| Diabetes mellitus is one of the major causes of death in the world, affecting about150million people whose blood and tissue glucose concentrations are not maintained intheir normal range. The quantitative monitoring of blood glucose is of great clinicalimportance for these patients to reduce the risks of diabetic emergency. In addition,rapid, simple, and practical glucose detection is essential for food and fermentationindustry. As we know, there are two major categories of electrochemical sensors forglucose monitoring. Enzymatic glucose sensors have been intensively studied fordecades, relying on the current response of glucose oxidation by the immobilizedglucose oxidase (GOx) on electrode substrates. Nonenzymatic glucose sensors arefabricated with metal such as Pt, Au, Ni, Cu that can directly oxide glucose under acertain applied potential. The great advantages of nonenzymatic glucose sensors overenzymatic glucose sensors are their long-term stability during detection andpreservation. In addition, nonenzymatic glucose sensors reveal minimal interferences byother redox-active molecules in blood sample.Nonenzymatic electro-oxidation of glucose is greatly enhanced at Ni and Cucompared with noble metal electrodes as a result of their electrocatalytic effect mediatedby Ni2+/Ni3+and Cu2+/Cu3+redox couples. Ni or Cu was usually deposited on substratematerials to enhance its performance of oxidation of glucose. Of the numerous types ofmatrices used today, one-dimensional nanostructure arrays exhibits large specificsurface areas and can enhance the rapid transport of reaction electrons from redoxcenter to metal substrate. These characteristics would enhance the peroformance ofbiosensors and indicate that the one-dimensional nanostructure arrays is promisingsupporting materials. Moreover, long-term monitoring of blood glucose levels will belimited by rapid surface fouling events that occur in serotonin solutions on variouselectrode surface for the strong absorption of serotonin and its oxidized species form,resulting in significant signal attenuation as well as reduced sensitivity and selectivityover time. The fouling substances generated on electrode surface are organic moleculesthat can be completely mineralized into CO2and H2O on a semiconductor surface underlight irradiation. In addition, one-dimensional nanostructure arrays naturally forms aSchottky-type contact and provides a direct electric pathway for photogenerated-electron transport that will improve the efficiency of a photocatalyticprocedure. Herein, we developed high performance and photo-refreshable glucosesensors by controllable fabrication of one-dimensional nanostructure arrays on Tisubstrates as described below:(1) Copper nanoparticles with a size of30~50nm are uniformly distributed on thesurface of the shell/core C/TiC nanofibers which are produced on a Ti alloysubstrate in situ and enable glucose detection in solution. The Cu/C/TiC electrodedisplays sensitivity up to415.02μAcm-2mM-1with favorable reproducibility,stability and potential applications for real sample analysis while suffering fromminimal interferences and is thus promising in clinical applications.(2) TiO2nanotube arrays (TiO2NTAs) prepared by anodization were nesting withcarbon from a simple glucose hydrothermal treatment method then furthercarbonized under an inert atmosphere to form C/TiO2NTAs. By introduction ofnickel nanoparticles with electrochemical deposition, Ni/C/TiO2NTAs exhibitsensitivity up to423.6μAcm-2mM-1with good reproducibility, stability andminimal interferences towards glucose determination.(3) A photo-refreshable glucose sensor was fabricated with Ni/NiTiO3/TiO2nanotubearrays that are prepared by a simple hydrothermal treatment of nickel acetate withanodized TiO2NTAs and in situ annealing under hydrogen flow. TheNi/NiTiO3/TiO2nanotube arrays exhibit excellent electrochemical performancetowards glucose monitoring with sensitivity up to366.0μAcm-2mM-1. Moreover,the Ni/NiTiO3/TiO2nanotube arrays can be readily refreshed to maintain the highsensitivity and reproducibility under light irradiation without damaging the surfacemicrostructure due to the high photocatalytic activity from the scaffold of TiO2NTAs. To the best of our knowledge, it is the first report to demonstrate aphoto-refreshable glucose sensor that can meet the requirement of long-termglucose monitoring in blood samples. This novel nonenzymatic glucose sensorexhibits fast response, high sensitivity, selectivity and reproducibility towardsglucose determination and therefore is promising for the future development ofnonenzymatic glucose sensors. |
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