Construction Of MOF-coated Gold And Silver Nano-optical Sensor And Multimodal Detection Of Active Molecules

Reactive sulfur species（RSS）and reactive oxygen species（ROS）play important roles in the physiological and pathological processes of cells,and their unique physiological homeostasis is closely related to human diseases such as cancer,cardiovascular disease,neurodegenerative disease and diabetes.In view of the problems that the current traditional detection methods of RSS and ROS cannot meet the requirements of in-situ monitoring and the use of a single mode sensor in complex samples is prone to false positives,this paper mainly constructed two kinds of gold and silver nano-optical sensors based on MOF coating,and realized the colorimetric/Raman/fluorescence/chiral multi-mode detection of RSS and ROS.It provides a new method with potential application for the detection of active species in cells.The main contents include:（1）In Chapter one,we introduced the importance of active species detection and its traditional analytical detection methods and techniques.Then the limitations of traditional methods for detecting active species and detection technology development trend were analyzed,based on this,advances the multimode optical sensors,Next,the basic principle of the colorimetric/SERS/fluorescence/chiral sensor based on metal-organic skeleton material and its current application in the field of disease surveillance were described respectively,finally puts forward the research idea of this paper.（2）In Chapter two,we synthesized a variety of nanomaterials,including Silver nanoparticle（Ag NPs）,gold nanoparticle（Au nanoparticles,Au NPs）,silver-coated gold nanoparticle（Au@AgNPs）,porous Zeolitic Imidazolate Framework-8（ZIF-8）coated Au@Ag nanoparticle（Au@Ag@ZIF-8）,Urchin-like Au-Ag Nanocrystals（UAA-NCs）,porous ZIF-8-coated UAA-NCs（UAA@ZIF-8）.The chiral material was coated with ZIF-8 coated UAA nanoparticles（UAA@ZIF-8-Ni Sx）,which laid a foundation for the later research.（3）In Chapter three,we synthesized a new Au@Ag@ZIF-8 optical sensor with O-Phenylenediamine（OPD）internal coding Surface-Enhanced Raman scattering（SERS）tags based on the free radical reaction was synthesized for multi-mode detection of sulfite.Firstly,silver-coated gold nanoparticles（Au@Ag NPs）were prepared,and then the highly enhanced and highly stable Au@Ag@ZIF-8 encoded in OPD was synthesized as signal probe and reaction probe.Sulfite was used as detecting object,the color of the detection system solution changes from colorless to green under the vision.On the other hand,due to the oxidation of OPD,the fluorescence intensity of the probe at 583 nm was significantly reduced and blue shift occurs.In addition,by monitoring the change of Raman signal,The results showed that the Raman peak at 1240 cm^-1 was shifted to 1268 cm^-1after radical reaction,which was due to the formation of OPD oxidation state with strong absorption.In addition,we investigated the reaction time dynamics of the sensor and the selectivity of the method in the presence of different concentrations of sulfite.The three-mode optical sensor realized anti-interference and specific detection,the detection limit of fluorescence signal was 1.4μmol/L mol/L,and the detection limit of SERS signal was1 nmol/L.The detection limit of UV signal was 5μmol/L.（4）In Chapter four,a novel UAA@ZIF-8-NiSx optical sensor was constructed for multimodal detection of reactive oxygen species.Firstly,UAA-NCs core-shell nanoparticles（UAA@ZIF-8）coated with porous ZIF-8 were prepared,and then overhand nanomaterials（Ni Sx-NPs）were coated on UAA@ZIF-8.Then,OPD with Raman signal was modified on the surface of the probe.The highly enhanced and highly stable UAA@ZIF-8-Ni Sx was formed as the signal probe,which had a strong and stable Raman signal.In addition,the UAA@ZIF-8-Ni Sx nanomodule showed an intense circular dichroism（CD）signal at 440 and 530 nm.In the presence of H₂O₂,Ni Sx-NPs on the surface of UAA@ZIF-8-Ni Sx will be degraded the experimental results revealed that UAA@ZIF-8-Ni Sx has been changed into UAA@ZIF-8 with degradation of Ni Sx,therefore,CD signal decreased with the increase of H₂O₂concentration.and the fluorescence signal intensity of OPD at 583 nm also decreases.At the same time,in the presence of UAA@ZIF-8,H₂O₂ rapidly catalyzed the Raman reporting molecule OPD,which was modified on the surface of the material,so that its Raman signal decreases with the increase of H₂O₂ concentration.In addition,as a chromogenic substrate,the color of the detection system solution changes from colorless to green under the vision.The sensor realized anti-interference and specificity detection,the detection limit of circular dichroism mode was 0.1μmol/L,UV mode was 1μmol/L,fluorescence mode was 0.1μmol/L,SERS mode was 1nmol/L.In conclusion,the optical sensor could detect H₂O₂ in a wider range and accurately by combining colorimetric/SERS/chiral three-mode detection.（5）In Chapter five,we summarized the research content,advantages of research methods and application prospects,analyzes the shortcomings of the current work,and prospects the follow-up research content.