Design And Performance Study Of Optical Fiber SPR Biosensor Based On Boric Acid Affinity Molecular Imprinting

Glucose is an essential energy source for the human body,but high blood glucose concentration can lead to many human diseases,including diabetes,cardiovascular disease and cancer.In many biological processes,normal protein glycosylation plays an extremely important and critical role,and abnormal glycosylation can cause cancer,Alzheimer’s disease,rheumatoid arthritis and other physiological diseases.With the improvement of people’s quality of life,people’s requirements for health detection are also increasing.Therefore,it is of great significance to prepare sensors that can detect glucose and glycoprotein.Optical fiber Surface Plasmon Resonance（SPR）sensing technology combines optical fiber sensing and SPR detection technology,which has the advantages of high sensitivity,real-time monitoring,fast detection,label-free detection and anti-electromagnetic interference.Boric acid has the ability to reversibly covalently bind to sugars and glycoproteins,and molecular imprinting technology has the ability to customize specific recognition template molecules.It has been developed as one of the most important tools for specific recognition,separation and analyte detection in chemistry,biology,materials and medicine.Therefore,boronic acid affinity molecular imprinting technology can be used to specifically recognize sugars and glycoproteins,and it has high affinity and good anti-interference ability,which can effectively replace antibodies and provide us with an antibody-free analytical sample detection.In this paper,three kinds of optical fiber SPR sensors were designed and prepared by probe structure.By combining the optical fiber probe with three different boric acid affinity molecularly imprinted polymers（MIPs）,the detection of glucose,ovalbumin and alpha-fetoprotein was realized.The main research work is as follows:（1）A probe fiber SPR sensor based on SiO₂-MIPs was fabricated for the detection of glucose.The bare core of plastic cladding multimode fiber（PCMF）was used as the sensing probe.The optimal sensing area length and silver film thickness were explored through experiments,and a 300 nm silver film was evaporated on the end face of the sensing probe.The silver film was deposited on the side of the bare core to excite the SPR phenomenon,and the SiO₂-MIPs material was coated on the silver film by a pulling coating machine.The experimental results show that the sensor can detect 0-0.1 ng/ml glucose solution,and the resonance wavelength shows a blue shift with the increase of glucose concentration.The sensitivity is 482.323 nm/（ng/ml）,the linearity is 0.991,and the detection limit is 3.94 pg/ml.The sensor has the characteristics of high sensitivity,good selectivity,small temperature cross sensitivity and good stability.（2）A probe-based optical fiber SPR sensor based on boronic acid affinity molecularly imprinted polymer was fabricated for the detection of ovalbumin（OVA）.The sensing area is a 1cm long PCMF bare core.A 300 nm silver film is deposited on the end face of the bare core to enhance the reflection,and a silver film is evaporated on the side of the bare core to excite the SPR effect.The boric acid polymer 4-vinylphenylboronic acid-ethylene glycol dimethacrylate（VPBA-EGDMA）was coated on the surface of the silver film by a pulling coating machine,and then VPBA-EGDMA-MIPs were prepared on the surface of the fiber by polymerization of dopamine.The experimental results show that the sensor can detect 0.1-800 pg/ml ovalbumin solution with a sensitivity of 2.617 nm/（log（pg/ml））,linearity of 0.987 and a minimum detection concentration of 0.1 pg/ml.The sensor has excellent selectivity to ovalbumin and good time and temperature stability.（3）A probe-based optical fiber SPR sensor was fabricated to detect alpha-fetoprotein（AFP）.The sensing probe was a bare core of PCMF with a length of 1 cm.Silver film was deposited on the end face of the probe to enhance reflection.The silver film was evaporated on the side of the bare core to excite the SPR phenomenon,and then the boronic acid functional modification was carried out on the silver film and the MIPs were prepared by the dehydration condensation of ethyl orthosilicate.Experiments show that the sensor can detect 0-1 ng/ml alpha-fetoprotein solution with a sensitivity of 2.718nm/（log（fg/ml））,linearity of 0.997 and a minimum detection concentration of 1 fg/ml..The sensor has excellent selectivity,good repeatability and time and temperature stability.