The study of surface properties of an IgE-sensitive aptasensor using an acoustic method.

We applied the acoustic transverse shear mode (TSM) method for study of the surface properties of a DNA aptasensor that specifically binds human immunoglobulin E (IgE). The biotinylated 45-mer DNA aptamers were immobilized on the surface of a self-assembled layer composed of a mixture of polyamidoamine dendrimers of the fourth generation with 1-hexadecanetiol covered by neutravidin. Using the TSM method, we studied the kinetics of changes of the series resonant frequency, f(s), and the motional resistance, R(m), of a quartz crystal transducer, used as a support for formation of the sensing layer. We have shown that attachment of the biotinylated DNA aptamers onto the surface covered by neutravidin results in a decrease of f(s), but in an increase of R(m). Similar changes of f(s) and R(m) were observed following addition of IgE. This suggests the contribution of friction forces to the crystal oscillation, which was taken into account in the calculation of the mass changes at the sensor surface following binding processes.