Antibodies and their replicae in microfluidic sensor systems-labelfree quality assessment in food chemistry and medicine

Sesame protein is one of the most potent food allergens making it an interesting topic for analytical chemistry and sensor approaches. Within this paper, we compare different strategies to obtain sensitive layers for this purpose: immobilizing natural anti-sesame IgY on the gold electrodes of a quartz crystal microbalance (QCM) leads to appreciable sensor responses with selectivity factors of about four towards brazil nut protein, which shows cross reactions in sesame allergy patients. Molecularly imprinted polymers (MIP) generated directly from sesame protein yield the same selectivity, but sensitivity is increased by a factor of three as compared to the natural antibodies. Synthesizing antisesame IgY MIP nanoparticles and utilizing these as templates in a surface imprinting procedure yields cavities exposing "copies" of the initial immunoglobulin molecules on their surfaces. On QCM1 these materials again show the same selectivity as the natural one, but sensitivity is increased by a factor of ten. Therefore, the templating process does not only yield rugged, robust materials but also gives way to substantially increased sensor responses due to the higher surface density of selective recognition sites on the respective sensor surface.