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In the immunology, there are two important types of biomolecular interaction: antigens-antibodies and receptors-ligands.
Monitoring the response rate and affinity of biomolecular interaction can help analyze the protein function, drug discover,
genomics and proteomics research. Moreover the association rate constant and dissociation rate constant of
receptors-ligands are the important parameters for the study of signal transmission between cells. Recent advances in
bioanalyzer instruments have greatly simplified the measurement of the kinetics of molecular interactions.
Non-destructive and real-time monitoring the response to evaluate the parameters between antigens and antibodies can
be performed by using optical surface plasmon resonance (SPR) biosensor technology. This technology provides a
quantitative analysis that is carried out rapidly with label-free high-throughput detection using the binding curves of
antigens-antibodies. Consequently, the kinetic parameters of interaction between antigens and antibodies can be obtained.
This article presents a low cost integrated SPR-based bioanalyzer (HPSPR-6000) designed by ourselves. This
bioanalyzer is mainly composed of a biosensor TSPR1K23, a touch-screen monitor, a microprocessor PIC24F128, a
microflow cell with three channels, a clamp and a photoelectric conversion device. To obtain the kinetic parameters,
sensorgrams may be modeled using one of several binding models provided with BIAevaluation software 3.0, SensiQ or
Autolab. This allows calculation of the association rate constant (ka) and the dissociation rate constant (kd). The ratio of
ka to kd can be used to estimate the equilibrium constant. Another kind is the analysis software OriginPro, which can
process the obtained data by nonlinear fitting and then get some correlative parameters, but it can't be embedded into the
bioanalyzer, so the bioanalyzer don't support the use of OriginPro. This paper proposes a novel method to evaluate the
kinetic parameters of biomolecular interaction by using Newton Iteration Method and Least Squares Method. First, the
pseudo first order kinetic model of biomolecular interaction was established. Then the data of molecular interaction of
HBsAg and HBsAb was obtained by bioanalyzer. Finally, we used the optical SPR bioanalyzer software which was
written by ourselves to make nonlinear fit about the association and dissociation curves. The correlation coefficient
R-squared is 0.99229 and 0.99593, respectively. Furthermore, the kinetic parameters and affinity constants were
evaluated using the obtained data from the fitting results.
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