• Journal of Pharmaceutical Investigation
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• 제38권4호
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• pp.255-259
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• 2008

The present study aimed to investigate the in-vitro characteristics of N4-amino acid derivatives of cytarabine for the oral delivery of cytarabine. After the synthesis of L-Ile-cytarabine, L-Leu-cytarabine and L-Arg-cytarabine, the gastrointestinal stability of each prodrug was examined using artificial gastric juice and intestinal fluids. The cellular uptake characteristics of prodrugs were also examined in Caco-2 cells. While L-Ile-cytarabine and L-Leu-cytarabine appeared to be stable in all the tested biological media during 4-hr incubation, L-Arg-cytarabine was rapidly disappeared within 5 min. Accordingly, the cellular uptake of L-Ile-cytarabine and L-Leu-cytarabine was significantly higher than that of its parent drug, cytarabine in Caco-2 cells but the cellular uptake of L-Arg-cytarabine was similar to that from its parent drug. The cellular uptake of L-Ile-cytarabine and L-Leu-cytarabine appeared to be saturable as drug concentration increased from 0.4 to 4 mM. Collectively, L-Ile-cytarabine and L-Leu-cytarabine could be promising candidates to improve the oral absorption of cytarabine via a saturable transport pathway.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.275-280
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• 2010

Actinobacillus actinomycetemcomitans is a gram-negative, nonmotile coccobacillus bacterium that is associated with several human diseases, including endocarditis, meningitis, osteomyelitis, subcutaneous abscesses and periodontal diseases. A full-length Omp1-like protein gene from A. actinomycetemcomitans was cloned into a pQE30 vector and overexpressed in Escherichia coli BL21(DE3) cells. The protein revealed sequence homologies to Seventeen kilodalton proteins (Skp) from Pasteurella multocida and E. coli that have been characterized as periplasmic chaperones. This soluble Omp1-like protein was successfully purified to homogeneity for further folding and functional studies. The purity, identity, and conformation of the protein were determined using sodium dodecyl sulfate polyacrylamide gel electrophoresis, matrix-assisted laser desorption ionization mass spectrometry, circular dichroism, fluorescence spectroscopic, and differential scanning calorimetric studies. We showed that the protein formed an oligomer larger than a tetramer. We found, further, that it is comprised of mostly $\alpha$-helices and boasts high thermal stability.

• Journal of Forest and Environmental Science
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• 제36권2호
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• pp.69-77
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• 2020

Lignocellulosic biomass has recalcitrant characteristics against chemical and biological conversion due to its structural heterogeneity and complexity. The pretreatment process to overcome these recalcitrant properties is essential, especially for the biochemical conversion of lignocellulosic biomass. In recent years, pretreatment methods using ionic liquids (ILs) and deep eutectic solvents (DESs) as the green solvent has attracted great attention because of their advantages such as easy recovery, chemical stability, temperature stability, nonflammability, low vapor pressure, and wide liquids range. However, there are some limitations such as high viscosity, poor economical feasibility, etc. to be solved for practical use. This paper reviewed the research activities on the pretreatment effect of various ILs including DESs and their co-solvents with organic solvents on the enzymatic saccharification efficiency of lignocellulosic biomass and the nanocellulose preparation from the pretreated products.

• 대한의용생체공학회:의공학회지
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• 제39권3호
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• pp.140-145
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• 2018

Cancer is a major burden of human disease worldwide. Current chemotherapy has severe side effects because the drugs affect whole body nonspecifically. In addition, the drugs to reach cancer cells are very limited. Over the last two decades, Drug Delivery System (DDS) using nanoparticles has suggested promising results to improve current limitations. In this study, we prepared PLGA nanoparticles with different charge properties and observed their stability and internalization effect to cancer cells. Results using Dynamic Light Scattering (DLS) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the size and chemical composition of the nanoparticles. The stability of the nanoparticles in pH buffers were variable depending on charge properties. The nanoparticles showed different cytotoxicity and internalization effects to MCF-7 human breast cancer cells. In conclusion, we demonstrated the importance of delicately engineered nanoparticles for better DDS in cancer.

• Mycobiology
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• 제30권4호
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• pp.233-239
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• 2002

The main aim of this study is to evaluate the efficiency of two biologically active compounds(Strom and F-760) in control of wheat root rot disease and its causal organisms. Fusarium graminearum, F. oxysporum, F. solani and Bipolaris sorokiniana were used as target organisms. In vitro, the two compounds showed fungicidal effect on all investigated pathogens resulted in suppression of radial growth and mycelial dry weight of them. Under greenhouse conditions, treatment of wheat grains with either Strom or F-760 before cultivation significantly reduced the percent of disease distribution as well as the mean disease rating of plants in both seedling and flowering stages. Fresh and dry weights of plants as well as water maintenance capacity were increased as the result of applying these compounds as seed dressing. Also data showed that the membrane stability of plants was injured as a result of infection with all investigated organisms, while this injury was alleviated when F-760 and Strom were applied. The $K^+$ efflux and the leakage of UV absorbing metabolites was stimulated with fungal infection. However, F-760 and Storm treatment partially retarded the stimulatory effect on leakage of $K^+$ and UV-absorbing metabolites of fungal infected plants. On the other side, the fungal infection had inhibitory effects on pigment fractions(chlorophyll a, b, and carotenoids) biosynthesis in wheat leaves. This retarding effect was partially or completely alleviated as the grains were treated with the applied compounds.

