Investigation Of Dopamine Reaction By Surface Plasmon Resonance

Surface plasmon resonance (SPR) biosensor has the advantages of a real-time detection, high sensitivity, without marking and in situ detecting. It has been widely utilized in environment detection, food analysis and biochemical analysis. Among them, biochemical analysis that is the greatest applying field has showed a trend with rapid and diversified developing, one of which is used for inspecting the interaction between molecules. Dopamine as a small-molecule that contains both catechol and amine has been widely applied, due to its capable of forming strong adhesive layers on various substrates. It can serve as a versatile platform for secondary surface modified reactions in biosensors including SPR sensor. This study spread out the research on numerical analysis and dopamine reaction system based on SPR which as the mainstay. Finally the dynamics analysis was as a way for improving the dopamine reaction system.First place, SPR curves were plotted using Winspall that was based on the Fresnel equations from three aspects:ultrapure water,50% ethanol aqueous solvent and pure ethanol. Results of simulation were compared with the experimental results by SPR sensor, it showed that there were errors between simulation and experiment, but Winspall could make a relatively effective prediction to the changing trend of SPR phenomenon. Subsequently, the optimal thickness of gold films was analyzed numerically from three aspects:gas phase, liquid phase and coupling monolayer. The results indicated that the optimal thickness was about 50nm.Second place, the system of dopamine reaction with gold films was firstly established and concluded by changing pH, concentration, buffer and time based on SPR sensor. Thus the reaction rules of dopamine and gold films in SPR were built; the optimum reaction condition of dopamine and gold films was 2mg/ml dopamine concentration, pH 8.6, Tris buffer; under this condition, a critical time of SPR phenomenon disappearing was injecting dopamine solution 16614s. Influence factors including pH, concentration, buffer and time were comprehensively analyzed in different buffer system. These laid a good foundation for dopamine reaction on SPR.At last, based on kinetic equations the SPR sensorgrams of dopamine reaction were to match in non-linearity by mathematical optimization analysis, and the results were calculated and analyzed. The association and dissociation constant between dopamine and gold films were obtained in different pH, concentration and buffer reaction system, then analyzed the relative changing rules. Thus provided a quantitative information for building reaction system of dopamine.