(German title: Entwicklung von immunanalytischen Schnelltestsystemen für Algentoxine)

Protecting consumers from toxic by-products in food is of fundamental importance. Targeted analysis for toxins is therefore required by law in many areas, at least in random samples (e.g. in the Fish Hygiene Ordinance). Algal toxins, which accumulate in fish and crustaceans through the food chain, are particularly dangerous for consumers.

In order to identify contaminated catches as soon as possible on the caught fish or at the latest when they are landed, immunoanalytical rapid tests for important algal toxins were developed as part of the co-operation project. In this way, it is possible to prevent fish or crustaceans enriched with toxins from being mixed with uncontaminated fish or crustaceans. Risks to the consumer can thus be ruled out. The rapid tests are based on dipstick sensor technologies (lateral flow test format), which are very easy to use and can be applied reliably (widely known in use as pregnancy or drug tests). The test result can be read with the naked eye after a few minutes (approx. 10 minutes) by not colouring the test line.

The detection of the toxin microcystin-LR (MC-LR) was carried out by a binding reaction of a colour marker with antibodies that recognise the toxin as an antigen. The antibodies were bound to gold nanoparticles. With a particle diameter of 40 nm, gold colloids have an intense red colour that can be easily detected by the human eye. Binding optimisation of the antibodies was initially carried out using the model system "anti-human chorionic gonadotropin (hCG)". Once the optimisations were complete, the binding parameters were successfully transferred to anti-MC-LR. The antigen MC-LR was immobilised for the binding interaction of the labelled antibodies on the membrane of the rapid test strip. To bind the antigen to the nitrocellulose membrane, it first had to be bound to the protein BSA. The rapid test strip (dipstick) produced in this way is able to detect microcystin-LR in aqueous samples after 16 minutes. Concentrations of up to 5 µg l^-1 can be detected. The test system was extended for analysing mussels with a pre-filtration membrane. The mussel meat is pre-processed using a hand press.