29 research outputs found
Dual Quinone Tagging for MALDI-TOF Mass Spectrometric Quantitation of Cysteine-Containing Peptide
A dual quinone tagging strategy is
designed for quantitation of
cysteine-containing peptide (CCP) with MALDI-TOF mass spectrometry.
The quinone compounds can rapidly and specifically bind to the thiol
group of cysteine residues by a Michael addition reaction, which is
used to identify both CCP and the number of cysteine residues in CCP
through the direct observation of untagged and tagged products. After
reduced with DL-dithiothreitol, the intramolecular disulfide bond
can also be identified. Using benzoquinone (BQ) and methyl-<i>p</i>-benzoquinone (MBQ) as dual tags and a peptide with an
amino acid sequence of SSDQFRPDDCT (C-pep1) as a model target, respectively,
the quantitation strategy is performed through the intensity ratio
of MBQ-tagged C-pep1 to BQ-tagged C-pep1 as the internal standard.
The logarithm value of the intensity ratio is proportional to C-pep1
concentration in a range from 5.0 to 5000 nM. The limit of detection
is as low as 2.0 nM. The proposed methodology provides a novel tool
for rapid characterization, identification, and quantitation of biomolecules
containing thiol reactive sites and has a promising application in
the large-scale detection and analysis of cysteine-containing biomolecules
PM<sub>2.5</sub>-Bound Organophosphate Flame Retardants in Hong Kong: Occurrence, Origins, and Source-Specific Health Risks
Organophosphate
flame retardants (OPFRs) are emerging organic pollutants
in PM2.5, which have caused significant public health concerns
in recent years, given their potential carcinogenic and neurotoxic
effects. However, studies on the sources, occurrence, and health risk
assessment of PM2.5-bound OPFRs in Hong Kong are lacking.
To address this knowledge gap, we characterized 13 OPFRs in one-year
PM2.5 samples using gas chromatography–atmospheric
pressure chemical ionization tandem mass spectrometry. Our findings
showed that OPFRs were present at a median concentration of 4978 pg
m–3 (ranging from 1924 to 8481 pg m–3), with chlorinated OPFRs dominating and accounting for 82.7% of
the total OPFRs. Using characteristic source markers and positive
matrix factorization, we identified one secondary formation and five
primary sources of OPFRs. Over 94.0% of PM2.5-bound OPFRs
in Hong Kong were primarily emitted, with plastic processing and waste
disposal being the leading source (61.0%), followed by marine vessels
(14.1%). The contributions of these two sources to OPFRs were more
pronounced on days influenced by local pollution emissions (91.9%)
than on days affected by regional pollution (44.2%). Our assessment
of health risks associated with human exposure to PM2.5-bound OPFRs indicated a low-risk level. However, further source-specific
health risk assessment revealed relatively high noncarcinogenic and
carcinogenic risks from chlorinated OPFRs emitted from plastic processing
and waste disposal, suggesting a need for more stringent emission
control of OPFRs from these sources in Hong Kong
A new liquid chromatography–fluorescence method for determination of perfluorooctanesulphonyl fluoride upon derivatisation with 1-naphthol
<div><p>Perfluorooctanesulphonyl fluoride (PFOSF), as a main precursor of perfluorooctanesulphonate (PFOS) that is ubiquitous in the environment, has been released to the environment with substantial quantity. Determination of PFOSF presents significant analytical challenges for using liquid chromatography with UV (LC–UV) and fluorescence detection (LC–FLD) due to the lack of chromophore in the molecular structure. In this study, a new method was developed by derivatising PFOSF with 1-naphthol to form 1-naphthylperfluorooctanesulphonate (NPFOS), which allowed rapid qualitative and quantitative analysis using LC–UV and LC–FLD. The derivatising product was confirmed from the analyses by proton nuclear magnetic resonance and quadrupole–time of flight mass spectrometry. The LC–FLD method demonstrated good linearity in the NPFOS concentration range from 20 pg µL<sup>−1</sup> to 20 ng µL<sup>−</sup><sup>1</sup> with a correlation coefficient better than 0.999, with the instrument detection limit of 1.5 pg µL<sup>−</sup><sup>1</sup>.</p></div
Three-Dimensional Mass Spectrometry Imaging Reveals Distributions of Lipids and the Drug Metabolite Associated with the Enhanced Growth of Colon Cancer Cell Spheroids Treated with Triclosan
