il Choi, Youngmin Hwang, Munemasa Mori, Jong-Sung Yu, and Do Nam Lee
- Subjects
Methicillin-Resistant Staphylococcus aureus ,Silicon ,Light ,Hydrogels ,General Medicine ,Fibroblasts ,Silicon Dioxide ,Biochemistry ,Anti-Bacterial Agents ,Mice ,Structural Biology ,Nickel ,Pseudomonas aeruginosa ,Animals ,Hyaluronic Acid ,Molecular Biology - Abstract
Bacterial infections have become a severe threat to human health and antibiotics have been developed to treat them. However, extensive use of antibiotics has led to multidrug-resistant bacteria and reduction of their therapeutic effects. An efficient solution may be localized application of antibiotics using a drug delivery system. For clinical application, they need to be biodegradable and should offer a prolonged antibacterial effect. In this study, a new injectable and visible-light-crosslinked hyaluronic acid (HA) hydrogel loaded with silicon (Si)-based nickel oxide (NiO) nanoflowers (Si@NiO) as an antibacterial scaffold was developed. Si@NiO nanoflowers were synthesized using chemical bath deposition before encapsulating them in the HA hydrogel under a mild visible-light-crosslinking conditions to generate a Si@NiO-hydrogel. Si@NiO synthesis was confirmed using scanning electron microscopy, transmission electron microscopy, and powder X-ray diffraction. As-prepared Si@NiO-hydrogel exhibited enhanced mechanical properties compared to a control bare hydrogel sample. Moreover, Si@NiO-hydrogel exhibits excellent antibacterial properties against three bacterial strains (P. aeruginosa, K. pneumoniae, and methicillin-resistant Staphylococcus aureus (99.9% bactericidal rate)) and negligible cytotoxicity toward mouse embryonic fibroblasts. Therefore, Si@NiO-hydrogel has the potential for use in tissue engineering and biomedical applications owing to its injectability, visible-light crosslink ability, degradability, biosafety, and superior antibacterial property.
- Published
- 2021
16. Bioactive Hydrogel Microcapsules for Guiding Stem Cell Fate Decisions by Release and Reloading of Growth Factors
- Author
-
Gulnaz Stybayeva, Doo Sup Choi, Harihara Baskaran, Michael Q. Slama, Kihak Gwon, Alexander Revzin, Alan M. Gonzalez-Suarez, Hye Jin Hong, Quinn P. Peterson, and Jong Kwang Hong
- Subjects
Stem cell fate ,Chemistry ,Growth factor ,medicine.medical_treatment ,medicine ,Spheroid ,Stem cell ,Fibroblast growth factor ,Induced pluripotent stem cell ,NODAL ,Transforming growth factor ,Cell biology - Abstract
Human pluripotent stem cells (hPSC) hold considerable promise as a source of adult cells for treatment of diseases ranging from diabetes to liver failure. Some of the challenges that limit the clinical/translational impact of hPSCs are high cost and difficulty in scaling-up of existing differentiation protocols. In this paper, we sought to address these challenges through the development of bioactive microcapsules. A co-axial flow focusing microfluidic device was used to encapsulate hPSCs in microcapsules comprised of an aqueous core and a hydrogel shell. Importantly, the shell contained heparin moieties for growth factor (GF) binding and release. The aqueous core enabled rapid aggregation of hPSCs into 3D spheroids while the bioactive hydrogel shell was used to load inductive cues driving pluripotency maintenance and endodermal differentiation. Specifically, we demonstrated that one-time 1h long loading of pluripotency signals, fibroblast growth factor (FGF)-2 and transforming growth factor (TGF)-β1, into bioactive microcapsules was sufficient to induce and maintain pluripotency of hPSCs over the course of 5 days at levels similar to or better than a standard protocol with soluble GFs. Furthermore, stem cell-carrying microcapsules that previously contained pluripotency signals could be reloaded with an endodermal cue, Nodal, resulting in higher levels of endodermal markers compared to stem cells differentiated in a standard protocol. Overall, bioactive heparin-containing core-shell microcapsules decreased GF usage five-fold while improving stem cell phenotype and are well suited for 3D cultivation of hPSCs.
