Research On Canine Distemper Virus Immunosensor Based On Etched Fiber Bragg Grating Localized Surface Plasmon Resonance

Biosensors have been widely used in the diagnosis and control of diseases,monitoring and prediction of environmental conditions,drug development and improvement and food safety.As the most typical representative of passive optical devices,fiber Bragg grating(FBG)has the advantages of high sensitivity,simple structure,absolute measurement,immunity to electromagnetic interference,small size and multiplexing in clinical applications,so it is widely used in biomedical detection.The field has application potential and research value.Since the FBG gate region is a regular circle and the grating period is short,the light energy is only coupled between the forward and reverse fundamental modes of the fiber core,and the evanescent field cannot interact with the external medium through the cladding,so the use of hydrofluoric acid(HF)solution etching to remove the cladding of the grating segment to obtain an etched FBG(Etched-FBG),so that its evanescent field can sense the change in the refractive index(RI)of the external environment.In order to further improve the refractive index sensitivity of FBG to the surrounding environment,large-sized gold nanoshells(Au NS)were immobilized on the surface of Etched-FBG by silane coupling agent(APTES).When the oscillation frequencies of the free electrons in the outer layer are equal,the localized surface plasmon effect(LSPR)will be excited,and an Etched-FBG-LSPR immunosensor with high sensitivity in the low refractive index range will be prepared and applied to canine distemper virus.detection.The main research contents of this topic are as follows:(1)In this paper,the development status of fiber grating sensors and LSPR sensors at home and abroad and the fiber grating LSPR sensors used in biological sensing are described in detail.According to the coupling theory of FBG,the sensing principle and the sensing principle of LSPR,the spectral characteristics of the Etched-FBG-LSPR sensor and the influencing factors of nano Au NS particles on the LSPR effect were analyzed.(2)According to the theoretical model of sensing,the simulation software Mode Solutions was used to simulate the refractive index sensitivity of FBG and Etched-FBG and the mode field change of Etched-FBG after modification of modified large-scale Au NS particles.The simulation results show that the resonant wavelength refractive index sensitivity of the Etched-FBG sensor is 11.17 nm/RIU,and the resonance intensity sensitivity is 3.14 d B/RIU.After the surface of the Etched-FBG sensor is modified with Au NS,the optical loss of the sensor increases and the reflection spectrum is broadened at the same time.The spectral changes of the Etched-FBG sensor and the Etched-FBG-LSPR sensor were analyzed by experiments,and the results showed that when the FBG was etched into the fiber core with HF,the resonant wavelength was blue-shifted(shifted in the short-wave direction),and the refractive index was between 1.333 and 1.357.In the range,the resonance wavelength sensitivity of the Etched-FBG sensor is 15.148 nm/RIU,and the resonance intensity sensitivity is 1.19 d B/RIU.After modification of Au NS,the EtchedFBG-LSPR sensor has a resonance wavelength sensitivity of 15.824 nm/RIU and a resonance intensity sensitivity of-21.123 d B/RIU due to the light wave loss caused by the LSPR effect on the surface of Au NS.The latter is ?20 times higher than the former.At this time,the resonance intensity is attenuated,the intensity sensitivity is enhanced,and the reflection spectrum is broadened.The experimental results are consistent with the simulation results.The resonance wavelength sensitivity of the Etched-FBG sensor was basically unchanged before and after the modification of the gold nanoshells,but the sensitivity based on the resonance intensity increased by ?20 times.(3)Canine distemper virus(CDV)immunosensor of Etched-FBG-LSPR was made.Aiming at the weak interaction between the evanescent field of FBG and the external environment,the gate region of FBG was etched with HF,and then a layer of Au NS nanoparticles was coated on its surface,and CDV antibody was modified to obtain EtchedFBG-LSPR immunosensor.Applied to the detection of canine distemper virus.The experimental results show that the detection sensitivity of the sensor for CDV antigen is ?-0.046 d B/log(mg/m L),the saturation concentration is ?10 ?g/ml,the detection limit is lower than 50 pg/m L,and the detection range is 50 pg/ml? 10 ?g/ml.In addition,control detection experiments were carried out using avian influenza(H9N2)antigen solution,rabies virus(RV)antigen solution,Newcastle disease(ND)antigen solution and CDV antigen solution: it was found that in complex environments,Etched-LSPR-FBG biosensor still has good specificity and clinical properties.