Jingyueh Jeng - Academia.edu (original) (raw)
Papers by Jingyueh Jeng
Analytica Chimica Acta, 2019
An ambient ionization tandem mass spectrometric approach was developed to rapidly screen multires... more An ambient ionization tandem mass spectrometric approach was developed to rapidly screen multiresidue pesticides on fruits and vegetables without sample preparation and chromatographic separation. The residual pesticides on fruits and vegetables were collected by sweeping a metallic probe across the sample surface for 2 cm. The analytes collected on the probe were desorbed and ionized in a thermal desorption electrospray ionization (TD-ESI) source, after which analyte ions were detected by a triple quadruple mass analyzer (QqQ) operated in multiple reaction monitoring (MRM) mode. With this TD-ESI/MS/MS approach, 308 pesticides were monitored, where a mixture containing 15 pesticide standards was successfully identified to demonstrate the capability of this approach to screen trace multiresidue pesticides. The approach had reasonable detection limits (<50 ppb) and reproducibility (RSD: 8.43%, n = 9) from the analysis of a benthiazole standard solution. Real samples including a tomato and bell pepper were analyzed using this TD-ESI/MS/MS approach. After TD-ESI/MS/MS analysis, the organic solvent extracts from the same samples were subjected to TD-ESI/MS/MS, gas chromatography mass spectrometry (GC-MS), and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis for validation.
This study demonstrated the feasibility of performing protein analysis with ultralow sample volum... more This study demonstrated the feasibility of performing protein analysis with ultralow sample volume by combining a tungsten oxide nanowire (TON) fiber with a minia-turized electrospray ionization interface. An increase in wettability of the tugsten surface after growing randomly oriented TON on its surface allows strong adhesion of ∼50 nL of the methanol solution at its tip. Under the influence of a high electric field, electrospray from a Taylor cone on the adhered methanol solution was observed and the multiply charged ions of protein molecules predissolved in the solution were detected. The synthesis of tungsten oxide nanowires (TON) on a tungsten wire can be achieved by simply heating the tungsten wire under an Ar atmosphere. 1-3 The TON will be grown on the surface of the wire through the reaction of tungsten with traces of oxygen; no external catalyst or solvent is required. Because of its large surface area and high conductivity, a tungsten fiber with TON on its surface may be used to increase the lateral resolution of scanning tunneling microscopy or behave as a conductive carrier in nanosensors. 4-6 Studies on the influence that a high electric field has on the liquid attached on the TON of a tungsten fiber remain rare, however; and no reports describe applying such material to chemical or biochemical analyses. In this study, we describe the generation of electrospray from traces of methanol solution on the TON and the applications of such a tungsten-TON fiber to protein analysis by mass spectrometry. EXPERIMENTAL SECTION The preparation of the TON on a tungsten fiber tip followed the procedures described by Gang Gu et al. 1 The surface of a tungsten fiber (250-µm diameter) was cleaned using an electro-chemical etching process by dipping the fiber into 0.5 N KOH solution and then applying an ac voltage (∼3-10 V) between the fiber and a platinum circle electrode. Subsequently, the fiber was placed into a tube furnace and was heated at 700 °C under an Ar atmosphere (Ar flow rate, 300 mL/min) for 30 min. The fiber was then cooled to room temperature before examining its surface composition using a scanning electron microscope. We found that, after this simple heat treatment process, the surface of the tungsten tip was modified with numerous TON (Figure 1a). The average length of the nanowires was ∼500 nm. The diameters of the nanowires ranged from 30 to 150 nm and remained uniform along their entire length. No tungsten nanoparticles were observed. The investigations into the hydrophilic properties (or wetta-bility) of the tungsten fiber surface were conducted by monitoring their contact angles (i.e., the angle between the water/air and water/solid interfaces at the three-phase boundary). Measurements of contact angle were performed in a sealed glass chamber at 100% humidity by using a microsyringe needle to place 0.5 µL of pure water onto the tungsten tip. An image of the drop was recorded a few seconds after droplet deposition. Each individual experiment was repeated