- Published
- 2021
17. High-performance amperometric carbon monoxide sensor based on a xerogel-modified PtCr/C microelectrode
- Author
-
Seonhwa Lee, Kihak Gwon, Heesu Kim, Bong Joo Park, and Jae Ho Shin
- Subjects
Materials Chemistry ,Metals and Alloys ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Instrumentation ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2022
18. Robust Copper Metal–Organic Framework-Embedded Polysiloxanes for Biomedical Applications: Its Antibacterial Effects on MRSA and In Vitro Cytotoxicity
- Author
-
Seonhwa Lee, Youngmee Kim, Do Nam Lee, So Hyeon Yang, Sung Jin Kim, Hyunjun Cho, and Kihak Gwon
- Subjects
Cu-MOF ,cytocompatibility ,Thermogravimetric analysis ,antibacterial agent ,Hydrosilylation ,polysiloxane (PS) ,General Chemical Engineering ,medicine.disease_cause ,Article ,lcsh:Chemistry ,chemistry.chemical_compound ,medicine ,General Materials Science ,Cytotoxicity ,Antibacterial agent ,chemistry.chemical_classification ,Chemistry ,fungi ,hydrosilylation ,Polymer ,lcsh:QD1-999 ,Staphylococcus aureus ,Drug delivery ,biomedical application ,Adhesive ,Nuclear chemistry - Abstract
Polysiloxanes (PSs) have been widely utilized in the industry as lubricants, varnishes, paints, release agents, adhesives, and insulators. In addition, their applications have been expanded to include the development of new biomedical materials. To modify PS for application in therapeutic purposes, a flexible antibacterial Cu-MOF (metal–organic framework) consisting of glutarate and 1,2-bis(4-pyridyl)ethane ligands was embedded in PS via a hydrosilylation reaction of vinyl-terminated and H-terminated PSs at 25 °C. The bactericidal activities of the resulting Cu-MOF-embedded PS (PS@Cu-MOF) and the control polymer (PS) were tested against Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus. PS@Cu-MOF exhibited more than 80% bactericidal activity toward the tested bacteria at a concentration of 100 μg⋅mL−1 and exhibited a negligible cytotoxicity toward mouse embryonic fibroblasts at the same concentration. Release tests of the Cu(II) ion showed PS@Cu-MOF to be particularly stable in a phosphate-buffered saline solution. Furthermore, its physical and thermal properties, including the phase transition, rheological measurements, swelling ratio, and thermogravimetric profile loss, were similar to those of the control polymer. Moreover, the low cytotoxicity and bactericidal activities of PS@Cu-MOF render it a promising candidate for use in medicinal applications, such as in implants, skin-disease treatment, wound healing, and drug delivery.
- Published
- 2021
19. Novel Metal-Organic Framework-Based Photocrosslinked Hydrogel System for Efficient Antibacterial Applications
- Author
-
Ihn Han, Seonhwa Lee, Youngmee Kim, Do Nam Lee, and Kihak Gwon
- Subjects
Staphylococcus aureus ,Materials science ,Pyridines ,macromolecular substances ,02 engineering and technology ,Polyethylene glycol ,Microbial Sensitivity Tests ,010402 general chemistry ,Ligands ,complex mixtures ,01 natural sciences ,Glutarates ,chemistry.chemical_compound ,PEG ratio ,Escherichia coli ,Humans ,General Materials Science ,Metal-Organic Frameworks ,Antibacterial agent ,Minimum bactericidal concentration ,fungi ,technology, industry, and agriculture ,Hydrogels ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Anti-Bacterial Agents ,chemistry ,Self-healing hydrogels ,Drug delivery ,Metal-organic framework ,0210 nano-technology ,Antibacterial activity - Abstract
Metal-organic frameworks (MOFs) can be applied in biology and medicine as drug delivery systems by carrying drugs on their surfaces or releasing bioactive ligands. To investigate the therapeutic potential of hydrogels that contain MOFs, three MOFs containing glutarate and 1,2-bis(4-pyridyl)ethylene ligands were synthesized by the previously reported hydrothermal or solvothermal reactions: Cu-MOF 1, Co-MOF 2, and Zn-MOF 3. Bioactive MOF-embedded hydrogels (hydrogel@Cu-MOF 1, hydrogel@Co-MOF 2, and hydrogel@Zn-MOF 3) were prepared by UV light-mediated thiol-ene photopolymerization using diacrylated polyethylene glycol (PEG), 4-arm-thiolated PEG, and MOFs. The activities of the MOF-embedded hydrogels were tested against the Gram-negative bacterium Escherichia coli and the Gram-positive bacterium Staphylococcus aureus. These MOF-embedded hydrogels were observed to be very stable, based on the release test of MII ions, and both hydrogel@Cu-MOF 1 and hydrogel@Co-MOF 2 showed excellent antibacterial activity. Although, in human dermal fibroblasts, hydrogel@Cu-MOF 1 showed no cytotoxic effects, it exhibited 99.9% antibacterial effects at the minimum bactericidal concentration. Physical properties such as the surface area and dimension of MOFs with different central metals appeared to be more important than the chemical properties of the ligands in determining the effects on bacteria. These MOF-embedded hydrogels may be useful in antibacterial applications such as cosmetics, treatment of skin diseases, and drug delivery owing to their low cytotoxicity and high bactericidal activity.
