Synthesis Of Mesoporous Magnetic Metal Organic Framework-based Nanocomposites And Investigation Of Sensing Performance

In recent years,nanocomposites have attracted much more attention due to their unique properties.Compared with macroscopic materials and homogenous materials,nanocomposites possess surface effect,bulk effect,quantum size effect,and quantum tunneling effect,as well as synergistic optimization effect among different components,which endow them with specific performance unlike regular materials,such as,optical effect,electric field effect,thermal effect,magnetic field effect,and sensing performance,and therefore make the nanocomposite-based sensors one of the research hot spots.In this study,we synthesized two mesoporous magnetic metal organic frameworks?MOFs?-based nanocomposites,and used them as electrochemical biosensing sensitive film.Then,the sensitive films were immobilized with biological probes,i.e.,heavy metal ions?Pb?II?/As?III??-targeted and epithelial tumor marker mucin?MUC1?-targeted aptamer strands,and used to sensitively detecting the Pb?II?/As?III?and MUC1 by cyclic voltammetry and electrochemical impedance spectroscopy.Results showed that,low detection limits were obtained,and the detection could be applied to real samples.Our work mainly includes three parts,the preparation of mesoporous magnetic MOFs-based nanocomposites,the construction of electrochemical biosensors based on the nanocomposites,and their detections towards heavy metal ions and MUC1.In this study,we used silicon dioxide?SiO2?as template,and ferrocene as raw material,to synthesize hollow h-mFe₃O₄@mC nanocomposite,followed by compositing with Fe?III?-based MOFs?Fe-MOFs?and zirconium hexacyanoferrate particles?ZrHCF?,respectively,the corresponding mesoporous magnetic MOFs-based nanocomposites?Fe-MOF@m Fe₃O₄@mC and ZrHCF@mFe₃O₄@mC?were prepared.The chemical structure and components,surface morphology and their influences on electrochemical performance were detailed studied.According to the characterizations,the as-prepared ultimate materials were consistent with the designed scheme.Fe-MOF@mFe₃O₄@mC nanocomposite was used as electrochemical biosensing sensitive film,through the bioaffinity of magnetic materials for the biomolecules,the aptamer strands were self-assembly onto the surface of the sensitive film.Results indicated that,Fe-MOFs had strong capacity to capture or store small molecules,and the guest molecules could easily disperse into their highly-ordered frameworks,making more biomolecules immobilized onto the sensitive film,and therefore improving the detetion sensitivities towards Pb?II?/As?III?.The proposed electrochemical aptasensor exhibited a broad concentration range from 0.01 to 10.0 nM of the heavy metal ions,and the detection limits were 2.27 / 6.73 pM towards Pb?II?/As?III?,which were lower than other same-type sensors.Meanwhile,the aptasensor showed high selectivity in the interference detection of other heavy metal ions,such as,Zn2+,Ag+,Ni2+,Mg2+,Ca2+,Cu2+and Mn2+;and also,the aptasensor showed favorable detection effect when applied to real samples.Besides,the aptasensor exhibited excellent regenerability,stability,and reproducibility.Based on the above study,we considered to use magnetic nanoparticles ZrHCF to composite with h-mFe₃O₄@mC,because the ZrHCF could form Zr-O-P bond with the aptamer strands,and the existence of this interaction made the aptamer strands preferably immobilized onto the surface of the material.ZrHCF@mFe₃O₄@mC nanocomposite was used as electrochemical biosensing sensitive film,and the aptamer strands were self-assembly onto its surface,to detect the MUC1 sensitively.Results indicated that,the existence of ZrHCF particles made more biomolecules immobilized onto the sensitive film,and therefore improving the detetion sensitivity towards MUC1.The proposed electrochemical aptasensor exhibited a broad concentration range from 0.01 to 1000 ng· m L-1of the MUC1,and the detection limit was 1.85 pg· m L-1towards MUC1,which was lower than other same-type sensors.Meanwhile,the constructed aptasensor showed high selectivity in the interference detection of bovine serum albumin?BSA?,immunoglobulin G?IgG?,and carcino embryonie antigen?CEA?solutions;and also,the aptasensor showed favorable detection effect when applied to real samples.Our work proposes a new thought for preparation of MOFs-based nanocomposites and construction of electrochemical biosensors,and suggests promising applications in environmental monitoring and biomedical fields.