An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization （MALDI） time-of-flight mass spectrometer for on-line bioaerosol detection and characterization,...An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization （MALDI） time-of-flight mass spectrometer for on-line bioaerosol detection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the con- denser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of bi- ological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detection that has the potential to provide rapid and reliable identification of airborne biological aerosols.展开更多
Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has bee...Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has been termed as hormone refractory. To identify the proteins that mediate progression to the hormone-refractory state, we used protein-chip technology for mass profiling of patients＇ sera. This study included 16 patients with metastatic hormone-refractory prostate cancer who were initially treated with androgen deprivation therapy. Serum samples were collected from each patient at five time points： point A, pre-treatment; point B, at the nadir of the prostate- specific antigen （PSA） level; point C, PSA failure; point D, the early hormone-refractory phase; and point E, the late hormone-refractory phase. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we performed protein mass profiling of the patients＇ sera and identified a 6 640-Da peak that increased with disease progression. Target proteins were partially purified, and by amino acid sequencing the peak was identified as a fragment of apolipoprotein C-I （ApoC-I）. Serum ApoC-I protein levels increased with disease progression. On immunohistochemical analysis, the ApoC-i protein was found localized to the cytoplasm of the hormone-refractory cancer cells. In this study, we showed an increase in serum ApoC-I protein levels in prostate cancer patients during their progression to the hormone-refractory state, which suggests that ApoC-I protein is related to progression of prostate cancer. However, as the exact role of ApoC-I in prostate cancer pathogenesis is unclear, further research is required.展开更多
A simple method was developed for rapid and direct profiling of alkaloids in medical herbs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS）. The dry herbs were first gro...A simple method was developed for rapid and direct profiling of alkaloids in medical herbs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS）. The dry herbs were first ground to powder and passed through a stainless steel sieve, mixed with the matrix solution to form a homogeneous suspension, which was then directly applied to MALDI analysis. Several matrices were investigated and 2,5- dihydroxybenzoic acid（DHB） was chosen as the optimized one, and the particle with small size was found to favor the analysis. Using this method, the profiles of alkaloids in several medical herbs were readily obtained, and the toxicities of crude and processed Radix Aconiti Lateralis Preparata were compared via the relative intensities of the peaks of the corresponding toxic components shown in their MALDI spectra. This method therefore provides a rapid and reliable protocol for obtaining profiles of alkaloids in medical herbs by using MALDI-TOF MS.展开更多
Introduction Single nucleotide polymorphisms （SNPs） are the most abundant DNA markers in the human genome occurring at a frequency of one in every 500--1000 nucleotides. A variety of methods have been used for the ...Introduction Single nucleotide polymorphisms （SNPs） are the most abundant DNA markers in the human genome occurring at a frequency of one in every 500--1000 nucleotides. A variety of methods have been used for the analysis of single nucleotide polymorphisms, including restriction fragment length polymorphism （RFLP）, direct sequencing by using laser-induced fluorescence detectionTM, fluorescence energy transfer, MALDI-TOF MS combined with primer extension or invasive cleavage, and fluorescence polarization. During the past two decades, mass spectrometry has become a very popular tool in the analysis of biomolecules and is perfectly suited to the analysis of single nucleotide polymorphisms （SNPs） due to its speed, low cost, and accuracy. In this work, we used MALDI TOF mass spectrometry to detect the fragments of restriction endonuclease hydrolysis of PCR products flanking a SNP located at paraoxonase 1（Q192R）. Compared with electrophoresis, this method requires less time of analysis and possess a higher accuracy.展开更多
Surface-assisted laser desorption/ionization mass spectrometry(SALDI-MS)uses inorganic nanomaterials as matrixes to facilitate desorption and ionization of analytes.Compared with the traditional matrix-assisted laser ...Surface-assisted laser desorption/ionization mass spectrometry(SALDI-MS)uses inorganic nanomaterials as matrixes to facilitate desorption and ionization of analytes.Compared with the traditional matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)technique,SALDI-MS has the advantages of less interference in the low mass range,better reproducibility and higher salt tolerance.It is highly suitable for the analysis of small molecule compounds.In recent years,researchers have developed a range of nanomaterials that are successfully applied to the field of small molecule drug and metabolite analysis including drug screening and quantification,drug delivery,metabolite profiling,biomarker discovery and so forth.This review summarizes the latest progress of SALDI-MS matrix materials such as metal-based,carbon-based,silica-based nanomaterials and organic framework nanomaterials and their applications.In addition,our perspective of SALDI-MS technology is also discussed for further advancement.展开更多
A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and sign...A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed.展开更多
Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how...Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.展开更多