three times to determine the average contact angles of three tungsten fibers. Application of trace sample solution (∼50 nL) to the tungsten fiber tip was simply done by dipping and removing the fiber from the sample solution. To apply more sample solution onto the tungsten fiber surface, 0.2 µL of the sample solution was deposited at the fiber tip by a pipet. The tungsten fiber was then placed ∼8 mm away from the ion-orifice inlet of the mass analyzer for ion detection. Mass spectrometric analysis was performed using a Bruker Bio-Tof Q mass spectrometer (Bruker Daltonics, Billerica, MA). The mass analyzer was scanned from m/z 200 to 2000 at a rate of ∼1 s/scan. RESULTS AND DISCUSSION The results of contact angle measurements showed, without modification, the contact angle of a tungsten fiber was 16.6° (Figure 2a). This indicates that the surface of the tungsten fiber is effectively hydrophilic (cf. the contact angles of most hydro-phobic metal surfaces, usually 150°). After surface modification with the TON, the contact angle of the fiber decreased to 6.1° (Figure 2b), which indicates that the surface of the tungsten-TON fiber became extremely hydrophilic. We found that traces
Tetrahedron, 2013
ABSTRACT In this study, we have successfully synthesized the click cluster of β-cyclodextrin (β-C... more ABSTRACT In this study, we have successfully synthesized the click cluster of β-cyclodextrin (β-CD) and NH2-terminated poly(amido amine) (PAMAM) dendrons via efficient Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC). The highly water-soluble click cluster, namely CDG2H, was carefully characterized by various analytical tools to confirm the structure and product purity. 1H NMR further resolved the degree of protonation at different pH, suggesting that a tetracationic peripheral attached to the primary face of β-CD at physiological condition. This polycationic character allows CDG2H to effectively bind with anionic targets through a synergistic effect combining host–guest and electrostatic interactions. The UV–visible absorption and fluorescence spectroscopic analyses both indicated that CDG2H has relatively higher binding affinity toward anionic binaphthyl model compounds than unmodified β-CD. In addition, because of the optically active cyclodextrin core, CDG2H still revealed significant chiral discrimination for enantiomeric binaphthyl pairs.
Rapid Communications in Mass Spectrometry, 2007
We describe an innovative approach -using a high concentration of trypsin-modified magnetic nanop... more We describe an innovative approach -using a high concentration of trypsin-modified magnetic nanoparticles (TMNPs) -for the rapid and efficient digestion of proteins at elevated temperature. The required digestion time could be reduced to less than 10 s. After digestion, the TMNPs were collected magnetically from the sample solution for reuse and the digested peptides were characterized using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Protein digestion was optimized when using the TMNPs (5 mg/mL) at 57-C; a significantly high peptide coverage was achieved for protein identification (e.g., 98% for lysozyme). Although a high concentration of TMNPs was used for digestion, the short digestion time led to much lower amounts of trypsin peptides being produced through self-digestion. As a result, interference in the mass spectrometric detection of the peptide ions was reduced significantly.
Proteome Science, 2013
Background: There is great interest in the design of small molecules that selectively target mino... more Background: There is great interest in the design of small molecules that selectively target minor grooves of duplex DNA for controlling specific gene expression implicated in a disease. The design of chiral small molecules for rational drug design has attracted increasing attention due to the chirality of DNA. Yet, there is limited research on the chirality effect of minor groove binders on DNA interaction, especially at the protein expression level. This paper is an attempt to illustrate that DNA binding affinity might not provide a full picture on the biological activities. Drug interacting at the genomic level can be translated to the proteomic level. Here we have illustrated that although the chiral bispyrrole-pyrrolidine-oligoamides, PySSPy and PyRSPy, showed low binding affinity to DNA, their influence at the proteomic level is significant. More importantly, the chirality also plays a role. Two-dimensional proteomic profile to identify the differentially expressed protein in Escherichia coli DH5α (E coli DH5α) were investigated.
