Isolated active metal atoms anchored on nitrogen-doped carbon matrix have been developed as the efficient catalyst for accelerating sluggish reaction kinetics of oxygen reduction reaction(ORR).The facile rational stru...Isolated active metal atoms anchored on nitrogen-doped carbon matrix have been developed as the efficient catalyst for accelerating sluggish reaction kinetics of oxygen reduction reaction(ORR).The facile rational structure engineering with abundant isolated active metal atoms is highly desirable but challenging.Herein,we demonstrate that atomically dispersed Fe sites(Fe-N4 moieties)on the hierarchical porous nitrogen-doped carbon matrix(Fe-SA-PNC)for high ORR activity can be achieved by a dual-template assisted strategy.By thermal decomposition of NH_(4)Cl template,the nitrogen-doped carbon matrix is generated based on the interaction with carbon precursor of citric acid.Meanwhile,the introduction of NaCl template facilitates the formation of hierarchical porous structures,which enable more active sites exposed and improve the mass transfer.Interestingly,the dual-template strategy can inhibit the formation of iron carbide nanoparticles(NPs)by generating porous structures and avoiding of the rapid loss of nitrogen during pyrolysis.The as-made Fe-SA-PNC catalysts with well-defined Fe-N_(4)active sites exhibit highly efficient ORR activity with a half-wave potential of 0.838 V versus the reversible hydrogen electrode,as well as good stability and methanol tolerance,outperforming the commercial Pt/C.The zinc-air battery(ZAB)constructed by Fe-SA-PNC also shows a higher peak power density and specific discharging capacity than that of Pt-based ZAB.The present work provides the facile strategy for tailoring nitrogen doping and porous structures simultaneously to prevent the formation NPs for achieving the well-dispersed and accessible single-atom active sites,paving a new way to design efficient electrocatalysts for ORR in fuel cells.展开更多
In this study,an ambient mass spectrometry(AMS)based method was developed for rapid detection of organophosphorus pesticides in strawberry.This method combines an electric arc and a microsyringe tip to realize tip-ass...In this study,an ambient mass spectrometry(AMS)based method was developed for rapid detection of organophosphorus pesticides in strawberry.This method combines an electric arc and a microsyringe tip to realize tip-assisted ambient electric arc ionization(TAAEAI).A high-voltage electric arc can be applied to the microsyringe tip to generate an electric field,which results in corona discharge at the microsyringe tip.The juiced strawberry sample loaded on the tip could be directly ionized with TAAEAI and then analyzed by a mass spectrometer.TAAEAI-MS was successfully applied to analyze 6 organophosphorus pesticides in three strawberry samples.Malathion and profenofos were detected from the investigated strawberry samples.This method could quantitatively determine the contents of organophosphorus pesticides in strawberry with high reproducibility,high precision,and high sensitivity.Sample matrices did not interfere with the pesticide analysis.The recoveries of organophosphorus pesticides spiked in strawberry samples varied between 82.6%and 116%with relative standard deviations(RSDs)less than 9.2%.The limits of detection(LODs)varied between 0.0124µg/g and 0.0245µg/g,while the limits of quantification(LOQs)varied between 0.0413µg/g and 0.0817µg/g.The coefficients of determination(R2)of the method were determined to be>0.995.The method established here may have potential application in the detection of organophosphorus pesticides in vegetables and fruits.展开更多
Small biomolecules(m/z<500)are the material basis of organisms and participate in life activities,but their comprehensive and accurate detection in complex samples remains a challenge.Matrix-assisted laser desorpti...Small biomolecules(m/z<500)are the material basis of organisms and participate in life activities,but their comprehensive and accurate detection in complex samples remains a challenge.Matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)is a powerful detection tool for molecular analysis with high throughput.The development of a new matrix is essential to improve the efficiency of the MALDI-MS for molecular compound detection.In this work,the sandwich-like gold nanoparticles@mesoporous silica nanocomposite@silver nanoparticles(Au@MSN@Ag)nanospheres were prepared by layer-by-layer super-assembly strategy,and can be used as a novel matrix for the quantitative detection and enrichment of small biomolecules by LDI-MS.The sandwich-like nanospheres form a unique plasma resonant cavity that effectively absorbs the laser energy,while the homogeneous mesoporous structure of MSN can lock the analyte,which is essential for efficient LDI of small molecules.Compared to traditional matrices,Au@MSN@Ag shows the advantages of low background,wide application range,high sensitivity,super high salt and protein tolerance,and good stability.For example,the detection limit of glucose was as low as 5 fmol,and showed a good linear relationship in the range of 1−750μg/mL.Au@MSN@Ag assisted LDI-MS allows the enrichment and detection of small molecules in traditional Chinese medicine(TCM)without derivatization and purification,classification of herbs using the accurate quantitative results oligosaccharides,and identification of gelatin by amino acid content.This research could help in designing more efficient nanostructure matrices and further explored the application of LDI-MS.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
基金funded by the Youth Innovation Promotion Association CAS(No.202055)the National Key R&D Program of China(Nos.2019YFA0709202 and 2020YFB2009004).
