Abstrakt

This study investigates the effects of varying concentrations of TiO2 NPs (from 0.00512 to 51.2 µg/mL) on the self-organisation of biohybrid systems formed by them and photosystem II-enriched photosynthetic membranes (PSII BBY). The superfine TiO2 NPs with diameters of ∼1 nm (quantum dots, QDs) can easily penetrate the membrane, modifying its lipid-protein matrix. Topographical changes to the PSII BBY–TiO2 QDs system were monitored by atomic force microscopy (AFM) in a liquid environment to ensure the physiological activity of PSII BBY. Membrane roughness increased with NP concentration, with root mean square roughness (Rq) ranging from 0.26 nm to 0.40 nm. Minkowski functionals revealed that TiO₂ concentrations ≥0.1 µg/µg induced significant topographical changes, with surfaces transitioning from valley-dominated to rough peaks and holes. Fractal and multifractal analysis confirmed the presence of self–affine structures, with fractal dimensions (FD) ranging from 2.201 to 2.283 and Hurst coefficients (H) below 0.5 for TiO2–treated samples, indicating short-range correlations. The PSII BBY control exhibited the highest multifractality, with a Δα of 1.372. The observed changes in the organisation of PSII BBY membranes under the influence of TiO2 QDs show that this is an important factor that, along with the high reactivity of the QDs surface in forming covalent bonds with biomolecules, will influence the modulation of the efficiency of light energy assimilation and water oxidation in this type of biohybrid system. Furthermore, our results demonstrate the potential dangers of altering cell membranes at a molecular level when living organisms are exposed to nanoparticles of this size. In our study, the TiO2 QDs were of anthropogenic origin, derived from commercially available TiO2 powder.