Enhanced Fiber-optic Surface Plasmon Resonance Technology Based On Supramolecular Interaction For Biochemical Molecule Detection

Fiber-optic surface plasmon resonance(SPR)sensing technique is an optical detection technique with the features of high-sensitivity,simple operation and online monitoring.It has the advantages of label-free and no damage to the samples,and has been widely used in many fields such as food safety,medical diagnosis and environmental monitoring.Bioactive molecules and ions such as glucose,amino acids and heavy metal ions are used as markers for disease diagnosis and monitoring the activities of organisms.Their content in living organisms is closely related to human health.Thus,high-precision detection of the dynamic changes of bioactive molecules and ions is of great significance for the early prevention and diagnosis of related diseases.However,biomolecules generally have small molecular weight and the low concentration,which causes little change in the dielectric constant on the surface of the SPR sensor chip.More,importantly,Traditional fiber-optic SPR sensors are insufficiently sensitive to detect small molecules or analytes with low concentration,which becomes a bottleneck of fiber optic SPR biosensing application.To break through the limitations of SPR detection technology such as poor molecular specificity recognition ability,low sensitivity,and low resolution,and meet the urgent needs of the development of common and important biomolecules and ion detection technologies,the fiber-based SPR sensor surface modification technologies for highly sensitive,stable and selective biomolecules detection was studied in this paper.The combination with varied supramolecular interaction and fiber-optic SPR sensor can realize biochemistry molecular recognition on glucose,amino acid and heavy metal ions.Meanwhile,the functional nanomaterials are used as SPR signal enhancer to improve the objective detection ability for biochemical molecules,then the targeted molecules could be precisely detected in complex samples.In this thesis,the major research works are listed as following:1.Combining functional Au NPs with boric acid molecules,we design and developed a sensitivity-enhanced fiber-optic SPR technology for glucose detection.The structure of gold film/boric acid-glucose-boric acid/Au NPs was constructed by using the complexation between boric acid molecules and o-dihydroxyl substances,we developed fiber-optic SPR glucose-biosensor which is functionally enhanced with functionalized Au NPs,and also used it for specific identification and detection of glucose biomolecules.Then,the phenylboric acid modified Au NPs was employed for SPR signal amplifying of these SPR sensor to realize the determination of trace glucose in urine.2.Based on the strong electric field coupling effect between functionalized Au NPs and gold films,the specific recognition and detection of mercury ions was realized by using the fiber-optic SPR sensor.Because mercury ions(Hg2+)complex with the N atom in pyridine,4-mercaptopyridine functionalized Au NPs can be used as signal enhancement labels to construct an SPR fiber sensor for Hg2+detection.As a result,the detection limit of Hg2+reaches 3.34 nM,which enables the monitoring of mercury ion recovery of standard tap water samples in real time.Similarly,when thymine functionalized gold nanoparticles were used as signal enhancer in the fiber based SPR,the selectivity and sensitivity of mercury ion detection was significantly improved,reaching a detection concentration as low as 80 nM.3.A competitive adsorption signal-enhancement technique for ultrasensitive heparin detection was investigated by using the SPR enhancement mechanism of label-free Au NPs.Owing to the competitive adsorption behavior between heparin molecules and Au NPs on the positively charged surface of the sensor,the heparin molecules showed stronger adsorption ability to PDDA than Au NPs when the concentration of heparin gradually increases,while the corresponding resonant wavelength significantly reduces.The concentration of heparin could be quantified according to the wavelength shifts,and then the determination of heparin in serum samples proved the practicability of this detection mechanism.4.A supramolecular self-assembled fiber-optic SPR sensor for arginine(Arg)chiral recognition was developed by using BSA as chiral recognition agent to amplify the sensing signal.The carboxyl group in the BSA molecule can be paired with the guanidine group in arginine through the supramolecular interaction,and the interaction between BSA and different arginine isomers is different.The supramolecular recognition processes of L-Arg and D-Arg with BSA,and the corresponding changes of SPR signal of the supramolecular self-assembled sensor were also investigated.The results showed that the binding ability between L-Arg and BSA was stronger than that of D-Arg.The enantiomer excess of D-Arg was determined by chiral determination,the added L-Arg was changed from 0%to 100%,and the correlation coefficient was 0.9748.Thereby,the chirality recognition of Arg was realized by using BSA to enhance the SPR signal.In conclusion,we summary our works and contents,list out the innovations of this dissertation,and also make some prospection of our future investigation.