Nanostructured Optical Waveguide Biosensor Based On Surface Plasmon Resonance

Surface plasmon resonance?SPR?biosensor is a mature optical biosensing method.It has been widely used in drug screening,food safety,environmental monitoring,life science research and other fields,due to its real-time,rapid,label-free and highly sensitive advantages.The low signal-to-noise ratio?SNR?and small specific surface area limit the detection level of the traditional gold-based SPR biosensor,mainly are the broad spectrum and weak enrichment capacity which limit the detection of specific adsorbents.The main work of this study is to conduct the research on the nanostructured optical waveguide biosensor which has a better detection level,based on the surface plasmon resonance.There are two main aspects:one is to introduce silver film which has better optical performance;the other is to introduce nanostructured waveguide layer on the surface of gold film.To this end,during the period of doctoral study,the following works have been done:First,conducting research on sensing optimization.The mainly theory we used are the principle of multilayer reflection and the effective medium theory?EMT?.The sensing characteristics of gold-based and silver-based SPR biosensor were compared by theoretical calculation,and it was found that the silver-based SPR biosensor has a higher SNR,which is beneficial to improve its refraction index resolution.After the theoretical calculation of the SPR based optical waveguide biosensor,we found that it has both TE and TM mode for detection,and each of them can be divided into many orders.The theoretical calculation also showed that the TE or TM mode with low-order has better sensing characteristics,and the TE mode is better than the TM mode.Second,the introduction of silver film with better optical performance.Although the silver-based SPR biosensor has better sensing characteristics,the silver has poor chemical stability,which needs to be protected.Through the stability tests via SPR angular spectrum,it was found that the 11-mercapto-1-undercanol?MUD?self-assembled molecular layer?SAM?can protect the silver film effectively,and its sensing stability was significantly improved.The silver-based SPR sensor has a level of 10^-7 RIU for the refractive index resolution and was applied to biomolecular detection.Third,resarch on the mesoporous nanostructured optical waveguide biosensor.In order to obtain an efficient,simple and low-cost preparation method for nanostructured waveguide chips,mesoporous silica thin films?MSF?with a thickness of more than 400nm were prepared on the surface of the gold film by an improved St?ber solution growth method.The refractive index resolution of MSF optical waveguide biosensor is better than that of traditional gold-based SPR biosensor.Further,it has a very good detection ability for small molecules,such as CTAB molecule,which the LOD can reach the 2nanomolar level.Fourth,research on the porous nanostructured optical waveguide biosensor.In order to improve adsorption ability of the nanostructured waveguide for big biomolecules,the porous anodic alumina?PAA?was prepared for the nanostructured optical waveguide via the so-called two-step anodic oxidation method.After being hydrophilic treated,the PAA film was mounted on the gold-based SPR chip directly and effectively,which simplified and reduced the degree of difficulty of preparation process.And the PAA optical waveguide biosensor was successfully applied in the high sensitivite detection of biomolecules,such as bovine serum albumin?BSA?.