| Glucose is a critical biological compound, which mainly carries out the energy conversion process in human body for growth and reproduction. The metabolic processes of glucose is influenced by blood glucose and insulin levels. When the bloods glucose is out of control or lack of insulin, the metabolic might be diordered leading to diabetes. It is hard to cure diabetes effectively. Thus, it is essential to control the blood glucose level for human life. Electrochemical glucose biosensors are the most common and practical method to detect the blood glucose levels, which can be grouped into two categories: enzymatic and non-enzymatic approaches. An enzymatic glucose biosensor possesses great specificity and selectivity but its stability is affected by many external factors. The non-enzymatic glucose biosensor has received more attentions due to its high stable and catalytic property. The advances of nanomaterials has brought new approach for development of next generation of biosensors, among them carbon nanomaterials are very promising due to their excellent stability, intrinsic conductivity, chemical versatility, ease of manipulation and biocompatibility.In this thesis, we concentrated on synthesis of novel carbon nanomaterials and further studied of their performances and applications in fabrication of electrochemical non-enzymatic glucose sensor. Detailed work includes: 1. RGO paper is built-up from exfoliated GO nanosheets through a modular approach followed by chemical reduction to maintain the conductivity and flexibility. The produced flexible RGO paper was used to construct a non-enzymatic electrochemical sensor and its performance was further investigated. 2. A flexible free-standing paper sensor was fabricated via in situ growth of Cu nanoflower on reduced graphene oxide(RGO) sheets towards amperometrically non-enzymatic detection of glucose. The low cost of copper(Cu) and graphene made the prepared sensor inexpensive. This Cu-RGO paper sensor exhibited high sensitivity(58.54 mA cm-2 mM-1) and the linear relation in a concentration range of 2 μM~2 mM and 2 mM~13 mM, which is attributed to the synergistic effects of graphene paper and Cu nanoflowers. The current response decreased to 86.1% of its original data when Cu-RGO electrode was bent for 100 times. The mechanism of Cu nanostructure formation and further growth from cubes to flowers was explored. The morphology effect on catalytic performance was studied, indicating that the Cu nanoflower has excellent catalytic activity due to its large reactive surface area. The prepared glucose sensor holds a great promise for inexpensive flexible electrochemical non-enzymatic glucose sensors. 3. A novel catalytically active nitrogen, sulfur, and iron co-doped carbon dots(N,S,Fe-CDs) were synthesized by hydrothermal treatment of blood plasma. It is found that the prepared carbon dots mainly contain carbon, oxygen and nitrogen element, and trace amounts of iron and sulfur element were also identified. The size of the nanodots was about 2.0-4.0 nm with an average diameter of 2.8 nm. The resulted nanodots exhibited strong fluorescence with a quantum yield of 32.6% and excellent peroxidase-like catalytic activity similar to enzyme. The mechanism of the catalysis activity was explored by optics and electrochemical methods. Moreover, the N,S,Fe-CDs could be utilized to fabricate non-enzymatic electrochemical sensor for glucose detection in neutral solution. The linear relationship with glucose concentrations was obtained in a concentration range from 1mM to 15 mM with a detection limit of 0.33 mM(S/N=3). The approach provides a new strategy for synthesis of catalytic nanomaterials and preparation of non-enzymatic electrochemical sensor.In summary, unique non-enzymatic glucose sensors were realized with multi-elements doped carbon dots, and were further tested conditions from alkaline to neutral solution to have better biocompatible, thus holding great promises in non-enzymatic glucose detections with non-enzymatic sensors. |
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