Research On Graphene Oxide Integrated Special Optical Fiber Grating LSPR Probe Biosensor

In recent years,local surface plasmon resonance?LSPR?sensors based on fiber gratings have been widely studied and applied in fields such as biomedicine and biochemistry.Compared with traditional Fiber Bragg Gratings?FBG?and Long Period Fiber Gratings?LPFG?,Excessively Tilted Fiber Gratings?ExTFG?have low temperature cross-sensitivity effect,so they have an advantage in the field of biological immunoassay witch extremely high stability requirements.The new two-dimensional nanomaterial graphene oxide?GO?is characterized by rich oxygen-containing functional groups and large specific surface area.Introducing GO to the surface of the biosensor can improve the modification effect of bio-functionalization,thereby improving the detection performance of the biosensor.However,there are currently few reports about GO integrated ExTFG biosensors,and most of the sensors are transmissive,which is not conducive to achieving in-situ detection.In this paper,a GO-modified LSPR probe biosensor is fabricated using ExTFG as a platform.The sensor is used to detect the Programmed cell Death 1Ligand 1?PD-L1?of liver cancer markers.?1?The coupling mode theory of ExTFG is explained in detail,and its spectral response characteristics are analyzed according to the phase matching conditions and mode coupling principle of ExTFG.The mechanism of LSPR's enhanced sensing performance is analyzed to lay a theoretical foundation for subsequent experiments.?2?A GO-integrated ExTFG-LSPR biosensor was fabricated to detect the PD-L1 biomolecule,and the specificity and clinicality of the sensor were measured and analyzed in a human serum environment.First,the large-sized gold nanoshell?AuNS?was modified on the surface of ExTFG to make the LSPR sensor.GO was used as a functional material and PD-L1 monoclonal antibody was used as a biological recognition unit to enhance the specificity of the sensor.Each modification step is through covalent binding,which makes the sensor have higher stability.Scanning electron microscope?SEM?and energy spectroscopy were used to evaluate the effectiveness and uniformity of GO coating.Detection of different concentrations of PD-L1 and analysis of sensing characteristics.The results show that the GO-integrated ExTFG-LSPR biosensor has a detection range of 0.038-38.46pM for PD-L1,maintains good linearity in the low concentration range of 0-1.92pM,R²=0.927,and sensitivity is as high as 0.114nm/pM.The calculated detection limit?LOD?was 0.076 pM.Adsorption of PD-L1 follows the Langmuir model,with The dissociation coefficient is².801×10^-12M.Finally,using the HF etch the grid region,the GO modified ExTFG-LSPR biosensor was remade using the same modification method.And the serum of four groups of healthy people and the serum of liver cancer patients are tested separately.The results show that the resonance wavelength of the biosensor is almost unchanged in the serum of healthy people,redshift⁰.049nm.And the redshift of the resonance wavelength in the serum of liver cancer patients is⁰.42nm,which proves that the sensor has good specificity and clinicality.?3?The probe structure of the GO integrated ExTFG-LSPR biosensor is realized.PD-L1 is detected,and the results are calculated and analyzed.Firstly,an experimental system is designed for the probe structure sensor,which can observe and collect data in real time.The reduction method is used to plate silver on the end surface of the probe to increase the reflectivity,and the end surface is sealed with a capillary glass tube to enhance the stability of the sensor.Using the same surface modification and biological functionalization methods as in Chapter 3,the spectral change trend of the sensor is the same as that of the transmission sensor.After the fabrication of the probe sensor,PD-L1 is detected.The detection method and data acquisition method are the same as those in Chapter 3.The results show that the probe GO integrated ExTFG-LSPR biosensor has detection range of 0.038-38.46pM for PD-L1 and maintains good linearity in the low concentration range of 0-1.92pM?R²=0.91?.The dissociation coefficient is².825×10^-12M,which is basically as same as those of the transmissive sensor.Due to the secondary coupling of the probe sensor,its detection sensitivity is 0.127nm/pm,increased by¹1.4%,and detection limit is0.071pm.Compared with the transmission sensor,the probe sensor has been improved...