Study Of Dynamic Light Enhancement-Based SPR Sensing Technology

Surface plasmon resonance(SPR)sensing technology has been widely used in the study of biomolecular interaction.It has the capabilities of label-free,real-time monitoring,easy to operate and so on.Due to the insufficient sensitivity of conventional SPR sensors,it is of great significance to develop a highly sensitive SPR sensor to detect biomarkers with low concentration effectively.Based on the chip materials and immunoassay method of SPR sensors,we used the gold-silver alloy film based SPR(AuAg-SPR)sensors and firstly proposed the dynamic light enhancement-based AuAg-SPR sensing method and the sandwich immunoassay structure was used as a carrier of gold nanoparticles(AuNPs)to achieve highly sensitive detection of trace biomarkers.Meanwhile,the multi-layer SPR sensing structure analysis algorithm was established to farther evaluate and optimize the sensing model and reduce the limit of detection(LOD)of biomarkers.The main research contents are as follows:(1)Combining the Fresnel formula and the Bruggeman equation,the multi-layer SPR sensing structure analysis algorithm was established which lied a theoretical foundation for evaluating and optimizing the SPR sensor structure,(2)Using the AuAg-SPR based sandwich immunoassay to detect cancer antigen 125(CA125)and the limit of detection(LOD)was 0.1 U/mL,which was 2 orders of magnitude lower than that of gold film based SPR(Au-SPR)sensors(20 U/mL).(3)Further improving the sensing method that proposing the dynamic light enhancement-based AuAg-SPR sensing method and the sandwich immunoassay structure was used as a carrier of AuNPs to detect C-reactive protein(CRP).Compared with the conventional sandwich immunoassay,the sensitivity of the improved method was increased by 5.56-fold and the LOD was 5 pg/mL,which was an order of magnitude lower than that of Au-SPR sensors(50 pg/mL).(4)Model simulation and numerically analysis were carried out using the multi-layer SPR sensing structure analysis algorithm.The sensitivity characteristics of AuAg-SPR sensors and the effective calculation of molecular adsorption parameters were completed.Then the effect of antigen size on detect results was studied and the mechanism of dynamic light enhancement effect was verified.Finally,the evaluation and optimization of SPR sensing model was realized.The innovation of this study are as follows:(1)It was firstly proposed the dynamic light enhancement-based AuAg-SPR sensing method and the sandwich immunoassay structure was used as a carrier of AuNPs to achieve highly sensitive detection of trace biomarkers.(2)The multi-layer SPR sensing model was established and the sensing model was evaluated and optimized by using multi-layer SPR sensing structure analysis algorithm.