Study Of SPR Sensing Technology Based On Graphene Sensitization

The sensitivity of conventional surface plasmon resonance(SPR)biosensor is insufficient,can only realize detection of relatively high concentrations of biomarkers,unable to effectively realize the high sensitive detection of trace concentrations of biomarkers.However,in the early stage of malignant diseases such as tumors,the concentration level of tumor markers is often very low,so it is urgent to develop a new SPR sensor that can effectively detect trace tumor markers.In this paper,the graphene film were used in SPR sensing chips based on the advantages of graphene itself.Combined with the immunoassay method,a novel SPR sensing method based on signal-layer graphene was proposed(SLG-SPR).On the basis of SLG-SPR,it takes the sandwich immune structure as its carrier.During the detection,the local surface plasmon resonance(LSPR)effect of Au NPs was shown to further enhance the SPR signal.Finally,the SPR biosensor model of multilayer structure is established,and the multilayer structure SPR biosensor analysis algorithm is proposed to further evaluate and optimize the biosensor model.The main research contents of this paper are as follows:(1)A signal-layer graphene based SLG-SPR sandwich immunoassay method combined with sandwich immune amplification detection method was proposed to quantitatively detect c-reaction protein(CRP),a biomarker of cardiovascular diseases,and the minimum detection limit was 5 pg/m L.Compared with the experimental results of conventional gold SPR(Au-SPR)sandwich immunoassay under the same condition,the biosensor sensitivity was improved by 3.93-folds.(2)To innovate the detection method,the Au NPs was proposed to further dynamically enhance SLG-SPR sensing sensitivity for quantitative detection of prostate-specific antigen(PSA)markers in Prostate cancer.Compared with the SLG-SPR sandwich immunoassay method used under the same conditions,its sensitivity was increased by 1.88-folds again,and its minimum detection limit was 5pg/m L.Meanwhile,compared with the minimum detection limit(500 pg/m L)obtained by the conventional Au-SPR biosensor under the same condition,it is 2 orders of magnitude lower.(3)A multilayer structure SPR sensing and detection model was innovative constructed,data was collected and processed,and a large number of SPR data sets containing spectral information were created.Combined with Fresnel equation andBruggeman equivalent refractive index formula,an analysis algorithm for multilayer structure SPR sensing and detection was developed,which provides theoretical basis and application guarantee for the establishment,improvement and evaluation of SPR sensing and detection model.(4)The theoretical simulation and numerical analysis of the SPR biosensor detection model are completed by using the multilayer structure SPR biosensor detection and analysis algorithm.Then through the training model and parameter tuning,the evaluation and optimization of the SPR biosensor detection model were completed,and the sensitivity characteristics of the new SLG-SPR biosensor were obtained.At last,the relationship between molecular adsorption parameters and molecular volume proportion is further studied,and to verify the principle of dynamic optical enhancement.