Fiber-optic evanescent wave biosensor of catecholamine neurotransmitter

Using quartz fiber-immobilized laccase, detection of catecholamine neurotransmitter is described in this work. Laccase is immobilized on the fiber-optic by means of 3-Aminopropyltriethoxysilane/ glutaraldehyde (APTES/GA) method. The oxidation products of adrenalin catalyzed by laccase would quantificationally absorb the fiber-optic evanescent wave according to the products' concentration. The optimal detection range of this fiber-optic biosensor is between 50-250ng/ml. The minimum detection limit is 10ng/ml. The analysis can provide result in only two minutes to detect one sample. Finally, the specificity of the biosensor is high. The special interference of other substrates of laccase such as o-phyenylenediamine (OPD) and benzenediol can be removed by controlling the pH of the reaction buffer. When the OPD concentration is 100ng/ml, the relative error is only 6.3%. On the other hand, the non-special interference is removed by employing double-channel differential analysis method.