Preparation And Characterization Of Polymer Optical Waveguide Biosensors

Optical waveguide biosensor is one of the hot research fields of optical biosensors.It has the characteristics of integration and multifunction.With the continuous development of nanomaterials,the unique local surface plasmon resonance(Localized Suface Plasmon Resonance,LSPR)of noble metal nanoparticles has become more and more widely used in the field of optical waveguide biosensor.Polymer optical waveguide biosensor based on the LSPR effect of gold nanoparticles,which is prepared by polymer materials,has the advantages of simple process,high sensitivity,good selectivity,and suitable for large-scale integration on silicon wafer.In this paper,device fabrication,performance testing and sensing testing of polymer waveguide biosensor are studied.The specific work is as follows:1.A 40 nm-sized gold nanosphere particle sol with uniform morphology and good dispersity was prepared by sodium citrate reduction method.Self-assembled monolayers(SAMs)were used to immobilize the gold nanosphere particles on the surface of the polymer film modified by chemical surface,and a polymer sensing film was prepared.The polymer sensing film was placed in a solution with different refractive index for UV-visible absorption test.The results showed that with the increase of the refractive index of the solution,the LSPR peak absorption intensity also gradually increased and showed a linear relationship.When the refractive index of the solution increased from 1.333 to 1.370,the peak absorbance increased by 5.3%and the sensitivity was 0.11 AA/RIU.2.Biosensing membranes were prepared by binding rabbit anti-human IgG antibodies to the surface of polymer sensing membranes via Au-S bonds and measuring the concentrations of human IgG antigen solution.The results showed that the intensity of the LSPR absorption peak of the biosensor membrane increased with the increase of human IgG antigen concentration.The lower limit of detection of human IgG antigen concentration is 0.1 ?g/ml,and the upper limit is 40 ?g/ml.After this value is exceeded,the absorbance intensity does not change significantly and tends to be saturated.Non-specific antigen-antibody binding tests showed that rabbit anti-human IgG antibodies did not react with rabbit IgG antigens,and the selectivity of the sensing membrane was better.3.A rectangular polymer optical waveguide sensor was fabricated using a polymer SU-8 material.The cross section of the optical waveguide was 114 ?m×52?m.The peak absorption intensity of the LSPR of the sensor increases with the refractive index of the NaCl solution added dropwise,and the relationship is linear.When the refractive index of the solution increases from 1.342 to 1.379,the peak absorption intensity of the LSPR sensor increases by 5.6%and the sensitivity is 2.3083.?A/RIU.Compared with the LSPR polymer sensing film,the sensitivity of the polymer optical waveguide sensor is increased by about 21 times,and the sensitivity is improved by about 24%compared with the polymer SU-8 optical waveguide sensor element having a section size of 12 ?m×?m.4.The rabbit anti-human IgG antibody was bound to the LSPR polymer optical waveguide,and a polymer optical waveguide biosensor for human IgG antigen detection was prepared,and the detection of the human IgG antigen solution was initially achieved.The concentration of the detected antigen was in the range of 0.1?g/ml to 40 ?g/ml,and the change in the absorbance intensity of the biosensor varied linearly with the increase in the concentration of the antigen.