Browsing by Author "Chen, Cheng-Tai"

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A two-matrix system for MALDI MS analysis of serine phosphorylated peptides concentrated by Fe3O4/Al2O3 magnetic nanoparticles
(2008-04-01)
Chen, Cheng-Tai
;
Chen, Yu-Chie
;
應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
Functional magnetic nanoparticle-based label free fluorescence detection of phosphorylated species
(2010)
Chen, Cheng-Tai
;
Chen, Yu-Chie
;
應用化學系
;
Department of Applied Chemistry
A label free fluorescence method for rapid detection of the presence of phosphorylated peptides/proteins in sample solutions using functional magnetic nanoparticles (MNPs) as the detection probes is demonstrated.
Glutathione-bound gold nanoclusters for selective-binding and detection of glutathione S-transferase-fusion proteins from cell lysates
(2009)
Chen, Cheng-Tai
;
Chen, Wei-Jen
;
Liu, Chao-Zong
;
Chang, Ling-Ya
;
Chen, Yu-Chie
A straightforward method for the rapid detection of the presence of glutathione S-transferase (GST)-tagged proteins from sample solutions using glutathione (GSH)-bound gold nanoclusters (Au@GSH NCs) with luminescence properties as the detection probes by simple observation with the naked eye was proposed in this study.
Metal oxide-assisted laser desorption/ionization mass spectrometry
(2006-07-06)
Chen, Yu-Chie
;
Chen, Cheng-Tai
;
Lin, Ya-Shiuan
The invention provides a simple, rapid and cost-effective metal oxide-assisted laser desorption/ionization mass spectrometry (MOALDI MS) without the addition of light-absorbing organic-matrix, comprising the use of (a) an inorganic metal oxide with light absorbing capability as an assisting material to render desorption/ionization of samples in laser desorption/ionization mass spectrometry and (b) a citric acid buffer as the proton source for enhancing the iorization efficiency for analytes. Metal oxide assisting materials is not only restricted to the uses of films. Metal oxide nanoparticles are also suitable to be used as the assisting materials. Low matrix background, stable surface feature, homogeneous sample deposition, and wide detectable mass range are the merits of MOALDI MS.
Nitrilotriacetic acid-coated magnetic nanoparticles as affinity probes for enrichment of histidine-tagged proteins and phosphorylated peptides
(2007-10-01)
Li, Yi-Cheng
;
Lin, Ya-Shiuan
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Tsai, Pei-Jane
;
Chen, Cheng-Tai
;
Chen, Wei-Yu
We herein demonstrate superparamagnetic Fe3O4 nanoparticles coated with nitrilotriacetic acid derivative (NTA) that can bind with different immobilized metal ions are capable of probing diverse target species. Immobilized Ni(II) on the surfaces of the NTA-magnetic nanoparticles have the capability of selectively trapping histidine (His)tagged proteins such as a mutated streptopain tagged with 6x His, i.e., C192S (MW similar to 42 kDa), from cell lysates. Enrichment was achieved by vigorously mixing the sample solution and the nanoparticles by pipetting in and out of a sample vial for only 30 s. After enrichment, the probe-target species could be readily isolated by magnetic separation. We also characterized the proteins enriched on the affinity probes using on-probe tryptic digestion under microwave irradiation for only 2 min, followed by matrix-assisted laser desorption/ionization mass spectrometry analysis. Using this enrichment and tryptic digestion, the target species can be rapidly enriched and characterized, reducing the time required for carrying out the complete analysis to less than 10 min. Furthermore, when either Zr(IV) or Ga (III) ions are immobilized on the surfaces of the NTA-magnetic nanoparticles, the nanoparticles have the capability of selectively enriching phosphorylated peptides from tryptic digests of alpha-, beta-caseins, and diluted milk. The detection limit for the tryptic digests of alpha- and,beta-caseins is similar to 50 finol.
Photoluminescence Determination of Aluminum Using Glutathione-Capped Gold Nanoclusters
(2016)
Baig, Mirza Muhammad Fahad
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Chen, Cheng-Tai
;
Chen, Yu-Chie
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應用化學系
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Department of Applied Chemistry
Aluminum is a common metal that is used extensively in daily life. However, over-exposure to aluminum may result in nervous systemrelated diseases. Thus, it is important to develop a rapid sensing method that can be used to screen samples. In this study, glutathione-capped gold nanoclusters with bright photoluminescence were demonstrated to be effective sensing probes for aluminum ions. The photoluminescence of glutathione-capped gold nanoclusters was enhanced in the presence of aluminum ions. The results show that glutathione-capped gold nanoclusters selectively determined aluminum ions in samples prepared in aqueous ammonium acetate buffer (pH 5.5). The acetate maintains the pH and serves as a chelating agent to interact with non-analyte metal ions. Therefore, other metal ions have little effect on the photoluminescence of the glutathione-capped gold nanoclusters. The photoluminescence of the glutathione-capped gold nanoclusters was switched on in samples containing aluminum ions. The selective sensing was based on chelation between the aluminum ions and ligands on the surface of the glutathione-capped gold nanoclusters. The limit of detection was estimated to be as low as approximately 100 nM. The method was used to determine the concentration of aluminum ions in lake water and soil extracts.
