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안준혁,정경원,나재운 한국고분자학회 2018 Macromolecular Research Vol.26 No.7
To induce a quick-drug release, lipoic acid (LA) was introduced to amine group of low molecular weight water-soluble chitosan (LMWSC) by coupling agent. The disulfide bond (-S-S-) of lipoyl group from LMWSC-grafted lipoic acid (LL) can response to glutathione (GSH) at cytoplasm with reducing environment, where LL can rapidly be disassembled via dissociation of disulfide bond (-S-S-) by GSH. The doxorubicin (DOX)-encapsulated LL (LLDOX) was prepared by dialysis method, which allowed quick release of DOX by destabilization of inner-hydrophobic core of LL when disulfide bond (-S-S-) was dissociated by GSH. To demonstrate a redoxresponsive release behavior of LLDOX, its drug release was accomplished under PBS buffer (pH 7.4) and GSH (10 mM) condition. In addition, the particle size and morphology of LL and LLDOX were respectively confirmed by DLS and TEM. The particle sizes of LL30% and LL60% were indicated as 268.8±30.9 and 308.1±11.9 nm, respectively. In addition, particle size of LLDOX was decreased more than that of LL. Also, surface charge of LLDOX was displayed to strong positive charge (LLDOX30%: 12.6±0.5 mV, LLDOX60%: 9.6±1.1 mV). Moreover, their morphological structure has a spherical shape. The cytotoxicity LL and LLDOX was confirmed by using MTT assay. Besides, to investigate the intracellular uptake of DOX from LLDOX against HeLa and AGS cell lines, fluorescence image was observed by using fluorescence microscopy. These results suggest that LL is an excellent as a drug carrier due to high anticancer effect by rapid drug release with redox-responsive effect.
안준혁,Choi Hyung Jin,Bang Junsung,손가연,오승주 나노기술연구협의회 2022 Nano Convergence Vol.9 No.46
Human voice recognition techniques have remarkable potential for clinical applications because information from acoustic signals can reflect human body conditions. This paper reports the fabrication of Ag nanocrystal (NC)-based multiaxial wearable strain gauge sensors by ink-lithography for voice recognition systems. Benefiting from the onestep-device-fabrication strategy of ink-lithography, which can yield Ag NC patterns with specific dimensions and endow physical properties, the Ag NC-based multiaxial strain sensors can be fabricated on an ultrathin substrate (~ 6 μm). Additionally, the coffee-ring effect can be induced onto the Ag NC patterns to realize high sensitivity and angle dependence (gauge factors G 0 ◦ = 11.7 ± 1.2 and G 90 ◦ = 105.5 ± 20.1); moreover, the voice onset time for voice recognition can be detected by the sensors. These features assist in distinguishing between voiced and voiceless plosive contrasts via measurements of contact-based voice onset time differences and can act as a cornerstone for further advancements in wearable sensors as well as voice recognition and analysis.
Synthesis and Characterization of Lipoic acid-grafted LMWSC for drug delivery
안준혁,변진원,강남규,최창용,나재운 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
We synthesized redox-sensitive LMWSC-g-LA using low molecular weight water-soluble chitosan(LMWSC) and lipoic acid(LA) with coupling agent. For the cancer therapy, doxorubicin was loaded into core of LMWSC-g-LA(LL) by hydrophobic interaction. In addition, DOX-loaded LL(LLDOX) was crosslinked by reduction of disulfide bond(-s-s-) into core with treated DTT for enhanced stability of particle. The characterization of core-crosslinked micelles were analyzed by FT-IR, <sup>1</sup>H-NMR, DLS, TEM, and CAC. The drug release behavior was confirmed in various in-vitro environment. Moreover, cytotoxicity and antitumor effect was accomplished by MTT assay. These results suggest that LL can apply as carrier for drug delivery. <sup>**</sup>This research was supported by The Leading Human Resource Training Program of Regional Neo industry through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT and future Planning(NRF- 2016H1D5A1910499)
안준혁,홍웅길,정경원,나재운 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
They had a problem that was led to sustained drug release in cancer cell, which induced to side effect and inefficient therapy. we used to lipoic acid (LA) and it was grafted of water chitosan (WC) by coupling agent. Chemical structure of LA-grafted water chitosan (LSC) was confirmed by 1H-NMR and FT-IR. Its critical aggregation concentration (CAC) was analyzed by fluorophotometer. Also, Doxorubicin (DOX)-loaded LWC (DLC) nanoparticles were produced by dialysis method. Its drug contents (DC) and encapsulation efficiency (EE) from DLWC was calculated by using UV-vis spectrophotometer. To demonstrate redoxresponsive effect of DLWC, drug release behavior was accomplished in presence GSH. Moreover, Cytotoxicity and anticancer activity conducted by using MTT assay. <sup>**</sup> These results suggest that redox-responsive DLWC is a superb anticancer agent for cancer therapy. (NRF-2016H1D5A1910499)
안준혁,정은희,홍웅길,정경원,박준규,나재운 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Number of researcher developed to drug carrier in order to delivery of hydrophobic drug in cancer cell. However, they have a problem that led to sustained drug release in tumor site. To solve these problem, we used to lipoic acid (LA) and it was introduced to back bone of water soluble chitosan by coupling agent. Structural analysis of LA-grafted water soluble chitosan (LWC) was accomplished by <sup>1</sup>H-NMR and FT-IR. Its critical aggregation concentration (CAC) was analyzed by fluorophotometer. Also, Doxorubicin (DOX)-loaded LWC (DLWC) nanoparticles were prepared by dialysis method. The drug contents and drug efficiency from DLWC was obtained by using UV-vis spectrophotometer. To demonstrate redox-sensitive effect of DLWC, drug release behavior was accomplished in presence GSH. Moreover, cytotoxicity conducted by using MTT assay. These results suggest that redox-sensitive LWC can apply as carrier for drug delivery. (NRF-2016H1D5A1910499).