| Label-free electrochemical immunosensor has the advantages of electrochemical and immune response at the same time,with strong specificity,high sensitivity,low cost and easy to operate.It has been favored by more and more researchers.In this paper,gold nanocages,hollow graphene balls,saccate Ag-Pd-Pt alloy were synthestized and used to modify electrodes for the detection of carcinoembryonic antigen.In addition,based on excellent electrical catalytic performance of chemical modified electrodes,gold nanoparticulates were electrodeposited to modify electrodes for the detection of chloride ion and hollow graphene balls and hollow Pt-Au alloy balls were used to modify electrodes for the detection of dopamine in this paper.The details are summarized as follow:?1?A label-free immunosensor for the detection of carcinoembryonic antigen was developed based on hollow graphene ball/polythionine/gold nanocage.Synthesized hollow graphene ball?HGB?was modified on the surface of glassy carbon electrode?GCE?followed by electropolymerizing thionine on it to adsorb gold nanocage.Anti carcinoembryonic antigen?anti-CEA?was immobilized on the surface of electrode to construct label-free immunosensor for the determination of carcinoembryonic antigen?CEA?.When anti-CEA binds with CEA antigen,the formed immunocomplex obstructed electron transfer and decreased the electrocatalysis of PTh.The decrease of differential pulse voltammetry?DPV?response of PTh was used to realize label-free detection of carcinoembryonic antigen.Under the optimal experimental conditions,the linear range was 0.580 ng/mL with the detection limit of 0.17 ng/mL,the linear correlation coefficient was 0.9932.This immunosensor has been used to detect CEA in serum sample,the results were satisfactory.?2?Synthetized hollow cystic palladium-silver-platinum alloy were modified on the surface of glassy carbon electrode?GCE?using chitosan?CHIT?.Taking advantage of large specific surface area,more reactive sites,good conductive ability,excellent catalytic properties and strong adsorption ability of hollow cystic palladium-silver-platinum alloy,carcinoembryonic antibody?anti-CEA?was immobilized on the surface of electrode to construct high sensitive immunosensor for the determination of carcinoembryonic antigen?CEA?.When immune reaction occurred between the anti-CEA and etection of carcinoembryonic antigen?CEA?,the formed immunocomplex covered palladium-silver-platinum alloy,which obstruct the electrocatalysis of palladium-silver-platinum alloy and increase the mass transfer resistance.By detecting the decrease of differential pulse voltammetry?DPV?response of potassium ferricyanide current signal,label-free detection of CEA can be realized.The performance of the immunosensor was studied.Under the optimal experimental conditions,the linear range was 0.580 ng/mL,the linear correlation coefficient was 0.9821.The detection limit was 0.17 ng/mL.This immunosensor can be used to detect CEA in serum samples.?3?A new type of chloride ion electrochemical sensor was developed based on its redox for the first time using electrodeposited gold nanoparticulates-modified electrode.The experimental conditions,stability and practicability of the sensor were optimized.The sensor has a good linear relationship within 3.0×10-5 to 3.0×10-2 M with the linear correlation coefficient of 0.999,the lower limit of detection is 1.0×10-5 M.?4?Dopamine is a kind of important central neurotransmitter,closely related to a variety of conditions.The concentration imbalance of dopamine in the body or used illegally are harmful to our health.Therefore,to establish a sensitive,accurate and convenient measuring method is important to the food safety and physiology research.In the fouth chapter,hollow graphene balls and Pt-Au alloy balls were synthesised and used to modify electrodes for the detection of dopamine hydrochloride.Under the optimal conditions,linear range for the determination of dopamine hydrochloride concentration is 1.0×10-61.0×10-4 M with a detecting limit 3.3×10-7M.The experimental results shows that the sensitivity,selectivity and stability of this sensor are good.It can be used for the detection of dopamine hydrochloride in real sample. |
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