- Published
- 2020
20. Delivery of nitric oxide-releasing silica nanoparticles for in vivo revascularization and functional recovery after acute peripheral nerve crush injury
- Author
-
Myoung-Ryul Ok, JaeHo Shin, JongWoong Park, JungIl Lee, JiHun Park, Yeong-Rim Kim, Kihak Gwon, HaeWon Hwang, Gayoung Jung, Joo-Yup Lee, and Jeong-Yun Sun
- Subjects
Developmental Neuroscience - Published
- 2022
21. Mechanical stimuli responsive and highly elastic biopolymer/nanoparticle hybrid microcapsules for controlled release
- Author
-
Kwanwoo Shin, Giyoong Tae, Youngmin Hwang, Siyeon Baek, Raja Rajamanickam, and Kihak Gwon
- Subjects
chemistry.chemical_classification ,Pressing ,Materials science ,Stimuli responsive ,technology, industry, and agriculture ,Biomedical Engineering ,Nanoparticle ,02 engineering and technology ,General Chemistry ,General Medicine ,Polymer ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Controlled release ,Polyelectrolyte ,0104 chemical sciences ,chemistry ,Monolayer ,engineering ,General Materials Science ,Biopolymer ,Composite material ,0210 nano-technology - Abstract
Mechanical stimulus is one of the universally accessible physical ways of triggering the drug release from their carriers. Hollow microcapsules made of polyelectrolyte multilayers by conventional methods are not elastic enough to respond to a large and repetitive mechanical deformation. Here, hybrid hollow capsules comprising alternating layers of inorganic colloidal particles and biopolymers were prepared by the layer-by-layer approach followed by freezing-assisted crosslinking of polymer layers. The size of the capsule was controllable by the size of sacrificial cores. These hybrid capsules were mechanically more stable and recover faster than polyelectrolyte capsules, and could be recovered elastically even after large and repetitive deformation up to 98% relative to their original dimensions. Drugs in a wide range of molecular weight up to 70 kDa Mw could be loaded into the hollow hybrid microcapsules and the release of loaded contents from these hybrid capsules could be controlled through the deformation by applying a weak force such as a finger pressing on them. Mechanical stimuli-responsive delivery of model drugs was demonstrated on a monolayer of these hybrid capsules.
- Published
- 2016
22. Heparin-immobilized gold-assisted controlled release of growth factors via electrochemical modulation
- Author
-
Young Ha Kim, Myung-Han Yoon, Seyeong Lee, Bo-young Kim, Giyoong Tae, and Kihak Gwon
- Subjects
General Chemical Engineering ,Basic fibroblast growth factor ,Nanotechnology ,Stimulation ,02 engineering and technology ,General Chemistry ,Heparin ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Controlled release ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,cardiovascular system ,Biophysics ,medicine ,Gold surface ,0210 nano-technology ,medicine.drug - Abstract
We developed a versatile platform for the electrochemical release of growth factors assisted by a heparin-immobilized gold surface. The controlled release of basic fibroblast growth factor (bFGF) from heparinized gold could be effectively modulated by biphasic electrochemical stimulation which actively controlled specific interactions between heparin and bFGF in a remote manner so that the released bFGF maintained its bioactivity.
