Bioinspired Fabrication, Functionalization, Application And Multichannel Design Of Optical Fiber Surface Plasmon Resonance Sensors

In this work,we are devoted to the study of the optical fiber surface plasmon resonance(SPR)sensors.Inspired by the adhesion and versatility of polydopamine(PDA),we developed the facile,rapid and effective strategies to fabricate the optic-fiber SPR and LSPR sensors by using the elelctroless plating(ELP),PDA-accelerated ELP and the extended galvanic replacement reaction(GRR).The morphology,sensitivity and stability of the fabricated sensors were characterized and evaluated.In addition,the mechanisms for the fabrication of the sensors were investigated and discussed in detail.After the surface modification,the fabricated SPR sensors were used in the biosensing.Meanwhile,the multichannel optic-fiber SPR spectrometer was designed and constructed.More deteails are given as follows:(1)A polydopamine-modified optical fiber SPR biosensor using electroless-plated gold films: Instead of the vacuum coating techniques,a sensitive and stable gold film optic-fiber SPR sensor was fabricated by using the ELP,together with a facile antibody immobilization method.The morphology,sensitivity and stability of the fabricated sensors were characterized and evaluated.An SPR biosensor was developed based on PDA-modified gold film,which was fabricated by a simple and quick spontaneous polymerization of dopamine(DA)on the gold film.Compared with the 11-mercaptoundecanoic acid-modified gold film surface,the PDA-modified gold film exhibited more effective antibody immobilization ability and higher sensitivity for the antigen detection.(2)Bioinspired fabrication of optical fiber SPR sensors for immunoassays using polydopamine-accelerated electroless plating: Inspired by the adhesion and versatility of PDA,we developed a facile,rapid and effective strategy for the preparation of optical fiber SPR sensors using the PDA-accelerated ELP.The bare optic-fiber was functionalized via a facile and rapid self-polymerization of DA.And the versatile PDA coating demonstrated a rapid and magical adsorption capability for gold seeds.Three key experiment parameters: DA polymerization temperature,DA polymerization time,and plating time were investigated and optimized in detail.The fabricated sensors exhibited higher sensitivity,better adhesion stability and reproducibility compared with those fabricated by the traditional ELP.Take the IgG detection as an example,the application properties of the fabricated sensors in biosensing were evaluated.(3)Facile synthesis and characterization of Au-Ag bimetallic nanorings with enhanced LSPR sensing activity: Ag nanoparticles(Ag NPs)were grown on the optic-fiber surface based on the chelating and redox activity of the catechol in PDA to the metal ions.The spherical Ag NPs were changed into Au-Ag bimetallic nanorings(Au-Ag NRs)via the GRR and ELP.SEM?HRTEM?EDS and XPS were used to characterize the surface morphology,structure as well as the distribution and valence of the Au and Ag element,respectively.The results showed that the inner diameter and outer diameter of the polycrystalline Au-Ag NRs were about 19 nm and 64 nm,respectively.The Au and Ag element with only zero valent were distributed uniformly in the nanorings.SPR data indicated that the sensitivity and oxidation resistance of the sensors were largely improved because of the morphological change from nanospheres to nanorings,and the element composition change from the Ag into the Au-Ag bimetal.To understand the formation mechanism of the Au-Ag NRs,SPR spectrometer and SEM were used to characterize the LSPR profile and morphology of the Au-Ag NRs formed with different reaction times.(4)Design of the multichannel optic-fiber SPR spectrometer: The multichannel optic-fiber SPR spectrometer was also developed in this work.The switch of the light source was realized by using the photoswitch,and the sample flow path was based on a tandem type.Flexibly bifurcated optical fiber,integrated sensors and F-style flow cell were designed for the more convenient and miniaturization spectrometer.The multichannel fiber-optic and prism mixed mode SPR spectrometer was constructed,and the different liquid concentrations were detected in order to evaluate the application properties of the spectrometer.