The application of
mass spectrometry imaging (MSI) to
explore the
responses of cancer cell spheroids (CCS) after treatment of exogenous
molecules has attracted growing attention. Increasing studies have
utilized MSI to image the two-dimensional distributions of exogenous
and endogenous molecules in planar CCS sections. However, because
CCS are volumetric and heterogenous, maintaining their three-dimensional
(3D) information is essential for acquiring a better understanding
of the tumor microenvironment and mechanisms of action of exogenous
molecules. Here, an established method of 3D MSI was applied to distinguish
the distributions of triclosan sulfate and endogenous lipids in three
microregions of colon CCS with an enhanced growth induced by the treatment
of triclosan, a common antimicrobial agent. The results of 3D MSI
showed that triclosan sulfate gradually accumulated from the periphery
to the entire structure of CCS and finally localized in the core region.
Spatial lipidomics analysis revealed that the upregulated phosphatidylethanolamine
(fold change (FD) = 1.26, p = 0.0021), phosphatidylinositol
(FD = 1.17, p = 0.0180), and phosphatidylcholine
(FD = 1.22, p = 0.0178) species mainly distributed
in the outer proliferative region, while the upregulated sphingomyelin
(FD = 1.18, p = 0.024) species tended to distribute
in the inner necrotic region. Our results suggest that a competitive
mechanism between inhibiting and promoting CCS growth might be responsible
for the proliferation of CCS treated with triclosan
Three-Dimensional Mass Spectrometry Imaging Reveals Distributions of Lipids and the Drug Metabolite Associated with the Enhanced Growth of Colon Cancer Cell Spheroids Treated with Triclosan
The application of
mass spectrometry imaging (MSI) to
explore the
responses of cancer cell spheroids (CCS) after treatment of exogenous
molecules has attracted growing attention. Increasing studies have
utilized MSI to image the two-dimensional distributions of exogenous
and endogenous molecules in planar CCS sections. However, because
CCS are volumetric and heterogenous, maintaining their three-dimensional
(3D) information is essential for acquiring a better understanding
of the tumor microenvironment and mechanisms of action of exogenous
molecules. Here, an established method of 3D MSI was applied to distinguish
the distributions of triclosan sulfate and endogenous lipids in three
microregions of colon CCS with an enhanced growth induced by the treatment
of triclosan, a common antimicrobial agent. The results of 3D MSI
showed that triclosan sulfate gradually accumulated from the periphery
to the entire structure of CCS and finally localized in the core region.
Spatial lipidomics analysis revealed that the upregulated phosphatidylethanolamine
(fold change (FD) = 1.26, p = 0.0021), phosphatidylinositol
(FD = 1.17, p = 0.0180), and phosphatidylcholine
(FD = 1.22, p = 0.0178) species mainly distributed
in the outer proliferative region, while the upregulated sphingomyelin
(FD = 1.18, p = 0.024) species tended to distribute
in the inner necrotic region. Our results suggest that a competitive
mechanism between inhibiting and promoting CCS growth might be responsible
for the proliferation of CCS treated with triclosan
Three-Dimensional Mass Spectrometry Imaging Reveals Distributions of Lipids and the Drug Metabolite Associated with the Enhanced Growth of Colon Cancer Cell Spheroids Treated with Triclosan
The application of
mass spectrometry imaging (MSI) to
explore the
responses of cancer cell spheroids (CCS) after treatment of exogenous
molecules has attracted growing attention. Increasing studies have
utilized MSI to image the two-dimensional distributions of exogenous
and endogenous molecules in planar CCS sections. However, because
CCS are volumetric and heterogenous, maintaining their three-dimensional
(3D) information is essential for acquiring a better understanding
of the tumor microenvironment and mechanisms of action of exogenous
molecules. Here, an established method of 3D MSI was applied to distinguish
the distributions of triclosan sulfate and endogenous lipids in three
microregions of colon CCS with an enhanced growth induced by the treatment
of triclosan, a common antimicrobial agent. The results of 3D MSI
showed that triclosan sulfate gradually accumulated from the periphery
to the entire structure of CCS and finally localized in the core region.