Native and methyl-esterified sialylated glycans were analyzed with 2,4,6-trihydroxyacetophenone（THAP）and 2,5-dihydroxybenzoic acid（DHB）as matrix by a matrix-assisted laser desorption/ionization time-of-flight mass...Native and methyl-esterified sialylated glycans were analyzed with 2,4,6-trihydroxyacetophenone（THAP）and 2,5-dihydroxybenzoic acid（DHB）as matrix by a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer（MALDI-TOF MS）.High quality negative-ion spectra of commercial sialylated glycan were obtained with THAP as matrix.Detection limit of the glycan was less than 0.1 pmol.After methyl esterification of sialic acid（SA）residue,sialylated glycans were detected sensitively in the positive-ion mode using DHB as matrix.Neutral and sialylated glycans from the mixture of asialofetuin and fetuin were methylesterified and simultaneously recognized in one manipulation.Methyl esterification of SA residue offers a convenient and sensitive way to identify the structure of N-linked glycans for glycan profiling.展开更多
High-molecular-weight disinfection byproducts(HMW DBPs)have been increasingly recognized as contaminants that pose potential hazards to human health.However,reliable analytical methods for exploring the properties and...High-molecular-weight disinfection byproducts(HMW DBPs)have been increasingly recognized as contaminants that pose potential hazards to human health.However,reliable analytical methods for exploring the properties and structures of these DBPs remain limited.This study presents a novel approach for detecting and identifying HMW DBPs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The experimental conditions were optimized by selecting super-2,5-dihydroxybenzoic acid(super-DHB)as the matrix and sodium trifluoroacetate as the cationization agent and employing the sandwich deposition method in reflection-positive ion mode with 90%laser intensity,resulting in the highest peak intensity for HMW DBPs.These optimized conditions enhanced peak reproducibility,yielding a signal-to-noise ratio of 134.9 and a coefficient of variation of 3.8%.With the new approach,five HMW DBPs were detected in simulated drinking water and identified as oligosaccharide carboxylic acids via isotopic pattern analysis,tandem mass spectrometry analysis in laser-induced dissociation mode,and database verification.展开更多
Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on m...Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on mor-phological and/or genomic criteria,which have their limitations.These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach.Recently,Matrix-Assisted Laser Desorp-tion/lonization Time-Of-Flight(MALDI-TOF)mass spectrometry,a new tool used which is routinely in clinical microbi-ology,has emerged in the field of malacology for the identification of freshwater snails.This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskali snail populations according to their geographicalorigin.Methods This study was conducted on 101 Bi.pfeifferi and 81 Bu.forskali snails collected in three distinct geo-graphical areas of Senegal(the North-East,South-East and central part of the country),and supplemented with wild and laboratory strains.Specimens which had previously been morphologically described were identified by MALDl-TOF MS[identification log score values(LSV)≥1.7],after an initial blind test using the pre-existing database.After DNA-based identification,new reference spectra of Bi.pfeiferi(n=10)and Bu.forskali(n=5)from the geographical areas were added to the MALDI-TOF spectral database.The final blind test against this updated database was per-formed to assess identification at the geographic source level.Results MALDI-TOF MS correctly identified 92.1%of 101 Bi.pfeifferi snails and 98.8%of 81 Bu.forskali snails.At the final blind test,88%of 166 specimens were correctly identified according to both their species and sampling site,with LSVs ranging from 1.74 to 2.70.The geographical source was adequately identified in 90.1%of 91 Bi.pfeifferi and 85.3%of 75 Bu.forskalii samples.Conclusions Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin.It outperforms the current DNA-based approaches in discriminating laboratory from wild strains.This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.展开更多
Gelsemium elegans Benth alkaloids are the main components of G.elegans and can cause acute toxicosis or even death.Although several studies have reported methods for detecting G.elegans alkaloids,a high-throughput and...Gelsemium elegans Benth alkaloids are the main components of G.elegans and can cause acute toxicosis or even death.Although several studies have reported methods for detecting G.elegans alkaloids,a high-throughput and environmental-friendly strategy for detection of multiple G.elegans alkaloids has not been realized.In this work,a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry method was developed for rapid detection of G.elegans alkaloids in human plasma and urine for diagnosis of poisoning.Multiple matrices and crys-tal spotting methods were evaluated to obtain stable and high peak intensities without“sweet spot”.We verified the methodology and obtained excellent results.The matrix effects with different dilutions were compared and good recoveries and a low relative standard deviation were obtained with a 40-fold dilution.This method could shorten the analysis time and greatly reduce the consumption of chemical solvents.Furthermore,it could be applied to quan-titative assessment of G.elegans alkaloid poisoning incidents.展开更多