- Published
- 2016
23. Improved near infrared-mediated hydrogel formation using diacrylated Pluronic F127-coated upconversion nanoparticles
- Author
-
Min-Gon Kim, Eun-Jung Jo, Giyoong Tae, Abhishek Sahu, Jae Young Lee, and Kihak Gwon
- Subjects
Materials science ,Infrared Rays ,Bioengineering ,Nanotechnology ,02 engineering and technology ,Polyethylene glycol ,Poloxamer ,010402 general chemistry ,01 natural sciences ,Polymerization ,Biomaterials ,chemistry.chemical_compound ,Mice ,Drug Delivery Systems ,Animals ,In situ polymerization ,Eosin Y ,technology, industry, and agriculture ,Hydrogels ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Photopolymer ,chemistry ,Mechanics of Materials ,Drug delivery ,Self-healing hydrogels ,NIH 3T3 Cells ,Nanoparticles ,0210 nano-technology - Abstract
In situ hydrogel synthesis based on photopolymerization has been recognized as a promising strategy that can be used for tissue augmentation. In this study, we developed an efficient in situ gelation method to prepare bulk hydrogels via near infrared (NIR)-mediated photopolymerization using acrylated polyethylene glycol and diacrylated Pluronic F127-coated upconversion nanoparticles (UCNPs). In our system, upon 980-nm laser irradiation, UCNPs transmit visible light, which triggers the activation of eosin Y to initiate polymerization. We found that the UCNPs coated with diacrylated Pluronic F127 can enhance the photopolymerization efficiency and thus enable the production of bulk hydrogel with requirement of a lower NIR light power compared to that required with the bare UCNPs. This photopolymerization approach will be beneficial to achieve in situ polymerization in vivo for various biomedical applications such as cell/drug delivery and construction of tissue augments.
- Published
- 2017
24. In situ formation of injectable and porous heparin-based hydrogel
- Author
-
Kiyoon Min, MeeiChyn Goh, Younghee Kim, Youngmin Hwang, Giyoong Tae, and Kihak Gwon
- Subjects
In situ ,food.ingredient ,Polymers and Plastics ,02 engineering and technology ,010402 general chemistry ,complex mixtures ,01 natural sciences ,Gelatin ,chemistry.chemical_compound ,food ,In vivo ,Polymer chemistry ,Materials Chemistry ,medicine ,Eosin Y ,Dissolution ,Organic Chemistry ,technology, industry, and agriculture ,equipment and supplies ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Photopolymer ,chemistry ,Chemical engineering ,Triethanolamine ,Leaching (metallurgy) ,0210 nano-technology ,medicine.drug - Abstract
In this study, by combining photopolymerization and particle leaching technique, in situ formation of porous hydrogel with pore interconnectivity was demonstrated in vivo upon subcutaneous injection into the back of mice as well as in vitro. A precursor solution containing thiolated heparin, PEG-diacrylate (PEG-DA), and gelatin microparticles (GMPs) as a fast dissolving porogen were photopolymerized by visible-light-initiated thiol-ene reaction with eosin Y (EY) as a photo initiator and triethanolamine (TEOA) as a co-initiator. Formation of porous structure of the hydrogel after subsequent leaching of GMPs was confirmed in an animal model as well as in a physiological environment. The physical characteristics of the hydrogel were analyzed, and the acute in vivo biocompatibility of this system was characterized.
