ИСТИНА

Microbial contamination control of indoor air is important for occupational and public health. Microscopic fungi Penicillium are common airborne genera, they cause allergies, chronic diseases. Beside the harm to the human health there is also a negative influence of microorganisms on manufacturing processes of medicines, foods and microelectronics. However, conventional microbiological methods are laborious, time-consuming or expensive, and usually unsuitable for on-site analysis. To overcome most of these drawbacks, it is possible to use synthetic receptors such as poly(3-aminophenylboronic acid) (poly(3-APBA)). Previously we reported on the novel reagentless detection principle allowing the discrimination of specific affinity bindings from nonspecific interactions.1 Poly(3-APBA) is able to selectively bind compounds possessing 1,2- or 1,3-diol moiety which leads to poly(3-APBA) conductivity increase. Upon complexation, the hybridization of the boron center shifts from sp2 to sp3, with the boronic acid moiety becoming an anionic and tetrahedral hydroxyl coordinate species. Hence, the mechanism of the observed conductivity increase in the presence of polyols can be referred to as polyaniline self-doping by “freezing” negative charges in ring substituents upon complexation. Since 1,2- and 1,3-diol functions are common structural elements of saccharides incorporated within fungi cell wall, poly(3-APBA) is able to bind to fungal cell wall surface, which consists mainly of β-1,3-glycan. In this work, we elaborated microsensor for direct detection of Penicillium chrysogenum in air. Impedimetric detection of P. chrysogenum in bioaerosol was carried out on interdigitated ultramicroelectrodes, modified with electropolymerized 3-APBA. It was first shown that the presence of the microorganism in air led to conductivity increase of poly(3-APBA) due to specific interaction of the cell wall functional groups with boronic acid moiety. Effect of poly(3-APBA) conductivity increase as a result of polymer self-doping in the presence of the fungi was confirmed by Raman spectroscopy. Detection of fungi with microsensor requires less than 20 minutes which is approximately 100 times faster than agar plate cultivation. Furthermore, microsensor is applicable to monitor fungal content in air within concentration range including the hygienic standard. The novel reagentless detection principle that we propose will ensure the analysis reliability, since it is based on affinity interactions. No additional chemicals and sample preparation are needed either. These advantages and compact size of microsensors opens the possibility to create embedded systems of air control in manufacturing processes and even in everyday life.