Rapid Communications in Mass Spectrometry - RAPID COMMUN MASS SPECTROM, 2003
This paper reports development of a non-mechanical electrospray ionization (ESI) method to genera... more This paper reports development of a non-mechanical electrospray ionization (ESI) method to generate electrospray from a droplet deposited on an optical fiber coated with a thin gold or Nafion film. Modification of the surface of the optical fiber in this manner increases its wettability, such that a droplet of the aqueous sample solution can adhere sufficiently strongly to the tip of the fiber. The aqueous sample solution was deposited near the tip of the fiber with a micropipette. When a high voltage (2000 V) was applied to the fiber by electrical connection through the gold film, the sample solution moved and hung at the tip of the fiber. Simultaneously, ESI was generated from the sample droplet. Multiply charged peptide and protein ions were detected by connecting the ESI source to a quadrupole mass analyzer. Copyright © 2003 John Wiley & Sons, Ltd.
Journal of the American Academy of Dermatology, 2006
We describe a 7-month-old male infant with a foreign body granuloma caused by monosodium glutamat... more We describe a 7-month-old male infant with a foreign body granuloma caused by monosodium glutamate (MSG) after a Bacille Calmette-Guérin (BCG) immunization. A ridged, erythematous, indurated plaque developed over a BCG injection site on his left upper arm 1 month after the first BCG immunization. Biopsy showed multiple noncaseating foreign body granulomas without detectable mycobacteria by both Ziehl-Neelsen stain and polymerase chain reaction assay. Birefringent crystals were identified in the foreign body giant cells with polarized light microscopy. The crystals were further determined to be glutamic acid by the method of fast atom bombardment. Hence, MSG, the only composite of BCG vaccine except the bacillus, was believed to be responsible for the granulomatous foreign body reaction. On review of the literature, we could find no previous report of an adverse reaction of BCG immunization attributable to MSG (glutamic acid).
Journal of Proteome Research, 2006
We report here using a novel technologyselectrospray-assisted laser desorption ionization (ELDI)/... more We report here using a novel technologyselectrospray-assisted laser desorption ionization (ELDI)/mass spectrometrysfor the rapid and sensitive detection of the major proteins that exist in dried biological fluids (e.g., blood, tears, saliva, serum), bacterial cultures, and tissues (e.g., porcine liver and heart) under ambient conditions. This technique required essentially no sample pretreatment. The proteins in the samples were desorbed using a pulsed nitrogen laser without the assistance of an organic matrix. The desorbed protein molecules were then post-ionized through their fusion into the charged solvent droplets produced from the electrospray of an acidic methanol solution; electrospray ionization (ESI) proceeded from the newly formed droplets to generate the ESI-like protein ions. This new ionization approach combines some of the features of electrospray ionization with those of matrix-assisted laser desorption ionization (MALDI), that is, sampling of a solid surface with spatial resolution, generating ESI-like mass spectra of the desorbed proteins, and operating under ambient conditions. Figure 10. (a) Positive-mode ELDI mass spectrum of the proteins in a sample of porcine liver tissue. Protein extracts of the porcine liver tissue as analyzed using (b) ESI-MS and (c) MALDI MS. The insets in panels a and b display the deconvoluted protein ion signals from the ELDI and ESI mass spectra.
Journal of Mass Spectrometry, 2002
Analytical Chemistry, 2003
A starlike water-soluble fullerene derivative, hexa(sulfonbutyl)fullerene (C60[(CH2)4SO3-]6; HSBF... more A starlike water-soluble fullerene derivative, hexa(sulfonbutyl)fullerene (C60[(CH2)4SO3-]6; HSBF), consisting of a C60 cage covalently bonded with six negatively charged sulfonate arms, was synthesized and used to selectively precipitate positively charged surfactants, amino acids, peptides, and proteins. The affinity of HSBF to the analytes depends on the charge, structure, and hydrophobic characteristics of the analytes. The ion pair precipitate was easily removed from the solution by centrifugation. After washing, the precipitate was redissolved in the solvent or buffer solution and the analyte was characterized by laser desorption ionization-time-of-flight mass spectrometry (LD-TOF). HSBF shows strong optical absorbance in the UV range, so no additional organic matrix was required to conduct LD-TOF analysis of small analytes. For the solution that contained five quaternary amines differing only in alkyl chain length, HSBF exhibits the highest affinity to the amine with the longest alkyl chain. Only the arginine signal was detected from the solution that contained 14 amino acids. The peptides with arginine as the end groups interacted most strongly with HSBF and could be selectively precipitated from a solution of a mixture of five peptides. The signals associated with a trace amount of charged peptides derived from the digestion of proteins by trypsin were greatly enhanced after concentration with HSBF. Among eight proteins in the sample solution, insulin had the strongest affinity to the HSBF and exhibited the strongest signal on the matrix-assisted laser desorption/ionization mass spectrum.
