Study on the development of carbon nanotube enhanced biosensor for gender determination of fish

To efficiently produce seedlings in aquaculture farms, it is essential to control the ratio of males and females by sex distinguishing. On the other hand, the concentration of 11-ketotestosterone (11-KT), which is contained in the plasma, would be an excellent indicator that is significantly different between males and female fish. However, the concentration of 11-KT is challenging to measure due to its low concentration. In this study, we attempted to develop a high-sense biosensor system enhanced by single-walled carbon nanotubes (SWCNTs) with high conductivity and improved the efficiency and accuracy of fish gender determination. First, a self-assembled monolayer (SAM)was formed on the surface of a disk-type gold electrode, and an anti-rabbit IgG was immobilized on the SAM end. Next, an anti-11-KT antibody was immobilized on this IgG antibody, and then SWCNTs were immobilized on the electrode surface to fabricate the biosensor. Then, we attempted to quantify 11-KT by analyzing the minor electrochemical changes on the electrode surface before and after the reaction of an anti-11-KT antibody with 11-KT as an antigen by cyclic voltammetry. Next, after examining the influence of various conditions (temperature, pH, reaction time) on the response value of this sensor, the specificity of the sensor using other hormones was confirmed. Furthermore, as an application of this sensor to the actual sample, the 11-KT concentration in a Nile tilapia (Oreochromis niloticus) plasma was measured and correlated with the measurement value obtained by the conventional method (ELISA) was compared.

Automated summary

Efficient production of seedlings in aquaculture farms requires control of male and female ratios through sex distinguishing. This study aims to develop a highly sensitive biosensor system utilizing single-walled carbon nanotubes (SWCNTs) to improve the efficiency and accuracy of fish gender determination. The concentration of 11-ketotestosterone (11-KT) in plasma is utilized as an indicator. The biosensor was fabricated by immobilizing an anti-11-KT antibody onto a disk-type gold electrode surface modified with a self-assembled monolayer (SAM) and SWCNTs.