Background Endometriosis is a common gynecological disease. This study aimed to screen proteins that were expressed differently in patients with endometriosis versus normal controls using proteomic techniques, surface...Background Endometriosis is a common gynecological disease. This study aimed to screen proteins that were expressed differently in patients with endometriosis versus normal controls using proteomic techniques, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry （SELDI-TOF-MS）.Methods Protein chip SELDI-TOF-MS combines the advantages of microarray and mass spectrometry, and can screen latent markers in sera of patients with endometriosis. Serum samples from patients and normal volunteers were analyzed by SELDI-TOF-MS. Results After comparing the serum protein spectra of 36 patients with 24 normal controls, 24 differently expressed potential biomarkers （P 〈0.01） were identified. Using Biomarker Pattern software, we established a tree model of the 60 serum protein spectra. When using the three bJomarkers to classify the samples, the sensitivity for diagnosing endometriosis was 91.7%, specificity was 95.8%, and coincidence rate was 93.3%. Then we used serum samples from 12 patients and 8 normal controls to validate the tree model and report the sensitivity for diagnosing endometriosis was 91.7%, specificity was 75%, and coincidence rate was 85%. Conclusions SELDI-TOF-MS may be a useful tool in high-risk population screening for endometriosis. The identification and application of the biomarkers need to further study.展开更多
Background Recently, due to the rapid development of proteomic techniques, great advance has been made in many scientific fields. We aimed to use magnetic beads （liquid chip） based matrix-assisted laser desorption/i...Background Recently, due to the rapid development of proteomic techniques, great advance has been made in many scientific fields. We aimed to use magnetic beads （liquid chip） based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） technology to screen distinctive biomarkers for lung adenocarcinoma （adCA）, and to establish the diagnostic protein profiles. Methods Using weak cation exchange magnetic beads （MB-WCX） to isolate and purify low molecular weight proteins from sera of 35 lung adCA, 46 benign lung diseases （BLDs） and 44 healthy individuals. The resulting spectra gained by anchor chip-MALDI-TOF-MS were analyzed by ClinProTools and a pattern recognition genetic algorithm （GA）. Results In the working mass range of 800-10 000 Da, 99 distinctive peaks were resolved in lung adCA versus BLDs, while 101 peaks were resolved in lung adCA versus healthy persons. The profile gained by GA that could distinguish adCA from BLDs was comprised of 4053.88, 4209.57 and 3883.33 Da with sensitivity of 80%, specificity of 93%, while that could separate adCA from healthy control was comprised of 2951.83 Da and 4209.73 Da with sensitivity of 94%, specificity of 95%. The sensitivity provided by carcinoembryonic antigen （CEA） in this experiment was significantly lower than our discriminatory profiles （P 〈0.005）. We further identified a eukaryotic peptide chain release factor GTP-binding subunit （eRF3b） （4209 Da） and a complement C3f （1865 Da） that may serve as candidate biomarkers for lung adCA. Conclusion Magnetic beads based MALDI-TOF-MS technology can rapidly and effectively screen distinctive proteins/polypeptides from sera of lung adCA patients and controls, which has potential value for establishing a new diagnostic method for lung adCA.展开更多
Thirteen extracting solutions of rare-earth metallofullerenes containing La,Ce,Pr,Nd Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm and Yb respectively have been investigated by means of matrix-assisted laser desorpuon/ ionization time-of-f...Thirteen extracting solutions of rare-earth metallofullerenes containing La,Ce,Pr,Nd Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm and Yb respectively have been investigated by means of matrix-assisted laser desorpuon/ ionization time-of-flight mass spectrometry.The influences of the positive-ion/negative-ion mode,laser intensity,ma trix and mass discrimination to the analytical results are studied,based on which the optimal analytical conditions have been determined.The results show that the extracting solutions contain large quantities of rare-earth metallofullerenes besides empty fullerenes.On the basis of comparing their relative intensities,the different structure stabilities and solubilities of metallofullerenes with different rare-earth metals encapsulated into the fullerene cages,as well as some possible reasons to those differences,are discussed.展开更多
Mass spectrometry imaging(MSI)has made the spatio-chemical characterization of a broad range of small-molecule metabolites within biological tissues possible.However,available matrix-assisted laser desorption/ionizati...Mass spectrometry imaging(MSI)has made the spatio-chemical characterization of a broad range of small-molecule metabolites within biological tissues possible.However,available matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)suffers from severe background interferences in low-mass ranges and inhomogeneous matrix deposition.Thus,surface-assisted LDI-MS(SALDI-MS)has been an attractive alternative for high-sensitivity detection and imaging of small biomolecules.In this study,we construct a new composite substrate,hydrophobic polydopamine(hPDA)-modified TiO_(2)nanotube(TDNT)coated with plasmonic gold nanoparticle(AuNP-hPDA-TDNT),as a dual-polarity SALDI substrate using an easy and cost-effective fabrication approach.Benefitting from the synergistic effects of TDNT semiconductor and plasmonic PDA modification,this SALDI substrate exhibits superior performance for dual-polarity detection of a vast diversity of small molecules.Highly reduced background interferences,lower detection limits,and spot-to-spot repeatability can be achieved using AuNP-hPDA-TDNT substrates.Due to its unique imprinting performance,various metabolites and lipids can be visualized within jatropha integerrima petals,ginkgo leaves,strawberry fruits,and latent fingerprints.More valuably,the universality of this matrix-free substrate is demonstrated for mapping spatial distribution of lipids within mouse brain tissue sections.Considered together,this AuNP-hPDA-TDNT material is expected to be a promising SALDI substrate in various fields,especially in nanomaterial development and life sciences.展开更多
Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and init...Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.展开更多
