Sensing picornaviruses using molecular imprinting techniques on a quartz crystal microbalance

Molecular imprinting techniques were adapted to design a sensor for the human rhinovirus (HRV) and the foot-and-mouth disease virus (FMDV), which are two representatives of picornaviruses. Stamp imprinting procedures lead to patterned polyurethane layers that depict the geometrical features of the template virus, as confirmed by AFM for HRV. Quartz crystal microbalance (QCM) measurements show that the resulting layers incorporate the template viruses reversibly and lead to mass effects that are 'almost an order of magnitude higher than those of nonspecific adsorption. Thus, for example, the sensor yields a net frequency effect of -300 Hz when applying a virus suspension with a concentration of ~100 [micro]g/mL with an excellent signal-to-noise ratio. The cavities are not only selective to shape but also to surface chemistry: different HRV serotypes (HRV1A, HRV2, HRV14, and HRV16, respectively) can be distinguished with the sensor materials by a selectivity factor of 3, regardless of the group (major/minor) to which they belong. The same selectivity factor can be observed between HRV and FMDV. Hence, imprinting leads to an 'artificial antibody' toward viruses, which does not only recognize their receptor binding sites, but rather detects the whole virus as an entity. Brunauer--Emmett--Teller (BET) studies allow simulation of the sensor characteristics and reveal the number of favorable binding sites in the coatings.