• 폴리머
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• 제37권3호
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• pp.294-301
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• 2013

Polymersomes made of biodegradable triblock copolymers based on poly(fumaric acid-co-sebacoyl chloride)/PEG (PEG-co-P(FA/SC)-co-PEG) were prepared and studied in aqueous solutions. TEM confirmed the formation of vesicles in aqueous media. Aggregation behavior of the copolymers was studied by fluorescence spectroscopy of 8-anilino-1-naphthalenesulfonic acid, and the critical aggregation concentration (c.a.c.) of the copolymer was found to be ${\sim}26.2{\mu}M$ indicating desirable stability of the vesicles. Dynamic light scattering revealed that the size of the vesicles was distributed within the range of 170-270 nm. Turbidity measurements confirmed the relative short-term stability of the polymersomes. Carboxyfluorescein, a hydrophilic compound, was simply encapsulated in the vesicles during polymersome preparation. The release of encapsulant from the polymersomes at 25 and $37^{\circ}C$ lasted about 3 weeks, and the rate of release followed a first-order kinetics. The release is speculated to be primarily carried out through diffusion. These results confirm that these polymersomes are promising as controlled-release carriers of various drugs.

• KSBB Journal
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• 제26권6호
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• pp.491-504
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• 2011

This review article provides an overview of the evolution of diphtheria vaccine, its value and its future. Diphtheria is an infectious illness caused by diphtheria toxin produced by pathogenic strains of Corynebacterium diphtheriae. It is characterized by a sore throat with membrane formation due to local tissue necrosis, which can lead to fatal airway obstruction; neural and cardiac damage are other common complications. Diphtheria vaccine was first brought to market in the 1920s, following the discovery that diphtheria toxin can be detoxified using formalin. However, conventional formalin-inactivated toxoid vaccines have some fundamental limitations. Innovative technologies and approaches with the potential to overcome these limitations are discussed in this paper. These include genetic inactivation of diphtheria toxoid, innovative vaccine delivery systems, new adjuvants (both TLR-independent and TLR-dependent adjuvants), and heat- and freeze-stable agents, as well as novel platforms for producing improved conventional vaccine, DNA vaccine, transcutaneous (microneedle-mediated) vaccine, oral vaccine and edible vaccine expressed in transgenic plants. These innovations target improvements in vaccine quality (efficacy, safety, stability and consistency), ease of use and/or thermal stability. Their successful development and use should help to increase global diphtheria vaccine coverage.

• 한국세라믹학회지
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• 제47권1호
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• pp.61-65
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• 2010

Ultrathin atomic layer deposition (ALD) coatings were found to enhance the performance of lithium-ion batteries (LIBs). Previous studies have demonstrated that $LiCoO_2$ cathode powders coated with metal oxides with thicknesses of $\sim100-1000{\AA}$ grown using wet chemical techniques improved LIB performance. In this study, $LiCoO_2$ powders were coated with conformal $Al_2O_3$ ALD films with thicknesses of only $\sim3-4{\AA}$ established using 2 ALD cycles. The coated $LiCoO_2$ powders exhibited a capacity retention of 89% after 120 charge-discharge cycles in the 3.3~4.5 V (vs. $Li/Li^+$) range. In contrast, the bare $LiCoO_2$ powders displayed only a 45% capacity retention. This dramatic improvement may result from the ultrathin $Al_2O_3$ ALD film acting to minimize Co dissolution or to reduce surface electrolyte reactions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.73-73
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• 2010

Various organic- and bio-conjugated nanoparticles have been studied extensively for biological applications in medical diagnoses and drug delivery systems. Gold nanoparticles (AuNP) and poly(ethylene glycol) (PEG) are known biocompatible materials to be used in vivo and are becoming increasingly important in biomedical applications. In this work, we investigated the stability of PEG-conjugated AuNPs, dialysis and centrifuge effects after synthesis or pegylation of AuNPs as a function of elapsed time by using ToF-SIMS imaging technique along with dynamic light scattering (DLS), UV-visible absorption spectroscopic and statistical analyses. Roughly 15-nm-sized AuNPs were synthesized in a citrate-conjugated form, and then converted into the thiol-terminated PEG (O-[2-(3-Mercaptopropionylamino)ethyl]-O'-methylpolyethyleneglycol, M.W.=5 kDa) form. Based on our data, we will show that ToF-SIMS imaging analysis along with DLS, UV-visible absorption and statistical analyses would be a useful method to evaluate stability of PEG-conjugated AuNPs in various environmental conditions.

• Journal of Pharmaceutical Investigation
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• 제40권6호
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• pp.379-386
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• 2010

Mono PEGylated rhG-CSF (PEG-G-CSF) prepared by utilizing unique PEG was purified and characterized by cation-exchange chromatography. A unique, trimer-structured PEG was chosen for PEGylation of rhG-CSF among various PEG moieties. The in-vitro bioactivity, stability, and pharmacokinetics of mono-PEG-G-CSF were examined and compared to those of native rhG-CSF. Mono PEG-G-CSF exhibited reduced in-vitro bioactivity to native rhG-CSF but showed an excellent in-vivo bioactivity and stability. Furthermore, it showed markedly reduced clearance in rats, thereby increasing the biological half-life by about 4.5-fold compared to that of native rhG-CSF. The results suggest that this unique, trimer-structured 23 kDa PEG can provide advantages to improve the bioactivity of therapeutic proteins in clinical use.