Background It is necessary to develop some innovative methods to reveal and discover the novel （SLE）-related protein molecules. In the present study, matrix-assisted laser desorption/ionization time of flight mass s...Background It is necessary to develop some innovative methods to reveal and discover the novel （SLE）-related protein molecules. In the present study, matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI- TOF MS） was employed to detect the differential expression of serum polypeptides in the patients with systemic lupus erythematosus （SLE） presenting with a family history or complicating with kidney injury so as to identify the proteins associated with the genetic factors and kidney injury in SLE. Methods The subjects recruited were divided into four groups, that is, a group of SLE patients with both family history and kidney injury, a group of SLE patients with only kidney injury but no family history, a group of SLE patients with neither family history nor kidney injury, and a control group consisting of healthy volunteers. By adopting MALDI-TOF MS analysis, the serum samples obtained from the three groups of SLE patients were examined and compared with those from the control group; the categorized peptide fingerprint profile was established via the biological data collected from the samples. Results The expression of protein with a mlz of 4207 Da increased significantly in SLE patients; the protein with a ml z of 2658 Da was expressed in all SLE patients; three proteins （with mlz of 1465, 5332, and 5900 Da respectively） were expressed in the SLE patients complicated with kidney injury and the protein with a mlz of 1943 Da was expressed in SLE patients with family history. Conclusion A number of differential proteins were successfully detected and identified through MALDI-TOF MS detection and these proteins may be associated with the genetic basis of SLE and the complicating kidney injury.展开更多
Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of meth...Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.展开更多
Microplastics loaded with phenanthrene and derivatives are widely detected in aquatic environments,and the coating of natural minerals or organic macromolecules may change the environmental behavior of microplastics.I...Microplastics loaded with phenanthrene and derivatives are widely detected in aquatic environments,and the coating of natural minerals or organic macromolecules may change the environmental behavior of microplastics.In this study,three kinds of composites with different coverage were prepared by coating goethite on the surface of polyvinyl chloride microplastics to investigate the adsorption and desorption behavior of phenanthrene(PHE)and 1-hydroxyphenanthrene(1-OHPHE),and the effect of mucin on desorption was inves-tigated.The results showed that goethite promoted the adsorption of PHE and 1-OHPHE by increasing the specific surface area of the composites.With the increase of the cover de-gree,the adsorption of PHE decreased because of the decrease in hydrophobicity;while the adsorption of 1-OHPHE initially increased and then decreased with the contributions of hydrophobic interaction and hydrogen bond.The adsorption of 1-OHPHE could be influenced by the pH and ionic strength primarily through electrostatic interactions and Ca2+bridg-ing.The goethite significantly increased the desorption hysteresis for two chemicals due to the complicated pore structures and increased adsorption affinity.Mucin promoted the desorption of PHE through competitive adsorption,and inhibit the desorption of 1-OHPHE through hydrophobic interaction,hydrogen bonding and Ca2+bridging.This study elucidated the effects of natural minerals on the adsorption and desorption behavior of organic pollutants on microplastics,briefly discussed the effects of organic macromolecules on the desorption behavior of pollutants with different properties,and emphasized the different environmental behaviors of pollutants.展开更多
This paper summarizes the mechanisms and environmental effects of interactions between microplastics and surfactants: surfactants adsorb onto microplastics surfaces through hydrophobic interactions and electrostatic f...This paper summarizes the mechanisms and environmental effects of interactions between microplastics and surfactants: surfactants adsorb onto microplastics surfaces through hydrophobic interactions and electrostatic forces, changing their surface properties and transport behavior. In addition, microplastics act as carriers influencing surfactant distribution. Environmental factors (pH, ionic strength, etc. ) significantly regulate this process. Current research still has limitations in areas such as desorption kinetics and combined pollution effects, necessitating in-depth studies under environmentally relevant conditions to provide a basis for risk assessment.展开更多
文摘An evaporation/condensation flow cell was developed and interfaced with the matrix-assisted laser desorption/ionization （MALDI） time-of-flight mass spectrometer for on-line bioaerosol detection and characterization, which allows matrix addition by condensation onto the laboratory-generated bioaerosol particles. The final coated particle exiting from the con- denser is then introduced into the aerodynamic particle sizer spectrometer or home-built aerosol laser time-of-flight mass spectrometer, and its aerodynamic size directly effects on the matrix-to-analyte molar ratio, which is very important for MALDI technique. In order to observe the protonated analyte molecular ion, and then determine the classification of bi- ological aerosols, the matrix-to-analyte molar ratio must be appropriate. Four experimental parameters, including the temperature of the heated reservoir, the initial particle size, its number concentration, and the matrix material, were tested experimentally to analyze their influences on the final particle size. This technique represents an on-line system of detection that has the potential to provide rapid and reliable identification of airborne biological aerosols.
