Synthesis And Analytical Application Of Functionalized Magnetic Mesoporous Carbon Materials

This dissertation summarizes the development of phthalate esters(PAEs)analysis and in vitro diagnostic methods for acute mycardial infarction(AMI),the solid phase extraction of magnetic hollow mesoporous carbon-molecularly imprinted polymers and its applications,the application of magnetic materials in the field of chemiluminescence(CL),and the latest advances in microfluidic paper-based devices(μPADs).Recently,due to advantages of good superparamagnetism,high specific surface area,excellent biocompatibility,and strong conductivity,functionalized magnetic mesoporous carbon materials have attracted much attention in the fields of bioanalysis,adsorption,drug release,catalysis,and environmental monitoring.Although functionalized magnetic mesoporous carbon materials have made some progress in the above fields,they have been rarely applied to separation and analysis of various substances.There are increasing demands for multiplex analysis in many fields such as clinical diagnosis,environmental analysis and food safety assessment,etc.However,multiplex analysis remains a great challenge.In this dissertation,for PAEs analysis with low concentration and complex sample matrix in real samples,we synthesized the yolk-shell magnetic mesoporous carbon molecularly imprinted polymers(Fe3O4@void@C-MIPs).On account of advantages of magnetic solid phase extraction(MSPE),such as rapid separation,high enrichment efficiency and large volume sample processing capacity,the synthetic Fe3O4@void@C-MIPs was used as a new solid phase adsorbent for the separation and preconcentration of PAEs in real samples.Furthermore,the detection of five PAEs in beverages and environmental water samples were successfully achieved.For the rapid and accurate diagnosis of AMI,we synthesized N-(4-aminobutyl)-N-ethylisoluminol(ABEI)/Co2+bifunctionalized mesoporous carbon materials(Co2+-ABEI-Fe3O4@void@C),and applied it as an immunoassay interface.In addition,based on the advantages of low price,high portability,low sample consumption,and easy handling of microfluidic paper-based devices(μPADs),we designed a new three-dimensional microfluidic paper-based device(3D μPAD),and use it as a detection platform to realize the simultaneous detection of three targets,such as copeptin,troponin I(cTnI)and fatty acid binding protein(h-FABP).Moreover,the established chemiluminescence immunoassay can be used for the detection of copeptin,h-FABP and cTnI in human serum samples.The main results are as follows:1.Using Fe3O4 particles as nuclear,TEOS as silicon source,resorcinol and formaldehyde as carbon source,we synthesized the yolk-shell magnetic mesoporous carbon(Fe3O4@void@C)through "one-pot" method.Fe3O4@void@C-COOH was obtained by oxidizing the Fe3O4@void@C.The Fe3O4@void@C-MIPs was prepared by using diisononyl phthalate as the dummy template,methacrylic acid as the functional monemer and ethylene glycol dimethacrylate(EGDMA)as the cross-linker,respectively.Transmission electron microscopy,fourier infrared spectrum,scanning electron microscopy,nitrogen adsorption-desorption and so on were applied to characterize the synthetic materials.The adsorption isotherm and kinetics of Fe3O4@void@C-MIPs showed that the Fe3O4@void@C-MIPs possessed good recognition,fast adsorption rates(approximately 20 min to reach equilibrium)and high adsorption capacities(569.2 mg/g)toward PAEs,which were ascribed to their uniformity and monodispersity.In addition,Fe3O4@void@C-MIPs exhibited excellent reusability for the adsorption of PAEs over six adsorption-desorption cycles.2.The synthetic Fe3O4@void@C-MIPs composites were used as the new solid-phase extraction sorbents to separate and concentrate the trace PAEs in real samples.Coupled with gas chromatography-mass spectrometer(GC-MS),the new method of Fe3O4@void@C-MIPs-SPE-GC/MS was established to determine five PAEs in real samples simultaneously.The research showed that the MMIPs-SPE-GC/MS enrichment factor of PAEs could be over 800.The established method owned a linear range of 0.035～12.2 μg/L with a correlation coefficient over 0.9961,and the limit of detection was 1.6～5.2 ng/L.The recovery of spiked samples was between 86.1～103.1%.Therefore,the synthesized Fe3O4@void@C-MIPs material has a great application prospect for the separation and enrichment of PAEs in real samples.3.Novel ABEI and Co2+bifuctionalized magnetic mesoporous carbon composites with yolk-shell structure(Co2+-ABEI-Fe3O4@void@C)were obtained via a simple method.ABEI as a CL reagent and Co2+ as a catalyst were successfully encapsulated into the magnetic Fe3O4@void@C substrate via π-π and electrostatic interaction,respectively.The synthetic Co2+-ABEI-Fe3O4@void@C showed a good magnetic separation property,which could remove residual ABEI molecules and Co2+under an external magnet.Furthermore,the synthetic Co2+-ABEI-Fe3O4@void@C exhibited good CL activity when reacted with H2O2 in alkaline solution as well as good electrochemiluminescence(ECL)activity in alkaline condition without extra co-reactant.The excellent CL/ECL property of the synthetic Co2+-ABEI-Fe3O4@void@C was attributed to the fact that Co2+immobilized in the Co2+-ABEI-Fe3O4@void@C catalyzed the decomposition of H2O2 to generate O2·-and HO’,thus expediting the CL/ECL reaction.This study reveals that magnetic mesoporous carbon composites with yolk-shell structure can provide large volumes for high loading efficiency of catalyst Co2+and CL molecules ABEI,resulting in high CL/ECL efficiency.The prepared Co2+-ABEI-Fe3O4@void@C adds a new member for the family of magnetic mesoporous carbon composites with yolk-shell structure,which may be of great application for constructing bioassays and biosensors.4.CL immunoassays for simultaneous detection of early AMI biomarkers,including copeptin,h-FABP,and cTnI,were developed by using Co2+/ABEI functionalized magnetic carbon composite(Co2+-ABEI-Fe3O4@void@C)as an interface and a 3D μPAD as a detection system.The sensing interface was fabricated by assembling Co2+-ABEI-Fe3O4@void@C with CS and Au-Ab sequentially to form Co2+-ABEI-Fe3O4@void@C-CS/Au-Ab.In the presence of Ag,Ag was captured to form an immunocomplex.Based on the catalysis of-COO-in the Ag,the CL intensity of Co2+-ABEI-Fe3O4@void@C could be enhanced,which enables quantative detection of specific Ag.Three immunocomplexes for copeptin,h-FABP,and cTnI were prepared by changing different Ab conjugated Au.In addition,a 3DμPAD with three detection zones for three immunocomplexes was designed and fabricated for simultaneous detection of copeptin,h-FABP,and cTnI.After injecting H2O2,three time-resolved CL peaks were acquired in one CL kinetic curve,which was applicable to quantitative determination of copeptin,h-FABP,and cTnI.According to the CL intensity,the concentrations of copeptin,h-FABP,and cTnI were determined in the range of 1～1000 pg/mL,with detection limits of 0.40 pg/mL,0.32 pg/mL,and 0.50 pg/mL,respectively.Based on the good magnetism of Co2+-ABEI-Fe3O4@void@C,three immunocomplexes containing copeptin,h-FABP,and cTnI were all separated successfully under an external magnet,avoiding interferences of sample matrix.The developed immunoassays with high sensitivity were able to detect copeptin,h-FABP,and cTnI in human serum samples.Besides,these multiplex 3D μPAD CL immunoassays are simple,low-cost,rapid,and sensitive,giving them great potential to be applied in the field of early diagnosis of AMI.