| Mesoporous material is a special kind of porous materials with tunable (2～50 nm) and regular pores. In addition, mesoporous material has many properties such as large surface area, strong absorption ability and rapid mass transportation. Until now, it has been extensively used in the areas of catalysis, separation, energy, materials, and so on. In this paper, mesoporous SiO2 and Al-doped mesoporous SiO2 were individually synthesized using cetyltrimethylamine bromide (CTAB) as template, and two kinds of modified electrodes were then prepared. Moreover, their application in bioelectrochemistry was investigated. The main work is as follows:Mesoporous SiO2 was synthesized in acidic condition using CTAB as template and tetraethyl orthosilicate (TEOS) as inorganic precursor, which characterized by scanning electron microscopy and infrared spectrometry. After that, a mesoporous SiO2 modified carbon paste electrode was prepared by directly mixing. The electrochemical response of uric acid at the unmodified and mesoporous SiO2 modified carbon paste electrodes was investigated. The mesoporous SiO2 modified electrode is more active to the electrochemical oxidation of uric acid, and greatly increases its oxidation signal. Further, the influence of supporting electrolyte, pH, scan rate, accumulation potential and accumulation time was examined on the electrochemical response of uric acid. After obtaining the optimized parameters, a highly sensitive and convenient electrochemical method was established for the determination of uric acid. The linear range is from 5.0×10-7 to 2.0×10-5 mol/L, and the limit of detection is 8.0×10-8 mol/L. Finally, this newly proposed method was used to determine uric acid in human serum, and the results were in good agreement with those obtained by enzymatic and colorimetric method.In the presence of CTAB, sodium aluminate and TEOS, an Al-doped mesoporous silica (denoted as Al-MCM-41) with Si/Al molar ratio of 30 was synthesized in alkaline condition according to the published literature. Then, an Al-MCM-41 modified carbon paste electrode was achieved. The electrochemical properties of unmodified and Al-MCM-41 modified carbon paste electrodes were investigated using K3[Fe(CN)6] as the electrochemical probe. The redox peak currents of K3[Fe(CN)6] remarkably increases and the peak potential separation becomes smaller at the Al-MCM-41 modified electrode. Additionally, the electrochemical behavior of epinephrine in different supporting electrolytes was studied. In 0.01 mol/L HClO4, the electrode process of epinephrine is simple, just showing an electrochemical reaction. However, the electrode process of epinephrine becomes complicated in pH 7.0 phosphate buffer, and is an electrochemical coupled chemical reaction. From the comparison, it was found that the mesoporous Al-MCM-41 modified carbon paste electrode efficiently catalyze the oxidation of epinephrine since it greatly increases the oxidation peak currnet and lowers the oxidation overpotential. Based on this, a new electrochemical method for the determination of epinephrine was developed. The linear range is between 8.0×10-7 and 1.0×10-4 mol/L. The limit of detection for 3-min accumulation is evaluated to be 3×10-8 mol/L. The relative standard deviation for 10 parallel determinations is 5.8%. Finally, this sensing method was applied to detect epinephrine in the urine samples with recovery from 97% to 102%.
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