文摘Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has been termed as hormone refractory. To identify the proteins that mediate progression to the hormone-refractory state, we used protein-chip technology for mass profiling of patients＇ sera. This study included 16 patients with metastatic hormone-refractory prostate cancer who were initially treated with androgen deprivation therapy. Serum samples were collected from each patient at five time points： point A, pre-treatment; point B, at the nadir of the prostate- specific antigen （PSA） level; point C, PSA failure; point D, the early hormone-refractory phase; and point E, the late hormone-refractory phase. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we performed protein mass profiling of the patients＇ sera and identified a 6 640-Da peak that increased with disease progression. Target proteins were partially purified, and by amino acid sequencing the peak was identified as a fragment of apolipoprotein C-I （ApoC-I）. Serum ApoC-I protein levels increased with disease progression. On immunohistochemical analysis, the ApoC-i protein was found localized to the cytoplasm of the hormone-refractory cancer cells. In this study, we showed an increase in serum ApoC-I protein levels in prostate cancer patients during their progression to the hormone-refractory state, which suggests that ApoC-I protein is related to progression of prostate cancer. However, as the exact role of ApoC-I in prostate cancer pathogenesis is unclear, further research is required.
基金Supported by the Major State Basic Research Development Program of China(No.2006CB5047060)the National Natural Science Foundation of China(Nos.30672600, 30772721)the Natural Science Foundation of Jilin Province, China (No.20060902)
文摘A simple method was developed for rapid and direct profiling of alkaloids in medical herbs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS）. The dry herbs were first ground to powder and passed through a stainless steel sieve, mixed with the matrix solution to form a homogeneous suspension, which was then directly applied to MALDI analysis. Several matrices were investigated and 2,5- dihydroxybenzoic acid（DHB） was chosen as the optimized one, and the particle with small size was found to favor the analysis. Using this method, the profiles of alkaloids in several medical herbs were readily obtained, and the toxicities of crude and processed Radix Aconiti Lateralis Preparata were compared via the relative intensities of the peaks of the corresponding toxic components shown in their MALDI spectra. This method therefore provides a rapid and reliable protocol for obtaining profiles of alkaloids in medical herbs by using MALDI-TOF MS.
文摘Introduction Single nucleotide polymorphisms （SNPs） are the most abundant DNA markers in the human genome occurring at a frequency of one in every 500--1000 nucleotides. A variety of methods have been used for the analysis of single nucleotide polymorphisms, including restriction fragment length polymorphism （RFLP）, direct sequencing by using laser-induced fluorescence detectionTM, fluorescence energy transfer, MALDI-TOF MS combined with primer extension or invasive cleavage, and fluorescence polarization. During the past two decades, mass spectrometry has become a very popular tool in the analysis of biomolecules and is perfectly suited to the analysis of single nucleotide polymorphisms （SNPs） due to its speed, low cost, and accuracy. In this work, we used MALDI TOF mass spectrometry to detect the fragments of restriction endonuclease hydrolysis of PCR products flanking a SNP located at paraoxonase 1（Q192R）. Compared with electrophoresis, this method requires less time of analysis and possess a higher accuracy.
基金State Key Laboratory of Natural and Biomimetic Drugs(Peking University)the National Natural Science Foundation of China(Grant No.21804123)。
文摘Surface-assisted laser desorption/ionization mass spectrometry(SALDI-MS)uses inorganic nanomaterials as matrixes to facilitate desorption and ionization of analytes.Compared with the traditional matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)technique,SALDI-MS has the advantages of less interference in the low mass range,better reproducibility and higher salt tolerance.It is highly suitable for the analysis of small molecule compounds.In recent years,researchers have developed a range of nanomaterials that are successfully applied to the field of small molecule drug and metabolite analysis including drug screening and quantification,drug delivery,metabolite profiling,biomarker discovery and so forth.This review summarizes the latest progress of SALDI-MS matrix materials such as metal-based,carbon-based,silica-based nanomaterials and organic framework nanomaterials and their applications.In addition,our perspective of SALDI-MS technology is also discussed for further advancement.
文摘A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed.
文摘Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.
基金Supported by the National Natural Science Foundation of China(30800193)Grant from Centre for International Mobility(CIMO),Finland
文摘Native and methyl-esterified sialylated glycans were analyzed with 2,4,6-trihydroxyacetophenone（THAP）and 2,5-dihydroxybenzoic acid（DHB）as matrix by a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer（MALDI-TOF MS）.High quality negative-ion spectra of commercial sialylated glycan were obtained with THAP as matrix.Detection limit of the glycan was less than 0.1 pmol.After methyl esterification of sialic acid（SA）residue,sialylated glycans were detected sensitively in the positive-ion mode using DHB as matrix.Neutral and sialylated glycans from the mixture of asialofetuin and fetuin were methylesterified and simultaneously recognized in one manipulation.Methyl esterification of SA residue offers a convenient and sensitive way to identify the structure of N-linked glycans for glycan profiling.
基金supported by the National Natural Science Foundation of China(Nos.22322605,22176089,22376099,and 22476096)the Fundamental Research Funds for the Central Universities,China(No.2024300400)the Natural Science Foundation of Jiangsu Province,China(No.BK20211509).
