Seznam abstraktů 2023: SEKCE D - MONITOROVÁNÍ A TOXICITA NANOMATERIÁLŮ

Unique physicochemical properties of synthesized nanoparticles (NPs) are increasingly being utilized in various areas of industry, including the production of commercial products of daily consumption and biomedicine. Moreover, the release of NPs into the environment, and thus the subsequent secondary exposure to NPs through the food chain increases the risk of chronic human exposure. Although kidneys are the primary organs of xenobiotic elimination, little attention has been paid to the kidneys in terms of nanotoxicological studies up to now. Therefore, we comprehensively evaluated the risk of four solid-core inorganic nanoparticles (TiO2NPs, SiO2NPs, Fe3O4NPs, and AuNPs) using the human renal proximal tubule epithelial TH1 cells with respect to cell viability and (epi)genome integrity. In addition, the accumulation, localization, and efficacy of the uptake of studied NPs inside the cells were monitored.
From all the tested NPs, only Fe3O4NPs induced slight cytotoxicity in TH1 cells exposed to high concentrations (> 700 μg/ml) for 24 h. Although, the studied NPs did not increase significantly the level of DNA strand breaks or oxidative DNA damage as revealed by comet assay, integrated analysis of methylome and transcriptome changes induced by chronic NPs-treatment of TH1 cells showed significantly deregulated genes with functional classification in immune response, DNA damage, and cancer-related pathways.
Interestingly, substantial differences were observed in the internalized amount of NPs in TH1 cells exposed to equivalent (2.2 μg/ml) concentration, with Fe3O4NPs being most efficiently taken up while the lowest quantity of particles was determined in TiO2NPs-treated cells. ACKNOWLEDGEMENTS: This work was supported by European Union’s Horizon 2020 research and innovation program under grant agreement No. 857381 (project VISION), No. 685817 (project HISENTS), and VEGA grant 2/0121/2

Nanodiamonds with variable surface chemistry and surface potential sign (NDs) can provide mediating abilities to traditional antibacterial substances, like Ag nanoparticles against bacteria. In this contribution, we investigate the impact of NDs and ND-Ag composites on selected gram-negative and gram-positive bacterial strains.
We analysed ND properties like size, surface charge (zeta potential), and coating using two sizes of HPHT (high-pressure/high-temperature) NDs (18 nm and 125 nm) with controlled zeta potential through oxygen (-35 mV, O-ND) and hydrogen (+40 mV, H-ND) terminations.
Polyvinylpyrrolidone and chitosan coating were used to immobilize Ag nanoparticles on the oxidized and hydrogenated ND surface, respectively. This technological step enhanced colloidal stability while preserving their original surface charge.
Surface chemistry, size and morphology of both NDs and ND composites, was analysed by FTIR, DLS and TEM measurements.
Before the microbiological experiments, we first established a sterilization protocol for the sterile usage of all studied materials and their post-sterilization stability was studied by FTIR and DLS measurements.
Subsequently, microbiological tests conducted in a liquid medium with a 0.1 mg/ml ND concentration revealed that positively charged H-ND-Ag composites (size 18 nm and 125 nm) exhibit the highest bacterial inhibition, especially against gram-negative strains.
The remaining nanocomposites exhibit only a mild inhibition towards both gram-positive and gram-negative bacteria. Surprisingly, H-NDs (18 nm) and O-ND-Ag (125 nm) promote the bacterial growth.
Our findings underscore the pivotal role of surface chemistry, size, and charge in dictating the antibacterial efficacy of nanocomposites. Our study provides insights into how nanomaterial properties impact bacterial responses, potentially guiding future antibacterial innovations.

Plastic waste has been becoming a growing threat to the environment and society. As most plastics are made from fossil fuel, eco-friendlier material, named bio-based plastics, made fully or partially from renewable sources, have been introduced and expected to be more biodegradable. However, their biodegradation and fate in the environment are not fully understood. Here, we studied the initial phase of plastic biodegradation, which was an attachment of freshwater microalga Raphidocelis subcapitata, on three types of starch-based bio-compostable plastic bags with the main component of polyethylene terephthalate (PET), PET-C made from corn starch, PET-CB made from cornstarch and beetroot, and PET- WPC made from wheat, potato and corn starch. Algal growth rate, biofilm formation, and changes in plastic properties were evaluated. The plastic pieces (1 x 1 cm2) were added into the algal culture and incubated at laboratory temperature and low light density. The algal growth was then monitored, the biofilm formation on the plastics was observed under an epifluorescence microscope, and the changes of plastic properties were analyzed by a scanning electron microscope (SEM) for morphology and a confocal microscope (CM) for surface roughness. After the first week, algal cells were already attached on the plastic surface forming colonies and biofilm. The highest cell density was found in samples with PET-WPC from wheat and potato starch following by PET-C and PET-CB from corn starch and corn start and beetroot.

The development of nanomaterials for various purposes has led to the diversification of their fields of application, but has also raised questions regarding the environmental safety of releasing NPs into the environment. In the biotechnology of microalgae and cyanobacteria, NPs can serve as biotechnological tools to control specific processes. In the field of biosecurity, these microorganisms can be used as study models for NP toxicity. Among the variety of metal nanoparticles, gold and silver nanoparticles stand out due to their multiple functionalities, unique properties, and wide practical applications.
The effect of 10 nm - sized Au and Ag nanoparticles stabilized in citrate has been studied on cyanobacterium A. platensis (spirulina) and microalga P. cruentum. Both cultures were grown in media with the addition of nanoparticles in different concentrations. It was found that AgNPs reduced the biomass production of A. platensis and altered its quality. In the case of P. cruentum culture, AgNPs provided a significant increase in the content of phycobiliproteins and lipids, while reducing the carbohydrate content. The effect of AuNPs resulted in increased phycobiliprotein and lipid content in A. platensis and P. cruentum biomass. In P. cruentum culture, AuNPs caused a significant reduction in protein content. In both cultures, nanoparticles induced an increase in the stress marker - malondialdehyde, and a decrease in the antioxidant activity.
Therefore, these microorganisms can be used as test objects to identify the toxic effects of NPs. At the same time, NPs can serve as tools for directing certain biotechnological processes in the cultivation technologies of spirulina and porphyridium.