文摘Isolated active metal atoms anchored on nitrogen-doped carbon matrix have been developed as the efficient catalyst for accelerating sluggish reaction kinetics of oxygen reduction reaction(ORR).The facile rational structure engineering with abundant isolated active metal atoms is highly desirable but challenging.Herein,we demonstrate that atomically dispersed Fe sites(Fe-N4 moieties)on the hierarchical porous nitrogen-doped carbon matrix(Fe-SA-PNC)for high ORR activity can be achieved by a dual-template assisted strategy.By thermal decomposition of NH_(4)Cl template,the nitrogen-doped carbon matrix is generated based on the interaction with carbon precursor of citric acid.Meanwhile,the introduction of NaCl template facilitates the formation of hierarchical porous structures,which enable more active sites exposed and improve the mass transfer.Interestingly,the dual-template strategy can inhibit the formation of iron carbide nanoparticles(NPs)by generating porous structures and avoiding of the rapid loss of nitrogen during pyrolysis.The as-made Fe-SA-PNC catalysts with well-defined Fe-N_(4)active sites exhibit highly efficient ORR activity with a half-wave potential of 0.838 V versus the reversible hydrogen electrode,as well as good stability and methanol tolerance,outperforming the commercial Pt/C.The zinc-air battery(ZAB)constructed by Fe-SA-PNC also shows a higher peak power density and specific discharging capacity than that of Pt-based ZAB.The present work provides the facile strategy for tailoring nitrogen doping and porous structures simultaneously to prevent the formation NPs for achieving the well-dispersed and accessible single-atom active sites,paving a new way to design efficient electrocatalysts for ORR in fuel cells.
基金supported by National Natural Science Foundation of China(No.21927810)the Project of Experimental Technology and Management(No.SYJS2020010)the laboratorybased open project in Sichuan Normal University(No.KFSY2020004).
文摘In this study,an ambient mass spectrometry(AMS)based method was developed for rapid detection of organophosphorus pesticides in strawberry.This method combines an electric arc and a microsyringe tip to realize tip-assisted ambient electric arc ionization(TAAEAI).A high-voltage electric arc can be applied to the microsyringe tip to generate an electric field,which results in corona discharge at the microsyringe tip.The juiced strawberry sample loaded on the tip could be directly ionized with TAAEAI and then analyzed by a mass spectrometer.TAAEAI-MS was successfully applied to analyze 6 organophosphorus pesticides in three strawberry samples.Malathion and profenofos were detected from the investigated strawberry samples.This method could quantitatively determine the contents of organophosphorus pesticides in strawberry with high reproducibility,high precision,and high sensitivity.Sample matrices did not interfere with the pesticide analysis.The recoveries of organophosphorus pesticides spiked in strawberry samples varied between 82.6%and 116%with relative standard deviations(RSDs)less than 9.2%.The limits of detection(LODs)varied between 0.0124µg/g and 0.0245µg/g,while the limits of quantification(LOQs)varied between 0.0413µg/g and 0.0817µg/g.The coefficients of determination(R2)of the method were determined to be>0.995.The method established here may have potential application in the detection of organophosphorus pesticides in vegetables and fruits.
基金the National Key R&D Program of China(Nos.2019YFC1604600,2017YFA0206901,2019YFC1604601,2017YFA0206900,and 2018YFC1602301)the National Natural Science Foundation of China(Nos.21705027,2197402951808328,61903235,42007218,and 51703109)+5 种基金the Major Scientific and Technological Innovation Project of Shandong(Nos.2018CXGC1406,2019JZZY010457 and 2019JZZY020309)The Natural Science Foundation of Shanghai(18ZR1404700)Construction Project of Shanghai Key Laboratory of Molecular Imaging(18DZ2260400)Shanghai Municipal Education Commission(Class II Plateau Disciplinary Construction Program of Medical Technology of SUMHS,2018-2020)The ability establishment of sustainable use for valuable Chinese medicine resources(2060302)The natural Science Foundation of Shandong Province,China(ZR2020QE228).
文摘Small biomolecules(m/z<500)are the material basis of organisms and participate in life activities,but their comprehensive and accurate detection in complex samples remains a challenge.Matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)is a powerful detection tool for molecular analysis with high throughput.The development of a new matrix is essential to improve the efficiency of the MALDI-MS for molecular compound detection.In this work,the sandwich-like gold nanoparticles@mesoporous silica nanocomposite@silver nanoparticles(Au@MSN@Ag)nanospheres were prepared by layer-by-layer super-assembly strategy,and can be used as a novel matrix for the quantitative detection and enrichment of small biomolecules by LDI-MS.The sandwich-like nanospheres form a unique plasma resonant cavity that effectively absorbs the laser energy,while the homogeneous mesoporous structure of MSN can lock the analyte,which is essential for efficient LDI of small molecules.Compared to traditional matrices,Au@MSN@Ag shows the advantages of low background,wide application range,high sensitivity,super high salt and protein tolerance,and good stability.For example,the detection limit of glucose was as low as 5 fmol,and showed a good linear relationship in the range of 1−750μg/mL.Au@MSN@Ag assisted LDI-MS allows the enrichment and detection of small molecules in traditional Chinese medicine(TCM)without derivatization and purification,classification of herbs using the accurate quantitative results oligosaccharides,and identification of gelatin by amino acid content.This research could help in designing more efficient nanostructure matrices and further explored the application of LDI-MS.
基金Supported by National Natural Science Foundation of China(11601501,11671374,and 71731010)Anhui Provincial Natural Science Foundation(1708085QA02)Fundamcntal Rescarch Funds for the Central Universities(WK2040160028)。
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.
