title: Wireless biosensor system for real-time cholesterol monitoring in fish "Nile tilapia".
abstract: The rapidly increasing demand for cultured fish as a food resource requires simple, effective methods for controlling fish health in culture conditions. Plasma total cholesterol levels are significantly related to fish mortality following bacterial challenge, and are thus a good indicator of the general health of fish. We developed a wireless biosensor system to continuously monitor the total cholesterol concentration in fish (Nile tilapia, Oreochromis niloticus). The biosensor was constructed with Pt-Ir wire (phi0.178 mm) as the working electrode and Ag/AgCl paste as the reference electrode. Cholesterol oxidase and cholesterol esterase were immobilized on the working electrode using glutaraldehyde. The sensor output was linear and strongly correlated with the cholesterol level (R=0.9970) in the range of 2.65-403 mg dl(-1). This range covers the range of total cholesterol levels in fish. To avoid blood coagulation and proteins coalescing on the sensor, we implanted the sensor in the fluid under the scleral surface of the eyeball (EISF). The EISF is presumed to reflect the levels of most blood components and does not include the substances contained in blood that inhibit sensor measurement. Total cholesterol concentrations in blood and EISF were strongly correlated (R=0.8818, n=72) in the blood total cholesterol range of 74-480 mg dl(-1). Therefore, we used EISF as an alternative to blood and performed continuous in vivo-monitoring of the total cholesterol concentration in fish. We also investigated the application of the calibration method and wireless monitoring system. These applications enabled us to securely monitor total cholesterol levels in free-swimming fish in an aquarium for over 40 h. Thus, our newly developed sensor provided a rapid and convenient method for real-time monitoring of total cholesterol concentrations in free-swimming fish.
authors.affiliation: Department of Ocean Sciences, Faculty of Marine Science, Tokyo University of Marine Science and Technology, Tokyo, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Yoneyama
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yonemori
authors.forename: Masataka
authors.initials: M
authors.lastname: Murata
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ohnuki
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hibi
authors.forename: Tetsuhito
authors.initials: T
authors.lastname: Hayashi
authors.forename: Huifeng
authors.initials: H
authors.lastname: Ren
authors.forename: Hideaki
authors.initials: H
authors.lastname: Endo
mesh_terms: D000465:Algorithms; D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002138:Calibration; D002784:Cholesterol / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D002789:Cholesterol Oxidase / Q000737:chemistry / Q000378:metabolism; D023681:Cichlids / Q000097:blood*; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods*; D004567:Electrodes, Implanted; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry; D018670:Monitoring, Ambulatory / Q000295:instrumentation / Q000379:methods; D015203:Reproducibility of Results; D018030:Silver Compounds / Q000737:chemistry; D002787:Sterol Esterase / Q000737:chemistry / Q000378:metabolism; D013550:Swimming
chemical_list: D004800:Enzymes, Immobilized; D018030:Silver Compounds; D002784:Cholesterol; D006861:Hydrogen Peroxide; D002789:Cholesterol Oxidase; D002787:Sterol Esterase; C037548:silver chloride