Research On Nanofilm Modified Label-free Biosensing Technology Based On Coreless Fiber

Due to the small refractive index difference of the low-concentration biological analyte in medical detection,the detection signal of the optical fiber sensor based on the refractive index response characteristic is extremely weak,and the identification biomolecules directly fixed on the optical fiber surface usually cannot achieve the perfect effect.Therefore,it is necessary to introduce different immobilization technologies to identification biomolecules,and then construct sensitive film on the optical fiber sensor surface,so as to improve the sensitivity of the label-free optical fiber biosensor for low-concentration biomolecules.In this dissertation,different immobilization technologies of the identification biomolecules are used.The single mode-coreless-single mode(SCS)structure is act as a biosensing transducer,converting the optical signal change of the antibody on the coreless fiber(CLF)surface and the antigen analyte induced by the specific reaction into the transmission spectrum change.The SCS biosensing structures successfully detect the low-concentration antigen biomolecules.The main contents of this dissertation are as follows:Firstly,the transmission characteristic and the refractive index response characteristic of the SCS optical fiber sensing structure are simulated theoretically by using the beam propagation method based on the interference transmission theory.In order to determine the structure parameters of the SCS used in biosensing experiments,the effects of the CLF structure parameters on the signal distribution are analyzed.Meanwhile,the refractive index and temperature response characteristics of the SCS optical fiber sensing structure are analyzed experimentally.Secondly,on the basis of the biological detection principle of the nanofilm modified SCS optical fiber sensing structure,a SCS label-free optical fiber biosensing structure based on 3-aminopropyltriethoxysilane is proposed by the coupling characteristics of aminosilane and successfully achieves the concentration sensitivity of the rabbit immunoglobulin G(Ig G)biomolecules.The experimental results are analyzed theoretically and the performance detection of the SCS biosensing structure is studied experimentally.Thirdly,a SCS label-free optical fiber biosensing structure based on electrostatic layer-by-layer self-assembly is proposed by the strong adsorption capacity of polyelectrolyte and successfully achieves the concentration sensitivity of the rabbit Ig G.The number of electrostatic self-assembly layers for sensitive film is determined and the performance detection of the SCS biosensing structure is studied experimentally.Finally,the SCS label-free optical fiber biosensing structure coated with graphene oxide(GO)is proposed by the large specific surface area and good biocompatibility of GO and successfully achieves the concentration sensitivity of the rabbit Ig G.The performance detection of the SCS biosensing structure is studied experimentally.Furthermore,the performances of the SCS label-free optical fiber biosensing structure modified with three nanomaterials are compared and analyzed.