Spatial lipidomics analysis revealed that the upregulated phosphatidylethanolamine
(fold change (FD) = 1.26, p = 0.0021), phosphatidylinositol
(FD = 1.17, p = 0.0180), and phosphatidylcholine
(FD = 1.22, p = 0.0178) species mainly distributed
in the outer proliferative region, while the upregulated sphingomyelin
(FD = 1.18, p = 0.024) species tended to distribute
in the inner necrotic region. Our results suggest that a competitive
mechanism between inhibiting and promoting CCS growth might be responsible
for the proliferation of CCS treated with triclosan
Three-Dimensional Mass Spectrometry Imaging Reveals Distributions of Lipids and the Drug Metabolite Associated with the Enhanced Growth of Colon Cancer Cell Spheroids Treated with Triclosan
The application of
mass spectrometry imaging (MSI) to
explore the
responses of cancer cell spheroids (CCS) after treatment of exogenous
molecules has attracted growing attention. Increasing studies have
utilized MSI to image the two-dimensional distributions of exogenous
and endogenous molecules in planar CCS sections. However, because
CCS are volumetric and heterogenous, maintaining their three-dimensional
(3D) information is essential for acquiring a better understanding
of the tumor microenvironment and mechanisms of action of exogenous
molecules. Here, an established method of 3D MSI was applied to distinguish
the distributions of triclosan sulfate and endogenous lipids in three
microregions of colon CCS with an enhanced growth induced by the treatment
of triclosan, a common antimicrobial agent. The results of 3D MSI
showed that triclosan sulfate gradually accumulated from the periphery
to the entire structure of CCS and finally localized in the core region.
Spatial lipidomics analysis revealed that the upregulated phosphatidylethanolamine
(fold change (FD) = 1.26, p = 0.0021), phosphatidylinositol
(FD = 1.17, p = 0.0180), and phosphatidylcholine
(FD = 1.22, p = 0.0178) species mainly distributed
in the outer proliferative region, while the upregulated sphingomyelin
(FD = 1.18, p = 0.024) species tended to distribute
in the inner necrotic region. Our results suggest that a competitive
mechanism between inhibiting and promoting CCS growth might be responsible
for the proliferation of CCS treated with triclosan
Occurrence and Partitioning of Bisphenol Analogues in Adults’ Blood from China
Widespread human exposure and associated
adverse health effects
led to regulations on the usage of bisphenol A (BPA). Several bisphenol
analogues (BPs) have been introduced as BPA alternatives in various
applications. However, these BPs have been shown to exhibit similar
or even stronger endocrine-disrupting activities compared with that
of BPA. Currently, information on the human exposure to BPA alternatives
remains limited. In this study, nine BPs were quantified in 81 pairs
of plasma and red blood cell (RBC) samples from Chinese participants.