Analytical Chemistry, 2005
This study demonstrated the feasibility of performing protein analysis with ultralow sample volum... more This study demonstrated the feasibility of performing protein analysis with ultralow sample volume by combining a tungsten oxide nanowire (TON) fiber with a miniaturized electrospray ionization interface. An increase in wettability of the tugsten surface after growing randomly oriented TON on its surface allows strong adhesion of ∼50 nL of the methanol solution at its tip. Under the influence of a high electric field, electrospray from a Taylor cone on the adhered methanol solution was observed and the multiply charged ions of protein molecules predissolved in the solution were detected.
Background: There is great interest in the design of small molecules that selectively target mino... more Background: There is great interest in the design of small molecules that selectively target minor grooves of duplex DNA for controlling specific gene expression implicated in a disease. The design of chiral small molecules for rational drug design has attracted increasing attention due to the chirality of DNA. Yet, there is limited research on the chirality effect of minor groove binders on DNA interaction, especially at the protein expression level. This paper is an attempt to illustrate that DNA binding affinity might not provide a full picture on the biological activities. Drug interacting at the genomic level can be translated to the proteomic level. Here we have illustrated that although the chiral bispyrrole-pyrrolidine-oligoamides, PySSPy and PyRSPy, showed low binding affinity to DNA, their influence at the proteomic level is significant. More importantly, the chirality also plays a role. Two-dimensional proteomic profile to identify the differentially expressed protein in Escherichia coli DH5α (E coli DH5α) were investigated.
Analytica Chimica Acta, 2019
An ambient ionization tandem mass spectrometric approach was developed to rapidly screen multires... more An ambient ionization tandem mass spectrometric approach was developed to rapidly screen multiresidue pesticides on fruits and vegetables without sample preparation and chromatographic separation. The residual pesticides on fruits and vegetables were collected by sweeping a metallic probe across the sample surface for 2 cm. The analytes collected on the probe were desorbed and ionized in a thermal desorption electrospray ionization (TD-ESI) source, after which analyte ions were detected by a triple quadruple mass analyzer (QqQ) operated in multiple reaction monitoring (MRM) mode. With this TD-ESI/MS/MS approach, 308 pesticides were monitored, where a mixture containing 15 pesticide standards was successfully identified to demonstrate the capability of this approach to screen trace multiresidue pesticides. The approach had reasonable detection limits (<50 ppb) and reproducibility (RSD: 8.43%, n = 9) from the analysis of a benthiazole standard solution. Real samples including a tomato and bell pepper were analyzed using this TD-ESI/MS/MS approach. After TD-ESI/MS/MS analysis, the organic solvent extracts from the same samples were subjected to TD-ESI/MS/MS, gas chromatography mass spectrometry (GC-MS), and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis for validation.
