Study On Unlabeled Impedance Immunosensors For Determination Of Dairy Cattle Progesterone

Progesterone is a kind of steroidhormone produced in the corpus luteum and placenta in pregnancy after ovulation of female animal. The hormone content in dam body changes with activities of ovarian, dam body progesterone levels will be much higher than the basic level during pregnancy, and will continue until delivery. Therefore, the accurate detection of progesterone content can diagnose early pregnancy of livestock, and increase the efficiency of livestock breeding to increase desirable livestock production benefits.Traditional progesterone determination methods are as follows, Latex Agglutination Inhibition Test (LAIT), Enzyme-Linked ImmunoSorbent Assay (ELISA), Enzyme Immunoassay (E1A) and Radioimmunoassay (RIA). These methodsare expensive and too complex to manage, so they do not meet the needs of production of animal husbandry in China. In this paper, the progesterone monoclonal antibody was immobilized on a screen printed electrode, the biosensor for rapid detection of progesterone content is developed and experiments The main contributions of this paper are as follows,(1) In order to increase the stability and sensitivity ofscreen printing electrode, screen printing gold electrode is processed by electrochemical method (by cyclic voltammetry in sulfuric acid). The experiment shows: after the treatment,the ratio of electrode oxidation current and reduction current can be achieved by 1.02, while the untreated screen printed electrode ratio is0.94, obviously improves the electrochemical activity ofscreen printed gold electrodes.(2)The process of screen printed gold electrode beingmodified by protein Asolutionof 0.1g/mL is characterized by AC impedance method, and progesterone impedance immunosensors are prepared by fixing progesterone monoclonal antibody with different concentrations on golden electrodes already modified byprotein A. In the optimization process found that progesterone monoclonal anti with a concentration of 8ng/mL is more suitable for the preparation of sensor.(3)Progesterone with varied concentration of 50ng/mL,25ng/mL,12.5ng/mL,6.25,3.125ng/mL,1, 5625ng/mL and Ong/mL is tested by the prepared sensor in AC impedance methods.The quantitative determination of progesterone concentration is realized by the corresponding relation between the impedance value and progesterone concentration.(4)The equivalent circuit of impedance is fitted by using the Zsimpwin software with the measured impedance data ,and the value and fitting error of equivalent circuit is presented,so that further accurate analysis is possible.(5) A weak signal detection device is designed and is prepared for producing a portable progesterone determination instruments based on the impedence immunosensor.