| Due to the high selectivity and high sensitivity, electrochemical sensors play an important role in the field of analysis, which can rapidly and exactly provide analytical results. Electrochemical sensors have been widely used in some fields, including environment monitoring, food detection and biomedical detection.Carbon nanomaterials have attracted tremendous attention and thus inherited numerous applications in electrochemical sensors because of their favorable electro-conductivity and large specific surface area, which are beneficial to greatly changing micro-structure of electrode surface and efficiently improving the selectivity and sensitivity of sensors. In this work, carbon-based composite electrode materials were prepared and used for the construction of electrochemical sensors, whose electrocatalytic activities towards small biological molecules were furtherly studied. The main contents of this work were as follows:(1) Natural clay of attapulgite (ATP) was used to adsorb Cu2+ in order to obtain Cu2+-ATP. Graphite oxide (GO) and Cu2+-ATP were simultaneously reduced by hydrazine hydrate under mild hydrothermal conditions in one pot, and subsequently dried in air to obtain cuprous oxide-attapulgite/graphene composites (Cu2O-ATP/RGO). The Cu2O-ATP/RGO/GCE showed electrocatalytic activity towards oxidation of glucose at low oxidation potential, and exhibited sensitive linear amperometric responses to glucose in concentration range of 4.0×10-5～3.0×10-3 mol L-1 (R=0.996) with the detection limit of 2.1×10-6 mol L-1. The as prepared modified electrode was highly selective to glucose and showed no reponse to other common interfering species in biological fluids, such as dopamine (DA), ascorbic acid (AA) and uric acid (UA).(2) ATP was used as hard template in the preparation of poly aniline (PANI) by in-situ polyrization. Copper oxide-multiwalled carbon nanotubes (CuO-MWCNTs) was prepared by hydrothermal method. The PANI-ATP/CuO-MWCNTs showed electrocatalytic activity towards oxidation of glucose at low oxidation potential and exhibited sensitive linear amperometric responses to glucose in concentration range of 8.0 X 10-6～6.8 ×10-4 mol L-1 (R= 0.996). The detection limit was calculated as 3.4×10-6 mol L-1. The as prepared modified electrode was highly selective to glucose in the presence of common interfering species in biological fluids, such as DA, AA, UA, ethanol and H2O2.(3) CNHs with large specific surface area and excellent electro-conductivity were used to stabilize electropolymerized polyglycine (PGLY). PGLY/CNHs/GCE catalyzed the electrooxidation of DA, AA and UA at 0.2 V,0.1 V and 0.4 V respectively, realizing the simultaneous determination of them in one system. As prepared modified electrode exhibited linear responses to DA, AA and UA in the concentration ranges of 6.0×10-7～2.0×10-4 mol L-1,-6.0×10-4～1.2×10-3 mol L-1 and 5.4×10-5～2.0×10-4 mol L-respectively. The detection limits were down to 2.5×10-8 mol L-1 for DA,3.2×10-5 mol L-1 for AA and 4.5×10-6 mol L-1 for UA (S/N=3), respectively.(4) Based on the excellent electro-conductivity and large specific surface area of MWCNTs and large numbers of edge defects of GNSs, we prepared MWCNTs/GNSs composite and studied the electrocatalytic activities of MWCNTs/GNSs/GCE towards acetaminophen (AC) and DA. MWCNTs/GNSs/GCE electrocatalyzed the oxidation of AC and DA at potentials of 0.4 and 0.2 V, respectively, without the interference of AA. As-prepared modified electrode exhibited linear responses to AC and DA in the concentration ranges of 2.0×10-6～2.4×10-4 mol L-1 (R= 0.999) and 2.0×10-6～2.0×10-4 mol L-1 (R=0.998), respectively. The detection limits were down to 2.3 x 10-7 mol L-1 for AC and 3.5×10-7 mol L-1 for DA (S/N=3). |
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