This study demonstrated the feasibility of performing protein analysis with ultralow sample volum... more This study demonstrated the feasibility of performing protein analysis with ultralow sample volume by combining a tungsten oxide nanowire (TON) fiber with a minia-turized electrospray ionization interface. An increase in wettability of the tugsten surface after growing randomly oriented TON on its surface allows strong adhesion of ∼50 nL of the methanol solution at its tip. Under the influence of a high electric field, electrospray from a Taylor cone on the adhered methanol solution was observed and the multiply charged ions of protein molecules predissolved in the solution were detected. The synthesis of tungsten oxide nanowires (TON) on a tungsten wire can be achieved by simply heating the tungsten wire under an Ar atmosphere. 1-3 The TON will be grown on the surface of the wire through the reaction of tungsten with traces of oxygen; no external catalyst or solvent is required. Because of its large surface area and high conductivity, a tungsten fiber with TON on its surface may be used to increase the lateral resolution of scanning tunneling microscopy or behave as a conductive carrier in nanosensors. 4-6 Studies on the influence that a high electric field has on the liquid attached on the TON of a tungsten fiber remain rare, however; and no reports describe applying such material to chemical or biochemical analyses. In this study, we describe the generation of electrospray from traces of methanol solution on the TON and the applications of such a tungsten-TON fiber to protein analysis by mass spectrometry. EXPERIMENTAL SECTION The preparation of the TON on a tungsten fiber tip followed the procedures described by Gang Gu et al. 1 The surface of a tungsten fiber (250-µm diameter) was cleaned using an electro-chemical etching process by dipping the fiber into 0.5 N KOH solution and then applying an ac voltage (∼3-10 V) between the fiber and a platinum circle electrode. Subsequently, the fiber was placed into a tube furnace and was heated at 700 °C under an Ar atmosphere (Ar flow rate, 300 mL/min) for 30 min. The fiber was then cooled to room temperature before examining its surface composition using a scanning electron microscope. We found that, after this simple heat treatment process, the surface of the tungsten tip was modified with numerous TON (Figure 1a). The average length of the nanowires was ∼500 nm. The diameters of the nanowires ranged from 30 to 150 nm and remained uniform along their entire length. No tungsten nanoparticles were observed. The investigations into the hydrophilic properties (or wetta-bility) of the tungsten fiber surface were conducted by monitoring their contact angles (i.e., the angle between the water/air and water/solid interfaces at the three-phase boundary). Measurements of contact angle were performed in a sealed glass chamber at 100% humidity by using a microsyringe needle to place 0.5 µL of pure water onto the tungsten tip. An image of the drop was recorded a few seconds after droplet deposition. Each individual experiment was repeated three times to determine the average contact angles of three tungsten fibers. Application of trace sample solution (∼50 nL) to the tungsten fiber tip was simply done by dipping and removing the fiber from the sample solution. To apply more sample solution onto the tungsten fiber surface, 0.2 µL of the sample solution was deposited at the fiber tip by a pipet. The tungsten fiber was then placed ∼8 mm away from the ion-orifice inlet of the mass analyzer for ion detection. Mass spectrometric analysis was performed using a Bruker Bio-Tof Q mass spectrometer (Bruker Daltonics, Billerica, MA). The mass analyzer was scanned from m/z 200 to 2000 at a rate of ∼1 s/scan. RESULTS AND DISCUSSION The results of contact angle measurements showed, without modification, the contact angle of a tungsten fiber was 16.6° (Figure 2a). This indicates that the surface of the tungsten fiber is effectively hydrophilic (cf. the contact angles of most hydro-phobic metal surfaces, usually 150°). After surface modification with the TON, the contact angle of the fiber decreased to 6.1° (Figure 2b), which indicates that the surface of the tungsten-TON fiber became extremely hydrophilic. We found that traces
Tetrahedron, 2013
ABSTRACT In this study, we have successfully synthesized the click cluster of β-cyclodextrin (β-C... more ABSTRACT In this study, we have successfully synthesized the click cluster of β-cyclodextrin (β-CD) and NH2-terminated poly(amido amine) (PAMAM) dendrons via efficient Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC). The highly water-soluble click cluster, namely CDG2H, was carefully characterized by various analytical tools to confirm the structure and product purity. 1H NMR further resolved the degree of protonation at different pH, suggesting that a tetracationic peripheral attached to the primary face of β-CD at physiological condition. This polycationic character allows CDG2H to effectively bind with anionic targets through a synergistic effect combining host–guest and electrostatic interactions. The UV–visible absorption and fluorescence spectroscopic analyses both indicated that CDG2H has relatively higher binding affinity toward anionic binaphthyl model compounds than unmodified β-CD. In addition, because of the optically active cyclodextrin core, CDG2H still revealed significant chiral discrimination for enantiomeric binaphthyl pairs.
