Immobilized bi-enzymatic system for the determination of biogenic amines in solution

Biogenic amines are a group of important organic bases involved in the metabolism of living organisms and present in biological fluids, food or beverages. Their identification and quantification represent relevant issues in the field of bio-analytical and food chemistry. Beyond the traditional detection techniques, other methods have been recently exploited, as enzymatic-based systems. Herein, diamine-oxidase (DAO) and soybean peroxidase (SBP) were immobilized onto silica spherical monoliths (prepared from biowaste-derived substances) to realize a practical and fast enzymatic system, able to quantify biogenic amines in solution. The mechanism consisted in the oxidation of amines by DAO with the formation of H2O2, which in turn activated the SBP reaction producing an indamine dye. The amount of amine was indirectly determined by the spectroscopic measurement of the final product. Preliminary kinetic tests on DAO/SBP catalytic system using histamine as DAO substrate showed the maximum activity at pH 8. Furthermore, the stability of the functionalized monoliths over several reaction cycles and their catalytic action towards cadaverine, tyramine, tyrosine and histamine were studied. The results showed that the immobilized DAO/SBP system was effective in the determination of different substrates for many cycles, reaching a detection limit comparable to chromatographic methods.