Detection Of Protein Secondary Structure By Surface Plasmon Resonance Of Graphene Grating

Protein is an important component of all cells and tissues in human body.Research shows that the occurrence of many diseases is related to the change of protein structure.In this paper,the surface plasmon resonance and infrared spectroscopy are combined to simulate the detection of protein secondary structure in amide I band by finite-difference time-domain method.Surface plasmon resonance sensor is a kind of high-tech for detection.The surface plasmon resonance is excited by light wave incident on the metal surface,but the active chemical properties of the metal limit its application as a sensing element.Graphene is a kind of two-dimensional crystal material composed of carbon atoms,which has good stability and electrical properties similar to metals.What's more,Graphene has strong controllability.Therefore,in recent years,graphene surface plasmon resonance biosensor technology has become a research hotspot in the field of biological detection.Based on the properties of graphene and the characteristics of the grating periodic structure,a graphene grating-based surface plasmon resonance biosensor is proposed in this paper.The design model was simulated by using the finite-difference time-domain method.Then,it is combined with infrared spectroscopy to study the detection of protein secondary structure,which provided a new idea for the development of surface plasmon resonance sensors.Firstly,the research status of surface plasmon resonance sensor and graphene are analyzed,and then the chemical potential,conductivity,dispersion relation and other characteristics of graphene are introduced.The excitation principle of SPR is analyzed,and the time-domain finite difference method is simply introduced.Secondly,using graphene instead of metal to support surface plasmon resonance,a grating type surface plasmon resonance sensor based on graphene is proposed.This sensor can realize the high localization of energy,strengthen the interaction between light and detection materials,and detect the change of refractive index of the sensor to be measured through the change of reflection spectrum consumed.The effects of parameters such as substrate thickness,grating structure parameters,and graphene Fermi level on sensorperformance are analyzed through finite-difference time-domain method.The optimal structure is obtained by selecting the parameters that make the best performance of the sensor.On this basis,the maximum linear detection range and sensitivity of the sensor are analyzed.Before the work of protein secondary structure detection,the structure of the sensor is first fine-tuned so that its resonance peak is located in the amide I band,which is conducive to detection.The protein model is based on the absorption curve of protein secondary structure simulated by MATLAB.It is placed on the sensor model,and the situation of the protein in dry environment and water environment is simulated and analyzed.And then,the model of protein secondary structure was changed to observe whether the change of the signal obtained from the detection is consistent with the change of the protein model.Finally,the effect of this method in prion research is verified.The result shows that the sensor can be used to detect the secondary structure of protein in vitro.