Synthetic receptors for selectively detecting erythrocyte ABO subgroups.

Surface imprinting techniques with erythrocytes as templates yield polymer coatings with selective recognition sites towards red blood cells. The resulting cavities in the respective surface exhibit selectivity between blood subgroups as shown by Quartz Crystal Microbalance (QCM) measurements. Mass sensitive effects in the kilohertz range could be observed for concentrations down to 0.5 x 10(8) cells/mL. Frequency response as well as recovery of the sensor took place within a few minutes, indicating that no covalent binding is involved. Linear concentration dependence over a defined region provides ideal conditions for cross selectivity measurements. A1 imprinted sensor coatings resulted in an effect of 40 kHz when exposed to the template blood group, while A2 erythrocytes yielded just 11% of that value on the same layer. Furthermore, A2 imprinted coatings incorporated only one third the amount of A1 erythrocytes as compared to A2 ones. Therefore, imprinted materials depict the entire cell surface and utilize it for recognition, whereas natural antibodies bind on the defined antigen position and thus usually cannot distinguish between cells carrying different amounts of them.