Browsing by Author "Chang, Chia-Yu"

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A Novel Metallo-beta-Lactamase Involved in the Ampicillin Resistance of Streptococcus pneumoniae ATCC 49136 Strain
(2016-05-23)
Chang, Chia-Yu
;
Lin, Hui-Jen
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Li, Bor-Ran
;
Li, Yaw-Kuen
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分子醫學與生物工程研究所
Streptococcus pneumoniae, a penicillin-sensitive bacterium, is recognized as a major cause of pneumonia and is treated clinically with penicillin-based antibiotics. The rapid increase in resistance to penicillin and other antibiotics affects 450 million people globally and results in 4 million deaths every year. To unveil the mechanism of resistance of S. pneumoniae is thus an important issue to treat streptococcal disease that might consequently save millions of lives around the world. In this work, we isolated a streptococci-conserved L-ascorbate 6-phosphate lactonase, from S. pneumoniae ATCC 49136. This protein reveals a metallo-beta-lactamase activity in vitro, which is able to deactivate an ampicillin-based antibiotic by hydrolyzing the amide bond of the beta-lactam ring. The Michaelis parameter (K-m) = 25 mu M and turnover number (k(cat)) = 2 s(-1) were obtained when nitrocefin was utilized as an optically measurable substrate. Through confocal images and western blot analyses with a specific antibody, the indigenous protein was recognized in S. pneumoniae ATCC 49136. The protein-overexpressed S. pneumonia exhibits a high ampicillin-tolerance ability in vivo. In contrast, the protein-knockout S. pneumonia reveals the ampicillin-sensitive feature relative to the wild type strain. Based on these results, we propose that this protein is a membrane-associated metallo-beta-lactamase (MBL) involved in the antibiotic-resistant property of S. pneumoniae.
An L-ascorbate-6-phosphate lactonase from Streptococcus pneumoniae ATCC 49136 strain reveals metallo-beta-lactamase activity
(2016-05)
Chang, Chia-Yu
;
Li, Bor-Ran
;
Li, Yaw-Kuen
;
分子醫學與生物工程研究所
;
應用化學系
Carboxylated nanodiamond-mediated CRISPR-Cas9 delivery of human retinoschisis mutation into human iPSCs and mouse retina
(2020-01-01)
Yang, Tien-Chun
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Chang, Chia-Yu
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Yarmishyn, Aliaksandr A.
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Mao, Yen-Shiang
;
Yang, Yi-Ping
Nanodiamonds (NDs) are considered to be relatively safe carbon nanomaterials used for the transmission of DNA, proteins and drugs. The feasibility of utilizing the NDs to deliver CRISPR-Cas9 system for gene editing has not been clearly studied. Therefore, in this study, we aimed to use NDs as the carriers of CRISPR-Cas9 components designed to introduce the mutation in RS1 gene associated with Xlinked retinoschisis (XLRS). ND particles with a diameter of 3 nm were functionalized by carboxylation of the surface and covalently conjugated with fluorescent mCherry protein. Two linear DNA constructs were attached to the conjugated mCherry: one encoded Cas9 endonuclease and GFP reporter, another encoded sgRNA and contained insert of HDR template designed to introduce RS1 c.625C>T mutation. Such nanoparticles were successfully delivered and internalized by human iPSCs and mouse retinas, the efficiency of internalization was significantly improved by mixing with BSA. The delivery of ND particles led to introduction of RS1 c.625C>T mutation in both human iPSCs and mouse retinas. Rs1 gene editing in mouse retinas resulted in several pathological features typical for XLRS, such as aberrant photoreceptor structure. To conclude, our ND-based CRISPR-Cas9 delivery system can be utilized as a tool for creating in vitro and in vivo disease models of XLRS. Statement of significance X-linked retinoschisis (XLRS) is a prevalent hereditary retinal disease, which is caused by mutations in RS1 gene, whose product is important for structural organization of the retina. The recent development of genome editing techniques such as CRISPR-Cas9 significantly improved the prospects for better understanding the pathology and development of treatment for this disease. Firstly, gene editing can allow development of appropriate in vitro and in vivo disease models; secondly, CRISPR-Cas9 can be applied for gene therapy by removing the disease-causative mutation in vivo. The major prerequisite for these approaches is to develop safe and efficient CRISPR-Cas9 delivery system. In this study, we tested specifically modified nanodiamonds for such a delivery system. We were able to introduce Rs1 mutation into the mouse retina and, importantly, observed several XLRS-specific effects. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd.
