Preparation And Biological Application Of MoS₂ Based Magnetic-raman Composites

Rapid ultra-sensitive bioassay is an important guarantee for diagnosis of disease.MoS₂micro-nano materials are biocompatible and structurally stable.Resonance Raman scattering（RRS）signal with easily identifiable fingerprint characteristics can also be provided when they were stimulated by a visible light（532 nm）.The RRS signal is not easily interfered by background fluorescence,indicating a promising application for bioassays with low concentration and high sensitivity.Using the RRS of MoS₂as the labeling signal,with the assistant of superparamagnetic nanomaterials,the detection time and the sensitivity can be improved benefit from the rapid magnetic enrichment.Finally,a rapid ultrasensitive biomolecular detection can be expected.In this thesis,MoS₂based magnetic-Raman composites were prepared.The physical properties and the performances of the magnetic-Raman biosensors were studied.The main results obtained are as follows:（1）MoS₂ micromaterials were obtained by liquid-phase exfoliation,followed by deposition of Fe₃O₄nanoparticles by co-precipitation method.Magnetic-Raman micromaterial composites were obtained and the physical properties were analyzed.The results showed that Fe₃O₄nanoparticles were deposited on the surface of MoS₂micrometer sheets.The MoS₂/Fe₃O₄composites exhibited obvious Raman properties and superparamagnetic properties.The Raman vibration peaks of Fe₃O₄were gradually appeared when the power of exciting light was increased,owing to the phonon-electron interaction between MoS₂and Fe₃O₄.The optimal excitation conditions were obtained.The feasibility of MoS₂/Fe₃O₄based rapid bioassay of human Ig G was initially validated:the detection time was shortened to 6 min with the assistant of an external magnetic field,and the detection limit was 100 n M.（2）The flower-like MoS₂/Fe₃O₄ magnetic-Raman nanocomposites were obtained by hydrothermal method.A magnetic-assisted rapid detection of human Ig G molecules were realized.The results showed that MoS₂nanoflowers were connected with Fe₃O₄nanoparticles through Fe-S covalent bonds.The composites were superparamagnetic,and easily identifiable resonance Raman peaks were observed.The flower-like MoS₂/Fe₃O₄composites were used to optimize the detection performance of human Ig G molecules.Benefits from the magnetic enrichment,the detection limit was reduced from 100 f M to 0.1f M,and the detection time was further shortened to 1 min.（3）The biocompatibility of Au nanoparticles and the advantage of local surface plasmon resonance were exploited.The MoS₂/Fe₃O₄/Au ternary composites were constructed to achieve rapid and ultrasensitive detection of low concentration target molecules.The composites were also superparamagnetic after the introduction of Au,and the characteristic Raman signal of MoS₂was enhanced.The FTIR results indicated that the ternary composites based bio-probe contained biological groups such as amide bonds and-S-S-bonds.The detection limit was reduced to 0.01 f M with the assistance of an external magnetic field,enabling fast and ultrasensitive detection.Such multifunctional materials are good candidates for early and rapid diagnosis of various pathogens.