Browsing by Author "Bai, Yi-Ling"

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Inhibition of the lethality of Shiga-like toxin-1 by functional gold nanoparticles
(2018-01-01)
Li, Chun-Hsien
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Bai, Yi-Ling
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Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Escherichia coli O157:H7 is a pathogen, which can generate Shiga-like toxins (SLTs) and cause hemolytic-uremic syndrome. Foodborne illness outbreaks caused by E. coli O157:H7 have become a global issue. Since SLTs are quite toxic, effective medicines that can reduce the damage caused by SLTs should be explored. SLTs consist of a single A and five B subunits, which can inhibit ribosome activity for protein synthesis and bind with the cell membrane of host cells, respectively. Pigeon ovalbumin (POA), i.e. a glycoprotein, is abundant in pigeon egg white (PEW) proteins. The structure of POA contains Gal-(14)-Gal-(14)-GlcNAc ligands, which have binding affinity toward the B subunit in SLT type-1 (SLT-1B). POA immobilized gold nanoparticles (POA-Au NPs) can be generated by reacting PEW proteins with aqueous tetrachloroauric acid in one-pot. The generated POA-Au NPs have been demonstrated to have selective trapping-capacity toward SLT-1B previously. Herein, we explore that POA-Au NPs can be used as protective agents to neutralize the toxicity of SLT-1 in SLT-1-infected model cells. The results show that the cells can be completely rescued when a sufficient amount of POA-Au NPs is used to treat the SLT-1-infected cells within 1h.
Selective Detection of Shiga-like Toxin 1 from Complex Samples Using Pigeon Ovalbumin Functionalized Gold Nanoparticles as Affinity Probes
(2017-05-31)
Li, Chun-Hsien
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Bai, Yi-Ling
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Selvaprakash, Karuppuchamy
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Mong, Kwok-Kong Tony
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Chen, Yu-Chie
Escherichia coli 0151:H7 is a foodborne pathogen. This bacterial strain can generate Shiga-like toxins (SLTs), which can cause serious sickness and even death. Thus, it is important to develop effective and sensitive methods that can be used to rapidly identify the presence of SLTs from complex samples. Pigeon egg white (PEW) contains abundant glycoproteins, including pigeon ovalbumin (POA) (similar to 60%). POA possesses Gal-alpha(1 -> 4)-Gal-beta(1 -> 4)-GlcNAc termini,. which can recognize the B subunits in SLT type 1 (SLT-1B). Thus, POA is a suitable probe for trapping SLT-1B. In this work, we used PEW proteins as starting materials to react with aqueous tetrachloroauric acid for generation of PEW-protein-immobilized gold nanoparticles (AuNPs@PEW) via one-pot reactions. We demonstrated that the generated AuNPs@PEW were mainly dominated by POA-immobilized Au NPs. The as-prepared AuNPs@PEW were used as affinity probes to selectively probe SLT-1B from complex cell lysates derived from E. coli 0157:H7. The selective trapping step can be completed within similar to 90 s under microwave heating (power = 450 W) to enrich sufficient SLT-1B for Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis. Furthermore; this approach:can be used to detect SLT-1B at a concentration as low as similar to 40 pM. The feasibility of using the proposed method to selectively detect SLT-1B from ham contaminated by E. coli 0157:H7 was also demonstrated.
Tail Fiber Protein-Immobilized Magnetic Nanoparticle-Based Affinity Approaches for Detection of Acinetobacter baumannii
(2019-08-06)
Bai, Yi-Ling
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Shahed-Al-Mahmud, Md.
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Selvaprakash, Karuppuchamy
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Lin, Nien-Tsung
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Chen, Yu-Chie
Acinetobacter baumannii (A. baumannii) strains are common nosocomial pathogens that can cause infections and can easily become resistant to antibiotics. Thus, analytical methods that can be used to rapidly identify A. baumannii from complex samples should be developed. Tail fiber proteins derived from the tail fibers of bacteriophages can recognize specific bacterial surface polysaccharides. For example, recombinant tail proteins, such as TF2 and TF6 derived from the tail fibers of bacteriophages phi AB2 and phi AB6, can recognize A. baumannii clinical isolates M3237 and 54149, respectively. Thus, TF2 and TF6 can be used as probes to target specific A. baumannii strains. Generally, TF2 and TF6 are tagged with a hexahistidine (His(6)) for ease of purification. Given that His(6) possesses specific affinity toward alumina through His(6)-Al chelation, TF2- and TF6-immobilized alumina-coated magnetic nanoparticles (Fe3O4@Al2O3 MNPs) were generated through chelation under microwave heating (power, 900 W) for 60 s in this study. The as-prepared TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al(2)O(3 )MNPs were used as affinity probes to trap trace A. baumannii M3237 and 54149, respectively, from sample solutions. Matrix-assisted laser desorption/ionization mass spectrometry capable of identifying bacteria on the basis of the obtained fingerprint mass spectra of intact bacteria was used as the detection tool. Results demonstrated that the current approach can be used to distinguish A. baumannii M3237 from A. baumannii 54149 by using TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al(2)O(3 )MNPs as affinity probes. Furthermore, the limits of detection of the current method for A. baumannii M3237 and 54149 are similar to 10(5) and similar to 10(4) cells mL(-1), respectively. The feasibility of using the developed method to selectively detect A. baumannii M3237 and 54149 from complex serum samples was demonstrated.