| The construction of chemo/biosensors is one of the most promising and interesting subject in analytical chemistry and biochemistry. Especially, capacitive sensor, based on the principle of plate-capacitor capacitance, was a new technique and has been attracted considerable interests. It has lots of advantages, such as high sensitivity, specificity, label-free, ordinary instruments and real-time monitoring, et al.In addition, cyclodextrin (CD), having an interior hydrophobic cavity and an exterior hydrophilic environment, as a buildup element of second generation supramolecule, can accommodate many organic, inorganic and biological molecules in their toroidal cavity to form stable host-guest inclusion complexes. Therefore, they have been attracted much attention by the researchers of supramolecular chemistry. Based on the inclusion complexes, molecular recognition and selective accumulation for guest molecules, CD and its derivatives have been applied to design the novel chemical sensors with molecular selectivity.The main work of this thesis is summarized as follows:1. A novel capacitive immunosensor was developed for the direct detection of transferrin based on ultrathinγ-alumina sol-gel-derived film and gold nanoparticles. The prepared capacitive sensor can provide high sensitivity and specificity because of the ultrathin inorganic film with high permittivity and good biocompatibility of gold nanoparticles. Compared with a capacitive immunoassay based on antibody-embedded ultrathinγ-alumina sol-gel-derived film, the novel immunosensor presented a lower detection of 0.05 ng ml-1 and a wider linear response range of 1-75 ng ml-1 for transferrin detection.2. A novel method for real-time investigating the binding interaction between human serum albumin (HSA) and salicylic acid with capacitive sensing technique was proposed. The kinetic of the binding process was quantitatively studied and the kinetic parameters, such as the binding and dissociation rate constants and the binding equilibrium constant, were firstly reported.3. A simple, sensitive and reliable method based on a combination of muti-walled carbon nanotubes with incorporatedβ-cyclodextrin (β-CD-MWNTs) and a polyaniline (PANI) film-modified glass carbon (GC) electrode has been developed for determination of dopamine (DA) in the presence of ascorbic acid (AA). The electrochemical behavior of DA at the chemically modified electrode was investigated by cyclic voltammetry (CV). The analytical response of theβ-CD-MWNTs/PANI film to the electrochemical behavior of DA was better than that of a MWNTs/PANI film, a PANI film, or a bare glassy carbon (GC) electrode. Under the conditions chosen, a linear calibration plot was obtained in the range of 1.0×10-7-1.0×10-3 mol l-1and the detection limit was 1.2×10-8 mol l-1。Interference from AA was effectively eliminated and the sensitivity, selectivity, stability, and reproducibility of the electrode were excellent for determination of DA.4. An electrochemical sensor for hydroquinone (HQ) usingβ-cyclodextrin/poly (N-acetylaniline)/carbon nanotube composite (β-CD/PAA/MWNTs) modified glassy carbon electrode has been developed. Complexation of HQ withβ-CD modified on the glassy carbon electrode (GCE) was examined by cyclic voltammetry (CV). HQ was included in the cavity ofβ-CD and reversible voltammograms were observed. The effects of scan rate, pH and accumulation time on the peak current of HQ were discussed in detail. The anodic currents increased linearly with HQ concentration from 1×10-6 to 5×10-3 mol l-1 with a detection limit (S/N=3) of 8×10-7 mol l-1. The linear regression equation was expressed as I/μA=0.4197+15.3036CHQ/mmol l-1 with a correlation coefficient of r=0.9999. This electrochemical sensor showed excellent reproducibility, stability and recovery for the determination of HQ. |
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