Rapid Communications in Mass Spectrometry, 2007
We describe an innovative approach -using a high concentration of trypsin-modified magnetic nanop... more We describe an innovative approach -using a high concentration of trypsin-modified magnetic nanoparticles (TMNPs) -for the rapid and efficient digestion of proteins at elevated temperature. The required digestion time could be reduced to less than 10 s. After digestion, the TMNPs were collected magnetically from the sample solution for reuse and the digested peptides were characterized using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Protein digestion was optimized when using the TMNPs (5 mg/mL) at 57-C; a significantly high peptide coverage was achieved for protein identification (e.g., 98% for lysozyme). Although a high concentration of TMNPs was used for digestion, the short digestion time led to much lower amounts of trypsin peptides being produced through self-digestion. As a result, interference in the mass spectrometric detection of the peptide ions was reduced significantly.
Proteome Science, 2013
Background: There is great interest in the design of small molecules that selectively target mino... more Background: There is great interest in the design of small molecules that selectively target minor grooves of duplex DNA for controlling specific gene expression implicated in a disease. The design of chiral small molecules for rational drug design has attracted increasing attention due to the chirality of DNA. Yet, there is limited research on the chirality effect of minor groove binders on DNA interaction, especially at the protein expression level. This paper is an attempt to illustrate that DNA binding affinity might not provide a full picture on the biological activities. Drug interacting at the genomic level can be translated to the proteomic level. Here we have illustrated that although the chiral bispyrrole-pyrrolidine-oligoamides, PySSPy and PyRSPy, showed low binding affinity to DNA, their influence at the proteomic level is significant. More importantly, the chirality also plays a role. Two-dimensional proteomic profile to identify the differentially expressed protein in Escherichia coli DH5α (E coli DH5α) were investigated.
Rapid Communications in Mass Spectrometry - RAPID COMMUN MASS SPECTROM, 2003
This paper reports development of a non-mechanical electrospray ionization (ESI) method to genera... more This paper reports development of a non-mechanical electrospray ionization (ESI) method to generate electrospray from a droplet deposited on an optical fiber coated with a thin gold or Nafion film. Modification of the surface of the optical fiber in this manner increases its wettability, such that a droplet of the aqueous sample solution can adhere sufficiently strongly to the tip of the fiber. The aqueous sample solution was deposited near the tip of the fiber with a micropipette. When a high voltage (2000 V) was applied to the fiber by electrical connection through the gold film, the sample solution moved and hung at the tip of the fiber. Simultaneously, ESI was generated from the sample droplet. Multiply charged peptide and protein ions were detected by connecting the ESI source to a quadrupole mass analyzer. Copyright © 2003 John Wiley & Sons, Ltd.
Journal of the American Academy of Dermatology, 2006
We describe a 7-month-old male infant with a foreign body granuloma caused by monosodium glutamat... more We describe a 7-month-old male infant with a foreign body granuloma caused by monosodium glutamate (MSG) after a Bacille Calmette-Guérin (BCG) immunization. A ridged, erythematous, indurated plaque developed over a BCG injection site on his left upper arm 1 month after the first BCG immunization. Biopsy showed multiple noncaseating foreign body granulomas without detectable mycobacteria by both Ziehl-Neelsen stain and polymerase chain reaction assay. Birefringent crystals were identified in the foreign body giant cells with polarized light microscopy. The crystals were further determined to be glutamic acid by the method of fast atom bombardment. Hence, MSG, the only composite of BCG vaccine except the bacillus, was believed to be responsible for the granulomatous foreign body reaction. On review of the literature, we could find no previous report of an adverse reaction of BCG immunization attributable to MSG (glutamic acid).
