Browsing by Author "Lee, Kai-Chieh"

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Functional gold nanoparticle-based antibacterial agents for nosocomial and antibiotic-resistant bacteria
(2016-10)
Kuo, Yen-Ling
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Wang, Sin-Ge
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Wu, Ching-Yi
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Lee, Kai-Chieh
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Jao, Chan-Jung
Aim: Medical treatments for bacterial-infections have become challenging because of the emergence of antibiotic-resistant bacterial strains. Thus, new therapeutics and antibiotics must be developed. Materials & methods: Arginine and tryptophan can target negatively-charged bacteria and penetrate bacterial cell membrane, respectively. Synthetic-peptides containing arginine, tryptophan and cysteine termini, in other words, (DVFLG) 2 REEW 4 C and (DVFLG) 2 REEW 2 C, as starting materials were mixed with aqueous tetrachloroauric acid to generate peptide-immobilized gold nanoparticles (i.e., [DVFLG] 2 REEW 4 C-AuNPs and [DVFLG] 2 REEW 2 C-AuNPs) through one-pot reactions. Results & discussion: The peptide immobilized AuNPs exhibit targeting capacity and antibacterial activity. Furthermore, (DVFLG) 2 REEW 4 C-AuNPs immobilized with a higher number of tryptophan molecules possess more effective antibacterial capacity than (DVFLG) 2 REEW 2 C-AuNPs. Nevertheless, they are not harmful for animal cells. The feasibility of using the peptide-AuNPs to inhibit the cell growth of bacterium-infected macrophages was demonstrated. Conclusion: These results suggested that the proposed antibacterial AuNPs are effective antibacterial agents for Staphylococci, Enterococci and antibiotic-resistant bacterial strains.
Molecular recognition between insulin and dextran encapsulated gold nanoparticles
(2016-11)
Lee, Kai-Chieh
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Chiang, Hsiang-Ling
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Chiu, Wei-Ru
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Chen, Yu-Chie
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應用化學系
Insulin is a peptide hormone that can regulate the metabolism of carbohydrates and lipids. This hormone is closely related to glucose-uptake in cells and can control blood glucose levels. Dextran is a polysaccharide composed of glucose units. In this study, we discovered that dextran-encapsulated gold nanoparticles (AuNPs@Dextran) and nanoclusters (AuNCs@Dextran) can be used to recognize insulin. The dissociation constant of insulin toward AuNPs@Dextran was estimated to be approximate to 5.3x10(-6)M. The binding site on insulin toward the dextran on the nanoprobes was explored as well. It was found that the sequence of numbers 1-22 on the insulin B chain can interact with the dextran encapsulated nanoprobes. Additionally, we also demonstrated that the dextran-encapsulated nanoprobes could be used as concentration probes to selectively enrich trace amounts of insulin (approximate to 1pM) from serum samples. Copyright (c) 2016 John Wiley & Sons, Ltd.
Revisiting the quantitative features of surface-assisted laser desorption/ionization mass spectrometric analysis
(2016-10-28)
Wu, Ching-Yi
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Lee, Kai-Chieh
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Kuo, Yen-Ling
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Chen, Yu-Chie
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應用化學系
Surface-assisted laser desorption/ionization (SALDI) coupled with mass spectrometry (MS) is frequently used to analyse small organics owing to its clean background. Inorganic materials can be used as energy absorbers and the transfer medium to facilitate the desorption/ionization of analytes; thus, they are used as SALDI-assisting materials. Many studies have demonstrated the usefulness of SALDI-MS in quantitative analysis of small organics. However, some characteristics occurring in SALDI-MS require certain attention to ensure the reliability of the quantitative analysis results. The appearance of a coffee-ring effect in SALDI sample preparation is the primary factor that can affect quantitative SALDI-MS analysis results. However, to the best of our knowledge, there are no reports relating to quantitative SALDI-MS analysis that discuss or consider this effect. In this study, the coffee-ring effect is discussed using nanoparticles and nanostructured substrates as SALDI-assisting materials to show how this effect influences SALDI-MS analysis results. Potential solutions for overcoming the existing problems are also suggested. This article is part of the themed issue \'Quantitative mass spectrometry\'.
Using Dextran-encapsulated gold nanoparticles as insulin carriers to prolong insulin activity
(2017-08-01)
Lee, Kai-Chieh
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Chen, Wen-Jie
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Aim: Diabetes mellitus is commonly treated with painful insulin injections. We aim to explore drug carriers that can prolong insulin activity. Materials & methods: Dextran-encapsulated gold NPs (AuNPs@Dextran) that can bind with insulin are used as insulin carriers. The affinity (Kd = similar to 42pM) between insulin and insulin receptors on the cells is much higher than that (Kd = similar to 4.02 mu M) of insulin and AuNPs@ Dextran. Thus, insulin released from the AuNP@Dextran- insulin conjugates to maintain kinetic equilibrium and prefers to bind to the insulin receptor. The slow release of insulin from the AuNP@ Dextran-insulin conjugates facilitates the lasting of insulin activity. Results & discussion: AuNP@ Dextran-insulin conjugates can prolong insulin activity to 12 h, whereas free form insulin loses activity after 4 h in adipocyte cells. Conclusion: AuNPs@ Dextran are suitable carriers that can prolong insulin activity.