- Published
- 2017
25. A Creatinine Biosensor with Reduced Interference from Creatine
- Author
-
Kihak Gwon, Hyunwoo Gu, Eunhye Lim, and Jae Ho Shin
- Subjects
chemistry.chemical_compound ,Creatinine ,Biochemistry ,biology ,Chemistry ,biology.protein ,Creatine kinase ,Creatine ,Biosensor - Abstract
크레아티닌 센서의 생체시료 측정 시 가장 심각한 방해 작용을 발생하는 물질인 크레아틴을 효과적으로 제거하기 위하여 creatine kinase와 adenosine triphosphate를 사용한 두 번째 효소층을 도입하여 크레아틴에 대한 방해작용을 현저히 감소시켰다. 또한 평면형 소형 크레아티닌 센서를 개발하기 위해 탄소전극 표면에 Pt black(Pt-B)을 도입하여 표면적을 증가시킴으로써 전기화학적 감응 특성을 증가시킨 스크린 프린팅 방식의 Pt-B/C 전극을 제작하였다. 최적화된 소형 크레아티닌 센서를 흐름계 카트리지에 장착하여 미지시료를 측정한 결과 5% 이내의 오차 범위 내에서 우수한 측정 정확성과 재현성을 보임을 확인하였다.Abstract : The planar-type amperometric creatinine biosensor employing an additional enzymelayer containing creatine kinase and adenosine triphosphate was developed to eliminate severeinterference from creatine. In the additional enzyme layer, an interfering substance, creatine isconverted to noninterfering product, phosphocreatine. Furthermore, the carbon electrode elec-troplated with Pt black(Pt-B) was employed to fabricate creatinine biosensors with improvedsensor performance(e.g., sensitivity, reliability, and reproducibility). The creatinine levels in anunknown sample were determined within less than 5% errors using creatinine microsensorsequipped in a flow-cell cartridge.Keywords : Creatinine biosensor, Creatine interference, Creatine kinase
- Published
- 2012
26. Modulation of cell adhesion of heparin-based hydrogel by efficient physisorption of adhesive proteins
- Author
-
Mihye Kim, Yang-Jung Kim, Giyoong Tae, and Kihak Gwon
- Subjects
Materials science ,Polymers and Plastics ,Cell growth ,General Chemical Engineering ,Organic Chemistry ,Cell ,technology, industry, and agriculture ,macromolecular substances ,Heparin ,complex mixtures ,Tissue culture ,medicine.anatomical_structure ,Biochemistry ,Physisorption ,Materials Chemistry ,medicine ,Biophysics ,Cell adhesion ,Fibroblast ,Actin ,medicine.drug - Abstract
Fibrinogen as well as collagen, cell adhesive proteins, were adsorbed efficiently onto a heparin-based hydrogel. The physisorption of these proteins was strong and stable so that the bound proteins were not easily released from the hydrogel at physiological condition. After the physisorption of fibrinogen or collagen type I onto the hydrogel, National Institute of Health/3-day transfer, inoculum 3×105 cells (NIH/3T3) fibroblasts attached and spread well on the hydrogel, whereas the bare hydrogel or serum treated hydrogel showed poor cell attachment. Cell proliferation was also remarkably enhanced by the physisorption of these cell adhesive proteins, similar to that on tissue culture plate. Open image in new window
- Published
- 2012
27. Visible-light-initiated thiol-acrylate photopolymerization of heparin-based hydrogels
- Author
-
Mihye Kim, Amy Fu, Kihak Gwon, Julia A. Kornfield, and Giyoong Tae
- Subjects
Polymers and Plastics ,Light ,Cell Survival ,Kinetics ,Bioengineering ,Electron donor ,Polymerization ,Biomaterials ,chemistry.chemical_compound ,Mice ,Polymer chemistry ,Materials Chemistry ,medicine ,Animals ,Sulfhydryl Compounds ,Eosin Y ,Heparin ,Hydrogels ,Photopolymer ,Cross-Linking Reagents ,chemistry ,Acrylates ,Triethanolamine ,Self-healing hydrogels ,NIH 3T3 Cells ,Photoinitiator ,Ethylene glycol ,medicine.drug ,Nuclear chemistry - Abstract
An in situ heparin-based forming hydrogel that cures under visible-light is formulated using eosin Y as a photoinitiator with triethanolamine as an electron donor to initiate reaction of thiolated-heparin with acrylate-ended poly(ethylene glycol). Formulations and irradiation conditions are presented for control of heparin content (1.6 to 3.3% w/v), modulus (100–10 000 Pa), and gelation time (30–600 s). Encapsulation of 3T3 fibroblasts in the hydrogel gave over 96% viability for all conditions examined. In vitro characterization of epidermal growth factor released from the hydrogel confirmed that the growth factor remains bioactive. The ability to deliver growth factors, fast gelation kinetics under visible light, and independent control of physical and biochemical properties makes this system a promising candidate for use in regenerative medicine. In particular, irradiation conditions that achieve gelation in 150s are compatible with the stringent light exposure limits of the retina, which affords a wide safety margin for use with other tissues.
