4Sensor is a competitive test involving specific receptors and generic monoclonal antibodies in one single operation.
The test requires the use of two components :
The first component is a microwell containing predetermined amounts of both receptors and antibodies linked to gold particles.
The second is a dipstick made up of a set of membranes with specific capture lines.
For a valid test, the upper red control line has to be visible after the second incubation. The other 4 lines are the specific “test” lines placed below the control line. The line for Tetracyclines is located above the Chloramphenicol line which is located above the Streptomycin line while the ß-lactams antibiotics (penicillins and cephalosporins) line is the last line below.
When the reagent from the microwell is re-suspended with a milk sample, both receptors and monoclonal antibodies will bind the corresponding analytes if present during the first 5-minute incubation at 40°C. Afterwards, when the dipstick is dipped into the milk, the liquid starts running vertically on the dipstick and passes through capture zones. When the sample is free of antibiotics, a colour development occurs at the specific capture lines, indicating the absence of the targeted analytes in the milk sample. On the contrary, the presence of antibiotics in the sample will not cause the coloured signal to appear at the specific capture lines.
The detection of residual antibiotics such as beta-lactams, tetracyclines, streptomycin and chloramphenicol in milk is of great concern for the dairy industry because of the potential interfering and adverse effects of antibiotic residues frequently found in milk. Since January 2011, the Russian Dairy Authority has consolidated the requirements for drug residue screening in milk. According to the new Russian Federal Law 163 (2010), dairy producers should test for all the above antibiotics on a routine basis. This regulation applies also to milk imported into Russia, Belarus and Kazakhstan, as a new Customs Union has been established between the 3 countries.
In order to answer these specific requirements, Unisensor has developed a multiplex dipstick assay for the rapid and simultaneous detection of betalactams, tetracyclines, streptomycin and chloramphenicol in milk. This unique test does not require any sample preparation and gives a clear result by visual observation or using an instrumental reader in 10 minutes. The presence of each antibiotic family can be discriminated thanks to the use of 4 separate test lines. This rapid dipstick assay is therefore ideal for European factories exporting milk to the Customs Union.