文摘High-molecular-weight disinfection byproducts(HMW DBPs)have been increasingly recognized as contaminants that pose potential hazards to human health.However,reliable analytical methods for exploring the properties and structures of these DBPs remain limited.This study presents a novel approach for detecting and identifying HMW DBPs via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.The experimental conditions were optimized by selecting super-2,5-dihydroxybenzoic acid(super-DHB)as the matrix and sodium trifluoroacetate as the cationization agent and employing the sandwich deposition method in reflection-positive ion mode with 90%laser intensity,resulting in the highest peak intensity for HMW DBPs.These optimized conditions enhanced peak reproducibility,yielding a signal-to-noise ratio of 134.9 and a coefficient of variation of 3.8%.With the new approach,five HMW DBPs were detected in simulated drinking water and identified as oligosaccharide carboxylic acids via isotopic pattern analysis,tandem mass spectrometry analysis in laser-induced dissociation mode,and database verification.
文摘Background Freshwater snails of the genera Bulinus spp.,Biomphalaria spp.,and Oncomelania spp.are the main intermediate hosts of human and animal schistosomiasis.Identification of these snails has long been based on mor-phological and/or genomic criteria,which have their limitations.These limitations include a lack of precision for the morphological tool and cost and time for the DNA-based approach.Recently,Matrix-Assisted Laser Desorp-tion/lonization Time-Of-Flight(MALDI-TOF)mass spectrometry,a new tool used which is routinely in clinical microbi-ology,has emerged in the field of malacology for the identification of freshwater snails.This study aimed to evaluate the ability of MALDI-TOF MS to identify Biomphalaria pfeifferi and Bulinus forskali snail populations according to their geographicalorigin.Methods This study was conducted on 101 Bi.pfeifferi and 81 Bu.forskali snails collected in three distinct geo-graphical areas of Senegal(the North-East,South-East and central part of the country),and supplemented with wild and laboratory strains.Specimens which had previously been morphologically described were identified by MALDl-TOF MS[identification log score values(LSV)≥1.7],after an initial blind test using the pre-existing database.After DNA-based identification,new reference spectra of Bi.pfeiferi(n=10)and Bu.forskali(n=5)from the geographical areas were added to the MALDI-TOF spectral database.The final blind test against this updated database was per-formed to assess identification at the geographic source level.Results MALDI-TOF MS correctly identified 92.1%of 101 Bi.pfeifferi snails and 98.8%of 81 Bu.forskali snails.At the final blind test,88%of 166 specimens were correctly identified according to both their species and sampling site,with LSVs ranging from 1.74 to 2.70.The geographical source was adequately identified in 90.1%of 91 Bi.pfeifferi and 85.3%of 75 Bu.forskalii samples.Conclusions Our findings demonstrate that MALDI-TOF MS can identify and differentiate snail populations according to geographical origin.It outperforms the current DNA-based approaches in discriminating laboratory from wild strains.This inexpensive high-throughput approach is likely to further revolutionise epidemiological studies in areas which are endemic for schistosomiasis.
基金supported by the National Natural Science Foundation of China(Grant No.32372448)Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2023A1515012605)+2 种基金the Science and Technology Program of Guangdong Administration for Market Regulation,China(Grant No.2023CS01)the Science and Technology Program of National General Customs Administration of China(Grant No.2022HK108)the Science and Technology Program of Shantou City,China(Grant No.STKJ2023024).
文摘Gelsemium elegans Benth alkaloids are the main components of G.elegans and can cause acute toxicosis or even death.Although several studies have reported methods for detecting G.elegans alkaloids,a high-throughput and environmental-friendly strategy for detection of multiple G.elegans alkaloids has not been realized.In this work,a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry method was developed for rapid detection of G.elegans alkaloids in human plasma and urine for diagnosis of poisoning.Multiple matrices and crys-tal spotting methods were evaluated to obtain stable and high peak intensities without“sweet spot”.We verified the methodology and obtained excellent results.The matrix effects with different dilutions were compared and good recoveries and a low relative standard deviation were obtained with a 40-fold dilution.This method could shorten the analysis time and greatly reduce the consumption of chemical solvents.Furthermore,it could be applied to quan-titative assessment of G.elegans alkaloid poisoning incidents.
基金This study was supported by the grants from Beijing Municipal Science ＆ Technology Commission （No.H030930040230） and the National Natural Science Foundation of China （No.30772319）.
文摘Background Endometriosis is a common gynecological disease. This study aimed to screen proteins that were expressed differently in patients with endometriosis versus normal controls using proteomic techniques, surface-enhanced laser desorption/ionization time-of-flight mass spectrometry （SELDI-TOF-MS）.Methods Protein chip SELDI-TOF-MS combines the advantages of microarray and mass spectrometry, and can screen latent markers in sera of patients with endometriosis. Serum samples from patients and normal volunteers were analyzed by SELDI-TOF-MS. Results After comparing the serum protein spectra of 36 patients with 24 normal controls, 24 differently expressed potential biomarkers （P 〈0.01） were identified. Using Biomarker Pattern software, we established a tree model of the 60 serum protein spectra. When using the three bJomarkers to classify the samples, the sensitivity for diagnosing endometriosis was 91.7%, specificity was 95.8%, and coincidence rate was 93.3%. Then we used serum samples from 12 patients and 8 normal controls to validate the tree model and report the sensitivity for diagnosing endometriosis was 91.7%, specificity was 75%, and coincidence rate was 85%. Conclusions SELDI-TOF-MS may be a useful tool in high-risk population screening for endometriosis. The identification and application of the biomarkers need to further study.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 30570795） and Program for New Century Excellent Talents in University （No. NECT-06-0845） and the Program in Science and Technology of Xi＇an, Shaanxi Province （No. S F08009（1））.Acknowledgement： We are grateful to HU Xiao-hui for the technical guidance.