In human plasma, the predominant BPs was BPA, bisphenol S (BPS), and
bisphenol AF (BPAF), with the mean concentrations of 0.40, 0.15, and
0.073 ng/mL, respectively. BPA (accounting for 63% of total BPs) and
BPS (18%) were the major BPs in the RBC fraction. Mass fractions in
plasma (<i>F</i><sub>p</sub>) were found to be highest for
BPS (mean, 0.78), followed by BPAF (0.71) and BPA (0.67), indicating
strong partitioning to the plasma fraction. However, bisphenol AP
was more frequently detected in the RBC fraction. Estimated total
daily intake (EDI) of BPA was in the range of 0.0048–0.75 μg/kg
bw/day for the participants, and adults aged >50 years had comparatively
lower EDI. To our knowledge, this is the first study to assess the
occurrence and partitioning of BPA alternatives in paired human plasma
and RBCs from the Chinese general population
Enantiomeric Recognition of Amino Acid Salts by Macrocyclic Crown Ethers Derived from Enantiomerically Pure 1,8,9,16-Tetrahydroxytetraphenylenes
Asymmetric synthesis of (<i>R</i>,<i>R</i>)-
and (<i>S</i>,<i>S</i>)-1,8,9,16-tetrahydroxytetraphenylenes
was achieved from starting material (2<i>R</i>,3<i>R</i>)-butane-2,3-diol and (2<i>S</i>,3<i>S</i>)-butane-2,3-diol respectively by utilizing a center-to-axis strategy.
A series of crown ether compounds <b>20</b>, <b>24</b>, and <b>25</b> and their corresponding enantiomers derived
from chiral tetrahydroxytetraphenylene were synthesized in enantiomerically
pure forms. Enantiomeric recognition properties of these hosts toward l- and d-amino acid methyl ester hydrochloride were
studied by the UV spectroscopy titration. The tetramer hosts (<i>S</i>,<i>S</i>,<i>S</i>,<i>S</i>,<i>ÂS</i>,<i>S</i>,<i>S</i>,<i>S</i>)-<b>20</b> and (<i>R</i>,<i>R</i>,<i>ÂR</i>,<i>R</i>,<i>R</i>,<i>R</i>,<i>ÂR</i>,<i>R</i>)-<b>20</b> exhibited the best enantioselectivities toward l- and d-alanine methyl ester hydrochloride salt with <i>K</i><sub>L</sub>/<i>K</i><sub>D</sub> = 4.1 and <i>K</i><sub>D</sub>/<i>K</i><sub>L</sub> = 3.9, respectively.
The new chiral macrocyclic hosts would further enrich the host–guest
chemistry
Enantiomeric Recognition of Amino Acid Salts by Macrocyclic Crown Ethers Derived from Enantiomerically Pure 1,8,9,16-Tetrahydroxytetraphenylenes
Asymmetric synthesis of (<i>R</i>,<i>R</i>)-
and (<i>S</i>,<i>S</i>)-1,8,9,16-tetrahydroxytetraphenylenes
was achieved from starting material (2<i>R</i>,3<i>R</i>)-butane-2,3-diol and (2<i>S</i>,3<i>S</i>)-butane-2,3-diol respectively by utilizing a center-to-axis strategy.
A series of crown ether compounds <b>20</b>, <b>24</b>, and <b>25</b> and their corresponding enantiomers derived
from chiral tetrahydroxytetraphenylene were synthesized in enantiomerically
pure forms. Enantiomeric recognition properties of these hosts toward l- and d-amino acid methyl ester hydrochloride were
studied by the UV spectroscopy titration. The tetramer hosts (<i>S</i>,<i>S</i>,<i>S</i>,<i>S</i>,<i>ÂS</i>,<i>S</i>,<i>S</i>,<i>S</i>)-<b>20</b> and (<i>R</i>,<i>R</i>,<i>ÂR</i>,<i>R</i>,<i>R</i>,<i>R</i>,<i>ÂR</i>,<i>R</i>)-<b>20</b> exhibited the best enantioselectivities toward l- and d-alanine methyl ester hydrochloride salt with <i>K</i><sub>L</sub>/<i>K</i><sub>D</sub> = 4.1 and <i>K</i><sub>D</sub>/<i>K</i><sub>L</sub> = 3.9, respectively.
The new chiral macrocyclic hosts would further enrich the host–guest
chemistry