Enhanced bioconjugation on sputtered palladium nano-thin-film electrode
(2019-03-04)
Chang, Chia-Yu
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Chen, Wei
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Su, Chien-Hao
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Chang, Pang-Chia
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Huang, Yun-Tzu
A highly reactive surface with an enhanced ability for chemical bonding relies on the presence of specifically coordinated atoms and step edges at the surface. In this study, an electrode with a unique Stranski-Krastanov-like thin film, with an epitaxial sputtering of a palladium (Pd) nanoparticle double layer on the polyethylene terephthalate substrate, was developed. On the surface of this flexible Pd-nano-thin-film (NTF) electrode with a (1 1 1) containing surface, DNA probes can be quickly immobilized in as short a period as 20 min, which is 24 times faster than that on the gold electrode. A DNA-based anticancer compound (ACC) sensing and screening process that would use the DNA functionalized Pd-NTF electrode as the biosensor was then proposed. Interestingly, the developed biosensor could detect DNA and ACCs, such as doxorubicin, tetra-O-methyl nordihydroguaiaretic acid, and Taxol via interactions with solutions containing 1 mu l ACCs within 11 min, and the sensitivity of the ACC solution is similar to 0.1 mu M (similar to 36 pg per-test), as detected by electrochemical impedance spectroscopy. Moreover, this highly reactive surface can be used in regular sensors and other interfaces, in scientific applications. (C) 2019 Author(s).
Polymer photodetector with voltage-adjustable photocurrent spectrum
(2010-01-25)
Chen, En-
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Chang, Chia-Yu
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Shieh, Ji-Ting
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Tseng, Shin-Rong
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Meng, Hsin-Fei
Polymer photodetectors with voltage-adjustable photoresponse from visible to near infrared range are demonstrated. Poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) blend is used as the active layer. The photoresponse can be continuously adjusted by the thickness of the active layer as well as the applied voltage bias. The thickness of the active layer is varied from 250 nm to 16.2 mu m. The mechanism for the photoresponse adjusted by the thickness can be attributed to the absorption of the photons in the infrared range by thick PCBM layer. The mechanism for the photoresponse adjusted by the applied bias can be attributed to the carrier recombination reduction when the applied bias increases. The adjustable photodetector also has high operating speed up to 10 kHz.
Surface active flexible palladium nano-thin-film electrode development for biosensing
(2019-09-01)
Chang, Chia-Yu
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Huang, Yun-Tzu
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Chang, Pang-Chia
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Su, Chien-Hao
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Hsu, Kuo-Chen
Metal atoms on surface edges or with specific coordinates possess high surface potentials, and serve as core atoms for organic molecule bonding. However, these active metal atoms may lose their activity by self-diffusion on the surface. A polyethylene terephthalate (PET) substrate provided a stable rough surface in nanoscale for metal atoms absorption and formation of a stable and active nano-thin-film (NTF) surface. However, the NTF surface roughness decreased with increasing thickness of palladium (Pd) granules, indicating that the surface growth of the Pd film followed a Stranski-Krastanov-like growth model. Therefore, the proper thickness of Pd-NTF on PET substrate (Pd NTF-PET) was developed for electrochemical impedance spectroscopy (EIS). Protein was immobilized on the Pd NTF-PET electrodes within 15 min and its biosensing sensitivity was as low as 0.1 ng per-test in 1 mu l. We expect that the developed Pd NTF-PET electrode can be used for other biosensing applications as well.
The fabrication and application of Ni-DNA nanowire-based nanoelectronic devices
(2019-06-01)
Chang, Pang-Chia
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Chang, Chia-Yu
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Jian, Wen-Bin
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Yuan, Chiun-Jye
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Chen, Yu-Chang
DNA is a self-assembled, double stranded natural molecule that can chelate and align nickel ions between its base pairs. The fabrication of a DNA-guided nickel ion chain (Ni-DNA) device was successful, as indicated by the conducting currents exhibiting a Ni ion redox reaction-driven negative differential resistance effect, a property unique to mem-elements (1). The redox state of nickel ions in the Ni-DNA device is programmable by applying an external bias with different polarities and writing times (2). The multiple states of Ni-DNA-based memristive and memcapacitive systems were characterized (3). As such, the development of Ni-DNA nanowire device-based circuits in the near future is proposed.