文摘Background Recently, due to the rapid development of proteomic techniques, great advance has been made in many scientific fields. We aimed to use magnetic beads （liquid chip） based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） technology to screen distinctive biomarkers for lung adenocarcinoma （adCA）, and to establish the diagnostic protein profiles. Methods Using weak cation exchange magnetic beads （MB-WCX） to isolate and purify low molecular weight proteins from sera of 35 lung adCA, 46 benign lung diseases （BLDs） and 44 healthy individuals. The resulting spectra gained by anchor chip-MALDI-TOF-MS were analyzed by ClinProTools and a pattern recognition genetic algorithm （GA）. Results In the working mass range of 800-10 000 Da, 99 distinctive peaks were resolved in lung adCA versus BLDs, while 101 peaks were resolved in lung adCA versus healthy persons. The profile gained by GA that could distinguish adCA from BLDs was comprised of 4053.88, 4209.57 and 3883.33 Da with sensitivity of 80%, specificity of 93%, while that could separate adCA from healthy control was comprised of 2951.83 Da and 4209.73 Da with sensitivity of 94%, specificity of 95%. The sensitivity provided by carcinoembryonic antigen （CEA） in this experiment was significantly lower than our discriminatory profiles （P 〈0.005）. We further identified a eukaryotic peptide chain release factor GTP-binding subunit （eRF3b） （4209 Da） and a complement C3f （1865 Da） that may serve as candidate biomarkers for lung adCA. Conclusion Magnetic beads based MALDI-TOF-MS technology can rapidly and effectively screen distinctive proteins/polypeptides from sera of lung adCA patients and controls, which has potential value for establishing a new diagnostic method for lung adCA.
基金Project supported by the National Natural Science Foundation of China
文摘Thirteen extracting solutions of rare-earth metallofullerenes containing La,Ce,Pr,Nd Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm and Yb respectively have been investigated by means of matrix-assisted laser desorpuon/ ionization time-of-flight mass spectrometry.The influences of the positive-ion/negative-ion mode,laser intensity,ma trix and mass discrimination to the analytical results are studied,based on which the optimal analytical conditions have been determined.The results show that the extracting solutions contain large quantities of rare-earth metallofullerenes besides empty fullerenes.On the basis of comparing their relative intensities,the different structure stabilities and solubilities of metallofullerenes with different rare-earth metals encapsulated into the fullerene cages,as well as some possible reasons to those differences,are discussed.
基金the National Natural Science Foundation of China(Nos.31901911 and 21904142)the Natural Science Foundation of Guangdong Province(Nos.2019A1515011521 and 2022A1515011385)supported by the Young Talent Support Project of Guangzhou Association for Science and Technology(No.QT20220101031).
文摘Mass spectrometry imaging(MSI)has made the spatio-chemical characterization of a broad range of small-molecule metabolites within biological tissues possible.However,available matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)suffers from severe background interferences in low-mass ranges and inhomogeneous matrix deposition.Thus,surface-assisted LDI-MS(SALDI-MS)has been an attractive alternative for high-sensitivity detection and imaging of small biomolecules.In this study,we construct a new composite substrate,hydrophobic polydopamine(hPDA)-modified TiO_(2)nanotube(TDNT)coated with plasmonic gold nanoparticle(AuNP-hPDA-TDNT),as a dual-polarity SALDI substrate using an easy and cost-effective fabrication approach.Benefitting from the synergistic effects of TDNT semiconductor and plasmonic PDA modification,this SALDI substrate exhibits superior performance for dual-polarity detection of a vast diversity of small molecules.Highly reduced background interferences,lower detection limits,and spot-to-spot repeatability can be achieved using AuNP-hPDA-TDNT substrates.Due to its unique imprinting performance,various metabolites and lipids can be visualized within jatropha integerrima petals,ginkgo leaves,strawberry fruits,and latent fingerprints.More valuably,the universality of this matrix-free substrate is demonstrated for mapping spatial distribution of lipids within mouse brain tissue sections.Considered together,this AuNP-hPDA-TDNT material is expected to be a promising SALDI substrate in various fields,especially in nanomaterial development and life sciences.
基金National Natural Science Foundation of China(52275328,51875157)。
文摘Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.
