An optical biosensor based on a multiarray of enzymes for monitoring a large set of chemical classes in milk

In this paper we projected and realized a biosensor platform which combines an optical system, intimately integrated with an array of biomediators able to provide a helpful tool for safety management of the milk. Optical feature selection of various enzymes was performed for monitoring compounds of various chemical classes and metabolic markers of cow's wellness. The detection of selected analytes was evaluated through biomediators of C. reinhardtii cells, and acetylcholinesterase, tyrosinase, urease, β-galactosidase and d-lactate dehydrogenase enzymes. The analyses were performed by fluorescence that for the algal cells was based on chlorophyll a fluorescence emission while for enzymes was guaranteed by the use of fluorescein 5(6)-isothiocyanate or 5(6)-carboxynaphthofluorescein. The LODs, reported with the units of EU legislation, were 1.1 ng/kg for diuron, 0.6 μg/L for chlorpyrifos, 1.2 μg/L for catechol, 13.8 mg/dL for urea, 0.06 g/L for lactose, and 19.5 ppm for d-lactic acid.