Rapid enrichment of phosphopeptides and phosphoproteins from complex samples using magnetic particles coated with alumina as the concentrating probes for MALDI MS analysis
(2007-01-05)
Chen, Cheng-Tai
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Chen, Wei-Yu
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Tsai, Pei-Jane
;
Chien, Kun-Yi
;
Yu, Jau-Song
In this study, we used nanocomposite magnetic particles coated with alumina as the affinity probes to selectively concentrate phosphorylated peptides and proteins from a low volume of sample solution. Tryptic digest products of phosphoproteins including alpha- and beta-caseins, human protein phosphatase inhibitor 1, nonfat milk, egg white, and a cell lysate were used as the samples to demonstrate the feasibility of this approach. In only 30 and 90 s, phosphopeptides and phosphoproteins sufficient for characterization by MALDI-MS were enriched by the particles, respectively. Proteins trapped on the particles could be directly digested on the particles. The same particles in the digest solution were employed for enrichment of phosphopeptides. We estimated the required time for performing the enrichment of phosphopeptides from complex samples and characterization by MALDI MS was within 5 min. A small volume (50 mu L) and a low concentration (5 x 10(-10) M) of tryptic digest product of a phosphoprotein sample could be dramatically enriched and characterized using this approach.
Rapid enrichment of phosphopeptides from tryptic digests of proteins using iron oxide nanocomposites of magnetic particles coated with zirconia as the concentrating probes
(2007)
Lo, Chun-Yuen
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Chen, Wei-Yu
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Chen, Cheng-Tai
;
Chen, Yu-Chie
;
應用化學系
Iron oxide nanocomposites of magnetic particles coated with zirconia were used as affinity probes to selectively concentrate phosphopeptides from tryptic digests of alpha- and beta-caseins, milk, and egg white to exemplify the enrichment of phosphopeptides from complex samples. Phosphopeptides, in quantities sufficient for characterization by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), were enriched by the affinity probes within only 30 s. The affinity probe-target species conjugates were separated from the sample solution simply by applying an external magnetic field. The detection limit for tryptic digest of beta-casein using this approach is similar to 45 fmol. Furthermore, we combined this enrichment method with a rapid enzymatic digestion method, that is, microwave-assisted enzymatic digestion using magnetic particles as the microwave absorbers, to speed up the tryptic digest reactions. Thus, we alternatively enriched phosphoproteins on the zirconia-coated particles followed by mixing with trypsin and heated the mixture in a microwave oven for 1 min. The particles remaining in the mixture were used as affinity probes to selectively enrich phosphopeptides from the tryptic digestion product by pipeting, followed by characterization using MALDI MS. Using the bifunctional zirconia-coated magnetic particles as both the affinity probes and the microwave absorbers could greatly reduce the time for the purification and characterization of phosphopeptides from complex samples.
Surface-assisted laser desorption/ionization mass spectrometry on titania nanotube arrays
(2008-07-01)
Lo, Chun-Yuan
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Lin, Jia-Yi
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Chen, Wei-Yu
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Chen, Cheng-Tai
;
Chen, Yu-Chie
Titania nanotube arrays (NTA) generated from anodizing processes are tested as the substrate for surface-assisted laser desorption/ionization mass spectrometry (SALDI MS). The background generated from fitania NTA is very low, making the approach suitable for the analysis of small molecules. The upper detectable mass is similar to 29 kDa. Homogeneous sample deposition leads to good shot-to-shot reproducibility and suitability for quantitative analysis. Additionally, phosphopeptides can be selectively trapped on the fitania NTA substrate, as illustrated by simply depositing a tryptic digest of beta-casein followed by titania NTA SALDI MS analysis. The detection limit for small organics and peptides is in low fmol.
Trapping performance of Fe3O4 @ Al2O3 and Fe3O4 @ TiO2 magnetic nanoparticles in the selective enrichment of phosphopeptides from human serum
(2008-03-01)
Chen, Cheng-Tai
;
Chen, Yu-Chie
;
應用化學系
;
應用化學系分子科學碩博班
;
Department of Applied Chemistry
We have previously demonstrated that both alumina-coated iron oxide magnetic nanoparticles (Fe3O4 @ Al2O3) and titania-coated iron oxide magnetic nanoparticles (Fe3O4 @ TiO2) are effective affinity probes for phosphopeptides from the tryptic digests of phosphoproteins. The major advantage of these two types of affinity probe is the ease of isolating the affinity probe-target species conjugates from complex samples based on their magnetic property. Only a short time is required to enrich phosphorylated species in sufficient amounts for MALDI MS analysis by vigorously mixing the suspension of the sample and affinity nanoparticles through pipeting in and out of a sample vial for 30 sec. We herein evaluate the trapping performance of Fe3O4 @ Al2O3 and Fe3O4 @ TiO2 magnetic nanoparticles as the affinity probes to selectively enrich phosphopeptides from human serum under the same experimental condition. The peaks derived from fibrinopeptide A containing a phosphorylated serine dominate the matrix-assisted laser desorption/ionization (MALDI) mass spectra of the sample obtained after using the affinity probes to selectively enrich their target species from human serum. Furthermore, only phosphorylated fibrinopeptide A residues, which appeared in the MALDI mass spectrum, as Fe3O4 @ Al2O3 magnetic nanoparticles are employed as the affinity probes for the serum sample. However, non-phosphopeptides also appear in the MALDI mass spectrum when using Fe3O4 @ TiO2 magnetic nanoparticles as the affinity probes for the same serum sample. The results suggest that the specificity of Fe3O4 @ Al2O3 magnetic nanoparticles for phosphopeptide is superior to that of Fe3O4 @ TiO2 magnetic nanoparticles.
Using Gold Nanoclusters As Selective Luminescent Probes for Phosphate-Containing Metabolites
(2012-07-03)
Li, Po-Han
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Lin, Ju-Yu
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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.