- Published
- 2014
28. A biocompatible method of controlled retrieval of cell-encapsulating microgels from a culture plate
- Author
-
Giyoong Tae, Mihye Kim, and Kihak Gwon
- Subjects
Materials science ,Cell Survival ,Biophysics ,macromolecular substances ,complex mixtures ,Biochemistry ,Chitosan ,chemistry.chemical_compound ,Humans ,Polylysine ,Hyaluronic Acid ,Electrochemical potential ,Microscopy, Confocal ,technology, industry, and agriculture ,Substrate (chemistry) ,Hydrogels ,Electrochemical Techniques ,Hep G2 Cells ,Silane ,Polyelectrolyte ,Photopolymer ,chemistry ,Chemical engineering ,Electrode ,Self-healing hydrogels - Abstract
We report a biocompatible method of selectively retrieving 3-D cell-encapsulating hydrogel microstructures from a culture substrate. First, poly(L-lysine)/hyaluronic acid (PLL/HA) polyelectrolyte multilayers (PEMs) with methacrylated chitosan (GMA-Chi) on top were formed on an ITO substrate. Then, a cell-encapsulating hydrogel micropattern was formed; a HepG2 cell-encapsulating heparin-based hydrogel micropattern was fabricated by thiol–ene photopolymerization. The application of an oxidative potential of 2 V resulted in the detachment of the cell-encapsulating hydrogels by the dissolution of PEMs. The time of complete retrieval of the hydrogels was controllable by modulating the number of PEM layers. The applied potential did not affect the viability or the function of the cells in the entire hydrogels. In contrast, when a reductive electrochemical potential (−1.8 V) was applied to a silane-modified ITO to release cell-encapsulating hydrogels by the desorption of silane [Chem. Commun., 2009, 5865], extensive cell death at the bottom of the hydrogel adjacent to the electrode was observed.
- Published
- 2014
29. Highly sensitive potentiometric strip test for detecting high charge density impurities in heparin
- Author
-
Hakhyun Nam, Youngjea Kang, Kihak Gwon, Jae Ho Shin, Mark E. Meyerhoff, and Geun Sig Cha
- Subjects
Detection limit ,Chromatography ,Heparin ,Polymers ,Potentiometric titration ,Chondroitin Sulfates ,Electrochemical Techniques ,Microfluidic Analytical Techniques ,Electrochemistry ,Polyelectrolytes ,Vinyl chloride ,Article ,Analytical Chemistry ,Quaternary Ammonium Compounds ,Polyvinyl chloride ,chemistry.chemical_compound ,Magnetics ,Membrane ,chemistry ,Electrode ,medicine ,Polyvinyl Chloride ,Electrodes ,medicine.drug - Abstract
Contamination of heparin with oversulfated chondroitin sulfate (OSCS) became a matter of grave concern in the medical field after many fatal responses to OSCS tainted heparin products occurred during the 2007-2008 period. Even though standard lab-based analytical techniques such as nuclear magnetic resonance (NMR) and strong anion-exchange high performance liquid chromatography (SAX-HPLC) have proven useful for monitoring the OSCS content in heparin products, an easy-to-use, quick, portable, and cost-efficient method is still needed for on-site monitoring during and after the heparin production. In this report, a disposable strip-type electrochemical polyion sensor is described for detection of low levels of OSCS contamination in heparin. A magnetic actuator is incorporated into this simple electrode-based microfluidic device in order to create the mixing effect necessary to achieve equilibrium potential changes of the sensor within a microfluidic channel. The planar membrane electrode detector within the sample channel is prepared with a tridodecylmethylammonium chloride (TDMAC)-doped poly(vinyl chloride) (PVC) membrane essentially equivalent to previously reported polyanion-sensitive electrodes. When the concentration of heparin applied to the single-use strip device is 57 mg/mL (in only 20 μL of sample), the same concentration recommended in the NMR analysis protocol for detecting OSCS in heparin, the detection limit is 0.005 wt % of OSCS, which is ca. 20 times lower than the reported detection limit of the NMR method.
- Published
- 2011
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.