Unusual photodegradation reactions of Asteraceae and Poaceae grass pollen enzymatic extracts on P25 photocatalyst.

In previous studies, it was demonstrated that photocatalysis by TiO nanoparticles can be effective for decomposition of pollen grains and pollen allergen extracts (PAEs) for Cupressus arizonica and Platanus hybrida species. In this work, the chemical and photochemical processes of five types of PAEs belonging to family Asteraceae, tribe Astereae, and family Poaceae, tribes Poeae and Triticea, were studied. It was confirmed that the PAEs suffered almost complete decomposition, which likely led to gaseous final products. For the species of Poeae tribe, i.e., Poa pratensis, Festuca pratensis, and Avena sativa, an unusual surface chemical modification of the photocatalyst consisting in the appearance of new bands on fine core level spectra of Ti 2p, C 1s, and O 1s was observed. These changes were associated with possible doping of TiO with C and N by pollen extracts. This was accompanied by a red shift of absorption spectra. The results suggest that some components of Poeae pollen can be grafted on TiO surface and they can activate the photocatalyst in the visible range. These findings can open a new pathway to eco-friendly chemical engineering of photocatalysts using organic biological compounds.