Browsing by Author "Lin, Ju-Yu"

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Functional gold nanoclusters as antimicrobial agents, for antibiotic-resistant bacteria
(2010-07-01)
Chen, Wei-Yu
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Lin, Ju-Yu
;
Chen, Wei-Jen
;
Luo, Liyang
;
Diau, Eirc Wei-Guang
Aims: Our aim was to demonstrate that lysozyme-directed generation of gold nanoclusters (Au NCs) are potential antimicrobial agents for antibiotic-resistant bacteria and broad labeling agents for pathogenic bacteria. Materials & methods: Lysozyme is an enzyme that is capable of hydrolyzing the cell walls of bacteria. In this study, we demonstrated the generation of functional Au NCs by using lysozyme as the sequester and the reducing agent for Au precursors at 40 degrees C. In addition, to shorten the reaction time, the reaction was conducted under microwave irradiation within a short period of time for the first time. Results: The bioactivity of the lysozyme on the Au NCs was retained. Therefore, the as-prepared lysozyme Au NCs with desirable fluorescence feature were successfully employed to be broad-band labeling agents for pathogenic bacteria. Furthermore, we also demonstrated that the lysozyme Au NCs can be used to effectively inhibit the cell growth of notorious antibiotic-resistant bacteria, including pan-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis. Conclusion: The potential of employing the lysozyme Au NCs for bacterial labeling and as antimicrobial agents is expected.
Functional magnetic nanoparticle-based trapping and sensing approaches for label-free fluorescence detection of DNA
(2011-10-30)
Lin, Ju-Yu
;
Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
In this study, a label-free fluorescence detection method for DNA was designed using functional magnetic nanoparticles (MNPs) as affinity probes. With the advantage of magnetic feature, MNP-based affinity probes can be easily manipulated for trapping and sensing target species. Two types of MNP-based nanoprobes for trapping and detecting target DNAs were fabricated. The basic strategy for this approach is the use of trapping probes to concentrate target DNAs selectively from complex samples. The detection probes are then used as fluorescence reporters to explore the level of the target species. Trapping probes were constructed by covalently immobilizing probe DNA molecules complementary to the target DNA. Detection nanoprobes were made by linking a fluorescent dye, riboflavin-5'-monophosphate (RFMP), onto the surface of the core/shell Fe(3)O(4)@Al(2)O(3) MNPs via Al-phosphate chelation. The fluorescence derived from RFMP molecules became invisible when molecules were attached onto the MNP surface. However, after phosphorylated species (e.g., DNA molecules) replaced RFMP from the surface of the RFMP-Fe(3)O(4)@Al(2)O(3) MNPs under microwave heating for 15 s, the RFMP molecules released from the MNPs enhanced the fluorescence intensity in the solution. Based on the measurement of the fluorescence intensity, the level of target DNA in the samples was determined. The remaining DNA molecules on the RFMP-Fe(3)O(4)@Al(2)O(3) MNPs were characterized by using matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). The detection limit for DNA was as low as 40 pM using this approach. (C) 2011 Elsevier B.V. All rights reserved.
Using Gold Nanoclusters As Selective Luminescent Probes for Phosphate-Containing Metabolites
(2012-07-03)
Li, Po-Han
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Lin, Ju-Yu
;
Chen, Cheng-Tai
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Ciou, Wei-Ru
;
Chan, Po-Han
Glutathione-bound gold nanoclusters (AuNCs@GSH) can emit reddish photoluminescence under illumination of ultraviolet light. The luminescence of the AuNCs@GSH is quenched when chelating with iron ions (AuNCs@GSH-Fe3+), presumably resulting from the effective electron transfer between the nanoclusters and iron ions. Nevertheless, we found that the luminescence of the gold nanoclusters can be restored in the presence of phosphate-containing molecules, which suggested the possibility of using AuNCs@GSH-Fe3+ complexes as the selective luminescent switches for phosphate-containing metabolites. Phosphate-containing metabolites such as adenosine-5'-triphosphate (ATP) and pyrophosphate play an important role in biological systems. In this study, we demonstrated that the luminescence of the AuNCs@GSH-Fe3+ is switched-on when mixing with ATP and pyrophosphate, which can readily be observed by the naked eye. It results from the high formation constants between phosphates and iron ions. When employing fluorescence spectroscopy as the detection tool, quantitative analysis for phosphate-containing metabolites such as ATP and pyrophosphate can be conducted. The linear range for ATP and pyrophosphate is 50 mu M to sub-millimolar, while the limit of detection for ATP and pyrophosphate are similar to 43 and similar to 28 mu M, respectively. Additionally, we demonstrated that the luminescence of the AuNCs@GSH-Fe3+ can also be turned on in the presence of phosphate-containing metabolites from cell lysates and blood plasma.