Enantiorecognition And Its Mechanism Of Surface Plasmon Resonance Chiral Sensor For Amino Acids Based On Functionalized Graphene-molecular Imprinted Polymers Composite

Surface plasmon resonance?SPR?is a kind of physical optical technique which is based on changes in the refractive indices caused by the interaction between the ligand and the receptor on the surface of the sensing chip.This technique provides advantages such as detecting the molecular interactions directly,high sensitivity and excellent response performance.Molecularly Imprinting Technology?MIT?is a new technique that simulates the interaction between antigen and antibody,which can achieve selective identification and specificity.In this thesis,a MIT-SPR chiral sensor was constructed to identify the chiral amino acid and its recognition mechanism was studied.The main contents and results of the thesis are as follows:1.Preparation and characterization of functionalized graphene molecularly imprinted polymers:The chiral functionalized graphene molecularly imprinted polymers were synthesized at 60?with?one pot method?using L-Trp as template molecule,dopamine hydrochloride?DA?as functional monomer,ammonium persulfate?APS?as initiator.Then,the hydrochloric acid-Methanol solution was used to remove template molecules in the resultant polyers.The condition of preparing functionalized graphene molecularly imprinted polymers was optimized.The optimal mass ratio of GO to L-Trp was 0.6,the molar ratio of DA to L-Trp was 1,the optimal mass ratio of ammonium persulfate?APS?to DA was 2,the reaction time was 4h.Under the optimal condition,the adsorption capacity of L-Trp reached the maximum number of 50 mg g^-1 and the separation factor was 1.55.2.Construction and analysis of molecular imprinting sensor:The MIT-SPR sensor chip was fabricated by photopolymerization and thermal polymerizationrespectively.The results of scanning electron microscopy showed that the films prepared by thermal polymerization were more uniform and had an average thickness of 13.65?m.While the average thickness of photopolymer chips was 29.25?m.SPR analysis showed that the response of the sensor chip to L-Trp was higher than D-Trp.Compared with D-Trp,the sensor chip hada better linear relationship for L-Trp in the range of 0.15-2.5 mmolL^-1 with a linear correlationof0.99.MIP-SPR showed good affinity for L-Trp,and the binding rate constant and dissociation rate constant were 7×10⁶,9×10^-6respectively.3.Study on recognition mechanism of functionalized graphene molecularly imprinted chiral SPR sensors on chiral amino acids:The results of molecular simulation showed that the binding ability of L-Trp with polydopamine was higher than that ofD-Trp.There were two hydrogen bonds between D-Trp and polydopamine,however,there were three hydrogen bonds between L-Trp and poly dopamine.The intermolecular hydrogen bond interaction between the amino hydrogen of L-Trp and the phenolic hydroxyl oxygen of polydopamine plays a key role in the binding sites,which resulted in the close match of spaceshape and chemical groups to L-Trp.Thus the specific recognition of functionalized graphene molecular imprinted polyme to L-Trp was achieved.