文摘Background It is necessary to develop some innovative methods to reveal and discover the novel （SLE）-related protein molecules. In the present study, matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI- TOF MS） was employed to detect the differential expression of serum polypeptides in the patients with systemic lupus erythematosus （SLE） presenting with a family history or complicating with kidney injury so as to identify the proteins associated with the genetic factors and kidney injury in SLE. Methods The subjects recruited were divided into four groups, that is, a group of SLE patients with both family history and kidney injury, a group of SLE patients with only kidney injury but no family history, a group of SLE patients with neither family history nor kidney injury, and a control group consisting of healthy volunteers. By adopting MALDI-TOF MS analysis, the serum samples obtained from the three groups of SLE patients were examined and compared with those from the control group; the categorized peptide fingerprint profile was established via the biological data collected from the samples. Results The expression of protein with a mlz of 4207 Da increased significantly in SLE patients; the protein with a ml z of 2658 Da was expressed in all SLE patients; three proteins （with mlz of 1465, 5332, and 5900 Da respectively） were expressed in the SLE patients complicated with kidney injury and the protein with a mlz of 1943 Da was expressed in SLE patients with family history. Conclusion A number of differential proteins were successfully detected and identified through MALDI-TOF MS detection and these proteins may be associated with the genetic basis of SLE and the complicating kidney injury.
基金supported by the National Special Fund for the Development of Major Research Equipment and Instrument(No.2020YFF01014503)the Young Taishan Scholars(No.tsqn201909039)the College 20 Project fromJi Nan Science&Technology Bureau(No.2021GXRC058).
文摘Formic and acetic acids are the most abundant gaseous organic acids and play the key role in the atmospheric chemistry.In iodine-adduct chemical ionizationmass spectrometry(CIMS),the low utilization efficiency of methyl iodide and humidity interference are two major issues of the vacuum ultraviolet(VUV)lamp initiated CIMS for on-line gaseous formic and acetic acids analysis.In this work,we present a new CIMS based on VUV lamp,and the ion-molecular reactor is separated into photoionization and chemical ionization zones by a reducer electrode.Acetone was added to the photoionization zone,and the VUV photoionization acetone provided low-energy electrons for methyl iodide to generate I−,and the addition of acetone reduced the amount of methyl iodide by 2/3.In the chemical ionization zone,a headspace vial containing ultrapure water was added for humidity calibration,and the vial changes the sensitivity as a function of humidity from ambiguity to well linear correlation(R2>0.95).With humidity calibration,the CIMS can quantitatively measure formic and acetic acids in the humidity range of 0%-88%RH.In this mode,limits of detection of 10 and 50 pptv are obtained for formic and acetic acids,respectively.And the relative standard deviation(RSD)of quantitation stability for 6 days were less than 10.5%.This CIMS was successfully used to determine the formic and acetic acids in the underground parking and ambient environment of the Shandong University campus(Qingdao,China).In addition,we developed a simple model based formic acid concentration to assess vehicular emissions.
基金supported by the National Natural Science Foundation of China(Nos.42077337 and 42277228)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515011560)the Science and Technology Planning Project of Guangzhou(Nos.202002030297 and 202002020072).
文摘Microplastics loaded with phenanthrene and derivatives are widely detected in aquatic environments,and the coating of natural minerals or organic macromolecules may change the environmental behavior of microplastics.In this study,three kinds of composites with different coverage were prepared by coating goethite on the surface of polyvinyl chloride microplastics to investigate the adsorption and desorption behavior of phenanthrene(PHE)and 1-hydroxyphenanthrene(1-OHPHE),and the effect of mucin on desorption was inves-tigated.The results showed that goethite promoted the adsorption of PHE and 1-OHPHE by increasing the specific surface area of the composites.With the increase of the cover de-gree,the adsorption of PHE decreased because of the decrease in hydrophobicity;while the adsorption of 1-OHPHE initially increased and then decreased with the contributions of hydrophobic interaction and hydrogen bond.The adsorption of 1-OHPHE could be influenced by the pH and ionic strength primarily through electrostatic interactions and Ca2+bridg-ing.The goethite significantly increased the desorption hysteresis for two chemicals due to the complicated pore structures and increased adsorption affinity.Mucin promoted the desorption of PHE through competitive adsorption,and inhibit the desorption of 1-OHPHE through hydrophobic interaction,hydrogen bonding and Ca2+bridging.This study elucidated the effects of natural minerals on the adsorption and desorption behavior of organic pollutants on microplastics,briefly discussed the effects of organic macromolecules on the desorption behavior of pollutants with different properties,and emphasized the different environmental behaviors of pollutants.
基金Supported by Zhaoqing University Innovation and Entrepreneurship Training Program for College Students (X202410580130).
文摘This paper summarizes the mechanisms and environmental effects of interactions between microplastics and surfactants: surfactants adsorb onto microplastics surfaces through hydrophobic interactions and electrostatic forces, changing their surface properties and transport behavior. In addition, microplastics act as carriers influencing surfactant distribution. Environmental factors (pH, ionic strength, etc. ) significantly regulate this process. Current research still has limitations in areas such as desorption kinetics and combined pollution effects, necessitating in-depth studies under environmentally relevant conditions to provide a basis for risk assessment.
