Fabrication And Properties Of Glucose Biosensor Based On Nanostructured Materials

In this dissertation, gold nanowire arrays and graphene were applied on thepreparation and study of glucose biosensor. Physical adsorption and cross-linkingmethod with glutaraldehyde (GLA) and boline serum albumin (BSA) were employed toimmobilize glucose oxidase onto these two nanostructured materials. The influence onglucose biosensors’ performance, such as the diameter of nanowires, applied potentials,were discussed in this work, repectively. What’s more, direct electrochemistry ofglucose oxidase (GOx) was achieved and the detection mechanism of glucose biosensorbased on direct electron transfer was investigated. On the other hand, flow injectionanalysis was combined with as-prepared glucose biosensor to improve the efficiency ofthe biosensor.Firstly, glucose biosensor based on highly ordered gold nanowire arrays wasstudied. Anodic alumina oxide with highly ordered pores was used as templates forelectrodeposition of gold nanowires. What’s more, the diameter of gold nanowirescould be controlled by changing the diameter of AAO pores. Then a cross-linkingmethod was employed to immobilize glucose oxidase with a component of4.5v/v%GLA,4.8w/v%BSA and200U/mL GOx. The results of scanning electron microscopeshowed that cross-linking solution contains GOx uniformly covered on the surface ofgold nanowire arrays. It also presented a porous structure, which was benefit to thereaction between biosensor and analyte. Furthermore, an optimal performance ofbiosensor was obtained by adjusting the diameter of nanowires. And it was found thatthe nanowires prepared with AAO template of80nm in diameter showed the highestsensitivity. On the other hand, the response of biosensor under the potential of0.7Vwas optimal.Secondly, biosensors based on graphene was constructed and studied. Graphenewas prepared with a modified Hummer’s method and fixed on the surface of gold discelectrode. Then glucose oxidase was fixed on the surface of graphene by absorption.Finally, nafion was covered on the outside as a protection membrane. The CV results ofbiosensor in0.05mol/L N2-saturated phosphoric buffer solution (PBS) presented aquasi reversible redox peak. Further confirmation was investigated and the peak currentshowed a linear dependent on scan rate. It indicated a redox reaction of flavin adeninedinucleotide (FAD) happened, which proved the direct electron transfer between GOxand electrode surface. Then the mechanism of third generation biosensor was discussed after comparing CVs of biosensor in PBS processed by different atmosphere. Thedetection of glucose based on this mechanism was employed and a good performancewas achieved.Thirdly, graphene was modified on the surface of gold nanowires with aelectro-adsorption method. Scanning electron microscope and X-ray photoelectronspectroscopy were used to characterize the complex nanostructure and the resultsshowed that graphene was immobilized uniformly on gold nanowire arrays. Theas-prepared electrode showed a much better response to hydrogen peroxide (H2O2) thanplain gold electode. Then the determination of glucose under positive potentials provedthat glucose biosensor based on graphene modified gold nanowire arrays had betterperformance than those only based on graphene or nanowires. Finally, the biosensorachieved a sensitivity of40.25A mM-1cm-2and a liner range from0.02mmol/L to3mmol/L.Finally, in order to improve the performance of biosensor on real sample detection,horseradish peroxide was added into cross-linking solution to decrease the detectionpotential of as-prepared biosensors. On the other hand, flow injection analysis (FIA)was applied on glucose detection to enhance the throughput of biosensors. The resultsshowed that the biosensor presented good reponse to glucose at a low potential of0.05V. After discussing the influence of components of cross-linking solution on response,an optimal enzyme solution contained4.5v/v%GLA，3.6w/v%BSA，200U/mLGOx，40U/mL HRP was achieved. The optimization of sampling time and speed werealso studied and sampled with a speed of60r/min and time of40s showed best. Afterthat, the biosensor presented an excellent performance with a sensitivity of25.34A·mM-1·cm-2and a liner range from5mol/L to1000mol/L. Moreover, the antiinterference detection was dicussed and the biosensor showed almost no response touric acid (UA), NO3-and Cl-. Finally, a real sample of natural water was determinatedand the biosensor performaned well, with low standard deviation and good recoveryrate.