It is difficult to determine estrogens directly by electrochemical methods because estradiol, estrone and estriol are hydrophobic and electroinactive. Thus, they are only determined by the indirect electrochemical tec...It is difficult to determine estrogens directly by electrochemical methods because estradiol, estrone and estriol are hydrophobic and electroinactive. Thus, they are only determined by the indirect electrochemical techniques. In this paper, based on the voltammetric behavior of estrogens(estradiol, estrone and estriol) on the Nafion\|modified glassy carbon electrode in the presence of CTAB, a novel direct electroanalytical method for the determination of the total amounts of estradiol, estrone and estriol was developed. In pH=8.00 phosphate buffer and in the presence of 6×10\+\{-5\} mol/L CTAB, estradiol, estrone and estriol have very sensitive oxidation peaks at 0.38 V(\%vs\%. SCE) at Nafion\|modified glassy carbon electrode after being accumulated for 3 min at -0.50 V. This peak can be used to determine trace level of estradiol, estrone and estriol. It was found that estradol, estrone and estriol have the similar electrochemical responses on the Nafion\|modified electrode in the presence of other long\|chain cationic surfactants, such as CPB, STAB, CATAB, LTAB. It is observed that the enhancement effect is highest in the presence of CTAB, and the peak current is CTAB concentration\|dependent. However, in the presence of long\|chain anionic surfactants, such as SDBS, and long\|chain nonionic surfactants, such as Triton X\|100, estradiol, estrone and estriol have no voltammetric responses on the Nafion\|modified glassy carbon electrode. The mechanism for the oxidation of estradiol in this system has been discussed, and the reactant site for the oxidation of estradiol has been verified to be the hyrdoxyl group in A\|ring.展开更多
In this work,two kinds of novel microfluidic cells separation chips were described on the principle of crossflow filtration by using micro-electro mechanical systems(MEMS) technology.Whole blood is a complex mixture o...In this work,two kinds of novel microfluidic cells separation chips were described on the principle of crossflow filtration by using micro-electro mechanical systems(MEMS) technology.Whole blood is a complex mixture of various cells,such as red blood cells(RBC),white blood cells(WBC) and so on.Separation and collection of different kinds of cells is the required first step for the subsequent clinical and basic research assays.One-level filtration microfluidic chips with three coiled channels spaced by two arrays of parallel microfabricated filtration barriers of post-type or dam-type along the stream,were successfully used to separate and collect RBC and WBC from whole blood via their different sizes.The effects of the dilution times and the length of separation channels with different filtration barriers on RBC separation efficiency were investigated.When the whole blood was diluted by 50 times,the RBC separation efficiency was 91.2% and the WBC separation efficiency was 27.4% by using the microfluidic chip with dam-type filtration barriers of 160 mm long.The WBC separation efficiency was two times more than that by using microfluidic chip based on the dead-end filtration principle.The second kind of microfluidic chip had multilevel filtration barriers of post-type which was used to separate and collect plasma,RBC and WBC from whole blood.展开更多
文摘It is difficult to determine estrogens directly by electrochemical methods because estradiol, estrone and estriol are hydrophobic and electroinactive. Thus, they are only determined by the indirect electrochemical techniques. In this paper, based on the voltammetric behavior of estrogens(estradiol, estrone and estriol) on the Nafion\|modified glassy carbon electrode in the presence of CTAB, a novel direct electroanalytical method for the determination of the total amounts of estradiol, estrone and estriol was developed. In pH=8.00 phosphate buffer and in the presence of 6×10\+\{-5\} mol/L CTAB, estradiol, estrone and estriol have very sensitive oxidation peaks at 0.38 V(\%vs\%. SCE) at Nafion\|modified glassy carbon electrode after being accumulated for 3 min at -0.50 V. This peak can be used to determine trace level of estradiol, estrone and estriol. It was found that estradol, estrone and estriol have the similar electrochemical responses on the Nafion\|modified electrode in the presence of other long\|chain cationic surfactants, such as CPB, STAB, CATAB, LTAB. It is observed that the enhancement effect is highest in the presence of CTAB, and the peak current is CTAB concentration\|dependent. However, in the presence of long\|chain anionic surfactants, such as SDBS, and long\|chain nonionic surfactants, such as Triton X\|100, estradiol, estrone and estriol have no voltammetric responses on the Nafion\|modified glassy carbon electrode. The mechanism for the oxidation of estradiol in this system has been discussed, and the reactant site for the oxidation of estradiol has been verified to be the hyrdoxyl group in A\|ring.
文摘In this work,two kinds of novel microfluidic cells separation chips were described on the principle of crossflow filtration by using micro-electro mechanical systems(MEMS) technology.Whole blood is a complex mixture of various cells,such as red blood cells(RBC),white blood cells(WBC) and so on.Separation and collection of different kinds of cells is the required first step for the subsequent clinical and basic research assays.One-level filtration microfluidic chips with three coiled channels spaced by two arrays of parallel microfabricated filtration barriers of post-type or dam-type along the stream,were successfully used to separate and collect RBC and WBC from whole blood via their different sizes.The effects of the dilution times and the length of separation channels with different filtration barriers on RBC separation efficiency were investigated.When the whole blood was diluted by 50 times,the RBC separation efficiency was 91.2% and the WBC separation efficiency was 27.4% by using the microfluidic chip with dam-type filtration barriers of 160 mm long.The WBC separation efficiency was two times more than that by using microfluidic chip based on the dead-end filtration principle.The second kind of microfluidic chip had multilevel filtration barriers of post-type which was used to separate and collect plasma,RBC and WBC from whole blood.