Journal of Proteome Research, 2006
We report here using a novel technologyselectrospray-assisted laser desorption ionization (ELDI)/... more We report here using a novel technologyselectrospray-assisted laser desorption ionization (ELDI)/mass spectrometrysfor the rapid and sensitive detection of the major proteins that exist in dried biological fluids (e.g., blood, tears, saliva, serum), bacterial cultures, and tissues (e.g., porcine liver and heart) under ambient conditions. This technique required essentially no sample pretreatment. The proteins in the samples were desorbed using a pulsed nitrogen laser without the assistance of an organic matrix. The desorbed protein molecules were then post-ionized through their fusion into the charged solvent droplets produced from the electrospray of an acidic methanol solution; electrospray ionization (ESI) proceeded from the newly formed droplets to generate the ESI-like protein ions. This new ionization approach combines some of the features of electrospray ionization with those of matrix-assisted laser desorption ionization (MALDI), that is, sampling of a solid surface with spatial resolution, generating ESI-like mass spectra of the desorbed proteins, and operating under ambient conditions. Figure 10. (a) Positive-mode ELDI mass spectrum of the proteins in a sample of porcine liver tissue. Protein extracts of the porcine liver tissue as analyzed using (b) ESI-MS and (c) MALDI MS. The insets in panels a and b display the deconvoluted protein ion signals from the ELDI and ESI mass spectra.
Journal of Mass Spectrometry, 2002
Analytical Chemistry, 2003
A starlike water-soluble fullerene derivative, hexa(sulfonbutyl)fullerene (C60[(CH2)4SO3-]6; HSBF... more A starlike water-soluble fullerene derivative, hexa(sulfonbutyl)fullerene (C60[(CH2)4SO3-]6; HSBF), consisting of a C60 cage covalently bonded with six negatively charged sulfonate arms, was synthesized and used to selectively precipitate positively charged surfactants, amino acids, peptides, and proteins. The affinity of HSBF to the analytes depends on the charge, structure, and hydrophobic characteristics of the analytes. The ion pair precipitate was easily removed from the solution by centrifugation. After washing, the precipitate was redissolved in the solvent or buffer solution and the analyte was characterized by laser desorption ionization-time-of-flight mass spectrometry (LD-TOF). HSBF shows strong optical absorbance in the UV range, so no additional organic matrix was required to conduct LD-TOF analysis of small analytes. For the solution that contained five quaternary amines differing only in alkyl chain length, HSBF exhibits the highest affinity to the amine with the longest alkyl chain. Only the arginine signal was detected from the solution that contained 14 amino acids. The peptides with arginine as the end groups interacted most strongly with HSBF and could be selectively precipitated from a solution of a mixture of five peptides. The signals associated with a trace amount of charged peptides derived from the digestion of proteins by trypsin were greatly enhanced after concentration with HSBF. Among eight proteins in the sample solution, insulin had the strongest affinity to the HSBF and exhibited the strongest signal on the matrix-assisted laser desorption/ionization mass spectrum.
Analytical Chemistry, 2005
This study demonstrated the feasibility of performing protein analysis with ultralow sample volum... more This study demonstrated the feasibility of performing protein analysis with ultralow sample volume by combining a tungsten oxide nanowire (TON) fiber with a miniaturized electrospray ionization interface. An increase in wettability of the tugsten surface after growing randomly oriented TON on its surface allows strong adhesion of ∼50 nL of the methanol solution at its tip. Under the influence of a high electric field, electrospray from a Taylor cone on the adhered methanol solution was observed and the multiply charged ions of protein molecules predissolved in the solution were detected.
Background: There is great interest in the design of small molecules that selectively target mino... more Background: There is great interest in the design of small molecules that selectively target minor grooves of duplex DNA for controlling specific gene expression implicated in a disease. The design of chiral small molecules for rational drug design has attracted increasing attention due to the chirality of DNA. Yet, there is limited research on the chirality effect of minor groove binders on DNA interaction, especially at the protein expression level. This paper is an attempt to illustrate that DNA binding affinity might not provide a full picture on the biological activities. Drug interacting at the genomic level can be translated to the proteomic level. Here we have illustrated that although the chiral bispyrrole-pyrrolidine-oligoamides, PySSPy and PyRSPy, showed low binding affinity to DNA, their influence at the proteomic level is significant. More importantly, the chirality also plays a role. Two-dimensional proteomic profile to identify the differentially expressed protein in Escherichia coli DH5α (E coli DH5α) were investigated.