AFB1-AP conjugate for enzyme immunoassay of aflatoxin B1 in corn samples

This article describes the conjugation between aflatoxin B1 (AFB1), one of the major mycotoxins, and alkaline phosphatase (AP), one of the most used enzymes for immunoassays. In addition, an application of the ELISA method for aflatoxin B1 determination in corn is presented. Three AFB1-AP conjugates in different toxin-enzyme ratios were prepared and tested. The ELISA results, developed with the most effective conjugate obtained, showed a satisfactory working range between 2.4 and 4000ng of toxin/g of corn. The detection limit was 2ng/g in corn samples, and recoveries ranged from 105 to 120%

Bi-enzyme alcohol biosensors based on genetically engineered alcohol oxidase and different peroxidases

We report on the development of a bi-layer bi-enzyme biosensor architecture using different peroxidases and alcohol oxidase from Hansenula polymorpha C-105 as biological recognition elements. The sensor architecture comprises a first layer containing either horseradish peroxidase or royal palm tree peroxidase crosslinked with an Osmium complex-modified redox hydrogel. On top, a second layer was formed by electrochemically induced precipitation of a cathodic electrodeposition paint simultaneously entrapping alcohol oxidase isolated from a genetically modified strain of Hansenula polymorpha C-105. The sensor architecture was optimized with respect to effective electron transfer and stability of the enzyme. The main characteristics of the biosensors are an apparent maximal current I-max(app) of 572-940 nA, an apparent Michaelis constant K-M(app) of 9.5 mM, a sensitivity of 60-98 nA mM(-1) and an improved operational stability represented by a deactivation constant of 1.5-2.0 x 10(-4) min(-1)