Study Of The Interaction Between Human IgG And Papain By SPR Biosensor

Surface Plasmon Resonance （SPR） technology, which can monitor the interactionbetween biomoleculars online, is a high sensitivity, label-free and quick detection technology.The advantages of SPR Biosensor, such as high sensitivity, label-free and quick detection etc.,made it widely used in life science, medical diagnosis and pharmaceutical science, foodsecurity and other fields. Since Liedberg and his coworkers used SPR technology in theresearch of chemical sensor, the research and application of SPR technology have achieved arapid development and gradually become the hot spot and research frontier in the biosensorfield in the world. SPR biosensors have been powerful tools in analytical science.The interaction between biomoleculars is a basic life phenomenon. The body functionsof living entity are achieved by the interactions between biomoleculars. The interactionbetween biomoleculars has been one of the most important research points of modern lifescience. Proteins are basic biomoleculars of life entity. They play special functions in the vitalprocess. The interaction between proteins has been the research focus of life science and itsrelated scientific fields. Traditional analytical methods, such as Radioimmunoassay,Enzyme-linked immunosorbent assay, Affinity chromatography etc., have some weak points.For example: label dependent, costly, time-consuming, low sensitivity, and so on.According to the problems above, we choose Fourier Transform-Surface PlasmonResonance biosensor as the analytical tool to study the interactions between proteins. Themain research contents are listed as follows.1. MPA was used to modify the sensor chip by self-assemble monolayer technology.BSA was immobilized onto the sensor chip by covalently cross-linking technology. Scanningelectronic microscope （SEM） was used to characterize the modification of the sensor chip.The SEM result was compared to the result of the FT-SPR biosensor. The result showed thatBSA could be firmly bound to the sensor surface which was modified by MPA andEDC/NHS.2. BSA was chosen as the model protein to study the application of FT-SPR on theinteractions between proteins. To form the basement membrane, MPA was fixed onto thesensor surface by SAM technology. BSA was covalently bound to the basement membrane tomake BSA as the surface of the biosensor chip. Papain was used as reactive protein to studythe interaction between BSA and papain by FT-SPR biosensor. With the concentration asX-axis and the response signal as Y-axis, the fitted curve y＝－1.122×10^-2x＋1.407wasobtained. The KAof the interaction between BSA and papain was1.122×10^-2. The results showed that the interaction between BSA and papain was weak. It was consistent with theliterature. This experiment showed that the FT-SPR biosensor could be used to analysis theinteraction of proteins.3. The interaction between hIgG and papain was monitored by FT-SPR biosensor. HIgGwas covalently bound onto the MPA basement membrane. Series of papain concentrationwere used to study the interaction between hIgG and papain by FT-SPR biosensor. Todemonstrate the specificity of the signal, which was caused by the interaction between humanIgG and papain, we choose elastin as a reference protein. The result indicated that the signalwe obtained was specifically caused by the interaction between human IgG and papain. It wasfound that within a certain concentration range, the reaction rate of papain and hIgG waspositively correlated with the concentration of papain. With papain concentration as X-axisand FT-SPR wavenumber shift as Y-axis, a linear fit curve was obtained. The correlationcoefficient of the linear fit curve was0.99382. According to the experimental data, theminimum reaction concentration of papain was estimated to be in the range of1μg·mL^-1to2μg·mL^-1. When the papain concentration was100μg·mL^-1, about10%of immobilized hIgGwas cleaved by papain. It was consistent with the work reported previously.