Browsing by Author "Wei, Jia-Lin"

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Using gadolinium ions as affinity probes to selectively enrich and magnetically isolate bacteria from complex samples
(2020-05-29)
Wei, Jia-Lin
;
Huang, De-Yi
;
Chen, Yu-Chie
;
應用化學系
;
Department of Applied Chemistry
Magnetic trapping has been employed in the development of analytical methods owing to its ease and simplicity in handling samples. Nevertheless, the generation of functional probes is usually time consuming. A new and simple affinity method that uses gadolinium ion (Gd3+), a magnetic ion, as affinity probe for magnetic tapping of pathogenic bacteria was demonstrated in the present study. Escherichia coli O157:H7, Staphylococcus aureus, and Acinetobacter baumannii were selected as model bacteria. The model bacteria were magnetically isolated after incubation in Tris buffer (pH 8) containing Gd3+ (0.1 M) under microwave heating (power: 180 W, 90 s x 3). The resultant Gd3+-bacterium conjugates possessed sufficient magnetism, resulting in magnetic aggregations by an external magnet (similar to 4,000 Gauss). For ease of magnetic isolation, the sample containing Gd3+-bacterium complexes was stirred by a small magnet. After 1 h, the magnet attached with precipitates, i.e., Gd3+-bacterium conjugates, was readily removed using a pair of tweezers. The bacteria in the resultant conjugates were characterized by matrix-assisted laser desorption/ionization mass spectrometry. The limits of detection of the current approach toward E. coli O157:H7, S. aureus, and A. baumannii in complex samples were similar to 10(4)-10(5) cells mL(-1). (C) 2020 Published by Elsevier B.V.
Using Magnetic Ions to Probe and Induce Magnetism of Pyrophosphates, Bacteria, and Mammalian Cells
(2018-09-12)
Wei, Jia-Lin
;
Chen, Yu-Chie
;
應用化學系
;
Department of Applied Chemistry
Magnetic isolation using magnetic nanoparticles (MNPs) as trapping probes have been widely used in sample pretreatment to shorten analysis time. Nevertheless, to generate MNPs is time-consuming. Furthermore, the generated MNPs have to be further functionalized to gain the capability of recognizing their target species. Thus, an alternative approach that can impose magnetism to nonmagnetic species by simply using magnetic ions as the probes is developed in this study. That is, we employ magnetic ions (Fe3+, Co2+, and Ni2+) that can interact with nonmagnetic species containing oxygen-containing functional groups as the probes. Pyrophosphate (PPi), bacteria, and mammalian cells were selected as the model samples. Our results show that the as-prepared magnetic ion PPi conjugates gain sufficient magnetism and can be readily aggregated by applying an external magnetic field. Moreover, the magnetic trapping is reversible. The PPi-containing conjugates can lose their magnetic property simply using ethylenediaminetetraacetic acid or aluminum ions as competing agents to remove or to replace, respectively, the conjugated magnetic ions. In addition, bacteria and mammalian cells that possess abundant oxygen-containing functional groups on their cell surfaces can be selectively probed by magnetic ions and gain sufficient magnetism for magnetic isolation from complex serum samples.