DEVELOPMENT OF LABEL-FREE BIOSENSOR FOR DETECTING STEROID HORMONE CONCENTRATION IN FISH

Abstract

A novel label-free immunosensor for detecting steroid hormone was developed. The principle of the sensor system is based on differences in the electrochemical activity induced by an immunoreaction that depends on the levels of steroid hormone in the sample. A gold electrode functionalized with 3-mercaptopropionic acid (MPA) self- assembled monolayer was used to fabricate electrochemical immunosensor. In addition, single-wall carbon nanotube (SWCNT) was selected to expandthe dynamic range of the sensor. The sensor was immersed into a sample solution and measurements were determined by cyclic voltammetry. Each electrochemical measurement including sample immerse only took about 15min. In this study, we introduced an application of our sensor in detecting 17, 20β- dihydroxy-4-pregnen- 3-one (DHP). The immunosensor showed a specific response to DHP, and the oxidation peak current linearly decreased in the range of 7.8-500.0pg ml-1 (without SWCNT) and 15.6-50000.0pg ml-1 (with SWCNT). The sensor system was then applied to monitor DHP of goldfish (Carassiusauratus) and was compared with the levels of the same samples determined using ELISA as the convention method. Blood plasma of fish was collected every 3h after administering a DHP inducer. A good relationship (coefficient: 0.934) was observed between DHP levels determined by both methods. Keyword: Biosensor, Steroid hormone, Immunoassay, Fish, Single-walled carbon nanotube